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土壤供氮能力是影响土壤氮素利用效率的一个重要指标,再生水灌溉和施氮水平均影响着土壤供氮能力,研究不同施氮水平对长期再生水灌溉土壤氮素的转化特征可为合理施肥及农产品增产增效提供理论依据.本研究选择河南新乡洪门试验站温室大棚内长期再生水灌溉和清水灌溉土壤,试验共设8个处理:A(N200)(施氮量200 mg·kg-1)、A(N160)(施氮量160 mg·kg-1)、A(N140)(施氮量140 mg·kg-1)、A(N100)(施氮量100 mg·kg-1)、A(N0)(施氮量0 mg·kg-1)、E(清水灌溉常规施氮)、CK(清水灌溉不施氮)、Re CK(再生水灌溉不施氮),采用实验室内常温培养法,分别在培养的7、14、21、28、35、42 d测定土壤铵态氮、硝态氮及全氮含量,并分析了土壤氮素矿化量和氮素矿化速率的变化,通过Freundlich线性等温吸附模型及一级动力学方程拟合了土壤吸附参数Kd和氮素矿化势N0.结果发现,培养前期土壤氮素矿化较快,释放的氮量较高,中后期变化较慢,土壤供氮平稳,同一时段不同处理间土壤累积矿化氮量存在显著差异(p<0.05),表明不同外源氮肥输入对土壤氮素的矿化能力影响显著,A(N160)处理的供氮能力最强;同时,在培养前期Re CK处理的土壤氮素矿化累积量显著高于CK处理,表明再生水灌溉较清水灌溉促进了土壤氮素的矿化,显著提高了土壤氮素活性;土壤氮素的矿化速率随着培养时间的增加而逐渐降低,但降幅依次减小并趋于平稳,且不同施氮处理再生水灌溉土壤氮素矿化速率显著高于清水灌溉;不同土壤肥力水平(B0)、外源施氮A(N160)调控,土壤氮素矿化潜势可表达为N0=B0+117.5072t-0.1062.因此,外源氮肥输入显著影响了土壤氮素释放节律,再生水灌溉辅以适宜的施氮量可促进土壤氮素矿化,提高土壤氮素活性.
Soil nitrogen availability is an important index affecting soil nitrogen use efficiency. Both reclaimed water irrigation and nitrogen application affect soil nitrogen availability. The study on the conversion characteristics of nitrogen fertilization with long-term reclaimed water irrigated by different N application rates may be rational fertilization and This study chose long-term reclaimed water irrigation and clean water irrigation in the greenhouse of Hongmen Experimental Station in Xinxiang, Henan Province. The experiment included 8 treatments: A (N200) (200 mg · kg-1 N) , A (N160) (N application rate was 160 mg · kg-1), A (N140) (N application rate was 140 mg · kg-1), A (N 0) (0 mg · kg-1 N), E (conventional irrigation with fresh water), CK (no irrigation with fresh water), Re CK (no irrigation with reclaimed water) , The contents of ammonium nitrogen, nitrate nitrogen and total nitrogen in soil were determined at 7, 14, 21, 28, 35 and 42 d after cultivation, and the changes of soil nitrogen mineralization and nitrogen mineralization rate were analyzed. The Freundlich linear isothermal adsorption model and the first-order kinetic equation fit the soil adsorption parameters Kd and nitrogen mineralization potential N0. The results showed that soil nitrogen mineralization was faster in the early stage of culture , The release of nitrogen is higher, changes slowly in the late, soil nitrogen stable, the same period of different treatments of soil cumulative mineralized nitrogen significant difference (p <0.05), indicating that different input of nitrogen on soil nitrogen N (N160) treatment had the strongest nitrogen supply ability. At the same time, the accumulation of soil N mineralization by Re CK in the early stage of cultivation was significantly higher than that of CK treatment, which indicated that the irrigation of reclaimed water and fresh water promoted the increase of soil nitrogen Mineralization significantly increased the soil nitrogen activity. The mineralization rate of soil nitrogen decreased with the increase of incubation time, but decreased in turn decreased and stabilized, and different N fertilizer treatments reclaimed water irrigation soil nitrogen The mineralization rate was significantly higher than that of fresh water irrigation. Under different soil fertility levels (B0) and exogenous nitrogen application A (N160), the N mineralization potential could be expressed as N0 = B0 + 117.5072t-0.1062. Nitrogen input significantly affected the soil nitrogen release rhythm. Irrigation with reclaimed water supplemented with appropriate amount of nitrogen could promote soil nitrogen mineralization and increase soil nitrogen activity.