5 Residue Management in Pulse Intercropping -A Precursor for Soil Quality Improvement in Rainfed Regions Ummed Singh*, Narendra Kumar, C.S. Praharaj, K.K. Hazra and M. Senthil Kumar Indian Institute of Pulses Research, Kanpur, Uttar Pradesh, India-208 024 singhummed@yahoo.co.in Key words: Intercrop, Pulse Residue, SMBC, Soil Quality Crop residues added through growing food crops accrues substantial benefits in terms of SOC and conservation of resources including recycling of nutrients (Venkatesh at al. 2013). Besides their diverse uses through food for human, feed and fodder for ruminants, wastes for composting and burying in-situ and mulches as soil cover; addition of crop residues and/or minimum tillage sustains crop productivity and restores soil fertility. An analysis suggests that India generates around 500 million tonnes of crop residues every year retaining substantial amount of mineral nutrients as a component for crop uptake. For example, in cereals alone around 25% of N & P, 50% of S and 75% of K uptake are retained back in residues, and are subjected to further recycling as a valuable source of nutrients in soil. In pulses however, its residue add more nutrients in soil compared with cereals due to low C: N ratio. Pulses, like pigeonpea and chickpea also add substantial biomass through leaf fall and plant residues resulting in long-term improvement in soil quality and productivity of crops. This is further enhanced through conservation of soil moisture through incorporation of above ground biomass and mulching (Wilhelm et al. 2004). Therefore, soil organic matter is important in relation to soil fertility, sustainable agricultural systems, and crop productivity, and there is concern about the level of organic matter in many soils, particularly with respect to global warming (Venkatesh at al. 2013). Long-term experiments since 1843 at Rothamsted provide the longest data sets on the effect of soil, crop, manuring, and management on changes in soil organic matter especially under temperate climatic conditions. Trends in long-term crop yields also show that as yield potential has increased, yields are often larger on soils with more organic matter compared to those on soils with less. Under arid and semi-arid conditions of India, declined soil quality as a result of deteriorated soil fertility associated with low soil organic carbon (SOC) and limiting soil moisture (LSM) is thus, the major constraint in realizing higher productivity of crops (Praharaj 2013). In rainfed agro-ecology, monsoon crops are dependent on rainfall water while the succeeding fall planted crops are dependent on residual soil moisture, reinforced sometimes with one or two supplementary irrigations. Under the above situation, short duration crops, like sorghum, pearlmillet, mungbean, cowpea and cluster bean followed by chickpea, lentil, mustard and barley during fall are preferred due to their satisfactorily yield levels. In addition growing of a pulse intercrop like, cowpea, green gram and black gram in a cereal system could supplement the sole crop yield besides acting as an insurance against aberrant weather situations (Johnston et al. 2009). A recent study carried out during 2012-13 at Indian Institute of pulses Research, Kanpur under Indo- Gangetic plains of India suggests that higher pearl millet equivalent yield (PEY) was recorded when the cereal component is intercropped with green gram (PEY of 3612 kg/ha) and cowpea (3227 kg/ha) over the sole cereal (2635 kg/ha) crop. Improved moisture conservation practices also results in higher relative leaf water content (RWC, 62.2%) at 90 days in fall planted chickpea under the combined practice of mulching and one supplemental irrigation (similar to the combined effect of mulching + two irrigations). Similar benefits are also observed under adequate crop nutrition (recommended crop nutrition). Improvement in soil physico-chemical (decrease in bulk density and soil penetration resistance, and increase in water holding capacity) and biological properties (soil microbial biomass carbon up to 450 μg/g soil and dehydrogenase activity up to 21 μg TPF/24 hr/g soil) inclusive of higher residual nutrient status (available N, P, K, S, Zn and Fe and organic carbon for chickpea) are also evident under