Abstract

Agroforestry systems (AFS) are economically viable and provide diverse ecosystem services. We studied the long-term effects of tree-based AFS on carbon and nitrogen pools in Punjab, India. The selected systems were poplar with fodder–wheat rotation (T1), eucalyptus with fodder–wheat rotation (T2), sole fodder–wheat rotation (T3), poplar with citrus (kinnow) (T4), eucalyptus with citrus (T5), sole citrus (T6) and fallow land (T7). At the 0–15 cm soil depth, T1 and T2 had 87.9 and 70.6% higher soil organic carbon (SOC), respectively, than T3, while T4 and T5 had 37.4 and 30.2% higher SOC, respectively, than T6. At all soil depths, SOC was lowest under fallow land and decreased with depth. The soil carbon pools (very labile, labile, less labile and recalcitrant carbon) were highly positively correlated with SOC and were higher in T1 and T2 than in other land-use systems. Water-soluble carbon, microbial biomass carbon, total N, ammonium N and nitrate N were highest in T1 and decreased with depth. Carbon management index was significantly higher in T1 and T2 than other systems. Therefore, poplar- and eucalyptus-based AFS with fodder–wheat rotation were more efficient in improving soil carbon and nitrogen status along with sustainability of the systems.

摘要

农林业系统 (AFS) 在经济上可行并提供多样化的生态系统服务。我们研究了基于树木的 AFS 对印度旁遮普邦碳和氮库的长期影响。选择的系统是杨树与饲料-小麦轮作 (T1)、桉树与饲料-小麦轮作 (T2)、唯一饲料-小麦轮作 (T3)、杨树与柑橘 (kinnow) (T4)、桉树与柑橘 (T5)、唯一的柑橘 (T6) 和休耕地 (T7)。在 0-15 cm 土壤深度处，T1 和 T2 的土壤有机碳 (SOC) 分别比 T3 高 87.9% 和 70.6%，而 T4 和 T5 的 SOC 分别比 T6 高 37.4% 和 30.2%。在所有土壤深度，休耕地的 SOC 最低，并随深度降低。土壤碳库（非常不稳定、不稳定、不稳定和顽固的碳）与 SOC 高度正相关，并且在 T1 和 T2 中高于其他土地利用系统。水溶性碳、微生物生物量碳、全氮、铵态氮和硝态氮在 T1 中最高，随着深度的增加而降低。T1和T2的碳管理指数明显高于其他系统。因此，基于杨树和桉树的 AFS 与饲料 - 小麦轮作在改善土壤碳和氮状况以及系统可持续性方面更有效。