Herbage production and soil fertility changes in different pastures as influenced by fertilization under semi-arid conditions

Abstract

A field study was conducted between 2001 and 2004 on six different pasture systems [natural pasture, buffel grass (Cenchrus ciliaris L.), stylo (Stylosanthes hamata L.), buffel + stylo + shrub (Leucaena leucocephala L.), buffel + stylo + shrub + tree (Albizia lebbeck L.]. The performance under fertilized and unfertilized situations in re- lation to amount of rainfall received was analysed over the years. A total of 19 species were encountered in natural pasture which included 6 grasses, 5 legumes and 8 forbs. Significantly the highest pasture production (9.90 tiha) was recorded in buffel + stylo + shrub-based mixed pasture. Over all, there was about 21 3% increase in yield due to fertilizer application. The fodder shrub Leucaena contributed about 16% to the total biomass. The physico-chemical properties of soil improved under different pastures after 4 years in increasing water-holding capacity, pore space, and decreasing bulk density particularly under fertilized situation. The build up of organic carbon content was higher under sole Stylosanthes. The soil dehydrogenase and phosphatase enzymatic activ- ity were enhanced in both fertilized and unfertilized pastures. Dehydrogenase activity was the highest in fertil- ized pure legume. Supplementation of legume and top feeds viz,. Leucaena and Albizia in Cenchrus ciliaris based fodder improved the quality in crude protein, ether extract, calcium and phosphorus contents with reduc- tion in neutral detergent fibre and acid detergent fibre contents.