无机氮与蔬菜废弃物耦合对土壤氮矿化的影响

为探明有机废弃物添加量与不同无机氮水平耦合对土壤氮矿化的影响,设计了3个甘蓝废弃叶添加量[B1:200 g.kg 1(土),B2:400 g.kg 1(土),B3:550 g.kg 1(土)]和4个无机氮水平[N0:0 mg.kg 1(土),N1:25mg.kg 1(土),N2:50 mg.kg 1(土),N3:100 mg.kg 1(土)]交互的控制培养试验(25℃,65%的田间持水量)。试验结果显示:各氮处理下土壤净累积氮矿化量是空白对照的4～5倍,N1水平下土壤净累积氮矿化量显著高于其他氮水平。各甘蓝废弃叶添加量处理下土壤净累积氮矿化量是空白对照的3～5倍,且B2添加量下土壤净累积氮矿化量显著高于B1和B3。统计分析表明,氮处理和甘蓝废弃叶添加量之间的交互效应不显著(P=0.275),甘蓝废弃叶的添加是影响氮矿化的主要因素(Eta2=0.16),而供氮水平为次要因素(Eta2=0.07)。B1添加量下,培养前期(0～20 d)土壤净累积矿化量逐渐升高,后期保持稳定水平;但B2和B3添加量下,培养前期(30 d)土壤呈现矿化、固持、再矿化现象,后期土壤净累积矿化量逐渐升高。氮矿化速率结果说明,甘蓝废弃叶添加后氮素矿化主要发生在培养前30 d。对培养期间土壤净累积氮矿化量随时间变化做一级动力方程模拟,拟合效果良好(R2=0.62～0.89)。

Coupling effect of inorganic nitrogen and cabbage waste onsoil nitrogen mineralization

A 100-day laboratory incubation experiment was conducted under controlled conditions (25 °C and 65% moisture content) to determine the effect of addition of waste cabbage leaves [B1: 200 g?kg^-1(soil), B2: 400 g?kg^-1(soil), B3: 550 g?kg^-1(soil)] coupled with inorganic nitrogen [N0: 0 mg(N)?kg^-1(soil), N1: 25 mg(N)?kg^-1(soil), N2: 50 mg(N)?kg^-1(soil), N3: 100 mg(N)?kg^-1(soil)] on amended soil nitrogen (N) mineralization. Results showed that soil net accumulated N mineralization under different inorganic N treatments were 4~5 times of that under the control (CK). Furthermore, net accumulated N mineralization under N1 treatment was significantly higher than those under other N treatments. Net accumulated N mineralization under waste cabbage leaves treatments were 3~5 times of that under CK. Net accumulated N mineralization under B2 treatment was significantly higher than those under B1 and B3 treat-ments. Statistical analysis showed no significant interaction effect was noted (P=0.275) between inorganic N and waste cabbage leaves treatments. Waste cabbage leaves addition was the dominant driving factor (Eta²=0.16) of amended soil N mineralization while inorganic N supply was only a secondary factor (Eta²=0.07). In the early period (0~20 d) of the incubation treatment, net accumulated N mineralization gradually increased and then maintained a steady trend in the later stage under B1 treatment. However, N mineralization, immobilization and re-mineralization occurred in the early period of incubation (30 d) while net accumulated N mineralization increased gradually in the later stage under B2 and B3 treatments. The results of N mineralization rate showed that N mineralization mainly occurred in the first 30 days as affected by waste cabbage leaves addition. Also during incubation, a ?rst-order kinetics equation of amended soil net accumulated N mineralization fitted well with the days of incubation (R²=0.62~0.89).