Source and management of green manure : preliminary uniformity trial

Material Information

Source and management of green manure : preliminary uniformity trial
Series Title:
TropSoils field research brief ;, 16
Evensen, Carl.
Yost, Russell S. (Russell Shelley), 1945-
Wade, M. K. (Michael Karl)
Soil Management Collaborative Research Support Program.
Place of Publication:
Raleigh, NC
Soil Management Collaborative Research Support Program, North Carolina State University,
Publication Date:
Physical Description:
2 leaves ; 28 cm.


Subjects / Keywords:
Green manuring -- Indonesia.
Soil amendments -- Indonesia.
Spatial Coverage:


General Note:
Caption title.
General Note:
"July, 1985."
General Note:
At head of title: TropSoils-Indonesia.

Record Information

Source Institution:
University of Florida
Holding Location:
University of Florida
Rights Management:
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Resource Identifier:
156913223 ( OCLC )

Full Text
TROPSOILS Indonesia f WEST SUMATERA Field Research Brief No. 16
July, 1985
TITLE: Source and Management of Green Manure Preliminary
Uniformity Trial
RESEARCHERS: Carl Evensen, Russell Yost, and Mike Wade
OBJECTIVES: 1. To assess the inherant soil variablity in an
experimental site before application of
2. To use uniformity trial crop' yields as well as
soil analysis data to select least variable
plots and appropriate blocking pattern.
SOIL: probably a Typic Paleudult; clayey, kaolinitic,
isohyperthermic. FCC: Ceak. Cleared by manual tree
felling and then bulldozing during 82/83 wet season but
never cropped; heavily eroded in parts.
Since the purpose of this trial was to characterize soil
variability, no treatments were imposed. 75 plots of a 4x6m size were laid out, 40 kg P/ha was broadcast on all, and the soil was dug by hand hoeing to 15cm depth. Plots were laid out to avoid stumps, ash piles, heavily eroded patches, and other irregularities. OnTy 60 pTots wiTT be needed in the flowing trial; the extra 15 plots were planted to permit discarding of the plots with high within-plot variability and those plots dissimilar to surrounding plots in a block.
A semi-determinate local variety of cowpea was planted on March 4, 1985. Germination was delayed for over a week by drought and was fairly spotty. Replanting was done to fill gaps on March 27,. 1985. Because of uneven plant growth (due to both late replanting and the somewhat indeterminate nature of the cowpea variety) harvesting of pod was staggered over several weeks (harvests on 5/20 and 6/8). Plots were visually rated for uniform growth within plots and vigor of plant growth. These data, along with cowpea yields and soil analyses from each plot, were used to select plots to be included in each block.
Crop yields and soil analysis data sumarized before and after plot selection are shown in Table. I. For most of these parameters, the range and variation of values was reduced in going from 75 to 60 plots. However, the selected plots are still quite variable in soil properties and yield potential; much of this variation is grouped into the blocks. The soil is generally quite infertile and high in Al.

Table 1. Cowpea growth and soil test parameters sumarized from
the uniformity trial before and after plot selection.
S(kg7ha) --(meqTlOOg)-- (%)
75 Original Plots:
Mean : 653 1170 665 2.27 0.69 74
Deviation : 269 488 390 0.39 0.23 6.0
Minimum : 78 126 119 1.40 0.30 57
Maximum 1397 2568 2005 3.40 1.50 84
60 Selected Plots:
Mean : 654 1173 652 2.25 0.70 74
Deviation : 236 425 350 0.33 0.23 5.8
Minimum : 185 330 169 1.50 0.30 57
Maximum : 1116 1891 1415 3.00 1.50 83
To test the success of blocking and plot selection,
treatments were randomly assigned to the designated blocks and an analysis of variance was calculated using the cowpea yields from the uniformity trial. This is presented in Table 2. Since the treatments had not been imposed, a significant treatment effect could only have been due to inherent soil variability. However, treatment effects were non-significant while block effects were very highly significant, indicating that plot selection and blocking had been appropriate.
Table 2. Analysis of variance for uniformity trial yields.
Source df Grain Yield Pod Yield Vine Yield
Block 2
Treatment 19 ns ns ns
(0.18) (0.25) (0.15)
Error 38
* Significant at 0.001 level (Probability value)