Retentionof carbon(C)inarable soilshas beenconsidered as apotentialmechanismtomitigate soil degradation
and to sustain crop productivity. Hence, we appraised the 3-year effect of different conservation
agriculture (CA) practices on grain yield, biomass productivity and soil organic C (SOC) accumulation rates
under a tropical rice (Oryza sativa L.)-wheat (Triticum aestivum L.) and rice–wheat–green gram (mungbean
in Hindi; Vigna radiata) cropping systems. Results indicate mean (of three years) rice grain yield
under mungbean residue + direct seeded rice (DSR) followed by zero tilled wheat (ZTW) with rice residue
(RR) retention and zero tilled relay summer mungbean (MBR + DSR-ZTW+ RR-ZTMB) plots was similar to
farmers’ practice [transplanted rice (TPR)- conventionally tilled wheat(CTW)], despite TPR-CTWplotshad
∼18% higher rice yield than MBR + DSR-ZTW+ RR-ZTMB plots in the first year. The MBR + DSR-ZTW+ RRZTMB
treated plots had about 15 and 10% higher mean wheat grain yield and mean system productivity
(sum of grain yields of all crops) than TPR-CTW plots, respectively. The plots under DSR + brown manuring
(BM)-ZTW+ RR plots had comparable mean rice and wheat yields to MBR + DSR- ZTW+ RR-ZTMB
plots. Harvestable aboveground biomass productivity of MBR + DSR-ZTW+ RR-ZTMB treated plots was
∼2.89 Mg ha−1 yr−1 higher than TPR-CTW. Total estimated C input (∼12.1 Mg C ha−1 in three years) under
MBR + DSR-ZTW+ RR-ZTMB treated plots was ∼117 and 127% higher than DSR-ZTW and TPR-CTW treatments,
respectively. All CA plots had significantly higher gain (over initial value) in total SOC than that
in TPR-CTW and TPR-ZTW treatments in the 0–15 cm layer and the gain in total SOC in the plots under
MBR + DSR- ZTW+ RR-ZTMB was significantly higher than all CA plots, despite having similar total SOC
stocks.Again, plotsunderMBR + DSR-ZTW+ RR-ZTMBhad∼24%larger labileCpools thanthat of TPR-CTW
(3.1 g kg−1)treated plots in the topsoil. Soil bulk density under MBR + DSR- ZTW+ RR-ZTMB and DSR + BMZTW+
RR treated plots significantly decreased in the 5–15 cm layer compared to TPR-CTW plots. Thus,
the MBR + DSR-ZTW+ RR-ZTMB treatment (a novel CA practice), has considerable potential to retain C
in surface soil, decrease soil compaction and increase system (rice–wheat–green gram) productivity and
hence its adoption is recommended.
Retentionof carbon(C)inarable soilshas beenconsidered as apotentialmechanismtomitigate soil degradationand to sustain crop productivity. Hence, we appraised the 3-year effect of different conservationagriculture (CA) practices on grain yield, biomass productivity and soil organic C (SOC) accumulation ratesunder a tropical rice (Oryza sativa L.)-wheat (Triticum aestivum L.) and rice–wheat–green gram (mungbeanin Hindi; Vigna radiata) cropping systems. Results indicate mean (of three years) rice grain yieldunder mungbean residue + direct seeded rice (DSR) followed by zero tilled wheat (ZTW) with rice residue(RR) retention and zero tilled relay summer mungbean (MBR + DSR-ZTW+ RR-ZTMB) plots was similar tofarmers’ practice [transplanted rice (TPR)- conventionally tilled wheat(CTW)], despite TPR-CTWplotshad∼18% higher rice yield than MBR + DSR-ZTW+ RR-ZTMB plots in the first year. The MBR + DSR-ZTW+ RRZTMBtreated plots had about 15 and 10% higher mean wheat grain yield and mean system productivity(sum of grain yields of all crops) than TPR-CTW plots, respectively. The plots under DSR + brown manuring(BM)-ZTW+ RR plots had comparable mean rice and wheat yields to MBR + DSR- ZTW+ RR-ZTMBplots. Harvestable aboveground biomass productivity of MBR + DSR-ZTW+ RR-ZTMB treated plots was∼2.89 Mg ha−1 yr−1 higher than TPR-CTW. Total estimated C input (∼12.1 Mg C ha−1 in three years) underMBR + DSR-ZTW+ RR-ZTMB treated plots was ∼117 and 127% higher than DSR-ZTW and TPR-CTW treatments,respectively. All CA plots had significantly higher gain (over initial value) in total SOC than thatin TPR-CTW and TPR-ZTW treatments in the 0–15 cm layer and the gain in total SOC in the plots underMBR + DSR- ZTW+ RR-ZTMB was significantly higher than all CA plots, despite having similar total SOCstocks.Again, plotsunderMBR + DSR-ZTW+ RR-ZTMBhad∼24%larger labileCpools thanthat of TPR-CTW(3.1 g kg−1)treated plots in the topsoil. Soil bulk density under MBR + DSR- ZTW+ RR-ZTMB and DSR + BMZTW+RR treated plots significantly decreased in the 5–15 cm layer compared to TPR-CTW plots. Thus,the MBR + DSR-ZTW+ RR-ZTMB treatment (a novel CA practice), has considerable potential to retain Cin surface soil, decrease soil compaction and increase system (rice–wheat–green gram) productivity andhence its adoption is recommended.
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