Li Guanghao, Zhao Bin, Dong Shuting, Zhang Jiwang, Liu Peng, J Vyn Tony
State Key Laboratory of Crop Biology and College of Agronomy, Shandong Agricultural University, Tai'an, Shandong, PR China.
Agronomy Department, Purdue University, West Lafayette, Indiana, United States of America.
PLoS One. 2017 Jul 24;12(7):e0181774. doi: 10.1371/journal.pone.0181774. eCollection 2017.
Controlled release urea (CRU) has been widely adopted to increase nitrogen (N) use efficiency and maize production, but the impacts can range widely depending on water availability in the soil. In an experiment using Zhengdan 958 (a popular summer maize hybrid), three levels of water treatments (adequate water condition [W3], which maintained soil moisture at about 75% ± 5% of the soil's field capacity; mild water stress [W2], which maintained moisture content at 55% ± 5% of field capacity; and severe water stress [W1], which had a moisture content of 35% ± 5% of field capacity) and four levels of controlled release urea fertilizer (N0, N1, N2 and N3 were 0, 105, 210 and 315 kg N ha-1, respectively) were compared in a rainout shelter system with soil. The results revealed that CRU had significant effects on maize yields and N use efficiencies under different water conditions. The mean yields increased with increasing water levels and showed significant differences. Under W1, the accumulation of dry matter and N were limited, and N internal efficiency (NIE) and the apparent recovery efficiency of applied N (REN) decreased with N increases; yields of N1, N2, and N3 were similar. Under W2, the dry matter and N accumulation, as well as the yield, showed an increasing trend with an increase in N application, and the NIE and REN of N3 showed no difference from N2. Under W3, yields of N2 and N3 were similar and they were significantly higher than that of N1, but the agronomic N use efficiency (ANUE), REN, and the physiological NUE (PNUE) of N2 were 54.2, 34.9, and 14.4% higher, respectively, than those of N3. N application beyond the optimal N rate did not consistently increase maize yield, and caused a decrease in N use efficiencies. Highest overall dry matter, N accumulation, and yields were observed with N3 under W2, and those showed no differences with N2 and N3 under W3. Under this experimental condition, the CRU of 210 kg ha-1 was optimized when soil moisture content was 75% ± 5% of field capacity, but an N rate of 315 kg ha-1 was superior when soil moisture content during the entire growing season was maintained at 55% ± 5% of field capacity.
控释尿素（CRU）已被广泛应用于提高氮（N）利用效率和玉米产量，但根据土壤水分状况，其效果差异较大。在一项以郑单958（一种常见的夏玉米杂交种）为材料的试验中，在防雨棚系统中设置了三种水分处理水平（充足水分条件[W3]，保持土壤湿度在田间持水量的75%±5%左右；轻度水分胁迫[W2]，保持土壤湿度在田间持水量的55%±5%；重度水分胁迫[W1]，土壤湿度为田间持水量的35%±5%）和四个控释尿素肥料水平（N0、N1、N2和N3分别为0、105、210和315 kg N·ha-1）进行比较。结果表明，控释尿素在不同水分条件下对玉米产量和氮利用效率有显著影响。平均产量随着水分水平的提高而增加，且差异显著。在W1条件下，干物质和氮的积累受到限制，氮内部效率（NIE）和施氮表观回收率（REN）随施氮量增加而降低；N1、N2和N3的产量相似。在W2条件下，干物质和氮的积累以及产量随施氮量增加呈上升趋势，N3的NIE和REN与N2无差异。在W3条件下，N2和N3的产量相似且显著高于N1，但N2的农学氮利用效率（ANUE）、REN和生理氮利用效率（PNUE）分别比N3高54.2%、34.9%和14.4%。施氮量超过最佳施氮量并不能持续提高玉米产量，反而会导致氮利用效率降低。W2条件下N3的总干物质、氮积累和产量最高，W3条件下N2和N3的这些指标无差异。在此试验条件下，当土壤湿度为田间持水量的75%±5%时，210 kg·ha-1的控释尿素施用量为最佳，但当整个生长季土壤湿度保持在田间持水量的55%±5%时，315 kg·ha-1的施氮量更优。
