Recently conservation agriculture (CA) using the principles of zero tillage, crop residue management and suitable crop rotation has gained the momentum and quite popular among the farmers. Researchers throughout the globe have shown the potential of CA in enriching soil organic carbon storage in various soil types and cropping systems. But there is very limited study on the effect of CA on soil humic acid content and their stability and abundance of functional groups. An experiment was conducted in an Alfisols with four scenarios (designated as Sc) namely conventional farmers practice (Sc1) of transplanted rice (TPR) followed by conventional tilled broadcasted wheat (CT- wheat) with residue removal, transplanted rice (TPR) followed by zero tillage (ZT) wheat and mung bean with partial residue retention (Sc2), direct seeded rice (DSR) followed by ZT- wheat and mung bean with full residue retention (Sc3), ZT-maize followed by ZT-wheat and mung bean (Sc4) at the research farm of ICAR-Central Soil Salinity Research Institute, Karnal, Haryana, India. The objectives of this study were to assess the humic acid (HA) content and stability of soil carbon through desorption study and to characterize the functional groups of HA by Fourier Transform Infrared (FTIR) spectroscopy under different scenarios. HA was extracted from soil samples collected from 0 to 15 and 15–30 cm depth after rice harvesting in 2018 after nine years of the experiment. Results showed that Sc4 recorded significantly highest HA content at 0–15 depth (4.23 g/kg) and 15–30 cm soil depth (2.08 g/kg). Lower E4/E6 ratio revealed higher stability and humification of humic acid carbon under CA based scenarios. Lowest desorption rate constant (0.20/day) was observed under Sc4 indicating higher organic carbon stability in soil. Higher labile carbon and nitrogen was observed in soils under Sc3 as revealed through desorption study. FTIR spectroscopy results confirmed the prevalence of higher number of functional groups (OCO, CO or CHO) in HA under CA based scenarios with an order of Sc4 >Sc3 >Sc2 >Sc1. Therefore, CA is not only efficient in enriching the organic carbon in soil but also in more stable complex of HA with soil particles having long term implications in soil carbon sequestration for future posterity.

近年来，以零耕、残茬管理和适宜轮作为原则的保护性农业（CA）风靡一时，深受农民欢迎。全球的研究人员已经展示了 CA 在丰富各种土壤类型和种植系统中土壤有机碳储存方面的潜力。但关于CA对土壤腐植酸含量及其稳定性和官能团丰度的影响的研究非常有限。在Alfisols中进行了一项实验有四种情景（指定为 Sc），即传统农民实践（Sc1）移栽水稻（TPR），然后是去除残留物的传统耕作广播小麦（CT-小麦），移栽水稻（TPR），然后是零耕（ZT）小麦和部分残留保留的绿豆 (Sc2)、直播稻 (DSR) 其次是 ZT-小麦和完全保留残留的绿豆 (Sc3)、ZT-玉米然后是研究农场的 ZT-小麦和绿豆 (Sc4) ICAR-中央土壤盐度研究所，印度哈里亚纳邦卡纳尔。本研究的目的是通过解吸研究评估腐殖酸 (HA) 含量和土壤碳的稳定性，并通过傅里叶变换红外 (FTIR) 光谱在不同情况下表征 HA 的官能团。经过 9 年的试验，从 2018 年水稻收获后从 0 到 15 和 15-30 厘米深度收集的土壤样品中提取了 HA。结果表明，Sc4 在 0-15 深度（4.23 g/kg）和 15-30 cm 土壤深度（2.08 g/kg）记录了显着最高的 HA 含量。较低的 E4/E6 比率表明在基于 CA 的情况下腐植酸碳的稳定性和腐殖化程度较高。在 Sc4 下观察到最低的解吸速率常数（0.20/天），表明土壤中有机碳稳定性更高。通过解吸研究揭示，在 Sc3 下的土壤中观察到更高的不稳定碳和氮。FTIR 光谱结果证实了较高数量的官能团 (O 23 g/kg) 和 15–30 cm 土壤深度 (2.08 g/kg)。较低的 E4/E6 比率表明在基于 CA 的情况下腐植酸碳的稳定性和腐殖化程度较高。在 Sc4 下观察到最低的解吸速率常数（0.20/天），表明土壤中有机碳稳定性更高。通过解吸研究揭示，在 Sc3 下的土壤中观察到更高的不稳定碳和氮。FTIR 光谱结果证实了较高数量的官能团 (O 23 g/kg) 和 15–30 cm 土壤深度 (2.08 g/kg)。较低的 E4/E6 比率表明在基于 CA 的情况下腐植酸碳的稳定性和腐殖化程度较高。在 Sc4 下观察到最低的解吸速率常数（0.20/天），表明土壤中有机碳稳定性更高。通过解吸研究揭示，在 Sc3 下的土壤中观察到更高的不稳定碳和氮。FTIR 光谱结果证实了较高数量的官能团 (OÇ O，C在HA O或CHO）CA下基于情景与Sc4中> Sc3中> Sc2中> SC1的顺序。因此，CA 不仅能有效地富集土壤中的有机碳，而且还能使 HA 与土壤颗粒形成更稳定的复合物，对未来的土壤固碳具有长期影响。