高低畦种植模式下水氮耦合对冬小麦产量和水氮利用效率的影响

    Effects of water and nitrogen coupling on winter wheat yield and water or nitrogen use efficiency under high-low seedbed cultivation pattern

    • 摘要: 高低畦种植是在生产实践中摸索出的一套节水增产的冬小麦种植模式,尽管已被山东省列为农业主推技术,但由于建立时间尚短,其背后机理研究仍较薄弱,很大程度上制约了该模式的完善与推广应用。为探索高低畦冬小麦最佳的水氮管理制度,于2020-2022年开展田间试验,设置3个灌水定额(W1:120 mm、W2:90 mm、W3:60 mm)和3个施氮水平(N1:300 kg/hm2、N2:240 kg/hm2、N3:180 kg/hm2),以水氮充足的平作种植为对照(CK,灌水定额120 mm,施氮量300 kg/hm2),测定了不同生育期土壤含水率、成熟期地上部生物量和产量,并计算了麦田耗水量、水分利用效率、氮肥偏生产力和净利润等指标。结果表明:1)与平作种植相比,高低畦种植的麦田耗水量无明显差异,但冬小麦产量、水分利用效率、氮肥偏生产力和净利润分别提高14.8%~17.6%、15.9%~16.9%、14.8%~17.6%和58.9%~112.6%,说明高低畦种植模式具有增产与节水有机统一的良好潜力。2)灌水水平和施氮水平均对高低畦种植麦田耗水量产生极显著影响(P<0.01);高低畦种植模式的产量、地上部生物量、水分利用效率、氮肥偏生产力和净利润的水氮耦合效应明显;W2N2与W1N1产量差异不显著(P>0.05),而水分利用效率和氮肥偏生产力也显著增加(P<0.05);说明适量节水减氮不会显著降低产量,且可获得较高的水分利用效率和氮肥偏生产力。二元二次回归分析得出,当耗水量为536.3~559.4 mm(灌水定额为99.2~115.4 mm),施氮量246.5~299.4 kg/hm2时,可以使高低畦种植模式冬小麦产量、水分利用效率和净利润的综合效益最大化。研究为冬小麦高低畦种植模式下水氮优化管理策略的构建提供理论依据和技术支撑。

       

      Abstract: Abstract: High and low seedbed cultivation has been widely used to combine ridge and flat planning patterns during wheat production in Shandong Province of the North China Plain (NCP). Land utilization rate and crop productivity can be better improved with the higher efficiency of water-nitrogen use for sustainable production, compared with flat cultivation. The winter wheat is planted on both alternate high and low beds on the flat land under cultivation. However, it is still lacking on the underlying mechanism of this cultivation pattern for better improvement and popularization. This study aims to clarify the effects of different water and nitrogen rate on grain yield, water consumption, aboveground biomass, water use efficiency, nitrogen partial fertilizer productivity, and net benefits. A field experiment was also carried out during the 2020-2021 and 2021-2022 growing seasons using a split zone design. The main area was divided into three levels of nitrogen rates (N1: 300, N2: 240, and N3: 180 kg/hm2). The subplot was set as the three levels of irrigation quotas (W1: 120, W2: 90, and W3: 60 mm). The flat cultivation with 120 mm irrigation amount and 300 kg/hm2 nitrogen amount was set as the control (CK) group. A systematic evaluation was implemented to determine the effects of water and nitrogen management on crop productivity, as well as water and nitrogen use efficiency under high and low seedbed cultivation. The results showed that the high and low seedbed cultivation significantly improved the crop grain yield by 14.8%-17.6%, water use efficiency by 15.9%-16.9%, nitrogen partial fertilizer productivity by 14.8%-17.6%, and net benefits by 23.9%-32.7%, compared with the flat cultivation. Consequently, high and low seedbed cultivation was a reliable agronomic practice for higher water or nitrogen use efficiencies and crop productivity, although there was no significant difference in the water consumption between high and low seedbed cultivation and flat cultivation. The coupling of water and nitrogen posed significant effects on water consumption, grain yield, aboveground biomass, water use efficiency, nitrogen partial fertilizer productivity, and net benefits (P<0.01). Specifically, the W2F2 decreased the crop yield by 2.8%-3.3% (P>0.05), whereas, the water use efficiency increased (P<0.05), compared with the W1F1. The optimal water and nitrogen rate was obtained in the higher water use efficiency, nitrogen partial fertilizer productivity, and net profits. The regression and spatial analysis demonstrated that the grain yield, water use efficiency, and net profits reached 95%-100% of the maximum simultaneously, when the water consumption was 536.3-594.3 mm, and the nitrogen application was 246.5-299.4 kg/hm2 in 2020-2021, while the water consumption was 527.2-559.4 mm, and the nitrogen application was 221.0-303.1 kg/hm2 in 2021-2022. An optimal combination was achieved in the water consumption of 536.3-559.4 mm (irrigation quota of 99.2-115.4 mm), and the nitrogen application of 246.5-299.4 kg/hm2, in order to maximize the grain yield, water use efficiency, and net profits. Therefore, a reasonable technical and theoretical reference can be offered for the multi-objective management of the water and nitrogen of winter wheat under high and low seedbed cultivation in areas with similar climate conditions to the NCP. Further study can be focused on the management of water and fertilizer (nitrogen, phosphorus, and potassium) rate of winter wheat under high and low seedbed cultivation with the various varieties and the soil type.

       

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