两种三熟套作体系中的氮素转移及吸收利用

 【目的】探讨“小麦/玉米/大豆”(以下简称麦/玉/豆)和“小麦/玉米/甘薯”(以下简称麦/玉/薯)两种三熟套作体系的氮素种间竞争促进作用和高效吸收利用特性。【方法】采用根系分隔盆栽试验和15N土壤稀释标记法,研究两种三熟套作体系的氮素转移及吸收利用情况。【结果】不分隔与分隔相比,两种体系中小麦的15N总吸收量和15N作物回收率提高,土壤残留15N%丰度及总N含量降低。“麦/玉/豆”中玉米的15N总吸收量、籽粒15N吸收量、15N作物回收率、土壤残留15N%丰度及总N含量提高17.62%、24.52%、17.63%、13.9%和10.1%,“麦/玉/薯”则降低50.19%、42.58%、33.42%、29.6%和5.2%;降低了大豆的15N总吸收量、籽粒15N吸收量和15N作物回收率,但土壤总N含量提高6.06%;提高了甘薯的15N总吸收量和15N作物回收率,但土壤残留15N%丰度和总N含量降低0.9%和4.95%。【结论】两种体系均存在氮素种间竞争促进作用和氮素转移,“麦/玉/豆”较“麦/玉/薯”更有利于肥料氮的吸收、土壤肥力的保持和周年作物的可持续生产。

Analysis of the Nitrogen Transfer, Nitrogen Uptake and Utilization in the Two Relay-Planting Systems

【Objective】 The aim of this paper was to study the mechanisms of interspecific nitrogen facilitation and transfer in the relay-planting systems of wheat/maize/soybean and wheat/maize/sweet potato. 【Method】 The methods of root barrier and 15N-isotope dilution were used to investigate the nitrogen transfer, nitrogen uptake and utilization in the two relay-planting systems.【Result】 Comparing the no barrier with solid barrier, the results showed that the 15N total uptake and crop recovery rate of wheat were highly remarkable and 15N% abundance and N% content of soil was lower obviously than that of solid barrier. In the wheat/maize/soybean system with no barrier, the 15N total uptake, 15N grain uptake, 15N crop recovery rate, soil 15N% abundance and N% content of maize increased by 17.62%, 24.52%, 17.63%, 13.9% and 10.1%, respectively. But in the wheat/maize/sweetpotato system with no barrier, the value of above index reduced by 50.19%, 42.58%, 33.42%, 29.6% and 5.2%, respectively. For soybean, the 15N total uptake, 15N grain uptake, and 15N crop recovery rate reduced, but the soil N% content increased by 6.06%. For sweetpotato, the 15N total uptake and crop recovery rate increased, but soil 15N% abundance and N% content reduced by 0.9% and 4.95%. 【Conclusion】 There existed nitrogen interspecific competition and facilitation and nitrogen transfer in the two relay-planting systems. In the wheat/maize/soybean system, the nitrogen uptake from fertilizer, soil fertility remaining and sustainable crop production were better than the system of wheat/maize/sweetpotato.