Not AvailableMajor nutrient management systems for rice-wheat cropping were compared for their potential to
credit organic carbon (C) to the soil, its fractionation into active (very labile, VLc; labile, Lc) and passive
(less labile, LLc; non-labile, NLc) pools, and crop yield responses. A ten-year long experiment was used
to study effects of: (i) no inputs (Control, O), (ii) 100% inorganic fertilizers (F) compared to reduced
fertilizers inputs (55%) supplemented with biomass incorporation from (iii) opportunity legume crop
(Vigna radiata) (LE), (iv) green manure (Sesbania aculeata) (GM), (v) farmyard manure (FYM), (vi) wheat
stubble (WS), and (vii) rice stubble (RS). Maximum C input to soil (as the percentage of C assimilated in
the system) was in GM (36%) followed by RS (34%), WS (33%), LE (24%), and FYM (21%) compared to
O (15%) and F (15%). Total C input to soil had a direct effect on soil C stock, soil C fractions (maximum in
VLc and LLc), yet the responses in terms of biological yield were controlled by the quality of the biomass
(C:N ratio, decomposition, etc.) incorporated. Legume-based biomass inputs accrued most benefits for
soil C sequestration and biological productivity.Not Availabl
