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Conservation Tillage Impacts on Soil Aggregation and Carbon Pools in a Sandy Clay Loam Soil of the Indian Himalayas
Author(s) -
Bhattacharyya Ranjan,
Tuti M. D.,
Kundu S.,
Bisht J. K.,
Bhatt J. C.
Publication year - 2012
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2011.0320
Subject(s) - loam , tillage , soil carbon , conventional tillage , agronomy , kharif crop , bulk density , total organic carbon , environmental science , soil science , soil water , zoology , chemistry , crop , biology , environmental chemistry
Soil conservation and C sequestration are critical issues in rainfed farming of the Indian Himalayas. This study, conducted from 2003 through 2009 on a sandy clay loam soil (Typic Haplaquept) near Almora, India, evaluated the effect of seasonal tillage alterations (year‐round conventional tillage [CT–CT], year‐round no tillage [NT–NT], CT in the Rabi [winter] season and NT in the Kharif [summer/rainy] season (CT–NT) and the reverse [NT–CT] of the latter treatment) on soil organic carbon (SOC) retention, soil aggregation, aggregate‐associated C concentrations and particulate organic matter‐carbon (POM–C) in the 0‐ to 15‐cm soil layer. Results indicate that the plots under NT–NT, NT–CT, and CT–NT had nearly 16, 12, and 10% higher total SOC content compared with CT‐CT (∼12 g kg −1 soil) in the 0‐to 5‐cm soil layer. However, tillage had no impact on total SOC content in the subsurface (5‐ to 15‐cm) soil layer. Although the labile pools of SOC were positively affected by conservation tillage practices (CT–NT, NT–NT, and NT–CT), the less labile pool was only influenced by the continuous NT and NT–CT in the 0‐ to 5‐cm depth. Plots under NT–NT and NT–CT had about 27 and 19% higher labile SOC pool than CT–CT plots (5.65 g C kg −1 soil), and NT–NT and NT–CT plots had about 14 and 11% higher less labile SOC pool than CT–CT plots (2.61 g C kg −1 soil) in that soil layer. Plots under NT–NT and one seasonal tillage (NT–CT and CT–NT) also had higher macroaggregates and macroaggregate‐associated SOC after 6 yr of study than CT–CT plots. Greater proportion of microaggregates within macroaggregates in the plots under NT–NT compared with CT–CT was also observed in the surface layer only. The NT–CT plots had similar effects on all studied soil properties to CT–NT plots, apart from the mean weight diameter (MWD) and labile SOC pool in the 0‐ to 5‐cm soil layer were higher under former plots than the latter. Plots under NT–NT had about 10% higher coarse (250–2000 μm) intra‐aggregate particulate organic matter‐C (iPOM–C) within >2000 μm sand free aggregates in the 0‐ to 5‐cm soil layer compared with CT–CT plots. The fine (53–250 μm) iPOM–C within the 250‐ to 2000‐μm aggregates was also higher in the continuous NT plots compared with CT within both >2000 and 250 to 2000 μm sand free aggregate size classes in that soil layer. Thus, the adoption of continuous NT is the best management option for improvement of soil C under a rainfed lentil [ Lens esculentus (L.)]–finger millet [ Eleusine coracona (L.) Gaertn.] cropping system of the Indian Himalayas, as the management practice has the potential to improve productivity and soil aggregation with greater accumulation of POM‐C, and SOC stabilization apart from other known benefits like weed control, less cultivation cost, and higher profits.