IJAER

International Journal of Agriculture and Environmental Research™

ISSN 2455-6939

Title:
CONSERVATION AGRICULTURE WITH LEGUMINOUS SHRUBS AT DIFFERENT SPATIAL PATTERNS ENHANCES SMALLHOLDER PRODUCTIVITY OF MAIZE-LEGUME INTERCROPS IN DRY-LAND EASTERN KENYA

Authors:
Vincent Rabach , Oscar Masika, James Koske

Abstract:
Declines in soil fertility and water, prolonged dry-spells/droughts and erratic climatic patterns in general continue to undermine optimal agricultural productivity in Sub-Saharan Africa (SSA). Drier parts of Eastern Kenya already endure low/declining soil fertility, low soil water content, increased temperatures/atmospheric heat, and unpredictable rainfall and drought patterns. These have occasioned continued declines in smallholder farm productivity (below 1 Mg ha-1 against a potential of 6-8 Mg ha-1 ) and resiliency. Optimizing on on-farm soil water and fertility management through conservation agriculture (CA) technologies such as sustained soil cover/residue retention, micro-dosing and minimum tillage, integrated with selected tree species (for soil fertility enhancement, fodder, firewood) may hold in upgrading and developing resiliency towards extreme climatic risks among smallholder farming systems. Redressing the problem of increased food insecurity and productivity challenges requires a farming system that maximizes on yield productivity per unit water/nutrient and/or land. This study evaluated the best integration of Gliricidia sepium and Calliandra calothyrsus in a maize inter-cropping system under conservation agriculture (CA) among smallholder farmers in dryland Eastern Kenya, using completely randomized block design trials, where CA (minimum tillage) and conventional agricultural (COA) systems were evaluated. Gliricidia sepium and Calliandra calothyrsus were integrated at inter-row spacings of 4.5m, 3.0m and 1.5m; and 1m intra-row in each system in plots of 12 by 12 m, set up at the Agricultural Research Station (ATC) in Machakos, Kenya. Yield data was analyzed with mixed model of analysis of variance, treating tree species, inter/intra row tree spacing and CA/COA as fixed effects, while maize, legume, tree yield and replication were treated as random effects. Accounting for heteroscedasticity utilized modeling the covariance structure with power-of-the-mean using Genstat 14. Standard error of difference of means (SED) test (p < 0.05) was used to evaluate how significant treatments differed from each other. Results showed that Calliandra spaced at 3 or 4.5 m yielded significantly (p= 0.003 and 0.01) higher maize yield when compared to spacing Calliandra at 1.5. Yields (Grain=5.31 and stover=5.66 Mg ha-1 ) in Gliricidia spaced at 4.5 m were significantly (p=0.01) higher compared to yield in any other treatments tested. No significant (p=0.136) differences occurred in maize yields under CA or COA as sole and on integration with tree species. Yields at researcher managed trials were more than those at on farm trials, whereas in both, productivity of biomass; growth of canopy; heights and tree circumference were enhanced in CA than COA.

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