基于15N标记的干旱区滴灌肥料氮的去向和效益研究

【目的】采用¹⁵N示踪法，研究滴灌肥料氮与土壤氮素的转化和去向以及在土壤中的残留分布，为新疆滴灌春小麦氮肥优化管理提供科学依据。【方法】试验于2019年在石河子大学农学院试验站进行，供试春小麦材料为强筋型‘新春38’(XC38)和中筋型‘新春49’(XC49)。试验设7个施氮(N)水平：300、285、270、255、240、225和0 kg/hm²，分别记作N300、N285、N270、N255、N240、N225和N0处理。每个试验小区内，安装未封底的PVC管(直径11 cm，高65 cm)，管内施用与该处理等量的¹⁵N标记尿素。于小麦成熟期，测定PVC管内植株样品与土壤样品中的¹⁵N丰度，同时在小区内测定产量，计算氮素利用效率。【结果】两品种春小麦吸收的氮素来自肥料的比例为30.49%～36.06%，对土壤氮的依赖程度在60%以上。随着氮肥施用量的降低，对土壤氮的依赖程度逐渐增加。¹⁵N标记氮肥在土壤中的总残留率为24.05%～31.60%，主要集中在0—40cm土层，土...

Fate and efficiency of fertilizer nitrogen in spring wheat production under drip irrigation based on the 15N tracing method

  【Objectives】  The contribution of fertilizer to wheat N absorption and the behavior of residual fertilizer N in the soil were studied using the 15N tracing method. We aim to provide a scientific basis for optimal N fertilizer management in Xinjiang wheat production under drip irrigation.  【Methods】  Field experiment was conducted at the Experimental Station of College of Agriculture Shihezi University from April to July 2019, using spring wheat cultivars ‘Xinchun 38’ (XC38, high-gluten) and ‘Xinchun 49’ (XC49, medium-gluten) as test materials. The seven N-level treatments used were N 300, 285, 270, 255, 240, 225, and 0 kg/hm2, namely, N300, N285, N270, N255, N240, N225, and N0 treatments. A PVC tube (11 cm in diameter, 65 cm high) was installed in each plot, and the 15N labeled fertilizer was applied at the same N rate as the treatment plot. At maturity, the plant and 0–40 cm deep soil samples were collected from the PVC tube to determine 15N abundance and the N content; the dry biomass and wheat yield of he plot were also investigated simultaneously.  【Results】  Fertilizer applications accounted for 30.49%–36.06% of the N absorbed by the two wheat cultivars, with soil N contributing more than 60%. Higher N application rates result in a high contribution to wheat N. The 15N residual rate in soil was 24.05%–31.60%, and mainly concentrated in 0–40 cm soil layer. The 15N utilization rate increased at first and then decreased with a decline in the N application rate. In contrast, the 15N residue in the soil increased with increasing N application rates, while the 15N total recovery rate increased progressively. The amount of fertilizer N absorbed by wheat cultivar XC38 was 43.1–61.3 kg/hm2, accounting for 30.81%–34.39% of total N uptake. These values were higher than 42.3–54.5 kg/hm2 and 30.81%–32.50% recorded for XC49. The highest grain yield (7384.0 kg/hm2) of XC38 was obtained from N270 treatment, and XC49 had the highest yield (7236.1 kg/hm2) in N255 treatment.   【Conclusions】  Under the drip fertigation system, 19.79% of N fertilizer was average absorbed by wheat, and 27.86% average remained in 0–60 cm soil, with a average total recovery rate of 47.64%. Increasing the N fertilizer application rate enhances the nitrogen absorption by wheat and the proportion from fertilizer, and the residual amount in the soil, which becomes the supplement of the soil N pool. The strong gluten cultivar XC38 absorbs more N fertilizer than medium gluten cultivar XC49, which does not affect fertilizer N basic behavior. The proper N application rate for high yield, N use efficiency, and soil residue is 270 kg/hm2 and 255 kg/hm2 for XC38 and XC49, respectively.