Alley Cropping Agroforestry System for Improvement of Soil Health

Abstract

AbstractPractice of agroforestry system on tree-less lands provides a unique opportunity to improve soil health/quality while maintaining crop productivity in additional to provision of tree products to the rural farming communities. In nutrient poor tropical soils, introduction of agroforestry systems is proven to be sustainable and economical practice in many parts of the world. Among different systems/practice of agroforestry, alley cropping is one of the recently developed agroforestry techniques (during 1970’s) to overcome the management problems of the upland soils, and to incorporate the benefits of much needed tree fallow component. In alley cropping, agriculture crops are grown between hedgerows of planted shrubs and trees, preferably leguminous species, which are regularly/intermittently pruned to prevent light competition and shading to the companion crop. Alley cropping improves the soil physical, chemical and biological properties by improving the nutrient recycling through the addition of pruned leafy biomass, reduction in nutrient loss by erosion control and reducing leaching losses. The improved soil physical properties like soil aeration, aggregate stability and infiltration rate, in alley cropping may lead to regeneration of the degraded topsoil and thus may produce more stable aggregates and provide favourable soil media for the crop cultivation. The practice of Gliricidia and Leucaena alley has shown the improvement in the soil moisture availability during the dry season of the cropping period. The use of N fixing trees as hedgerow adds huge amount of nitrogen and potassium through its biological nitrogen fixation and pruned leafy biomass incorporation. While phosphorus is made available by the organic acids bind to Al and Fe oxides which released during the biomass decomposition, and reduces Al saturation and toxicity. Alley cropping proven to improve the soil biological properties like microbial biomass and enzyme activity through improvement in soil organic matter content through addition of tree leaf litter, fine roots, and crop residues. The improvement of all three soil properties ultimately improves the soil quality and soil health. The improved soil quality and modified microclimate ultimately increase the productivity of the associated crops. In recent years, alley cropping is recognised as potential agroforestry practice for soil carbon sequestration. Overall, alley cropping has the ability to improve soil quality by modifying soil properties. The improvement of soil properties is highly varied with different alley species, soil type, climate and the management practice. In general, alley cropping responds more effectively to intensive management and may not be a suitable system in arid areas. In alley cropping management, selection of suitable hedge row species based on soil and environmental condition is important to obtain the full benefits of this agroforestry system.KeywordsCarbon sequestrationHedge row intercroppingSoil qualityWater stable aggregates