To: JAMAICA AGRICULTURAL DEVELOPMENT FOUNDATION
Title: Study of Soil Characteristics as Developed in a Grass Mulch System of
Vegetable Cultivation in Jamaica
Introduction/backnround: The benefits of organic mulches to nonirrigated
crops in areas of limited or seasonal rainfall are widely acknowledged, but
little studied. Mulches composed of green or dried grasses, leaves, composted
plant parts and crop residues have been used successfully in all parts of the
world by small farmers and home gardeners for moisture conservation, improve-
ment in soil fertility and tilth and increase in cation-exchange capacity of
the soil resulting from increased organic-matter content. A system of
cultivation using organic mulching is particularly well suited to vegetable
crops because they are intensively cultivated and thus require a much smaller
volume of mulching materials than the agronomic crops.
A system of cultivation using dried guinea grass (Panicum maximum L.) for
mulching has been used for many years by vegetable farmers in south Saint
Elizabeth. The mulch is necessary because of low rainfall in the area,
coupled with a lack of available water for irrigation. The system has served
the farmers well. However, the proposed study is needed at this time for two
reasons: (1) the mix of crops being grown on small farms in the subject area
is changing. An example is the reduced prevalence of cassava and (2) there is
a possibility of obtaining a limited quantity of irrigation water for the area
in the future (Wilson, 1989).
Data from the proposed study will provide a better understanding of the
benefits and possible limitations of the present technology. They will also
provide a baseline of soil characteristics. This will establish a basis for
determining whether irrigation is rational and how much supplemental water
would be required. In addition, the information will indicate what parameters
might be improved by other technological changes.
The duration of the proposed study will be one calendar year, from
August, 1989 to August, 1990. It will combine a field trial on soil which has
been in fallow for at least four years with on-farm studies designed to
examine soil conditions of fields which have been under production for various
periods of time. The on-farm studies will provide a means to evaluate the
changes in soil characteristics over time under this system of cultivation.
The crop studied will be scallion, one of the most important vegetable crops
in the area.
Literature Review: Many beneficial effects on various soils have been
attributed to the use of "green manures" and dry organic mulches. These have
included moisture retention (Lal, 1974; Bond and Willis, 1969, 1970; Tukey and
Schoff, 1963), weed control (Crutchfield, 1984), moderating soil temperature
(Benincasa, et al., 1981) and fertility (Wade, et al., 1988). Mulches have
also been reported to be effective in control of certain insect pests
(Setiawan and Ragsdale, 1987), and nematodes. Some authors have stressed the
benefits to the soil which accrue as the mulch material decomposes, adding to
the organic matter content of the soil. Increased organic matter content adds
to the cation exchange capacity, the moisture-holding capacity, the physical
condition (tilth) of the soil and makes direct contributions to the plant
nutrients in the soil (Allison and Anderson, 1951; Brady, 1984). Specific
nutrient effects noted on soils under organic mulches include increased
available P and K (Famoso and Bautista, 1983), and Manganese (Wade, et al.
1988; Tukey and Schoff, 1963). Findings on pH changes under organic mulch
have been mixed. Herbert (1951) reported that mulches helped to maintain an
acid reaction, while Tukey and Schoff (1963) found no effect. Wade et al.,
(1988) on the other hand, stated that imported green manures ameliorated soil
acidity and could be substituted for liming to some extent with upland rice.
They also found that Al toxicity was reduced for soybean, apparently because
of the ability of the organic materials to tie up aluminum in the soil.
Negative effects of the incorporation of organic materials into the soil have
been observed in the tendency for the formation of certain toxic organic
compounds (Brady, 1984) and the tendency to tie up available N during organic
matter breakdown, increasing the need for nitrogen fertilizer (Allison and
The positive effects of organic mulch on crop plants are almost as
striking as those on soils. Increases in growth when mulches are used have
been reported in maize (Shekour et al) and tomatoes (Olsantan, 1985). Ramos
and Boddey (1987) reported increased germination and seedling survival with
organic mulch, while Chaudhary et al., (1985) found increases in root density
and leaf water potential. Famoso and Bautista (1983) associated sugarcane
mulch with higher leaf chlorophyll content in tomato.
There is little information in the literature regarding the specific
cultural technique of mulching with dried guinea grass as it is practiced by
vegetable farmers in Jamaica. Strohl (1985) briefly described the system and
stated that irrigation is needed in Jamaica during the dry season for the
sugarcane and winter vegetable crops. Daisley et al., (1986) conducted a
study in Antigua comparing soil moisture retention, weed growth, seed germina-
tion and yield in cowpeas and eggplant. They found that the use of mulch
suppressed weed growth, increased soil moisture retention, increased seed
germination and increased yields in eggplants and total dry weight accumula-
tion in cowpeas. The effects were maximized at a mulch rate of 4 t ha-.
Objectives and Beneficiaries: The objectives of this study will be threefold.
From controlled experiment:
(1) To determine the differential effects on soil conditions, plant growth
and yield of scallions in mulched versus unmulched plots over a single season.
From on-farm study:
(2) To measure soil parameters in the mulched fields under cultivation of
scallions in south Saint Elizabeth, providing a baseline for future study and
(3) Relate any differences in these parameters to the number of years in
cultivation in order to establish trends in the soil under this system.
The beneficiaries will be small farmers in Jamaica.
Materials and Methods:
The project will consist of two parts; an on-farm study and a field
trial. The on-farm study will be conducted on 12 to 16 locations and will
include fields which have been in production for varying periods of time.
Measurements will be made of the following soil parameters: pH, bulk density,
organic-matter content, compaction and mineral content. Soil moisture content
will be measured at three depths; 0-5 cm, 5-15 cm and 15-35 cm. Samples will
be taken from mulched areas in fields cultivated in scallions and from
adjacent unmulched areas. Differences in moisture between these mulched and
unmulched areas will be compared among the various locations. Moisture
differences between mulched areas and areas without mulch are preferred over
raw moisture content data because the time interval between most recent
rainfall and soil moisture measurement as well as the amount of rainfall may
vary from location to location. Samples for chemical and physical analysis
will be taken three times at each location; before mulching, at midseason and
during the harvest period. Moisture samples will be taken more frequently, at
weekly intervals, on a subset of locations in order to make allowance for
variance in rainfall among locations. Statistical analysis will be made using
regression with the number of years in production as the independent variable.
Dependent variables will be the previously mentioned measured parameters plus
major nutrient elements, available aluminum and average yields for the tested
fields. Each parameter will be analyzed separately to establish whether any
trends in soil conditions have been established over time under this system of
The field trial will be conducted using rented farm land. The design
will be randomized complete block with five replications and the treatments
will be unmulched, and mulched in accordance with local practice. The plots
will be prepared, mulched and planted in scallions which will be allowed to
grow to maturity (marketable size). Critical cultural practices, such as land
preparation and laying of mulch will be performed using hired local labor in
order to provide uniformity with the practices and techniques of the local
farmers. Soil measurements will be made three times during the season, as
described for the on-farm study, except that all plots will be analyzed for
moisture content weekly. In addition to the soil measurements, the following
plant factors will be evaluated: Average number of leaves, average leaf
height, average leaf width and total dry weight accumulation. Analysis of
this trial will be by ANOVA with each measured parameter evaluated for
significant differences between mulched and unmulched plots. Soil moisture
determinations will be made by drying and weighing. Soil chemistry analysis
will be relegated to the most reliable available laboratory.
Meteorological data will be determined for the area during the period by
the investigators. Daily rainfall, humidity, pan evaporation and average
temperatures will be determined at a central location. Rain gauges will also
be maintained on each of the farms in the weekly-measurement subset and will
be read on a weekly basis.
Item: Funds Requested:
1. Graduate student stipend 7000
Total personnel 7000
1. Two-way Gainesville, Fl. to Kingston (student and spouse) 2000
2. Site visits for principal investigator (2) 2000
Total travel 4000
C. Permanent Equipment
1. Drying Oven 914
2. Analytic balance and weights 2250
3. Soil penetrometer 400
4. Recording thermometer 815
Total equipment 4379
D. Operational expenses
1. Mileage, in country 1450
2. Labor 1000
3. Land rental 250
4. Sample analysis and mailing costs 300
Total operational expenses 3000
1. Weather recording equipment (gauges, thermometers) 150
2. Field supplies (hoes, measuring sticks, bags, etc.) 550
3. Production inputs (fertilizer, grass,etc.) 500
4. Miscellaneous notebooks, containers, calculator, etc.) 100
Total supplies 1300
Total costs $19,679
1. Allison, F.. and M.S. Anderson. 1951. The use of sawdust for
mulches and soil improvement. U.S.D.A. Circular 891. Washington D.C.
2. Benincasa, M., M.M.P. Benincasa, J.M. Santos, dos, and L.R. Lopes. 1981.
Effect of organic matter incorporation and mulching on the heat flux in a
cultivated soil. Cienc. Cult. Soc. Bras. Progr. Cienc. 33:558-563.
3. Bond, J.J. and W.O. Willis. 1969. Soil water evaporation: surface
residue rate and placement effects. Soil Sci. Soc. Amer. Proc. 33: 445-
4. Bond, J.J. and W.O. Willis. 1970. Soil water evaporation: first stage
drying as influenced by surface residue and evaporation potential. Soil
Sci. Soc. Amer. Proc. 34: 924-928.
5. Brady, Nyle C. 1984. The Nature and Properties of Soils. Macmillan
Publishing Company. New York
6. Chaudhary, T.T., Usha K. Chopra, and A.K. Sinha. 1985. Root growth,
leaf water potential and yield of irrigated summer mung bean (Phaseolus
aureus Roxb.) in relation to soil water status and soil temperature under
various mulches. Field Crops Res. 11: 325-333.
7. Crutchfield, Donald Andrew. 1984. The effect of wheat straw mulch on
weed control and corn growth. Ph.D. Diss. University of Nebraska-
8 Daisley, L.E.A., S.K. Chong, F.J. Olsen, L. Singh, and C. George. 1988.
Effects of surface-applied grass mulch on soil water content and yields
of cowpea and eggplant in Antigua. Trop. Agri. (Trinidad) 65:300-304.
9. Famoso, Erlinda B. and Ofelia K. Bautista. 1983. Sugarcane mulch and
nitrogen fertilizer for tomato (Lycopersicon lycopersicum (L.) Karsten)
production. (Philippines). Phil. Agr. 66: 109-125.
10. Herbert, John H., Jr. 1951. The effect of several organic mulches on
soil reaction, nitrates and growth of azaleas and camellias. M.S.
Thesis. University of Florida.
11. Lal, Ratan. 1974. Soil temperature, soil moisture and maize yield from
mulched and unmulched tropical soils. Plant and Soil. 40: 129-143.
12. Olasantan, F.O. 1985. Effects of intercropping, mulching, and staking
on growth and yield of tomatoes. Expl. Agri. 21: 135-144.
13. Ramos, Maria Lucrecia, and Robert M. Boddey. 1987. Yield and nodulation
of Phaseolus vulgaris and the competitivity of an introduced Rhizobium
strain: effects of lime, mulch and repeated cropping. Soil Biol.
Biochem. 19: 171-177.
14. Setiawan, Dwi P. and David W. Ragsdale. 1987. Use of aluminum-foil and
oat-straw mulches for controlling aster leafhopper, Macrosteles fas-
cifrons (Homoptera: Cicadellidae), and aster yellows in carrots. Great
Lakes Entomol. 20: 103-109.
15. Shekour, G.M., R.A.I. Brathwaite, and C.R. McDavid. 1987. Dry season
sweet corn response to mulching and antitranspirants. Agron. J. 79:629-
16. Strohl, R. 1985. Jamaica must increase irrigated area to meet staple
and export crop needs. Agribusiness Worldwide. July/Aug: 2-7.
17. Tukey, R.B. and W.L. Schoff. 1963. Influence of different mulching
materials upon the soil environment. Amer. Soc. Hortic. Sci. 82:68-76.
18. Wade, Michael K., Dan W. Gill, Hardjosubroto Subagjo, Mohammed Sudjadi,
and Pedro A. Sanchez. 1988. Overcoming soil fertility constraints in a
transmigration area of Indonesia. Trop. Soils Bulletin 88-01. North
Carolina State University.
19. Wilson, George. 1988. Personal communication.
Malcolm S. Davis
Vegetable Crops Department
University of Florida
Gainesville, FL 32611
Born, Emory University, Georgia, USA 1934
University of Florida, Graduate Student. 1987 present.
U.S. Naval Dental School, Certificate of Residency.
Emory University, D.D.S. 1957. Dentistry
University of Georgia, Predental Undergraduate, 1953
Awards and Honors:
U.S. Naval Dental School, Award for Excellence in
U.S. Naval Dental School, Award for Outstanding Scholarship
U.S. Naval Dental School, Award for Excellence in Research
Professional Positions Held:
Graduate Student. 1986-present. Vegetable Crops Department
University of Florida, Gainesville, Florida.
U.S. Navy Dental Officer. 1957-1985. Various Locations
Walker, T.L. and M.S. Davis. 1984. Treatment of large
periapical lesions using cannulization through the
involved teeth. Jour. of Endo. 10:215-220
Davis, M.S., S.W. Joseph and J.F. Bucher. 1971. Periap-
ical and intracanal healing following incomplete root
canal fillings in dogs. Oral Sur. 31:662:675.