【摘要】 为了进一步明确华北地区冬小麦-夏玉米种植体系周年氮肥利用效率及其影响因素与机制,试验在大田和原状土柱条件下进行了深层土壤放置15N标记氮肥试验,重点研究节水栽培冬小麦对夏玉米生育期淋洗到下层土壤的氮素利用能力。试验结果表明,大田条件下冬小麦根系空间分布与夏玉米存在明显差异,冬前苗期根系下扎深度可达1.0m,开花期最大根深已经超过2.0m。而且,小麦节水栽培(春季不灌水、春季灌2次水)相对于传统充分灌水模式(春季灌4次水)明显提高了根群中的下层根系比例。大田春不灌水和春灌2水条件下,冬小麦对于100~200cm深层土壤放置的15N标记氮肥均能吸收利用。土柱条件下15N标记氮肥试验进一步验证了春灌2水条件下小麦对深层土壤氮素的吸收作用,并表明植株对100~110cm、120~130cm、140~150cm各层土壤标记15N的回收率分别为16.26%、7.33%和4.38%。研究表明,节水栽培促进冬小麦根系深扎,较多的深层根系增强了小麦对深层土壤氮素的吸收和利用能力,有利于截获夏玉米季淋溶到下层土体的肥料氮,从而可减少肥料氮损失。更多还原

【Abstract】 In order to identify the subsoil nitrogen capture ability of winter wheat under water saving cultivation, experiments were conducted in the field and undisturbed soil columns respectively with ¹⁵N-labeled nitrogen placement in deep soil layer. The field site was divided into plots at 5×6 m² size. Fertilizers including 157.5kgN/hm²,138.5kg P₂O₅/hm²,113kg K₂O/hm² and 30kg ZnSO₄/hm² were applied as basal fertilizer before sowing. Three irrigation treatments in spring season （w0: no-irrigation, w2: two times irrigation , and w4: four times irrigation） were established and replicated three times in a randomized block design. In field , ¹⁵N-labeled nitrogen fertilizer was injected into different soil layer through polyvinyl chloride（PVC） tubes with a 2-cm diameter before sowing for w2 treatment and 5 days before anthesis for w0 treatment respectively, and in soil column, ¹⁵N-labeled nitrogen fertilizer was injected into the soil at 100¹10cm or 120～130cm or 140～150cm depth 48 days after sowing. Roots samples were obtained from all field plots at 3 growth stages [seedling before winter, anthesis and harvest] in 20cm increments to a depth of 200cm. Plant samples of winter wheat in field and soil column were taken at harvest stage. The atom of （）¹⁵N abundance in wheat grain was analyzed by mass spectrometry. In the field, significant difference existed in spatial root distribution between winter wheat and summer maize. The root depth of winter wheat could reach 1.0m at seedling stage and exceed 2.0m at anthesis stage. Compared with traditional cultivation（w4 treatment）in winter wheat, water-saving cultivation （w0 or w2 treatment ） significantly increased the weight percentage of root weight at deep soil, which could explain why ¹⁵N-labeled nitrogen placed in deep soil could be absorbed under w2 treatment or w0 treatment condition. In the undisturbed soil column, wheat could also capture ¹⁵N-labeled nitrogen in deep soil. Recovery rates of ¹⁵N-labeled nitrogen in 100～110cm,120～130cm,and 140～150cm soil layers were 16.26%、7.33% and 4.38% respectively. The results suggested that under water-saving cultivation rooting depth of winter wheat was increased, and more roots in subsoil could improved the ability of capturing and using soil nutrient （especially subsoil residual nitrogen from fertilizer of summer maize）,which is very important for the improvement of nitrogen fertilizer use efficiency in winter wheat-summer maize production system.更多还原