The effect of green manure, cowdung and their combinations on growth and grain yield of maize (zea mays L.) in low input systems
Date
2012-10-10
Authors
Bwembya, Shadreck
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Abstract
As small holder farmers intensify agricultural production, their land becomes more prone to soil degradation due to shorter or absence of fallow period. In order to use these pieces of land continuously, a deliberate soil management strategy which incorporates organic residues may provide multiple benefits of improving soil chemical and physical status. An experiment was carried out using Cassia spectsbilis (cassia) green manure and cowdung as organic soil amendments to improve soil chemical properties and increase maize yields. Organic manure treatments to supply 1, 2, 3 or 4 tons ha"' of cowdung alone, 2 tons ha'' cassia alone, 2 tons ha"' cassia with 1 ton ha"' cowdung, 2 tons ha"' cassia with 2 tons ha"' cowdung, 2 tons ha "' cassia with 3 tons ha"' cowdung and 2 tons ha' cassia with 4 tons ha"' cowdung were applied to a Misamfii red soil (Clayey Kaolinitic isohyperthermic Typic Haplustox). A grass fallow was used as a control. The plots were arranged as a randomized complete block design with 4 replications. Maize variety MMV 400 was planted in December and harvested at maturity in July. In the field, plant height, dry matter production, grain yield of maize were determined and nutrient uptake was calculated. Soil samples were collected at the beginning and end of the field study for analysis of the pH, organic C, total N, available P, exchangeable K, Ca, Mg and Na. There were no significant increases in the chemical properties of the soil among the treatments. The organic C was in the range of 1.2 -1.8 % while the N concentrations ranged from 0.6-0.8 % across all treatments. Generally the C/N ratios decreased from the initial figure of 20 to 18.9 in the plots with 2 tons ha"' cowdung + 2 tons ha"' cassia and 19.5 in the plots with 1 ton ha"' cowdung + 2 tons ha"' cassia. The average concentration of P increased substantially from the initial 1.8 mg kg"' to 6.7 mg kg"' in the control, 6.9 mg kg"' in the cowdung alone, 9.1 mg kg'' in the cassia alone and 7.4 mg kg"' in the cowdung + cassia plots. The treatments of cassia + cowdung produced significant average plant heights of 317 mm at the 4-6 leaf stage, 1208 mm at the ear-leaf stage and 1705 mm at the maturity stage compared with the control (192 mm, 760 mm and 1513 mm, respectively), the cassia alone (222 mm, 900 mm and 1558 mm, respectively) and the cowdung alone (186 mm, 811 mm and 1481
mm, respectively). The addition of cowdung + cassia gave significant average dry matter yield (2495 kg ha') over the control (1409 kg ha"'), the cassia alone (1832 kg ha"') and the cowdung alone (1437 kg ha"') treatments. The treatments with cassia + cowdung had an average grain yield of 2226 kg ha"' being 99 %, 41 % and 86 % grain yield increases over the cowdung alone (1120 kg ha"'), the control (1082 kg ha"') and the cassia (1195 kg ha"') treatments, respectively. Generally, grain yield increased with increasing levels of manure amendments. The application of the organic matter had no significant effect on plant tissue nutrient concentrations at all stages of growth. The use of cowdung + cassia, cassia alone, cowdung alone enhanced the uptake of N with the values of 3.06-5.20 kg ha", 1.51-2.19 kg ha"' and 1.69 kg ha"' respectively as compared to 1.35 kg ha"' in the control plot, at the 4-6 leaf stage. Significant increases occurred in K and Mg uptake at the 4-6 leaf stage especially for the treatments with the cowdung + cassia.
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Keywords
Corn -- Zambia , Crop science-effect of green manure,cowdung and their combinations on growth and grain yield of maize