不同缓/控释尿素在黄土台塬区春玉米的减量施用效果

本文通过田间试验研究了覆膜条件下,黄土台塬区6种缓/控释尿素减量施用对春玉米产量、氮肥利用率及氮素累积量等的影响,以确定适合本地区春玉米施用的缓/控释氮肥品种和用量,为本地区春玉米简约、高效施肥技术提供理论依据与技术支撑。以春玉米品种‘先玉335’为供试作物,设9个处理,分别为不施氮肥处理(N0)、农户常规施氮处理普通尿素,施氮量225 kg(N)·hm~(-2),N225]、普通尿素减量处理施氮量180 kg(N)·hm~(-2),N180]和6种缓/控释尿素减量处理施氮量180 kg(N)·hm~(-2)]。6种缓/控释尿素分别为树脂尿素、控失尿素(CLU)、硫包衣尿素(SCU)、脲甲醛(UF)、多肽尿素和稳定尿素。在玉米各生育时期采集地上部植株样品及耕层(0~20 cm)土样,分析耕层土壤无机氮含量,测定玉米植株氮素累积量及产量。施用氮肥可显著增加玉米产量,增产率在28%~65%。与N225相比,N180玉米产量显著降低19.1%,但各缓/控释尿素(减量20%)一次基施没有明显的减产效应,其中SCU与CLU分别增产4.5%和2.7%。与农户常规施肥相比,N180降低经济效益2 051$·hm~(-2);各缓/控释尿素(除UF)可增加玉米氮素累积量、提高氮肥利用率2.26%~12.69%,经济效益提高347~1 747$·hm~(-2),氮肥利用率和经济效益以SCU、CLU最高。大喇叭口期—吐丝期,缓/控释尿素氮素释放量大可能是提高氮肥吸收和利用率的原因之一。控失尿素和硫包衣尿素等缓/控释尿素减量(20%)并一次性基施,能维持产量不降低,提高氮肥利用率和经济收益,节约劳动力成本,可作为黄土台塬区春玉米简约化减量化施肥的一种选项。

Effect of different rates of slow/controlled release urea on nitrogen content in spring maize in loess highlands

A field experiment was conducted under plastic film mulching conditions in the highlands of the Loess Plateau area to study the effects of different rates of different types of slow and controlled release urea (via basal application at reduced rate) on grain yield, nitrogen use efficiency and nitrogen accumulation in spring maize. The aim of the study was to determine the optimum type and application rate of slow or controlled release urea via simplified and efficient fertilization techniques for spring maize production in the study area. Spring maize cultivar used in the study wasZea mays L. cv. 'Xianyu335'. The experiment consisted of nine treatments — no N use (N0), farmer conventional N fertilization common urea with application rate of 225 kg(N)·hm-2, N225], common urea N re-duction (application rate of 180 kg(N)·hm-2, N180], and N rate reduction with six kinds of slow or controlled release urea application rate of 180 kg(N)·hm-2], i.e., resin coated urea (RCU), controlled loss urea (CLU), sulfur coated urea (SCU), urea formaldehyde (UF), polypeptide urea (PU) and stabilized urea (SU). Plant and soil (0–20 cm layer) samples were collected at different growth stages for analysis of grain yield, plant N accumulation and soil inorganic N concentration. The application of N fertilizer in-creased grain yield of maize by 28%–65% relative to N0. Compared with N225, N180 decreased grain yield by 19.1%. The ap-plication of RCU, UF, PU and SU did not significantly reduce grain yield, while the application of SCU and CLU increased grain yield by 4.5% and 2.7%, respectively. Compared with N225, N180 reduced net income by 2051 ￥·hm-2. A total of six slow or controlled release urea (except for UF) increased plant N accumulation, but increased N use efficiency by 2.26%–12.69% and net income by 347–1747 ￥·hm-2. The highest N use efficiency and economic benefits were observed under SCU and CLU treatments. Greater N uptake and N use efficiency in slow or controlled release urea treatments partly resulted from greater N release during huge bellbottom stage to silking stage. Slow or controlled release urea (including CLU and SCU) via basal ap-plication at reduced amount (by 20%) maintained grain yield, improved N use efficiency and economic benefits, and saved labor cost. Therefore, it was recommended for used as an option for simplified and efficient fertilization in spring maize pro-duction in similar areas in the Loess Plateau.