| Material Information
||Source and management of green manure : : preliminary uniformity trial
||TropSoils field research brief ;, 16
||2 leaves ; 28 cm.
Yost, Russell S. (Russell Shelley), 1945-
Wade, M. K. (Michael Karl)
Soil Management Collaborative Research Support Program.
||Soil Management Collaborative Research Support Program, North Carolina State University,
||Green manuring -- Indonesia.
Soil amendments -- Indonesia.
||At head of title: TropSoils-Indonesia.
| Record Information
||University of Florida
||All rights reserved by the source institution and holding location.
||oclc - 156913223
T R OPSOiLS1
TROPSOILS Indonesia WEST SUMATERA
Field Research Brief No. 16
TITLE: Source and Management of Green Manure Preliminary
EXPERIMENT NO.: 3503
RESEARCHERS: Carl Evensen, Russell Yost, and Mike Wade
OBJECTIVES: 1. To assess the inherent 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 plots wi TT be needed in the fofT-wing
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 beforehand after plot selection.
GRAIN POD VINE
YIELD YIELD YIELD A1+H Ca+Mg Al Sat.
----- (kg/ha) ------ --(meq7l00g)-- (%)
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)
*** Significant at 0.001 level (Probability value)