Citation
Black Beans (Phaseolus Vulgaris) Response to Phosphorus and Potassium in Two Different Soils in Haiti

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Title:
Black Beans (Phaseolus Vulgaris) Response to Phosphorus and Potassium in Two Different Soils in Haiti
Creator:
Celestin, Franky
Place of Publication:
[Gainesville, Fla.]
Florida
Publisher:
University of Florida
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english
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1 online resource (70 p.)

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Soil and Water Sciences
Committee Chair:
Mylavarapu,Rao S
Committee Co-Chair:
Hochmuth II,George J
Committee Members:
Li,Yuncong
Jeune,Wesly

Subjects

Subjects / Keywords:
acidic-soil -- alkaline-soil -- black-beans -- fertilization -- haiti -- phosphorus -- potassium
Soil and Water Sciences -- Dissertations, Academic -- UF
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bibliography ( marcgt )
theses ( marcgt )
government publication (state, provincial, terriorial, dependent) ( marcgt )
born-digital ( sobekcm )
Electronic Thesis or Dissertation
Soil and Water Sciences thesis, M.S.

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Abstract:
In Haiti, black beans (Phaseolus vulgaris) are the most consumed among all kind of beans. However, Haiti experiences one of the lowest yield of black beans in the world (660 Kg ha-1). This is primarily due to poor soil and agronomic management, improper balance of nutrients in soil, and limited fertilizer application which can lead to malnutrition, ecosystem degradation, and food insecurity commonly seen in developing countries such as Haiti. However, without a calibrated soil test, farmers are not able to provide the appropriate amount of fertilizers to support plant growth. To evaluate black bean growth and yield, a pot study was conducted with two different soils (Kenscoff, acidic and Cabaret, alkaline) in Haiti using a completely randomized block design, replicated four times with four P (0, 44, 55, and 66 Kg P ha-1) and four K (0, 20, 40, and 60 Kg K ha-1) rates. Black beans in the alkaline soil achieved the highest yield of 3,011 Kg ha-1 when zero K was applied, and the acidic soil reached its optimum at 2,046 Kg ha-1 with the application of 44 Kg P ha-1. Additional amount of K, when the soil already tested high, reduced K uptake by the plants. Low levels of P recorded in soils required a high amount of P fertilizer to meet the crop needs, especially when P can be fixed on either Al and Fe (acidic soil) or Ca (alkaline soil). This research indicates that Mehlich-3 can be adopted to properly extract P and K in both acidic and alkaline soils in Haiti and can be used to conduct field calibration trials. This study will contribute to the first step in optimizing black beans production through better interpretation and nutrient recommendation of soil tests for Haitian soils. ( en )
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In the series University of Florida Digital Collections.
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Includes vita.
Bibliography:
Includes bibliographical references.
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Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (M.S.)--University of Florida, 2019.
Local:
Adviser: Mylavarapu,Rao S.
Local:
Co-adviser: Hochmuth II,George J.
Statement of Responsibility:
by Franky Celestin.

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UFRGP
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Applicable rights reserved.
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LD1780 2019 ( lcc )

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University of Florida Theses & Dissertations

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BLACK BEANS ( Phaseolus vulgaris ) RESPONSE TO PHOSPHORUS AND POTASSIUM IN TWO DIFFERENT SOILS IN HAITI By FRANKY CELESTIN A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2019

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2019 Franky Celestin

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To Mgr Guire Poulard and Mr and Mrs Joseph Celestin

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4 ACKNOWLEDGMENTS I would like to thank my ad visor, Dr. Rao Mylavarapu for his guidance and his ongoing support throughout my journey at the Soil Water Science Department University of Florida And, I would like to express my gratitude to my committee members Dr. George Hochmuth, Dr. Yuncong Li, an d Dr. Wesly Jeune for their precious contributions. I also want to thank my lab mates and everyone who, somehow, helped on this project. Thank you to the United States Agency for International Development (USAID) and its Feed the Future Haiti Appui la Re cherche et au Dveloppement Agricole (AREA) project for funding my research. Finally, all the glory to the Lord Jesus Christ.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 LIST OF ABBREVIATIONS ................................ ................................ ............................. 9 ABSTRACT ................................ ................................ ................................ ................... 10 CHAPTER 1 INT RODUCTION ................................ ................................ ................................ .... 12 2 LITERATURE REVIEW ................................ ................................ .......................... 17 Phosphorus ................................ ................................ ................................ ............. 17 Potassium ................................ ................................ ................................ ............... 18 Soil Fertility ................................ ................................ ................................ ............. 18 Mehlich 3 Extraction Method ................................ ................................ .................. 20 P and K Requirements for Bla ck Beans Production ................................ ................ 20 Black Beans Production ................................ ................................ .......................... 22 Beans Production Constraints ................................ ................................ ................ 22 3 MATERIALS AND METHODS ................................ ................................ ................ 24 Study Site ................................ ................................ ................................ ............... 24 Experimental Design and Treatments ................................ ................................ ..... 24 Data Collection, Soil and Plant Tissues Analysis ................................ .................... 25 Estimation of Nutrient Use Efficiency ................................ ................................ ...... 26 Statistical Analysi s ................................ ................................ ................................ .. 28 4 RESULTS AND DISCUSSION ................................ ................................ ............... 30 Background Analysis ................................ ................................ .............................. 30 Phosphorus ................................ ................................ ................................ ............. 31 Plant Height and Yield Parameters ................................ ................................ .. 31 Phosphorus Partitioning and Uptake ................................ ................................ 34 Phosphorus Use Efficiency ................................ ................................ ............... 36 Soil Characteristics ................................ ................................ ........................... 36 Potassium ................................ ................................ ................................ ............... 38 Plant Height and Yield Parameters ................................ ................................ .. 38 Potassium Partitioning and Uptake ................................ ................................ .. 39 Potassium Use Efficiency ................................ ................................ ................. 41

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6 Soil Characteristics ................................ ................................ ........................... 42 Optimizing Black Beans Yield in Haiti ................................ ................................ ..... 43 5 CONCLUSIONS ................................ ................................ ................................ ..... 58 APPENDIX A LAYOUT OF THE POTS ................................ ................................ ......................... 60 B PICTURES FROM THE EXPERIMENTS ................................ ............................... 61 C CORRELATION BETWE EN YIELD PARAMETERS ................................ .............. 62 Correlation Based on P Rates in Both Soils (Cabaret and Kenscoff) ...................... 62 Correlation Based on K Rates in Both Soi ls (Cabaret and Kenscoff) ...................... 62 LIST OF REFERENCES ................................ ................................ ............................... 63 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 70

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7 LIST OF TABLES Table pa ge 3 1 Different phosphorus and potassium rates applied in each experiment ............. 29 4 1 Summary of the chemical and physical pro perties of the soil profile from 0 to 30 cm, prior to the experiments. ................................ ................................ ......... 45 4 2 Effect of P rates on Leaf P concentration (%), plant height (cm), number of days to flowering (DtoF) at flowering, a nd plant height. ................................ ...... 46 4 3 Effect of K rates on Leaf K concentration (%), plant height (cm), number of days to flowering (DtoF) at flowering, and plant height. ................................ ...... 46 4 4 Effect of P rates on P concentration (%) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. ........................... 51 4 5 Effect of K rates o n K concentration (%) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. ........................... 51 4 6 Effect of P rates on P uptake (kg ha 1 ) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. ................................ ........ 52 4 7 Effect of K rates on K uptake (kg ha 1 ) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. ................................ ........ 52 4 8 Effect of P and K rates on Nutrient use efficiency. ................................ .............. 53 4 9 Soil pH, Organic Matter, and extractable P at floweri ng and harvest .................. 54 4 10 Soil pH, Organic Matter, and extractable K at flowering and harvest ................. 54 4 11 Correlation amongst black beans variables based on P rates and soil characteristics at Cabaret. ................................ ................................ .................. 55 4 12 Correlation amongst black beans variables based on P rates and soil characteristics at Kenscoff. ................................ ................................ ................. 55 4 13 Correlation amongst black beans variables based on K rates and soil characteristics at Cabaret. ................................ ................................ .................. 56 4 14 Correlation amongst black beans variables bas ed on K rates and soil characteristics at Kenscoff ................................ ................................ .................. 56 4 15 I nteraction means for yield response to P rates at a standard K level ................ 57 4 16 Interaction means for yield response to K rates at a standard P level ................ 57

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8 LIST OF FIGURES Figure page 3 1 Average rainfall for each month of the y ear at the study site adapted from accuweather.com, the rainfall for the growing season ................................ ........ 29 4 1 Effect of P rates on plant height starting 15 DAP to harverst,. ............................ 47 4 2 Effect of P rates on black beans yield in both soils ................................ ............. 48 4 3 Effect of K rates on plant hei ght starting 15 DAP to harverst .............................. 49 4 4 Effect of K rates on black beans yield in both soils ................................ ............. 50 A 1 A View of Both Experiments (Cabaret on top, Kenscoff at the bottom), 30 Days After Planting. ................................ ................................ ............................ 60 B 1 Evolution of the Experiment in the Alkaline Soil (Cabaret). ................................ 61 B 2 Evolution of the Experiment in the Acidic Soil (Kenscoff).. ................................ 61

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9 LIST OF ABBREVIATIONS CIRAD Centre de coopration internationale en recherche agronomique pour le dveloppement ( Agricultural Research Centre for International Development ) DAP Day After Planting DM Dry Matter DtoF Days to F lowering EMMA Emmergecy Market Mapping and Analysis Toolkit FAO Food and Agriculture Organization FEWSNET Famine Early Warning Systems Network GPP Grain Per Plant ICP OES Inductively Coupled Plasma Optical Emission Spectrometry K Potassium MARNDR Mi D veloppement Rural MOP Muriate of Potash N Nitrogen OM Organic Matter P Phosphorus PFP Partial Factor Productivity TSP Triple Superphosphate UF/IFAS University of Florida/Institute of Food an d Agricultures Ressources UNCCD United Nations Convention to Combat Desertification USAI USGS United States Geological Survey

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10 Abstract of Thesis Presented to the Graduate School of the University of Flo rida in Partial Fulfillment of the Requirements for the Degree of Master of Science BLACK BEANS ( Phaseolus vulgaris ) RESPONSE TO PHOSPHORUS AND POTASSIUM IN TWO DIFFERENT SOILS IN HAITI By Franky Celestin August 2019 Chair: Rao Mylavarap u Major: Soil and Water Sciences In Haiti, black beans (Phaseolus vulgaris) are the most consumed among all kind of beans. However, Haiti experiences one of the lowest yield of black beans in the world (660 Kg ha 1 ). This is primarily due to poor soil and agronomic management, improper balance of nutrients in soil, and limited fertilizer application which can lead to malnutrition, ecosystem degradation, and food insecurity commonly seen in developing countries such as Haiti. However, without a calibrated s oil test, farmers are not able to provide the appropriate amount of fertilizers to support plant growth. To evaluate black bean growth and yield, a pot study was conducted with two different soils (Kenscoff, acid ic and Cabaret, alkaline) in Haiti using a com pletely randomized block design, replicated four times with four P (0, 44, 55, and 66 Kg P ha 1 ) and four K (0, 20, 40, and 60 Kg K ha 1 ) rates. Black beans in the alkaline soil achieved the highest yield of 3,0 11 Kg ha 1 when zero K w as applied, and the acidic soil reached its optimum at 2,046 Kg ha 1 with the application of 44 Kg P ha 1 Additional amount of K, when the soil already tested high, reduced K uptake by the plants. Low levels of P recorded in soils required a high amount of P fertilizer to meet the crop needs, especially when P can be fixed on either Al and Fe (acidic soil) or Ca (alkaline soil). This research indicates that Mehlich 3

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11 can be adopted to properly extract P and K in both acidic and alkaline soils in Haiti and can be used to conduct field calibration trials. This study will contribute to the first step in optimizing black bean s production through better interpretation and nutrient recommendation of soil tests for Haitian soils

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12 CHAPTER 1 INTRODUC TION In Haiti, several kinds of beans are consumed daily as an accompaniment to other staples (rice, maize, sorghum, tubers) to make up the Haitian national dish of rice and black beans (FEWSNET, 2017). Among the different bean types, black beans ( Phaseolu s vulgaris ) are considered the most consumed and preferred because of their perceived higher iron content. As per the Emergency Market Mapping and Analysis report (EMMA, 2010), black beans in Haiti are listed as being primarily supplied from four sources: national production, imports from the Dominican Republic, imports from the United States, and food aid. Of the four sources, national production accounts for approximately 75 % of black beans consumed, imports account for approximately15%, and food aid, abo ut 10%. According to the Food and Agriculture Organization (FAO), Haiti has the lowest yield of black beans in the Caribbean and Latin America, approximately 660 Kg ha 1 in 2016, while the average yield in Cuba for the same year is almost double, 1,114 Kg ha 1 (FAO, 2016). However, agriculture is still considered the primary income generating (MARNDR, 2013). Haiti's agricultural system is based on small scale farms of about 0.54 ha per capita (MARNDR, 2012), leaving farmers without the financial capacity to invest in agricultural research to address soil fertility. Besides being one of the poorest and most food insecure nations in the world, Haiti also experiences soil erosio n and degradation. Haiti is dominated by calcareous soils (Guthrie & Shannon, 2004), where high pH leads to nutrient deficiencies, especially phosphorus (P). The problem of soil degradation and soil loss is further exacerbated by Haiti's topography, in whi ch upland

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13 areas represent 63% of the country's land surface with a slope greater than 20% (UNCCD, 2006). Unfortunately, the Department of Agriculture, known as Ministre de (MARNDR), has a l imited extension agents in the rural areas, where approximatively 93.5% of the farmers live (MARNDR, 2012; CIRAD, 2016). For black beans, production largely depends on the availability of nitrogen (N), P, potassium (K), and micronutrients such as zinc (Zn) manganese (Mn), and iron (Fe), in the soil. In a recent study on 1,047 soil samples collected from five different areas in Haiti, researchers from the University of Florida (UF) determined that approximately 74% of soils were insufficient in P based on t he Mehlich 3 (M 3) extraction method (Hylkema, 2011). Phosphorous (P) remains one of the major limitations for black bean production in both lowland and upland areas used for cultivation in Haiti. However, Haitian researchers and state agencies do not inve stigate the soil fertility issue much due to the lack of human resources and investment in this field. Rather than generating soil nutrient data to improve nutrient management of black bean s production, the government distributes fertilizer s to farmers at a highly subsidized price. Consequently, soil fertility research is still greatly lacking for most of the agricultural regions in Haiti and are at a loss for even basic information. In 2016, the majority of beans were produced in the western region of Hait i with 31% of total bean production (MARNDR, 2016). Within the western corridor, black beans are predominantly produced at Cabaret and Kenscoff locations. Located in a lowland area near the Cul de Sac plain, Cabaret soils are calcareous soils that represen t approximately 80% of Haitian agricultural soils (Woodring et al., 1924). The

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14 Cul de Sac plain was described by the USGS, as the most important agricultural area in Haiti due to its proximity and accessibility to Port Au Prince, the capital city of Haiti, which boasts a high population density (Taylor & Lemoine, 1949). However, rainfall is not evenly distributed in this area, and as a result, black beans are only grown once a year during the rainy season. Comparatively, Kenscoff soils are located in an upl and region of Haiti and represent acidic soils. In addition, black beans can be planted two to three times a year in Kenscoff depending on the variety grown and weather. The lack of knowledge on adequate agricultural practices leads Haitian farmers to make ineffective decisions regarding fertilization and soil management. In fact, s oil testing should be the first step in managing soil fertility, yet Haitian farmers seem not aware of the scientific method and process. Smallholder in Haiti are uninformed abou t proper management of fertilizers, application rates, timing, placement and sources, and therefore, soil is not replenished to fulfill the nutrient requirement of the crop, leading to low yields of 660 Kg ha 1 as reported by FAO (2016). Farmers do not per form soil tests to determine nutrient availability in the soil before planting, which would help them make better decisions regarding fertilization. There are no soil testing labs that farmers could access in the rural areas, where they are mostly located. One of the two soil testing labs, operated by state agencies, in Haiti (located in Port au Prince) is dysfunctional because there are no reagents in the Haitian market or power available for conducting analytical soil tests. Also, the technical skills are severely lacking among the few personnel that run the laboratories. The second soil testing lab (located in Croix Des Bouquets, Haiti) is not well known to the majority of farmers, due to lack of communication between extension agents and farmers.

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15 As of now, farmers rely on the color, such as the darkness of the soil, to infer whether the soil is fertile or not. Single fertilizers, other than urea, are not widely available in Haiti so Haitian farmers often use mixed fertilizers blends (N P K) to supply th e essentials nutrients. Since there are no fertilizer recommendations available, it always depends on what the farmers can afford. However, when it comes to making analytical, research based nutrient recommendations, the extraction method is crucial in thi s process. In Haiti, current lab procedures follow the Mehlich 1 extraction method for both acid and alkaline soils. However, this method is not calibrated to either type of soil, therefore potentially resulting in an improper interpretation, determination of nutrient content and subsequent improper fertilizer recommendations to farmers. In comparison, M 3, with its applicability across a wide range of soil pH levels, has the advantage of being valid in different types of soils (Mylavarapu et al., 2002). Wi th Haiti having both acid ic and alkaline soils, the M3 extraction procedure could, therefore, be more suitable. With their limited financial and human resources, smallholder s are vulnerable and facing multiple challenges, while simultaneously tackling cli matic changes (high temperature, heavy and erratic rainfall, extended periods of drought, etc.). Low availability of P and K is a major issue in Haiti, and if addressed, can provide solutions to ensure food security for Haitians. To understand the effects of P and K management and to address the soil fertility issues, a pot studies on P and K were conducted in black beans grown in two soils (Cabaret and Kenscoff) in Haiti. The specific objectives of this study were to i) evaluate the suitability of Mehlich 3 extraction method across the two major soils of Haiti, ii) evaluate the response of different P and K fertilizer rates on black

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16 bean growth and yield in two different soils in Haiti, and iii) determine P and K requirements for black bean production in Ha iti

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17 CHAPTER 2 LITERATURE REVIEW Phosphorus Phosphorus (P) is the second most important essential nutrient after N It is one of the main limit ed nutrient s for sustainable agricultural production in the world (Holford, 1997; Brady & Weil, 2008). As a macr onutrient, P plays numerous and important roles in plants. Included in nucleic acids, P plays a large role in plant reproduction, and subsequently, overall grain production. It is also decisive in transferring the biological energy that is critical for pla nt life and growth (Beegle & Durst, 2002). When soil does not have enough P available, it impacts plant growth and enhances micronutrient deficiencies, which will affect the physiological maturity (Guthrie & Shannon, 2004). In fact, researchers conclude th at P deficiency is the principal limitation to plant productivity, which is especially common in tropical and subtropical regions, such as Haiti (Raghothama, 1999; Lynch et al., 1992). Plants absorb P as orthophosphate in two forms, in acid soils as H 2 PO 4 and as HPO 4 2 in alkaline soils (Havlin et al., 2013). Phosphate is considered to be one of the least available plant nutrients in the soil (Raghothama and Karthikeyan, 2005), where approximately 80% of applied P becomes unavailable due to organic and ino rganic fixation (Holford, 1997). The availability of P primarily depends on the pH of the soil. In alkaline soil such as Cabaret, P is adsorbed onto the soil surfaces as magnesium phosphate and calcium phosphate. In acid soils like Kenscoff, P combines wit h aluminum (Al 3+ ) and iron (Fe 3+ ) to form aluminum phosphate and iron phosphates (Bolan, 1991). As of now, there is no P recommendation for black bean production in Haiti

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18 Potassium lable potassium (K) in the soil is only 1 2%. Potassium exists in the soil as exchangeable K and dissolved K + (Foth & Ellis, 1997; Meena et al., 2016). Due to its role in the synthesis and transport of photosynthesis in reproductive and storage organs, K i s vital for numerous crop growth and quality characteristics (Havlin et al., 2013) and when deficiency of K occurs, it becomes a limiting factor for crop production. Due to its role in controlling cell turgor and metabolic activity, K may mitigate water st ress (Beringer et al., 1983; Lindhauer, 1989), especially in tropical regions, where water availability is one of the limiting factors in increasing crop production (Wiersma & Christie, 1987). Besides N and P, K is the third macronutrient required by plant s (Read et al. 2006). Proper amount of K is essential for a plant to achieve its full yield potential and also for different aspects of product quality (Meena et al., 2016). The influence of K on plant growth and yield of food legumes has been demonstrated (Hanway & Johnson, 1985; Sangakkara, 1990). Supplying a sufficient amount of K will enhance the N fixation for legumes, particularly beans. Many researchers agree that K increases legume fixation to an equal or greater extent than it increases yield (Sang akkara et al., 1996; IPNI, 1998). However, a proper calibrated soil test, interpretation of crop K requirements and K recommendations are not available for black beans production on any soil type in Haiti Soil Fertility Soil infertility is a major contrib utor to chronic poverty and malnutrition in rural Haiti (Bargout & Raizada, 2013). Fertility is defined by FAO as the capacity of a soil to receive, store, and transmit energy to support plant growth. Increasing crop production

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19 relies on the ability of the and yield, though the dominant constraints reducing crop yield potential are the availability of water and nutrients (Havlin et al., 2013). Increasing and sustaining black bean yield prod uction is, therefore, not only a matter of adequate land preparation, insect disease, and weed control, but also of proper nutrient management in maintaining adequate soil fertility with complementary water management Crop yields in Haiti are among the l owest in the world and are expected to decrease further under continuous cropping without restorative inputs of nutrients (Zimmerman, 1986). One limiting factor for black bean production in developing countries has been attributed to P deficiency (Lynch, 1 995), where P availability in soil is influenced by three factors: pH, organic matter content, and right placement of P react with P to form calcium phosphate (fo rmula) which is insoluble. As a result, P availability in the soil is decreased (Havlin et al., 2013). Soils in subtropical and tropical areas are typically deficient in soil K due to fixation in different clay structures, and poor water management and re plenishments. According to CIAT (1992), about 15% of the bean s growing areas in Latin America and about 20% in Africa may be subject to K deficiency. The use of an adequate amount of K fertilizer is essential to improve beans yield (Rachael et al., 2010). The increment in yield resulting from the application of K is not due exclusively to the improved photosynthetic activity of the leaves, but also to the increase in total leaf area per plant (Alexandra, 1981; Read et al., 2006; Moore et al., 2012). In most tropical soils, K contents are low (Sangakkara et al., 1996), however, even soils that have an adequate

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20 reserve of K may not make it available fast enough to supply the amount required by the crop unless considered a slower growing crop or a low requireme nt crop in K (Kaddar et al., 1984; Brady & Weil, 2008). Mehlich 3 Extraction Method There are numerous extraction procedures to establish nutrient levels in the soil. However, the development of an extractant solution requires several years of research to calibrate it in accordance with a specific soil and to determine its suitability (Hochmuth et al., 2014 a ). In the absence of a standard soil test extractant calibrated for Haitian soils, Mehlich 3 (M3) extractant, which is used in a wide range of soil arou nd the world, was chosen for this study. It is known for being able to extract not only P in different types of soil, but also other macro and micronutrients (Mehlich, 1984). Crop nutrient recommendations from the University of Florida/Institute of Food and Agriculture Sciences Analytical Services Laboratories (UF/IFAS ANSERV Labs) reflect through field calibration studies the properties of Florida sandy soils such as low CEC, low pH, sandy texture, and low water holding capacity, although not directly fa ctored. Since soil testing is specific to the inherent characteristics (chemical and physical) and location of the soils on the landscape (Mylavarapu et al., 201 7b ), suitability of M3 for Haitian soils needs to be evaluated P and K Requirements for Black Bean s Production Essential nutrients must be provided to the plants in sufficient amounts for optimum growth and yield (Havlin et al., 2013). Plants absorb approximately equal amounts of N and K and are about twice as much as the absorbed P. This gives a N :P:K nutrient ratio of about 2:1:2 (Kaddar et al., 1984). However, soil nutrient management in soils using nutrient ratios is not practical. Soil fertility is a real issue in

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21 Haiti (Zimmerman,1986; McClintock, 2004; Bargout & Raizada, 2013). Hence, providi ng proper fertilizers to soils in order to meet the plant requirements is critical to improving soil fertility and, consequently, crop production. Phosphorus fertilizers have been used as a key element in increasing crop production in order to meet the fo od demand globally. In the last 150 years, researchers demonstrated the importance of P in producing yield, and why it is crucial to increase the plant available P in soils (Syers et al., 2008). Approximately 75% of total plant P requirement is utilized in early maturity stages of plants, signifying the importance of P in early plant development and growth (McKenzie & Middleton, 2013 ). Due to the high amount of P required by legumes such as black beans, P becomes the main constraint for these plants in perf orming N fixation, particularly in the tropics (Suleiman & Tran, 2015). Researchers proved that nodulated legumes need more P than non symbiotic plants that grow on mineral N source. The direct relationship between N fixation and P content in nodules docum ents the critical importance of P to legumes (Hussain, 2013). Adequate leaf P concentration of field grown crops range from 0.2 to 0.5% (Sanchez, 2007) However, it is considered to be excessive when the leaf tissue concentrations get higher than 1.00%. In tropical regions, P deficiency is most commonly found in Latin America (>50%) and Africa (35 50%) (CIAT, 1992; Thung,1990) Total crop K requirement is defined as the amount of K needed for a crop to produce the highest economic yield under a given set of growth conditions (Mengel, 1979). Sufficient K concentration in most plant species is relatively high, in the range of 1.0 to 4 .0% (Brady & Weil, 2008) The critical deficiency concentration of K in vegetative

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22 plant parts is normally less than 1.50% in ma ture leaf tissue. However, it is considered in excess when K critical values are greater than 5.00% (Jones, 2012). Symptoms of K deficiency in plants include yellowing of leaf edges, giving them a burnt appearance, reduced growth and incomplete development of roots (Das & Pradhan, 2016). Black Bean s Production Black beans are produced around the world and are grown in a broad range of environments and cropping systems (Gepts & Debouck, 1991). Black beans sold as dry beans are used solely for human consumpti on in Latin America and Central Caribbean (Schoonhoven & Voysest, 1981). Approximately 12 million metric tonnes of common beans are produced every year. Latin America is the largest producer, with about 5.5 million metric tonnes, with Brazil and Mexico bei ng the major producers. Africa is the second most important region, producing about 2.5 million metric tonnes The Caribbean region produced 279,753 ton ne s of dry beans in 2016 alone, leading by Cuba with 136,570 tons (FAO, 2016). Beans Production Constrai nts Black bean s production varies depending on the region (e.g., tropical or subtropical) and the influence of different factors such as water availability, fertilizers, appropriate technologies, and qualified human resources (Graham & Ranalli, 1997). In H aiti, black beans are grown in various regions that include lowland and upland areas. Irrigation systems are not prevalent where beans are cultivated and farmers, therefore, rely on the erratic rainfall to irrigate their crops. Many factors such as weeds, drought, heat stress, insects, diseases, and poor soil fertility affect black bean yields all over the world. Black beans are highly susceptible to diseases and insect attacks (CIAT, 1981). Agricultural practices such as weed suppression, tillage, sowing, irrigation, and

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23 harvesting are done manually by the farmers in many places in Haiti. Soil fertilization remains the primary constraint in increasing beans production in Haiti. Synthetic fertilizers are not affordable for many farmers or are not available i n the markets, making the use of chemical fertilizers very limited in Haiti (Stewart, 2011; Molnar et al ., 2015). Extension services and agents are severely limited in supporting farmers, negatively impacting agricultural production chains (Smucker et al. 2005; Sperling 2010; Smucker 2010). Based on the literature review, there is a critical need to explore soil physical and chemical properties in Haiti, which is primarily an agricultural country. Research on nutrient management practices needs to be initia ted to ensure stable yields to supply the domestic market first. Research need to be focused on the calibration of a soil testing method to provide nutrient recommendations. Extension agents will, then, be trained to properly interpret data to assure that farmers are following the recommendations. Understanding soil testing will help farmers in adopting the appropriate nutrient management practices depending on the pH of soil, or the irrigation management to avoid nutrients losses

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24 CHAPTER 3 MATERIALS AND METHODS Study Site The experiments were carried from August to December 2018 in Kenscoff, Haiti (Latitude 1826'44.4"N and Longitude 7217'39.2"W). Kenscoff is part of the morphological unit of the Massif de la Selle which culminates at Pic la Selle at 2 ,680 m (8,792 ft) altitude (Wynne Farm). The study area has an average annual rainfall of 1,638 mm. Temperature ranges between 13 and 33 degrees Celsius (USAI, MARNDR). Two Haitian soils, Cabaret (alkaline) and Kenscoff (acidic), were used in pots to condu ct this study. The soils used in this study were collected at 20 cm depth from the soil surface and brought to the site of the experiment Experimental Design and Treatments Two experiments one for each soil, were laid out in a completely randomized block design with four replications. Prior to potting, soil samples were collected to assess the nutrients (P and K) status of the soil. Using M 3 extraction solution, soil from Cabaret was determined to be low in P (1.34 mg kg 1 ) and very high in K (247 mg Kg 1 ), and soil from Kenscoff was low in P (22.98 mg Kg 1 ) and high in K (65.41 mg Kg 1 ). Since there are no fertilizer recommendations for black beans in Haiti, due to the absence of a calibrated soil test, IFAS recommendations for P and K rates for lima bea ns ( Phaseolus vulgaris ) 50 Kg P ha 1 and 0 Kg K ha 1 respectively (Mylavarapu et al., 201 4 ) were used as a guidance. Therefore, a range of rates was used for P and K treatments. In both soils, four rates of P were used as follows: 0, 44 Kg P ha 1 (0, 100 kg of P 2 O 5 ha 1 ), 55 and 66 Kg P ha 1 (125 and 150 Kg of P 2 O 5 ha 1 ), and K was applied as a constant rate of 20 Kg ha 1 (25 Kg ha 1 of K 2 O) in each treatment as a precautionary

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25 application. For the K experiments, four rates of K were also selected 0, 20 K g K ha 1 (25 K 2 O ha 1 ), 40 and 60 Kg K ha 1 (50 and 75 K 2 O ha 1 ), and 55 Kg P ha 1 (125 Kg of P 2 O 5 ha 1 ) was applied in each treatment at a constant rate. All experiments received 125 Kg N ha 1 Sources of fertilizers were triple superphosphate (TSP) [Ca(H 2 PO 4 ) 2 ] (0 46 0) for P, muriate of potash (MOP) [KCl] (0 0 60) for K, and urea [(NH 2 ) 2 CO] (46 0 0) for N. Before planting, TSP was incorporated 10 cm deep in the pots (Helm et al., 1990; Westermann, 2000), and MOP and Urea were used as side dressing. At em ergence, 30% of K and N were applied and the remaining ( 40 and 30% ) was applied 30 60 days after planting (DAP), respectively. Black bean ( var. zenith ) was used in this study and is adapted to grow in both lowland and upland regions in Haiti. One seed per pot (30 cm in diameter with a height 27 cm) was sown 5 cm deep Data Collection, Soil and Plant Tissues Analysis Soil samples were collected in both soils prior to the experiment at a depth of 30 cm using a standard hand auger. The samples were shipped to the UF/IFAS ANSERV Laboratories and subsequently analyzed to determine the nutrients (extractable P and K), soil pH levels, and organic matter (OM) content of the soils. Soil samples were collected from each treatment at 0 to 15 cm depth 30 DAP, 60 DAP, an d at harvest to measure pH, P, K, and OM content. Soil samples (before and during the experiment) were air dried by spreading the samples on a newspaper in a dry shaded area (Mylavarapu et al., 201 4 ) during a week at 32 C on average. Soil from Cabaret was pulverized to break up the clods; and both soils were sieved through a 2 mm sieve. Mehlich 3 extractant method was used for P and K in both soils and the inductively coupled plasma optical emission spectrometry machine (ICP OES Spectro CIROS, NJ) determin ed the concentration of P and K available in the soils. The texture and OM

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26 content of the soils was determined by hydrometer method and Walkley Black (WB), respectively. All soil analyses were conducted at the UF/IFAS ANSERV in Gainesville as per the stand ard procedures (Mylavarapu et al., 201 4 ). Plant height was measured every two weeks during the crop growth period starting from two weeks after planting to harvest. At flowering, fully developed leaves from the top were collected, which included the compou nd leaf (3 leaves) from each replication. At physiological maturity, number of grains per plant were collected and counted, and plant dry matter was separated into leaf blades, petioles, roots, and stems. Plant tissues, except grain yield, were dried in th e oven at 65C for 24 hours and finely ground using a 2 mm sieve (Laboratory Model 3 Mill, Thomas Wiley, Swedesboro, NJ). Black bean components (leaf blades, petioles, roots, stems and grain yield) were analyzed to determine P and K concentration. At 550C 0.20 mg of each tissue component was placed in a muffle furnace for 4 hours. The resulted ashes were mixed with 25 ml 0.5M hydrochloric acid (HCl). After settling for 30 minutes, each solution was poured into 25 ml vials and the nutrients (P and K) conce ntration were obtained using ICP OES. All tissue analyses were conducted at the UF/IFAS Analytical Services Laboratories in Gainesville as per the standard procedures (Mylavarapu et al., 201 4 ). Estimation of Nutrient Use Efficiency There are three methods (direct, difference, and balance) of estimating the efficiency of nutrients (Syers et al., 2008). Nutrient use efficiency is set to determine how well plants respond to a specific fertilizer rate, given the fact that nutrients are subject to loss such as l eaching, immobilization, and so on. The return from investment in inputs (fertilizers, labors) are the main concern of farmers when it comes to crop production (Cassman et al., 1998). A useful measure of this is termed as the partial

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27 factor productivity an d it is the ratio of grain yield to the amount of nutrient applied (Cassman et al. 1998; Snyder, 2007). The equation is set as follows: ( 3 1 ) w here PFP represents the Partial Factor Productivity, Yf is the fertilized grain yield, and Fa is the fertilizer applied. To evaluate the amount nutrient taken up by the plants, the concentration of the nutrient in the plant (not including the grain) and the dry matter were used. To calculate the nutrient (P or K) uptake, the following equation was used: ( 3 2 ) U n is the nutrient uptake (Kg ha 1 ), N is the concentration of the applied nutrient in the total dry matter, and DM is the dry matter. To express nutrient use efficiency, Syers et al. (2008) suggested the balance method to estimate the amount of nutrient taken up per unit of nutrient applied at physiological maturity. Known as percent nutrient recovery or partial nutrient balance, it is calculated as follows: ( 3 3 ) where is the percent recov ery, Un is the nutrient uptake, and Fa represents the surplus of the nutrient in the soil, and P recovery less than 100% reveals the deficiency of the nutrient and the nee ds for a better soil fertility management (Snyder & Bruulsema, 2007)

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28 Statistical Analysis Data were analyzed for each of the soils and for each of the nutrients (P and K) separately. All data were analyzed using statistical analysis software R 3.5.2 versi on (The R Foundation for Statistical Computing, Vienna, Austria, 2018). Shapiro Wilk test was used to state the normality of the data. Analysis of variance (ANOVA) was conducted on the data collected throughout the experiments, whe n significance difference s were observed Tukey Honest Significant Difference was used to identify moment correlation was used to find if there were any significant relationships between the quantitative vari ables.

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29 Table 3 1. Different phosphorus and potassium rates applied in each experiment Treatment P (Kg ha 1 ) Treatment K20 (Kg ha 1 ) P0 0 K0 0 P1 44 K1 20 P2 55 K2 40 P3 66 K3 60 Figure 3 1. Average rainfall for each month of the year at th e study site adapted from accuweather.com, the rainfall for the growing season (August to November 2018, the experiment was not affected by the rainfall in December) is in green

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30 CHAPTER 4 RESULTS AND DISCUSSION Background Analysis Important soil charact eristics used in evaluating an agricultural soil include texture, pH, OM content, and extractable nutrients. Cabaret soil was determined to be a clay loam soil with 43% sand, 28% silt, and 29% clay with a soil pH of 8.2 and OM of 1.3%. The M 3 extractable P was 1.34 mg Kg 1 and K was 247 mg Kg 1 Kenscoff soil was determined to be a sandy clay loam soil with 46% sand, 24% silt, and 30% clay with a soil pH of 6.02 and OM of 5.40%. The extractable P was 22.98 mg Kg 1 and K was 65.41 mg Kg 1 (Table 4 1 ). Mehli ch 3 soil test interpretations for P used for 1 ), Medium (26 45 mg Kg 1 ), and High (>46 mg Kg 1 ) and for K 3 5 mg Kg 1 ), Medium ( 3 6 60 mg Kg 1 ), and High (>6 0 mg Kg 1 ). In both soil s, clay proportion was high but the soil from Kenscoff has a higher percentage of sand, resulting in relatively higher water conductivity and drainage compared to Cabaret soil. Soil pH determines nutrient solubility and therefore plant availability. Both, low and high pH can potentially lead to nutrient deficiencies. Low extractable P in Kenscoff may be due to acidic pH of the soil, which favors the formation of insoluble complexes between P and aluminum (Al) and iron (Fe) (Sanchez & Uehara, 1980; Vance et al., 2003). Organic matter content is important in soil because it can contribute to enhanced soil aggregation, thus improving water infiltration, water holding capacity, drainage and microbial activity.

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31 Phosphorus Plant Height and Yield Parameters Cabar et s oil To better understand the role of P in influencing plant parameters, measurements of leaf P concentrations, plant height, and number of days to flowering (DtoF) were analyzed. At flowering, leaf P concentration and plant height were not impacted by P rates (0, 44, 55, and 66 kg ha 1). However, at harvest, plant height was significantly lowest at 32.4 and 39.0 cm (in the control and at 66 Kg ha 1) compared to 43.8 and 46.1 cm with 44, and 55 kg P ha 1 respectively (Table 4 2) Turuko and Mohammed (20 14) observed that higher P rates had no effect on common bean height grown in a clay loam soil. Rates that are too high will suppress the growth similar to when no P is applied in these inherently low P soils. It is possible that the highest amount of P ap plied was excessive and negatively affected plant growth Application of P did affect DtoF (Table 4 2 ), the lowest DtoF was 59 days (at 44 and 55 kg ha 1 ) and highest was 62 days (at 66 kg ha 1 ) and 64 days (in control). This shows that both zero P and hig hest P application can result in delayed DtoF. Consequently, a negative correlation was found between DtoF and black bean yield, where black bean yield decreased with increasing number of days to (or delayed) flowering (Table 4 1 1 ). In a study by Donald an d Hamblin (1976) on the principal characteristics of the ideotype seed crop, it was found that early flowering resulted in an increase in the time available for filling the grains, resulting in increased yield. Similarly, Pilbeam (2015) also stated that ea rly flowering might result in a higher yield compared to late flowering. Hence, by applying a minimum of 44 kg P ha 1 may be adequate in achieving early flowering in black beans, and therefore, higher yields.

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32 For total dry matter, no effect between P appl ication rates was observed (Table 4 2) The black bean yield of 2,553 kg ha 1 (55 Kg P ha 1 ) was recorded as the highest, when compared to the lowest yield of 1,224 Kg ha 1 observed in the control. The addition of P at > 55 kg ha 1 did not result in a sign ificant yield increase (Figure 4 2 ) Similarly, Bortolozo and Mylavarapu (2019) studying bush beans nutrition found that high P rates such as 66 Kg P ha 1 did not show any yield response. A significant correlation was found between black bean s yield and P uptake, indicating a rise in yield as P uptake increased (Table 4 11) This relationship was also observed by Manske et al., (2001) when studying the importance of P uptake efficiency versus P utilization for wheat yield in calcareous soils in Mexico who f ound that the majority of P taken up by the plants (which was comprised between 56 and 80% of the total uptake) was translocated into the grain where P uptake was recorded. The highest number of grains per plant (GPP) was 49 (55 Kg P ha 1 ), where the contr ol, 44 and 66 Kg P ha 1 yielded the same (27, 35, 27 GPP) (Table 4 2 ). This result indicates that applying 55 Kg P ha 1 was sufficient enough to meet the crop P requirement for producing high numbers of GPP and when it is below and above this rate, number of grain is negatively impacted. These results are in agreement with Gidago et al., (2011) who reported that higher yield was obtained by increasing P rates, and significant differences were also obtained in the number of grains per plants. Statistically higher GPP compared to control is potentially due to the translocation of P concentrations to the grain from the other plant components (leaf, petiole, stem, and roots).

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33 Kenscoff soil At flowering, leaf P concentration and DtoF were not affected by P ra tes (0, 44, 55, and 66 kg ha 1 ), however, it was found that plant height was influenced positively (Table 4 2 ). Corresponding to increasing P rates, there was an increasing trend in plant height, where the lowest plant height was measured at 11 cm (control ) and highest plant height was 63 cm (66 Kg P ha 1 ). At harvest, plant height was significantly higher with 78 cm in the treatment that received 66 Kg P ha 1 compared to the control, the application of 44 Kg P ha 1 and 55 Kg P ha 1 which measured 8.0, 51. 5, and 54.4 cm respectively. However, applications of 55 and 66 Kg P ha 1 recorded statistically similar plant heights (Table 4 2 ). Total dry matter was highest 2,082 Kg ha 1 with the application of 66 Kg P ha 1 compared to the control and the application of 55 Kg P ha 1 which recorded 13.4 and 1,358.7 Kg ha 1 respectively. Statistically similar dry matter was recorded with the application of 44 and 66 Kg P ha 1 which were 1,552 and 2,082 Kg ha 1 respectively (Table 4 2 ) There was a positive correlation between plant height and total dry matter (r = 0.70, p = 0.01), showing an increase in plant height resulted in an increase of dry matter (Table 4 1 2 ). In low testing soils, increasing phosphorus fertilization resulted in a significant increase in soybean yield as reported by Borges and Mallarino, 2000. The lowest black bean yield was measured 1,866 Kg ha 1 when 55 Kg P ha 1 was applied, compared to the highest yield of 3,377 Kg ha 1 at P rate of 66 Kg P ha 1 (Figure 4 2 ). However, statistically similar yield of 2,406 and 3,377 Kg ha 1 was recorded with the application of 44 and 66 Kg P ha 1 respectively. Yield s in the control were not recorded due to plant mortality that likely resulted from plants growing in low pH soil. Soil pH was measured at the flo wering and harvest stages of maturity and were 4.89

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34 and 4.51, where optimum pH for plant growth is typically around 6.5. Fageria and Santos (1998) found that 66 Kg P ha 1 was the appropriate amount of P needed to achieve the highest black bean yield in an acidic soil in Brazil with low P availability. However, in this experiment we found that 44 Kg ha 1 was enough to provide the highest yield, statistically. In the case of Haiti, more studies are needed to confirm which P rates (between 44 and 66 Kg ha 1 ) w ill be necessary to optimize yields of black beans in different soils. Black beans yields were strongly correlated with P uptake and the total dry matter therefore an increase in total dry matter and P uptake is crucial for achieving higher yield (Table 4 1 2 ) Phosphorus Partitioning and Uptake Cabaret s oil Phosphorus concentrations (%) in each of the plant components (leaf, petiole, stem, root, and grain) were not affected by P rates (Table 4 4 ). Nutrients, such as P, need to be within the sufficient ran ge (0.20 0.50%) in plant tissue to ensure optimum growth during the vegetative stage of the plants (Marschner et., 1995; Hochmuth et al., 2004 ). In each treatment, P was found within the sufficiency range in the plant tissue. This is probably due to the availability of P in the soil with the increasing rates of P fertilizers, where the plants may potentially absorb more than what they need resulting in a luxury consumption. Concentration of P in the leaf blades at harvest was 0.50%. In this experiment, P concentration in the plant was negatively correlated with plant height, showing the negative impact of excess P on plant height. Similar P uptake (kg ha 1 ) levels were observed among all four P rates in the various plant components ( petiole, leaf blade, stem, root) and in the whole plant, with the exception of the grain component ( Table 4 4 ) The application of 55 Kg P ha 1

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35 resulted in the highest P uptake of 12.33 kg ha 1 in the grain when compared to the P uptake of 5.50 kg ha 1 produced in control. Pla nt P uptake was significantly correlated with certain variables either positively ( dry matter and yield) or negatively (number of days to flowering). Organic matter, pH, plant P, and plant height showed no significant correlations with plant P uptake (Tab le 4 1 1 ). Kenscoff s oil Phosphorus concentration in the leaf blades, stem, root, and grain were similar among P rates (0, 44, 55, and 66 kg ha 1 ), with the exception of the petioles. The concentration of P in the petiole was lowest at 0.19%, when 44 kg ha 1 of P was applied. S imilar P concentrations of 0.21% and 0.22% were found between the 55 kg ha 1 and 66 kg ha 1 P rates. Petiole concentrations increased when P fertilizer application occurred, signifying that applying P will result in significant increa ses to P concentration (Table 4 4 ). Because P concentrations are within the sufficiency levels, applying at minimum 44 kg P ha 1 should be sufficient to maintain optimum levels of P concentration in the plant. Phosphorus uptake in leaf blades, petiole, and roots were not affected by P rates Application of P rates did have an effect on P uptake in the stem, but no significant differences were observed among the treatments. Phosphorus concentrations in the grain was higher, 16.78 Kg P ha 1 with the applicati on of 66 Kg P ha 1 compared to11.40 and 8.34 Kg P ha 1 where 44 and 55 Kg P ha 1 were applied respectively. Phosphorus taken up by the whole plant (leaf blades, petiole, stem, roots ,and grain combined) was statistically higher with 21.43 Kg ha 1 at 66 Kg P ha 1 compared 11.69 and 11.39 Kg ha 1 when 44 and 55 Kg P ha 1 were applied respectively (Table 4 6 ) Similar to observations in this experiment, Fageria and Baligar (2016)

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36 reported that to achieve the highest possible yield, increasing P concentration a nd uptake are among the most important mechanisms. As stated by Xie et al., (2016), P fertilization does not only affect plant growth and development, but also P uptake by translocating the P concentration of the dry matter (especially the leaf) to the gra in during the grain filling period. Application of an appropriate amount of P fertilizers is important to maximize the translocation, which will increase the yield (Xie et al., 2014). Phosphorus Use Efficiency Cabaret s oil The highest recovery of P was 12 .20% (55 kg P ha 1 ). When compared to the recovery of 6.50% at66 kg P ha 1 this indicates that applying >55 kg ha 1 of P fertilizer is excessive and will not lead to a higher recovery of P (Table 4 13). Similar trend was observed, where partial factor pro ductivity (PFP) was highest at 20.43 kg kg 1 (55 kg P ha 1 ), when compared to the 8.25 kg kg 1 found in the highest P rate (66 kg kg 1 ) (Table 4 8 ). In this study, P efficiencies decreased with the increasing rate of P which is similar to Fageria and Bali gar (2016) findings, inferring that P recovery was used more efficiently at lower rates. Kenscoff s oil The recovery of P was not impacted by the application of P fertilizer. The partial factor productivity was higher, but similar between 24.07 kg kg 1 (44 kg ha 1 ) and 22.52 kg kg 1 (66 kg ha 1 ) (Table 4 8 ). Soil Characteristics Cabaret soil At flowering soil pH, OM, and soil P concentrations ranged from 8.35 8.54, 2.16% 2.23%, and 8.14 18.87 mg kg 1 respectively (Table 4 9 ). The low concentration of ext ractable soil P could be attributed to the high soil pH (>8.00) and clay loam texture of the Cabaret soil (Sanchez, 2007). Clay loams have a high CEC (15 30 meq 100g 1 ) and when combined with high soil pH can result in precipitation of P as

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37 Ca P (Havlin et al., 2013; Leytem and Mikkelsen, 2005). Approximately 80% of applied P becomes unavailable due to organic and inorganic fixation (Holford, 1997). At harvest, a nalysis revealed a significant positive relationship between extractable P and P rates. The con trol (zero P application) recorded significantly lower P availability, 7.65 mg kg 1 compared to 44 and 66 Kg P ha 1 rates (43.67 and 55.30 mg kg 1 ), respectively. However, 44 and 66 Kg P ha 1 rates were statistically similar (Table 4 9 ) Application of P rates significantly enhanced P availability in soil but applying a P rate above 44 Kg P ha 1 did not result in increased P availability. Mehlich 3 extraction method indicated a n adequate P concentration in the soil at 41 mg Kg 1 and the application of 44 K g ha 1 of P was enough to maintain a high P availability in the soil at the end of the experiment. Kenscoff soil At flowering, extractable P and OM were statistically similar among all P rates. Soil pH was significantly lower in the control at 4.88 compar ed to 5.60, 6.95, and 6.51 where 44, 55, and 66 kg P ha 1 were applied respectively The lowest and second lowest pH was recorded as 4.88 and 5.60 in the control and 44 kg ha 1 respectively. At harvest, e xtractable P in the soil increased with the increa sing rates of P, where control, which had 4.6 mg Kg 1 was significantly lower compared to 44, 55, and the highest P rate 66 Kg P ha 1 with 43.1, 58, and 83.9 mg P Kg 1 respectively (Table 4 9 ). This indicates that silt and clay contents of the soils incre ase nutrient retention in general and particularly P, and therefore it is the management of P applications that optimizes plant production and yield levels

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38 Potassium Plant Height and Yield Parameters Cabaret s oil At flowering, leaf K concentration, pla nt height, and DtoF were not affected by the K rates (0, 20, 40, and 60 kg ha 1 ). The mean leaf K concentration, plant height, and DtoF ranged between 2.08% 2.49%, 31cm 37 cm, and 59 64 days, respectively (Table 4 3 ) These results suggest that K fertilize r applications do not affect leaf P accumulation, plant height or number of day to flowering of black beans, particularly when the extractable K in soils is High. As determined by the M 3 extraction method, soil K concentration measured at preplant was 247 mg kg 1 which is categorized as being High in the soil. Therefore, plant parameters were not expected to show improvement at any rate of K application (Viro, 1974). P lant height at harvest and dry matter were similar among all K rates. Number GPP was s ignificantly higher at 58 in the control, when compared to the lowest number of 26 GPP observed at the highest K rate (60 kg K ha 1 ) (Table 4 3 ). These results show that K fertilization was not needed to improve plant height, dry matter and number of GPP in Cabaret soil. Again, this is due to the high K concentration of 247 mg kg 1 determined at preplant by the M 3 extraction method. When K is an excess in the soil, it may depress plant growth and has a negative impact on crop yield (Viro, 1974). Black bea n yield was significantly higher at 3,0 11 Kg ha 1 in the control compared to 1,9 19 and 1,099 Kg ha 1 with the application of 40 and 60 Kg K ha 1 respectively (Figure 4 4 ). Extractable K was excessive in the soil prior to this experiment, the results showe d that adding K fertilizers will negatively impact the yield. Lucas (1968) stated that yield losses in vegetables can be a factor of excess in potassium, which usually bring too much salt in the soil. Black bean yield was negatively, significantly correlat ed with K

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39 concentration in the plant and number of days to flowering, and positively with K uptake and total dry matter Kenscoff s oil Number of days to flowering were not affected by the application of K fertilizer at any rate. Leaf K concentration was l owest at 0.72% in the control. However, similar leaf concentrations were observed 1.60%, 1.73, and 2.06% among the three K rates (20, 40, and 60 kg K ha 1 ), respectively. The lowest plant height was recorded at 20 cm in the control Similar plant heights at 39, 45, and 40 cm were observed among the three K rates (20, 40, 60 kg K ha 1 ), respectively (Table 4 3 ) At harvest, the lowest plant height, total dry matter and number of GPP were recorded as 26.8 cm, 232 kg ha 1 and 6 in the control, respectively compared to the three K rates (Table 4 3 ) Plant height at harvest was significantly correlated with the concentration of K in the plant and it recorded its highest correlation with the total dry matter (r = 0.94, p < 0.001), which clearly stated that the total dry matter was positively influenced by black beans growth (Table 4 14 ) Black bean yield was statistically lower at 2 27 Kg ha 1 in the control compared to 1,866, 2,613, and 1,9 0 9 Kg ha 1 (at 20, 40, and 60 Kg K ha 1 ), respectively (Figure 4 4 ). As s tated previously, the increased in the dry matter is strongly correlated with black beans yield, however, a negative relationship was found between black beans yield and the number of days the plants took to initiate the flowering stage Potassium Partitio ning and Uptake Cabaret s oil Comparing K rates, there were no statistical differences shown between K concentration in the leaf blades, petiole, roots, and grain yield. However, K concentration in the stem was significantly affected by K rates at 95% conf idence level, but no statistical differences were observed between the means (Table 4 5 ).

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40 Potassium uptake (kg ha 1 ) by leaf blades, petiole, stem, and roots were not different among the four K rates (0, 20, 40, and 60 Kg K ha 1 ), with the exception of th e grain. Lowest grain K uptake was observed with 17.80 Kg K ha 1 (60 Kg K ha 1 ) and 31.67 kg K ha 1 (40 kg K ha 1 ). On the other hand, higher uptake in the grain was recorded with 50.04 and 39.53 kg K ha 1 when the lowe st K rates of 0 kg K ha 1 and 20 kg K ha 1 were applied, respectively. Total uptakes in the plant were similar with 81.71, 68.71, and 56.38 kg K ha 1 and among the control, 20, and 40 kg K ha 1 (Table 4 7 ) These results show that K fertilizer applications above 0 and 20 kg K ha 1 negatively impacted K uptake, further emphasizing that K was in excess in the soil and no K fertilization was needed. Kenscoff s oil Potassium concentration in leaf blades and grain were not significantly affected by K rates. However, K concentration in the petiole was statistically higher at 3.45% with the application of 60 kg K ha 1 when compared to 0.50 and 2.19% K (0 and 40 Kg K ha 1 ) respectively. However, statistically similar results were found at 2.48 and 3.45% K with the application of 20 and 60 Kg K ha 1 C oncentration of K in the stem was significantly higher with 1.92% K at the highest K rates (60 Kg K ha 1 ) compared to 0.94 and 1.08% K recorded with the application of 0 and 40 Kg K ha 1 respectively. Statistically similar K concentration of 1.33 and 1.92% K was recorded between the 20 and 60 Kg ha 1 K rates. The roots recorded the lowest K concentration compared to other plant components, however, the highest K concentration in the roots at 0.48% K (60 Kg K ha 1 ) was statistically higher compared to 0.14% recorded in the control (Table 4 5) Overall, even with the high extractable K recorded in the soil prior to the experiment, plant component such as petiole, stem, and roots responded positively

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41 to the increase in K fertilization, where statistically highe r concentrations were observed with the application of the highest K rate (60 Kg K ha 1 ) compared to the control. Potassium uptake in leaf blade was not significantly affected by the K rates. Among the remaining plant components, the control treatment resu lted in the significantly lowest K uptake compared to all the K applied (20, 40, and 60 Kg K ha 1 ) (Table 4 7 ) Potassium uptake by the whole plant had a significant and negative correlation with the DtoF where the late flowering led to a decrease in plant uptake. Plant K uptake was also positively correlated to plant height at harvest and yield, which implies that the increase in K uptake led to an increase in yield. The greatest correlation was found between K uptake by the whole plant and dry matter (r = 0.97, p < 0.001) (Table 4 14 ) Niu et al., (2001), found that addition of K fertilizers increased maize grain yield in soil previously high in K, which is in accordance with the results from this experiment where extractable K where categorized as high (> 60 mg Kg 1 ). Mallarino et al., (1999) found that even in soil tested High in K before planting, the highest K rates applied increased K uptake more than the lowest rates which is in accordance with this experiment conducted with the soil from Kenscoff. Pot assium Use Efficiency Cabaret s oil The r esults indicate that K recovery decreased with the increasing rates of application. The highest K recovery was 275%, with the application 20 kg K ha 1 compared to 119 and 61% (40 and 60 kg K ha 1 ), respectively Su ch a trend was also observed, where PFP was highest at 102.14 Kg Kg 1 when compared to the 39.01 and 14.66 Kg Kg 1 found in the highest rates (40 and 60 kg K ha 1 ). Therefore, in both cases, the lowest K rate was more than adequate in supplying K to the p lants and applying even a K rate of 20 kg K ha 1 was inefficient (Table 4 8 ) This shows that the high K

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42 concentration recorded at preplant was probably enough for black bean production. However, further research is needed to test lower K rates and evaluat e P requirement for black beans grown in Haitian soils. Kenscoff s oil In this experiment, where the soil is already high in K, a pplication of 20 kg K ha 1 achieved the highest K recovery of 164% compared to 66% recorded with the highest K rate of 60 Kg K ha 1 The highest PFP was recorded at 69.92 kg yield kg 1 (20 kg K ha 1 ), when compared to the lowest 25.63 Kg yield Kg 1 PFP obtained when applying the highest K rate of 60 Kg K ha 1 (Table 4 8 ). These results are probably due to the high K concentration recorded at preplant (247 mg K Kg 1 ). For maize grown in acid soil, K recovery and PFP can be decreased by 50% as reported by Qiu et al., (2014), which is in agreement with our findings. Future research needs to look at measuring K use efficiency at lower rates in both soils to determine when low rates of K start to become limiting to black bean production. Soil Characteristics Caba ret s oil At flowering whe re only 30% of K rates was applied the lowest soil K concentration of 260.8 mg kg 1 was recorded in the control, with the highest K concentration of 311.8 mg kg 1 recorded at the rate of 60 kg K ha 1 However, there were no significant differences in extractable soil K at any rate of K application. At harvest, e xtractable K was statistically higher with 278 mg K Kg 1 where 60 Kg K ha 1 was applied compared to 235 mg K Kg 1 extracted in the control. Soil pH and organic matter were statistically the same at harvest (Table 4 1 0 ). These results indicate that even the 20 kg K ha 1 is not necessary in these so ils, when the M 3 extractable K levels are High.

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43 Kenscoff s oil At flowering, s oil extractable K was statistically lowest at 41.21 mg kg 1 (in the control) and 85.13 mg kg 1 (40 kg K ha 1 ) compared to 105.83 mg kg 1 and 151.70 mg kg 1 (at 20 and 60 kg K ha 1 ) respectively. At harvest, e xtractable K was statistically lower with 44.8 and 78.2 mg K Kg 1 in the control and where 40 Kg K ha 1 was applied compared to 116.6 and 138.4 mg K Kg 1 with the application of 20 and 60 Kg K ha 1 respectively. Soil pH was statistically lower with 4.78 and 5.60 in the control and at 40 Kg K ha 1 respectively compared to 6.68 and 6.86 with the application of 20 and 60 Kg K ha 1 (Table 4 1 0 ) A significant correlation was found between s oil pH and the concentration of K in pl ants. Consistent with soil samples collected before the experiment, extractable K remained high in both soils the amount of K supplied was able to fulfill black beans needs and remained highly available in Cabaret soil. However, Kenscoff soil showed posit ive response to the increase of K rates Optimizing Black Beans Yield in Haiti The average b lack beans yield in Haiti is 660 Kg ha 1 (FAO, 2016), which is the lowest among the Caribbean nations. Research on soil fertility stated that black beans yield can be limited by nutrients availability in the soil such P, and K. Soil testing is not predominant in Haiti, then fertilizers recommendations are made based on the purchasing power of each farmer, which lead to inadequate soil management and depletion of the available nutrients of the soil. This study tends to provide an appropriate P and K rates that can maximize black beans yield in both alkaline and acidic soil in Haiti. When comparing the effect of P fertilization between both soils, the acidic soil yield ed statistically higher 3,377 Kg ha 1 compared to the alkaline soil 1,238 Kg ha 1 with the application of 66 Kg P ha 1 (Table

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44 4 1 5 ). Further research is needed to address how black beans would respond with the same P rate s or lower without any addition of K fertilizer in the alkaline soil. Significant difference was also found between the soils when potassium was not applied where the alkaline soil recorded the highest yield of 3,0 11 Kg ha 1 compared to 227 Kg ha 1 in the acidic soil the remaining treatm ents were statistically similar (Table 4 1 6 ) The High extractable K recorded in the alkaline soil prior to the experiment was beyond sufficient to fufill the needs of the crop ; however, the acidic soil (Kenscoff) which was also determined to be High in e xtractable K did not result in a significance yield response when potassium was not added. T his result can be explained by the fact that the K extracted in t h e soil may not be readiliy available for the plants unless t he plant is classified as a low requirement cr op in K ( Kaddar et al., 1984 )

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45 Table 4 1. Summary of the chemical and physical properties of the soil profile from 0 to 30 cm, prior to the experiments Properties Cabaret Kenscoff Method of Analysis pH 8.2 0 6.02 1:2 ( Soil: water ) Extractable P (m g Kg 1 ) 1.34 22.98 Mehlich 3 Soil Extraction Extractable K (m g Kg 1 ) 247 65.41 Mehlich 3 Soil Extraction Organic Matter (%) 1.31 5.40 Walkley Black Texture Clay Loam Sandy Clay Loam Hydrometer Sand 43% 46% Silt 28% 24% Clay 29% 30%

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46 Table 4 2. Effect of P rates on Leaf P concentration (%) plant height (cm) number of days to flowering (DtoF) at flowering, and plant height (cm) total dry matter ( Kg ha 1 ), and number of grain per plant at harvest P (Kg ha 1 ) Flowering Harvest Cabaret Kens coff Cabaret Kenscoff Leaf P Height DtoF Leaf P Height DtoF Height DM GPP Height DM GPP 0 0.33 25 64 b 11 a 32.4 a 1,172 27 a 8.0 a 13.4 a 44 0.27 34 59 a 0.25 41 b 59 43.8 b 1,025 35 a 51.5 b 1,552.1 bc 58 ab 55 0.32 33 59 a 0.34 39 b 60 46.1 b 1,419 49 b 54.4 b 1,358.7 b 40 a 66 0.31 28 62 ab 0.30 63 c 59 39.0 ab 1,119 27 a 78.1 c 2,082.1 c 70 b Signif. ns ns ns *** ns ns ** *** Significant Means f ollowing by the same letters within each column are not significantly different by LSD 0.05 Dto F = number of days to flowering; OM = Organic Matter ; DM = Dry Matter ; GPP = number of Grain per plant Table 4 3. Effect of K rates on Leaf K concentration ( %) plant height (cm) number of days to flowering (DtoF) at flowering, and plant height (cm) total dry matter ( Kg ha 1 ), and number of grain per plant at harvest K (Kg ha 1 ) Flowering Harvest Cabaret Kenscoff Cabaret Kenscoff Leaf K Height DtoF Leaf K Height DtoF Height DM GPP Height DM GPP 0 2.08 37 59 0.72 a 20 a 64 47.5 1,631 58 b 26.8 a 232 a 6 a 20 2.28 33 59 1.60 b 39 b 60 46.1 1,419 49 ab 54.4 b 1,359 b 40 b 40 2.46 33 61 1.73 b 45 b 61 44.4 1,278 39 ab 61.6 b 1, 708 b 41 b 60 2.49 31 64 2.06 b 40 b 61 46.2 1,141 26 a 53.4 b 1,397 b 56 b Signif. ns ns ns *** ** ns ns ns ** ** *** Significant Means following by the same letters within e ach column are not significantly different by LSD 0.05 DtoF = number of days to flowering; OM = Organic Matter ; DM = Dry Matter ; GPP = number of Grain per plant

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47 Figure 4 1 Effect of P rates on plant height starting 15 DAP to harverst, A ) Cabaret B ) Kenscoff

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48 Figure 4 2. Effect of P rates on black beans yield in both soils A) Cabaret B) Kenscoff

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49 Figure 4 3. Effect of K rates on plant height starting 15 DAP to harverst, A) Cabaret, B) Kenscoff

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50 Figure 4 4 Effect of K rate s on black beans yield in both soils A) Cabaret, B) Kenscoff

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51 Table 4 4 Effect of P rates on P concentration (%) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest Cabaret Kenscoff P (Kg ha 1 ) Leaf Petio le Stem Root Grain Plant P Leaf Petiole Stem Root Grain Plant P 0 0.54 0.36 0.20 0.08 0.52 0.34 44 0.55 0.25 0.18 0.07 0.51 0.28 0.44 0.19 a 0.19 0.09 0.48 0.25 a 55 0.48 0.26 0.18 0.06 0.49 0.29 0.45 0.25 b 0.22 0.07 0.49 0. 30 b 66 0.62 0.33 0.23 0.09 0.55 0.36 0.48 0.25 b 0.21 0.07 0.50 0.30 b Significance ns ns ns ns ns ns ns ns ns ns ** Significant Means following by the same letters within each colu mn are not significantly different by LSD 0.05 Table 4 5 Effect of K rates on K concentration (%) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. Cabaret Kenscoff K (Kg ha 1 ) Leaf Petiole Stem Root Gra in Plant K Leaf Petiole Stem Root Grain Plant K 0 2.37 4.05 2.06 0.71 1.63 2.16 2.49 0.50 a 0.94 a 0.14 a 1.32 1.08 a 20 2.22 4.12 1.99 0.90 1.54 2.15 1.63 2.48 bc 1.33 ab 0.25 ab 1.42 1.43 b 40 2.33 3.97 2.39 0.81 1.63 2.23 2.01 2.19 b 1.08 a 0.27 ab 1.45 1.40 b 60 2.78 3.66 2.48 0.97 1.62 2.30 1.89 3.45 c 1.92 b 0.48 b 1.40 1.83 b Significance n s ns ns ns ns ns *** * ns *** Significant Means following by the same letters w ithin each column are not significantly different by LSD 0.05

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52 Table 4 6. Effect of P rates on P uptake (kg ha 1 ) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. Cabaret Kenscoff P (Kg ha 1 ) Leaf Petiole Stem Root Grain Plant Leaf Petiole Stem Root Grain Plant 0 1.66 0.40 0.82 0.17 5.50 a 8.55 44 0.87 0.35 0.99 0.17 9.10 ab 11.03 1.24 0.43 1.49 0.23 11.40 a 11.66 a 55 1.07 0.46 1.16 0.18 12.33 b 15.21 1.01 0.28 1.52 0.24 8.34 a 11.39 a 66 1.70 0.43 1.06 0.22 6.46 a 9.87 1.21 0.58 2.43 0.36 16.78 b 21.34 b Significance ns ns ns ns ns ns ns ns ** ** Significant Means following by the same letters within each column are not significantly different by LSD 0.05 Table 4 7 Effect of K rates on K uptake (kg ha 1 ) in the plant components (leaf, petiole, stem, root, and grain) and the whole plant at harvest. Cabaret Kenscoff K (Kg ha 1 ) Leaf Petiole Stem Root Grain Plant Leaf Petiole Stem Roots Grain Plant 0 5.64 8.51 14.84 2.69 50.04 b 81.71 b 2.97 0.14 a 0.93 a 0.11 a 2.91 a 4.06 a 20 5.13 7.97 13.39 2.69 39.53 b 68.71 ab 3.58 2.87 b 9.04 b 0.83 a 24.82 b 41.14 b 40 5.31 5.78 14.12 2.50 31.67 a 5 6.38 ab 5.00 2.95 b 8.69 b 1.14 b 38.50 b 56.27 b 60 6.97 6.66 12.16 2.22 17.80 a 45.81 a 4.38 4.28 b 12.36 b 1.98 b 26.84 b 49.48 b Significance n s ns ns ns ** ns ** *** *** ** *** S ignificant Means following by the same letters within each column are not significantly different by LSD 0.05

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53 Table 4 8 Effect of P and K rates on Nutrient use efficiency. Phosphorus Use Efficiency Cabaret Kenscoff ns P (Kg ha 1 ) P rec (%) PFP (Kg Kg 1 ) P rec (%) PFP (Kg Kg 1 ) 0 44 11.00 ab 17.83 ab 11.50 24.07 b 55 12.20 b 20.43 b 9.25 13.98 a 66 6.50 a 8.25 a 14.25 22.52 b Significance * ns ** Potassium Use Efficiency K (Kg ha 1 ) K rec (%) PFP (Kg Kg 1 ) K rec (%) PF P (Kg Kg 1 ) 0 20 275 b 102.14 b 164 b 69.92 b 40 119 a 39.01 a 112 ab 52.26 ab 60 61 a 14.66 a 66 a 25.63 a Significance *** *** ** Significant Means following by the same letters within each column are not significantly different by LSD 0.05 PFP = Partial Factor Productivity ; P rec = Phosphorus recovery ; K rec = Potassium recovery

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54 Table 4 9. Soil pH, Organic Matter (%), and extractable P (mg Kg 1 ) at flowerin g and harvest P (Kg ha 1 ) Flowering Harvest Cabaret Kenscoff Cabaret Kenscoff pH OM P pH OM P pH OM P pH OM P 0 8.35 2.23 8.14 4.88 a 5.30 13.19 8.33 2.33 7.65 a 4.51 a 5.12 4.6 a 44 8.45 2.18 11.70 5.60 b 5.22 25.07 8.35 2.25 43.67 b 5.09 a 5.50 43.1 b 55 8.47 2.16 12.53 6.95 c 5.13 21.11 8.39 2.31 61.66 b 6.68 b 5.17 58.0 b 66 8.54 2.19 18.87 6.51 c 5.47 31.25 8.37 2.19 55.30 b 6.16 b 5.54 83.9 c Significance ns ns ns *** ns ns ns ns *** *** ns *** Significant Means following by the same letters within each column are not significantly different by LSD 0.05 Table 4 10. Soil pH, Organic Matter (%), and extractable K (mg Kg 1 ) at flowering and harvest K (K g ha 1 ) Flowering Harvest Cabaret Kenscoff Cabaret Kenscoff pH OM K pH OM K pH OM P K pH OM K 0 8.57 2.31 260.80 a 4.89 a 4.94 41.21 a 8.39 2.27 235 a 4.74 a 5.33 44.8 a 20 8.47 2.16 282.62 ab 6.95 b 5.13 105.83 bc 8.39 2.31 246 ab 6.68 b 5.17 1 16.6 b 40 8.43 2.21 287.94 ab 6.26 b 5.34 85.13 a 8.35 2.23 256 ab 5.30 a 5.41 78.2 a 60 8.48 2.20 311.76 b 6.89 b 5.53 151.70 c 8.35 2.29 278 b 6.86 b 5.12 138.4 b Signif ns ns * ns *** ns ns *** ns *** Significant Means following by the same letters within each column are not significantly different by LSD 0.05

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55 Table 4 1 1 Correlation amongst black beans variables based on P rates and soil characteristics at Cabaret Variable Height Yield Plant P OM Dry Matter pH DtoF Yield 0.18 ns Plant P 0.55 0.12 ns OM 0.11 ns 0.37 ns 0.25 ns Dry Matter 0.03 ns 0.80 *** 0.23 ns 0.59 pH 0.02 ns 0.00 ns 0.24 ns 0.07 ns 0.13 ns DtoF 0.07 ns 0.50 0.38 ns 0.33 ns 0.23 ns 0.04 ns P uptake 0.00 ns 0.92 *** 0.22 ns 0.36 ns 0.77 *** 0.13 ns 0.55 Significant OM = Organic Matter ; DtoF = number of days to flowering Table 4 1 2 Correlat ion amongst black beans variables based on P rates and soil characteristics at Kenscoff Variables Plant Height Yield Plant P OM Dry Matter pH DtoF Yield 0.62 Plant P 0.33 ns 0.01 ns OM 0.31 ns 0.25 ns 0.11 ns Dry matter 0.70 0.93 *** 0.15 ns 0.33 ns pH 0.09 ns 0.15 ns 0.70 0.11 ns 0.34 ns DtoF 0.07 ns 0.43 ns 0.31 ns 0.07 ns 0.21 ns 0.49 ns P Uptake 0.63 0.98 *** 0.41 ns 0.20 ns 0.84 *** 0.19 ns 0.09 ns n Significant OM = Organic Matter ; DtoF = number of days to flowering

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56 Table 4 1 3 Correlation amongst black beans variables based on K rates and soil characteristics at Cabaret. Variable Height Yield Plant K OM Dry Matter pH DtoF Yield 0.01 ns Plant K 0.14 ns 0.64 ** OM 0.05 ns 0.09 ns 0.18 ns Dry Matter 0.30 ns 0.63 ** 0.41 ns 0.24 ns pH 0.08 ns 0.28 ns 0.08 ns 0.15 ns 0.46 ns DtoF 0.28 ns 0.57 0.11 ns 0.11 ns 0.16 ns 0.29 ns K uptake 0.16 ns 0.92 *** 0.62 0. 12 ns 0.84 *** 0.36 ns 0.34 ns Significant OM = Organic Matter ; DtoF = number of days to flowering Table 4 1 4 Correlation amongst black beans variables based on K rates and soil chara cteristics at Kenscoff Variables Plant Height Yield Plant K OM DM pH DtoF Yield 0.80 *** Plant K 0.63 ** 0.35 ns OM 0.38 ns 0.29 ns 0.14 ns DM 0.94 *** 0.89 *** 0.61 0.35 ns pH 0.40 ns 0.32 ns 0.64 ** 0.34 ns 0.48 ns DtoF 0.58 0.66 ** 0.34 ns 0.09 ns 0.66. ** 0.36 ns K Uptake 0.91 *** 0.95 *** 0.65 ** 0.34 ns 0.97 *** 0.50 0.67 ** Significant OM = Organic Matter ; DtoF = number of days to flowering

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57 Table 4 15. Interact ion means for yield response to P rates at a standard K level of 20 Kg K ha 1 Cabaret (C) Kenscoff (K) Contrast P C vs. K Yield (Kg ha 1 ) P (Kg ha 1 ) 0 1 224 342 b 44 1 783 342 ab 2 406 394 ab 0.247 55 2 55 3 342 a 1 86 6 342 b 0.170 66 1 23 8 342 b 3 377 342 a 0.000 Means following by the same letters within each column are not significantly different by LSD 0.0 5 The numbers in the column represent the p value for each treatment between the soil Table 4 16. Interaction means for yield response to K rates at a standard P level of 55 Kg K ha 1 Cabaret (C) Kenscoff (K) Contrast K C vs. K Yield (Kg ha 1 ) K (Kg ha 1 ) 0 3,011 310 a 227 427 b 0.000 20 2,553 295 ab 1,866 295 a 0.114 40 1,919 310 bc 2,613 295 a 0.119 6 0 1,099 295 c 1,909 295 a 0.071 Means following by the same letters within each column are not significantly different by LSD 0.0 5 The numbers in the column represent the p value for each treatment between the soils

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58 CHAPTER 5 CONCLUSION S This study evaluated the response of black beans to different P and K rates in two soils in Haiti. In both soils, yield was significantly different. Soil from Cabaret with a high pH, very high extractable K, and low P availability performed better when no K was applied using a constant rate of 5 5 Kg P ha 1 W hen analyzed for the effect of P rates, the yield and growth response from the application of 44 and 55 Kg P ha 1 were statistically similar using a constan t rate of 20 Kg K ha 1 In Kenscoff soil both P and K applications had a positive effect on black bean growth and yield. Located in the mountainous area of the western region of Haiti, Kenscoff has an acidic soil (pH=6.02), extractable K was high, and P w as low before the experiments. Even with the high plant available K extracted before the experiment, application of 20 Kg K ha 1 significantly increased black beans yield and growth. Amo n g the different P rates, application of 44 kg P ha 1 showed statistic ally the best performance, with a constant rate of 20 Kg K ha 1 Mehlich 3 extraction solution performed very well in both P and K experiments, proving it to be fitting for these two major Haitian soils. When increasing UF/ IFAS P recommendation (50 Kg P ha 1 ) for lima bean grown in sandy soils by 10%, soil from Cabaret reached its optimum yield, indicating that no more P is needed. In Kenscoff, the best yield performance was observed when decreasing IFAS recommendation for P by 10% combined with 20 Kg K ha 1 In this study, M 3 revealed to be an excellent extractant for both soils; however, each crop required a different amount of nutrients (either N, P, or K) and the crop response can vary depending on the production season. Further research needs to be don e to assess the suitability of M 3 in Haitian soils

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59 through field calibration trials, with various P and K rates in both acid and alkaline soils using different crops such as maize, rice, and sorghum

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60 APPENDIX A LAYOUT OF THE POTS Figure A 1. A View of Both Experiments (Cabaret on top, Kenscoff at the bottom), 30 Days After Planting. P hoto c ourtesy of author

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61 APPENDIX B PICTURES FROM THE EXPERIMENT S Figu re B 1. Evolution of the Experiment in the Alkaline Soil (Cabaret). Photo courtesy of autho r Figure B 2. Evolution of the Experiment in the Acidic Soil (Kenscoff). Photo courtesy of author.

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62 APPENDIX C CORRELATION BETWEEN YIELD PARAMETERS Correlation Based on P Rates in B oth S oils (Cabaret and Kenscoff) Correlation Based on K Rates in Both S oils (Cabaret and Kenscoff)

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64 Broughton, W. J.; Hernandez, G.; Blair, M.; Beebe, S.; Gepts, P., & Vanderleyden, J. ( 2003 ) Beans (Phaseolus spp.) model food legumes. Plant and Soil 252: 55 128 Brown, B. & Westermann, D.T. ( 2000 ) In Bean Research, Production, and Utilization Edited by Singh, S.P. 63 71 Cassman, K. G., Dobermann, A., & Walters, D. T. ( 2002 ) Agroecosystems, nitrogen use efficiency, and nitrogen management. AMBIO: A Journal of the Human Environment 31 (2), 132 141. Cassman, KG., Peng, S., Olk, D.C., Ladha, J.K., Reichardt, W., Dobermann, A., & Singh, U. ( 1998 ) Opportunities for increasing nitrogen use effici ency from improved resource management in irrigated rice systems. Field Crops Res 56, 7 38. CIAT (Centro Internacional de Agricultura Tropical). ( 1989 ) Bean production problems in the tropics. 2nd ed. Schwartz, H. F. & Pastor Corrales, M. A. (eds.). Cali Colombia. 726 p. CIAT (Centro Internacional de Agricultura Tropical). ( 1981 ) The CIAT Bean Program: research strategies for increasing production. CIAT series 02EB 2. Cali, Colombia. Clermont Dauphin, C., Y. Cabidoche, & J. Meynard. ( 2004 ) Diagnosis on the sustainability of an upland cropping system of southern Haiti. Agriculture, Ecosystems, and Environment 105:221 234. Das, I., & Pradhan, M. ( 2016 ) Potassium solubilizing microorganisms and their role in enhancing soil fertility and health. In Potassi um solubilizing microorganisms for sustainable agriculture (pp. 281 291). Springer, New Delhi. Dobermann, A. ( 2007 ) Nutrient use efficiency measurement and management. In Be lgium, p1 28. Fageria, N. K. & Filho, B. ( 2007 ) Dry Matter and Grain Yield, Nutrient Uptake, and Phosphorus Use Efficiency of Lowland Rice as Influenced by Phosphorus Fertilization. Communications in Soil Science and Plant Analysis 38 (9 10), 1289 1297. doi : 10.1080/00103620701328537 Fageria, N. K., & Baligar, V. C. ( 2016 ) Growth, yield and yield components of dry bean as influenced by phosphorus in a tropical acid soil. Journal of Plant Nutrition 39(4), 562 568. doi: 10.1080/01904167.2016.1143489 Fageria, N. K., & Santos, A. B. D. ( 1998 ) Phosphorus fertilization for bean crop in lowland soil. Revista Brasileira de Engenharia Agrcola e Ambiental 2(2), 124 127.

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65 Fageria, N. K., Baligar, V. C. & Li, Y. C. ( 2008 ) The Role of Nutrient Efficient Plants in Improving Crop Yields in the Twenty First Century. Journal of Plant Nutritio n, 31 ( 6 ) 1121 1157. Fageria, N. K., Zimmermann, P., & Baligar, C. ( 1995 ) Lime and phosphorus interactions on growth and nu trient uptake by upland rice, wheat, common bean, and corn in an Oxisol. Journal of Plant Nutritio n, 18 (11), 2519 2532. doi : 10.1080/01904169509365081 Franco, A. A., J. C. Pereira, & C. A. Neyra. ( 1979 ) Seasonal patterns of nitrate reductase and nitrogenase activities in Phaseolus vulgaris L. Plant Physiol 63:421 422. Freytag, G ., & Debouck, D. ( 2002 ) Taxonomy, distribution, and ecology of the genus Phaseolus ( Leguminosae Papilionoideae ) in No rth America, Mexico and central America. Botanical Research Institute of Texas (BRIT), Forth Worth, TX, USA. 298 p. Gepts Paul & Debouck DG. ( 1991 ) Origin, domestication, and evolution of the common bean, Phaseolus vulgaris. In Common Beans: Research for Crop Improvement Edited by: Voysest O, Van Schoonhoven A. Oxon. UK: CAB International;7 53. Gidago, G., Beyene, S., Worku, W., & Sodo, E. ( 2011 ) The response of haricot bean ( Phaseolus vulgaris L. ) to phosphorus application on ultisols at Areka, Southern Ethiopia. Journal of Biology, Agriculture and Healthcar e, 1 (3), 38 49. Graham & Ranalli. ( 1997 ) Common bean ( Phaseolus vulgaris L. ) Field Crops Research, 53 :131 146. Guthrie, R., & Shannon D. ( 2004 ) Soil profile descriptions for steep lands research s ites in Haiti. Auburn University, Auburn, AL. Hanway, J.J., & Johnson, J.W. ( 1985 ) Potassium nutrition of soybeans. In: Munson, R.D. (Ed.), Potassium in Agriculture. American Society of Agronomy Madison, WI, pp. 753 764. Havlin, John L.; Tisdale, Samuel L.; Nelson, Werner L., & Beaton, James D. ( 2013 ) Soil Fertility and Fertilizers: An Introduction to Nutrient Management. 8 th Edition. Upper Saddle River, N.J.: Prentice Hall. Helm, J. L., Grafton, K. F., & Schneiter, A. A. ( 1990 ) Dry bean production hand book. Hochmuth, G. J., R. Mylavarapu, & E. A. Hanlon. ( 2014a ) Developing A Soil Test Extractant: The Correlation and Calibration Processes SL 409. Gainesville: University of Florida Institute of Food and Agricultural Sciences.

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70 BIOGRAPHICAL SKETCH Franky Celestin grew up in Coteaux, Southern Haiti. He received his Bachelor of Science in a gronomy at the University of Notre Dame Haiti (UNDH) in 2015, majoring in crop production. In 2017, He was awarded a schorlarship from the USAID to pursue his Master of Science degree at the University of Florida in the Soil and Water Science Department under the supervision of Dr. Rao Mylavarapu.