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 ap plication of inorganic fertilizers and farmyard manure (FYM). Weeds we re controlled by hand or by the use of herbicides. The hand weeding tr eatment resulted in a lowering of the bulk density of the surface laye r (0-15 cm) and a significant increase in the subsurface (15-30 cm) de nsity. Application of FYM significantly increased the soil organic car bon (OC), infiltration rate, water retention, aggregation and aggregat e stability in water. Application of inorganic fertilizers had small b ut statistically significant effect in increasing soil OC.