华北平原夏玉米喷灌施氮制度优化. (Chinese)

Nitrogen fertilizer and rainfall can dominate the yield and nitrogen use efficiency for summer maize in the North China Plain. This study aims to explore the optimal schedule under sprinkler fertigation. Summer maize (Zea mays L) was selected as the experimental crop in a local cultivar (Zheng Dan No. 958). These experiments were carried out in Dacaozhuang of Hebei Province, China (37°28'N and 114°54'E) in the 2020 and 2021 seasons. The soil water content, soil nitrogen distribution, crop growth parameters, yield, water use efficiency, and nitrogen use efficiency were compared among sprinkler fertigation treatments with three nitrogen recommendations (local empirical value, mineral nitrogen, and improved mineral nitrogen) and (no, one and two) topdressing. Intermittent rainfall events were tested during the period from flare opening to the filling stage. A great rainfall event was defined as the cumulative rainfall exceeding 20 mm within a single day or several consecutive days. The topdressing date was applied 5 days after the great rainfall events, according to the rainfall forecast. As such, the normal rotation of the center pivot system was realized for all treatments. The proportion of basal N fertilizer was 40% in all top dressing treatments. The nitrogen type was urea (CO(NH 2 ) 2 , N=46%) in the growth period. All phosphorous (monoammonium phosphate, P 2 O 5 =46%) and potassium (potassium chloride, K 2 O=60%) were applied into the top 20 cm of soil as basal fertilizers before sowing. Surface irrigation with fertilizer broadcasting was used as the control treatment (CK) with improved mineral nitrogen and two topdressings following intermittent rainfall events during the period from flare opening to the filling stage. There were five treatments in each experimental year. All the treatments had 3 replicates and the same irrigation schedules. The plot area of each replicate was 0.39 hm² and controlled by a 20° rotation angle of the center pivot system. The CK treatment was arranged near the field with a total area of 0.48 hm² . The results showed that the moisture content of the 0-100 cm soil layer remained at a high level during the growing period of summer maize, indicating no need to irrigate. The increasing rate and times of nitrogen application improved the soil inorganic nitrogen content in the root zone of summer maize. The sprinkler irrigation treatment was greater than that of the control treatment. The lower residual nitrogen was observed in soil under the treatment of nitrogen amount in the nutrient balance and the total nitrogen basal after two years of summer corn harvest, compared with the reference surplus level (50 kg/hm² ). There was no significant difference in the leaf area index among different treatments. But the dry matter mass and nitrogen uptake of maize plants significantly increased by spraying irrigation treatment. The yield and nitrogen partial productivity significantly increased by 20%, compared with the control, respectively. The improved mineral nitrogen and two topdressings obtained the best performance among all sprinkler fertigation treatments. The results demonstrated that the growth index, yield, water, and nitrogen use efficiency of summer maize were closely related to the N recommendation and topdressing. The sprinkler fertilization of summer maize was recommended as the improved nutrient balance considering nitrogen surplus and the twice fertilizer application after heavy rainfall during the flared opening to filling period. The balance of the nitrogen pool was also maintained in the soil. The finding can provide a strong reference to improve the yield and nitrogen use efficiency in the North China Plain. [ABSTRACT FROM AUTHOR]

不合理的氮肥施用和较大的降雨量时空变化特征是限制华北平原夏玉米增产和肥料利用效率提高的关键因素。 为探究华北平原夏玉米最优喷灌施肥管理制度，于 2020 年和 2021 年在河北省邢台市大曹庄管理区开展试验，以地面灌 溉肥料撒施处理为对照，研究了喷灌施肥下 3 种施氮量确定方法（农户经验值、养分平衡法和改进养分平衡法）和 3 种 氮肥追施方法（不追肥、在大喇叭口-灌浆期内较大降雨后追施 1 次和追施 2 次）对土壤水氮分布、作物生长、产量以 及氮肥利用效率的影响。结果表明，受降雨影响，夏玉米生育期内 0～100 cm 土层的土壤含水率始终保持在较高水平。 施氮量和氮肥追施次数的增加均提高了夏玉米关键需肥阶段根区的土壤无机氮含量，且喷灌处理的增加量大于对照处理。 2 a 夏玉米收获后，养分平衡法确定施氮量处理和氮肥全部基施处理的土壤氮素残留量均低于参考盈余水平（50 kg/hm²）。 不同处理叶面积指数未出现显著差异，但氮肥追施 2 次的喷灌处理显著增加了玉米干物质量和植株吸氮量，产量和氮肥 偏生产力均分别比对照处理显著提高了 20%。考虑氮素盈余的改进养分平衡法和在大喇叭口期-灌浆期内较大降雨后追 施 2 次的施肥方法有助于维持土壤氮库平衡，且具有显著的增产和氮肥利用效率提高作用，可推荐为华北平原夏玉米喷 灌施肥制度。研究可为大型喷灌机在华北平原的推广应用提供参考。 [ABSTRACT FROM AUTHOR]

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