Abstract

Conservation horticulture is a new concept in management of soil health under perennial horticultural cropping systems. Experiments conducted reasonably over a long period on such soil management systems provide valuable information about sustainability of production systems. This paper reports the results of comprehensive investigations on soil chemical, physical, biochemical and biological properties of soils under conventional and conservation horticulture practices over a long period in drylnd mango orchards on Alfisols. Effects of conservation tillage, inter cropping and cover cropping on soil carbon fractions was measured by determination of loss on ignition, organic carbon (OC) and active carbon (AC). Soil biochemical properties were evaluated by measuring glomalin and extracellular enzymatic activities viz., dehydrogenase, urease, phosphomonoestrase and arylsulphatase and measurement of soil microbial biomass carbon (MBC) and carbon mineralization. Biological status was evaluated by estimating bacterial, actinobacterial and fungal populations, earthworms, micro arthropods and centipedes. Soil physical status was assessed by measuring bulk density, soil moisture status and infiltration rates.

Conservation horticultural practices improved the quality of soil, especially near the surface, by lowering the bulk density and enhancing infiltration rate. The soil aggregate formation and water stability have enhanced in plots with conservation practices because of higher production of glomalin compared with vegetable and orchard plots where conventional practices were followed. Relationship between measured infiltration and soil properties showed high average IRs in conservation plots due to high organic matter content, low bulk density values and enhanced exchangeable basic cations. Vegetable plots and conventional mango plots showed complete decline in earthworm and centipede population while plots with conservation practices showed a build-up of their population. Microbial and biochemical properties significantly improved in plots with conservation horticultural practices over orchard plots with conventional practices. Legumes as inter and cover crops were found to be superior in improving soil quality than sweet potato.

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