effect of conservation agriculture practices on oat fodder yield, water use efficiency, and microbial biomass c and n in rainfed dry area of north- west pakistan

crop productivity, water use efficiency (wue), and microbial biomass c and n in rainfed dry area are influenced by tillage, rotation, and crop residue management. field experiments were conducted during 2005-08 to study the effect of tillage, crop rotation, and crop residue retention on oat fodder yield, water use efficiency, and microbial biomass c (mbc) and n (mbn) under semi-arid conditions in north-west pakistan. the objective of the study was to identify suitable cultural practices and fodder cropping system with improved water use efficiency for a dry area. the treatments consisted of three rotations: i) oat–fallow–oat (o-f-o)-farmers’ practice, ii) oat– summer legume–oat (o-sl-o), and iii) oat–summer cereal–oat (o-sc-o). for each rotation, there were two tillage and two crop residue management treatments: i) tillage (crop residues removed) and tillage (crop residues retained), and ii) no-tillage (crop residues removed) and no-tillage (crop residues retained). basal doses of n60+p60 (kg ha-1) to oat, n90+p60 to summer cereals and n20+p60 (kg ha-1) to legumes were applied. changes in soil water storage were monitored with neutron moisture probe for calculation of wue. the results indicated that an average maximum dry matter yield (7.78 t ha-1) and wue (26.47 kg ha-1mm-1) was obtained under no-tillage+crop residues treatment. the tillage practices showed no-significant effect on oat dry matter yield and wue. the oat yield and wue was higher in o-f-o rotation compared to o-sl-o and o-sc-o. the surface soil (0-15 cm) analysis showed that mbc and mbn was consistently greater in the no-tillage+crop residues treatment. these results indicated that no-tillage+crop residue treatment was relatively more beneficial under the rainfed (dry) conditions.