Influence of farmyard manure, inorganic fertilizers and weed control practices on some soil physical properties in a long-term experiment

In a long-term experiment, soil physical properties were studied after 20 annual cycles of maize-wheat-fodder cowpea cropping with annual application of inorganic fertilizers and farmyard manure (FYM). Weeds were controlled by hand or by the use of herbicides. The hand weeding treatment resulted in a lowering of the bulk density of the surface layer (0-15 cm) and a significant increase in the subsurface (15-30 cm) density. Application of FYM significantly increased the soil organic carbon (OC), infiltration rate, water retention, aggregation and aggregate stability in water. Application of inorganic fertilizers had small but statistically significant effect in increasing soil OC.