氮肥调控剂对潮褐土中不同氮源氮素转化及油菜生长的影响

采用土壤培养和盆栽试验相结合的方法，研究了硝化抑制剂双氰胺(DCD)与纳米碳配合施用对尿素和碳酸氢铵在华北平原典型土壤潮褐土中转化的调控效果及其对油菜生长的影响.结果表明： 尿素和碳酸氢铵在施入土壤后的2周内，土壤无机氮的供应强度差别较大，2周以后则基本相似.2种氮源对油菜生长及氮素利用的影响在生育前期(播种后34 d)差异显著，但最终达到商品生物量收获时，氮源之间差异不大.DCD对尿素和碳酸氢铵在潮褐土中的转化表现出显著的硝化抑制作用，其抑制强度和有效抑制时间随DCD用量的增加而增强，且以对碳酸氢铵施入土壤后的硝化抑制效果更好.在本研究条件下，DCD用量以占肥料纯氮量的1.0%～1.5%相对较佳，可显著提高油菜产量，改善叶色，降低植株硝酸盐含量，提高氮肥利用率.纳米碳与DCD配合施用对土壤铵氧化有明显的协同抑制效果，且可以显著刺激油菜前期的生长发育和氮素利用，降低油菜硝酸盐含量.

Effects of nitrogen regulators on fertilizer nitrogen transformation in meadow cinnamon soil and on pakchoi growth.

Soil incubation test and pot experiment were conducted to investigate the effects of dicyandiamide (DCD) and its combination with nano-carbon on the transformation of fertilizers (urea and ammonium bicarbonate) nitrogen (N) in meadow cinnamon soil, a typical soil type in North China Plain, and on the growth of pakchoi (Brassica chinensis). In the first two weeks after applying urea and ammonium bicarbonate, the soil NH4+-N and NO3--N contents varied greatly, but little variation was observed since then. The effects of the applied fertilizer N on the pakchoi growth and its N use efficiency differed significantly at early growth stages, but had little difference at harvesting stage. The DCD inhibited the transformation of the fertilizer N (especially ammonium bicarbonate N) into nitrate markedly, and this effect increased with increasing DCD dose. Under the conditions of our experiment, the optimal application rate of DCD was 1.0-1.5% of applied fertilize N, which could increase the pakchoi yield significantly, improve the leaf color, decrease the plant nitrate contents, and increase the fertilizer N use efficiency. The combination of DCD and nano-carbon exerted a synergistic effect on inhibiting soil ammonium oxidation, and also, promoted the pakchoi growth and N utilization at early growth stages significantly and decreased the plant nitrate level at harvesting stage.