施氮和冬种绿肥对土壤活性有机碳及碳库管理指数的影响

为探讨冬季绿肥改良土壤的生态效应及确定合适比例的氮肥与绿肥翻压量，在“冬季绿肥 双季稻”复种型农作制度基础上，设置4×4双因素试验，研究不同紫云英翻压量和施氮水平对土壤活性有机碳库各组分及碳库管理指数的影响.结果表明： 单施绿肥能够显著促进土壤总有机碳和活性有机碳的累积.与对照相比，单施绿肥处理土壤总有机碳含量和活性有机碳含量分别平均增加22.2%、26.7%，但单施氮肥处理的土壤有机碳含量下降了0.6%～3.4%.与不施肥相比，单施绿肥和绿肥氮肥配施处理的土壤碳库管理指数分别平均增加了24.55和15.17，而单施氮肥处理减少了2.59.单施绿肥、绿肥氮肥配施和单施氮肥处理的土壤平均微生物生物量碳分别比对照高54.0%、95.2%和14.3%.活性有机碳含量与碳库管理指数存在极显著（P＜0.01）的相关性，与可溶性有机碳、微生物生物量碳也存在显著的相关性（P＜0.05）.水稻产量与活性有机碳含量和碳库管理指数均存在极显著的相关性，且相关系数明显大于总有机碳.可见在当地土壤肥力条件下，施有机肥或有机无机肥适当配施能提高土壤有机碳含量和土壤碳库管理指数，有利于改善土壤质量，提高土壤肥力.

Effects of nitrogen application and winter green manure on soil active organic carbon and the soil carbon pool management index.

Based on a copping system of “winter green manure double rice”, the 4× 4 two factor test was used to study the effects of different nitrogen (N) application levels and winter green manure application on soil active organic carbon (AOC) and the C pool management index. The aim was to explore the ecological effects of winter green manure on soil improvement and determine the appropriate application levels of N fertilizer and winter green manure for improved rice yield. Results were as follows: 1) Compared with the control, the SOC and AOC contents increased by 22.2% and 26.7%, respectively, under the green manure only treatment, but the SOC contents decreased by 0.6%-3.4% under the single N fertilizer treatment. Compared with the control, the soil C pool management index increased by 24.55 and 15.17 under the green manure only and green manure plus N fertilizer treatments, respectively, and reduced by 2.59 under the single N fertilizer treatment. Compared with no fertilization, the average microbial biomass carbon (MBC) increased by 54.0%, 95.2% and 14.3% under the green manure, green manure plus N fertilizer and single N fertilizer treatments, respectively. 2) The soil AOC content was significantly positively correlated with the C pool management index (P<0.01), and had a significant correlation with dissolved organic C and MBC (P<0.05). Rice yield was significantly positively correlated with AOC contents and the C pool management index, and the correlation coefficient was significantly greater than that with the total organic C. These results suggested that application of winter green manure at proper rates with inorganic fertilizer could increase SOC contents and the soil C pool management index, improve soil quality and fertility.