Abstract:
Although on-farm crop residues and animal manures proved
the most widely used organic materials for intensive small-scale vegetable
production by resource-poor smallholder farmers in southern African countries
their availability has become limited. In an effort to establish alternative
sources of organic materials for vegetable gardeners a soil fertility
study was conducted at Masvingo Teachers’College (30°52’
E; 20°07’ E, elev. >1100 m above sea level) about 5.5 km southeast
of Masvingo city in Zimbabwe. The experimental plots were laid out in
a Complete Randomized Design with four replicates, which were subjected
to three hyacinth-based organic matter treatments in order to determine
the effect of these alternatives to crop residues on leaf growth rate
and yield of vegetable rape. Our research results have conclusively shown
that the use of water hyacinth as organic fertilizer significantly improved
vegetable rape leaf length and yield. Vegetable rape leaves growing on
crop stover-free hyacinth matter were 12.3-12.8 mm longer and had about
11.5-67.3% higher rape leaf yield than those in crop stover-based hyacinth
compost matter. A vegetable rape yield gain of 1.8 t ha-1 was
recorded in plots subjected to green hyacinth matter soil treatment compared
with rape yield in plots treated with hyacinth compost matter. The use
of hyacinth matter significantly retards initial vegetable rape leaf growth
rate by about 1.47-5.9% compared with that in the zero organic fertilizer
control plots. Laboratory analysis of the two organic materials has shown
that hyacinth compost matter was nutritionally inferior to green hyacinth
manure. Total N content in the water hyacinth compost was about 72.6%
less than that in the green hyacinth. This study has shown that, green
hyacinth matter, an obnoxious water weed that greatly reduces the aesthetic
quality of public water bodies, is an effective alternative crop residue-free
organic fertilizer for small-scale vegetable production.
J. Masaka and S. Ndhlovu, 2007. The Effect of Different Forms of Water Hyacinth (Eichhornia crassipes) Organic Fertilizers on Leaf Growth Rate and Yield of Rape (Brassica napus). International Journal of Agricultural Research, 2: 254-260.
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