Fluctuations in soil management practices, temperature and moisture conditions can impact adsorption-desorption and bioavailability of phosphorus (P) in agricultural soils. Therefore, this study investigates P dynamics in straw-managed soils of Punjab collected from five treatments namely (1) conventional tillage (CT) after removal of rice straw (CT-R), (2) Treatment 1 plus biochar amendment at 2 Mg ha−1 (CT+biochar), (3) zero tillage with straw retention as mulch (ZT+RM), (4) CT with straw incorporation (CT+RI) and (5) CT after rice residue burned (CT+RB) after three years from an ongoing experiment in rice-wheat cropping system. The adsorption-desorption of P followed pseudo second order kinetics (R2> 0.99) and Freundlich isotherm (R2> 0.95) for all the treatments and temperatures. Freundlich adsorption capacity (KFads) varied with the physico-chemical soil properties and ranged from 10.9 to 28.5, 14.3–32.2, 18.3–40.2, and 22.5–56.5 μg1−ng−1mLn at 15, 25, 35, and 45 ± 1°C, respectively. The sequential order of P adsorption was as follows: CT+ biochar > CT+RB > ZT+RM > CT+RI > CT-R, irrespective of temperature. Thermodynamic parameters revealed feasible, spontaneous and endothermic process indicative of physio-sorption via. hydrogen bonding as the dominant mechanism in in-situ straw managed soils. The Freundlich desorption coefficient (KFdes) ranged from 54.8 to 85.2, 39.9–60.8, 23.4–37.0, 29.6–45.7 and 19.4–36.7 μg1−ng−1mLn in CT+ biochar, CT+ RB, ZT+RM, CT+RI, CT-R, respectively at studied temperatures and was greater than adsorption in all treatments indicating hysteresis. The desorption sequence was observed as: CT-R > CT+RI > ZT+RM > CT+ RB> CT+ biochar. The greater adsorption and slower desorption of P under in-situ straw managed treatments (CT+biochar, CT+RB and ZT+RM) than CT-R and CT +RI, particularly CT+ biochar compared to CT-R will lead to more P retention in soil matrix thereby preventing eutrophication and deterioration of surface waters.

中文翻译：

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稻草管理方案影响印度西北部稻麦系统中的土壤磷吸附-解吸、动力学和热力学


土壤管理实践、温度和湿度条件的波动会影响农业土壤中磷 （P） 的吸附-脱附和生物利用度。因此，本研究调查了从五个处理中收集的旁遮普邦秸秆管理土壤的磷动力学，即 （1） 去除稻草后的常规耕作 （CT-R），（2） 处理 1 加 2 Mg ha-1 的生物炭改良剂（CT+生物炭），（3） 秸秆保留作为覆盖物的零耕作 （ZT+RM），（4） 秸秆掺入 CT （CT+RI） 和 （5） 稻秸秆焚烧后 CT （CT+RB） 从正在进行的稻麦种植系统实验三年后。在所有处理和温度下，P 的吸附-解吸都遵循准二级动力学 （R2> 0.99） 和 Freundlich 等温线 （R2> 0.95）。Freundlich 吸附容量 （KFads） 随土壤物理化学性质而变化，在 15°C、25°C、35°C 和 45°C 下分别为 10.9 至 28.5、14.3–32.2、18.3–40.2 和 22.5–56.5 μg1−ng−1mLn ± 1mLn。P 吸附的顺序如下：CT+ 生物炭 > CT+RB > ZT+RM > CT+RI > CT-R，与温度无关。热力学参数揭示了可行的、自发的和吸热过程，表明物理吸附通孔。氢键是原位秸秆管理土壤中的主要机制。在研究温度下，Creundlich 解吸系数 （KFdes） 范围为 54.8 至 85.2、39.9–60.8、23.4–37.0、29.6–45.7 和 19.4–36.7 μg1−ng−1mLn 在 CT+ 生物炭、CT+ RB、ZT+RM、CT+RI、CT-R 中，并且在所有表明滞后的处理中都大于吸附。解吸顺序为：CT-R > CT+RI > ZT+RM > CT+ RB> CT+ 生物炭。 在原位秸秆管理处理（CT+生物炭、CT+RB 和 ZT+RM）下，磷的吸附更大且解吸更慢，尤其是与 CT-R 相比，CT+ 生物炭将导致更多的磷保留在土壤基质中，从而防止地表水富营养化和恶化。