麦秸还田下水氮管理对稻田土壤养分、酶活性及碳库的短期影响

Short-term Effect of Different Water and Nitrogen Managements on Paddy Soil Nutrient,Enzyme Activity and Carbon Pool Under Wheat Straw-returning Fields

为揭示麦秸还田下,稻麦轮作区水氮耦合关系,通过大田试验,研究了麦秸还田条件下,不同的水分管理(淹水灌溉、浅湿调控灌溉、常规灌溉)和氮肥量(180、225、270 kg·hm^(-2))对稻田土壤养分、土壤酶活性及土壤碳库的短期影响。结果表明,在相同水分管理下,随着施氮量的增加,稻田土壤有机质、全氮、速效钾、易氧化有机碳含量、蔗糖酶、过氧化氢酶活性以及水稻产量均呈先升高后降低趋势。与常规灌溉相比,当施氮量为180 kg·hm^(-2)时,浅湿调控灌溉可以显著提高稻田土壤全氮、铵态氮、硝态氮含量,淹水灌溉显著降低了土壤易氧化、水溶性有机碳含量和蔗糖酶、过氧化氢酶活性;当施氮量为225kg·hm^(-2)和270kg·hm^(-2)时,浅湿调控灌溉可以显著提高土壤全氮含量和水稻产量,淹水灌溉显著降低了水溶性有机碳、过氧化氢酶活性。因此,在麦秸还田条件下,与其他处理相比,浅湿调控灌溉和施氮量为225 kg·hm^(-2)的处理在短期内对提高土壤养分含量、增加土壤酶活性、碳库含量和水稻产量具有显著优势。本研究为该地区制定合理、高效的水肥管理措施提供了科学依据。

In order to reveal the relationship between water and nitrogen on paddy fields under wheat straw-returning conditions,a field experiment was conducted to study the short-term effects of different irrigation methods（ submerged irrigation,shallow-wet control irrigation,conventional irrigation） and nitrogen fertilization levels of 180,225,and 270kg·hm-（-2）,respectively,on soil nutrients,enzyme activity and carbon pool under wheat straw-returning conditions in paddy fields. The results showed that under the same water management,paddy soil organic matter content,total nitrogen content,available K content,easily oxidizable organic carbon content,invertase,catalase and rice yield all increased at first and then decreased with the increase of nitrogen application level. At the nitrogen application level of180 kg·hm-（-2）shallow-wet control irrigation can significantly improve the paddy soil total nitrogen,ammonium nitrogen and nitrate nitrogen content,submerged irrigation significantly decreased the soil readily oxidizable organic carbon content,water soluble organic carbon content and invertase, catalase activity, comparing with the conventional irrigation. At the nitrogen application level of 225 kg·hm-（-2）and 270 kg·hm-（-2）,shallow-wet control irrigation can significantly improve the paddy soil total nitrogen content and rice yield,submerged irrigation significantly reduced water soluble organic carbon content and catalase activity,compared with the conventional irrigation. Therefore,under shortterm condition,shallow-wet control irrigation mode with nitrogen application of 225 kg·hm-（-2）in the wheat strawreturning field had significant advantagesin improving soil nutrients,increasing soil enzyme activity,soil carbon pool content and rice yield,compared to other treatments. This study provided the scientific basis for formulating a reasonable and efficient management of water and fertilizer policy in this region.