Long-term effect of organic fertilizer and biochar on soil carbon fractions and sequestration in maize-black gram system

Abstract In the process of carbon storage, fractionation, and mineralization in soil, biochar and organic manure are essential. Regarding the impact of these interconnected procedures that link to soil C-cycling, there are still some doubts. At the ICAR-Sikkim Centre in Gangtok, India, a ten-year fi...
Ausführliche Beschreibung

Abstract In the process of carbon storage, fractionation, and mineralization in soil, biochar and organic manure are essential. Regarding the impact of these interconnected procedures that link to soil C-cycling, there are still some doubts. At the ICAR-Sikkim Centre in Gangtok, India, a ten-year field experiment was conducted during 2013–2022 to investigate the effects of maize stalk and cob biomass-derived biochar (pyrolyzed at 600 °C) and different organic manure (5.0 t $ ha^{−1} $ to 10.0 t $ ha^{−1} $) applications on soil carbon fractions and sequestration in maize-black gram system. The biochar was morpho-mineralogically characterized by SEM, TEM, EDS, TGA, FT-IR, and XRD. Types of organic manure and biochar significantly enhanced total carbon and oxidizable carbon. It also influenced water-soluble, hot water extractable, and particulate organic carbon than control. Combinations of biochar and organic manure both considerably lowered soil bulk density. The vermicompost influenced highest in particulate organic carbon and pig manure lowest compared to other manure and control. The treatment poultry manure 5 t $ ha^{−1} $ + biochar 2.5 t $ ha^{−1} $ (48.93) decreased water-soluble carbon (µg $ g^{−1} $ soil) significantly, followed by pig manure 5 t $ ha^{−1} $ + biochar 2.5 t $ ha^{−1} $ (52.33) as compared to control $ T_{1} $ (76.24) from initial value 71.39. An increase in organic manure and biochar application rate significantly increased carbon sequestration potential. Manures with biochar resulted in more influence on the annual rate of carbon sequestration than only manure without biochar. Among the manures with biochar, the treatment vermicompost 5 t $ ha^{−1} $ + biochar 5 t $ ha^{−1} $ (30.41) increased carbon retention efficiency (%) significantly, followed by goat manure 5 t $ ha^{−1} $ + biochar 5 t $ ha^{−1} $ (30.10), as compared to control $ T_{1} $ (3.53). Manures with biochar resulted in less influence in potentially mineralizable carbon than manure without biochar. FYM at 10 t $ ha^{−1} $ + biochar 5 t $ ha^{−1} $ (33.49) decreased potentially mineralizable nitrogen (mg $ NH_{4} $+-N $ kg^{−1} $) significantly, followed by pig manure 5 t $ ha^{−1} $ + biochar 5 t $ ha^{−1} $ (34.12) than manure without biochar. Our work unequivocally showed that applying biochar and organic manure to a maize-black gram system has great potential for C-sequestration and can play a vital role in C-fractionations. Ausführliche Beschreibung