An understanding of the dynamics of carbon (C) stock in soils, as impacted by management strategies, is necessary to identify the pathways of C sequestration in soils and for maintaining soil organic C (SOC) at a level critical for upkeeping soil health and also for restraining global warming. This is more important in tropical and subtropical region where soils are inherently low in organic C content and the production system is fragile. We evaluated the long-term role of crop residue C inputs to soil in SOC sequestration and also the critical value of C inputs for maintenance of SOC across five different ricebased cropping systems and four soil management practices including a fallow (no cultivation since initiation of the experiments) using five long-term (7-36 years) fertility experiments in subtropical India. Cropping per se always caused a net depletion of SOC. Such depletion was inversely proportional to the amount of crop residue C incorporated into the soils (r 5À0.92, P 5 0.001). Balanced fertilization with NPK, however, caused an enrichment (9.3-51.8% over the control) of SOC, its extent being influenced by the cropping systems. Long-term application of organic amendments (5-10 Mg ha À1 yr À1 ) through farmyard manure (FYM) or compost could increase SOC hardly by 10.7% constituting only 18% of the applied C, the rest getting lost through oxidation. The total quantity of soil C sequestered varied from À11.5 to 14.5 Mg C ha À1 and was linearly related (r 2 5 0.40, P 5 0.005) with cumulative crop residue C inputs to the soils. On an average, the rate of its conversion to SOC came out to be 6.4%. This was more in presence of added organics (6.9%) than in its absence (4.2%). For sustenance of SOC level (zero change due to cropping) we found that a minimum quantity of 2.9 Mg C is required to be added per hectare per annum as inputs. The cropping systems and the management practices that could provide C input higher than the above critical level are likely to sustain the SOC level and maintain good soil health in the subtropical regions of the Indian subcontinent.

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A field experiment on African marigold (Targets erecta L.) was conducted during winter season of 2014-15to study the foliar effect of Zn and SA of 20 treatment combinations having five concentrations of zinc (0.0, 0.25, 0.50, 0.75, and 1.0 %) and salicylic acid (0.0, 0.25, 0.50 and 1.0 mM/L).The treatmentZn4SA3 (Zinc 1% + Salicylic acid 1.0 mM/L) recorded the maximum plant height (77.41 cm), number of leaves per plant (314.10),earliest first flower bud appearance (39.78 days), maximum number of flowers per plant (62.33), maximum chlorophyll content (3.83mg/g) and maximum carotene content (3.07 mg/g)as compared to control where it was recorded minimum. These results are conclusive that foliar spraying with zinc 1.0% + salicylic acid 1.0 mM/L may positively increasedthe growth and flowering parametersof marigold.