PPM型高分子材料对土壤氮素缓释效应及转化特征的影响研究

How to improve nitrogen use efficiency has already been one of the most important problems for agriculture development. Drip irrigation has been applied to crop production in Xinjiang for over 50 years, for its effectiveness in increasing crop yield. While fertilizer efficiency and anti-clogging has being a challenge to traditional fertilizer. The mixture of polyacrylamide, polyvinyl alcohol and manganese sulfate (PPM) was chose in the experiment, and is a typical water-absorbent slow release polymer material developed by the project applicant. This project intends to explore the coupling effect of PPM-polymer materials and nitrogen fertilizer on yield and nitrogen use efficiency of drip irrigated wheat by using field experiment and 15N isotope tracing. The contents of this project are to: reveal the nitrogen adsorption characteristic of polymer materials under the soluble water condition, analyze the influences of polymer materials and nitrogen fertilizer interaction on nitrogen contents and compounds, soil animal individual and group amount and soil microbial community, identify the coupling effects of polymer materials and nitrogen fertilizer on nitrogen transformation and metabolism of wheat via drip irrigation. This study may provide a theoretical basis for economically rational nitrogen application programmer and enabling the high nitrogen use efficiency of drip irrigation in arid area.

提高肥料利用率是当前农业生产迫切需要解决的问题。滴灌技术在增加作物产量同时，对传统化肥肥效提升也提出了新的挑战。本项目利用已研发的具有保水缓释效果的水溶性PPM型高分子材料为对象，分析PPM型高分子材料与氮肥配施后，氮素在土壤-作物系统的积累转化过程，土壤组分变化以及土壤动物和微生物群落多样性，揭示水溶条件下PPM型高分子材料对氮素吸附特征，阐明PPM型高分子材料与氮肥配施后土壤氮素缓释效应及转化机理，探讨滴灌条件下PPM型高分子材料与氮肥耦合调控途径，为进一步提升干旱区氮肥利用率提供基础理论和技术支持。

提高肥料利用率是当前农业生产迫切需要解决的问题，项目利用已研发的具有保水缓释效果的水溶性以聚丙烯酰胺为主的高分子材料（PPM）材料为对象，分析PPM与氮肥配施后，氮素在土壤-作物系统的释放利用过程，以及土壤微生物群落多样性，揭示水溶条件下PPM对氮素吸附特征，阐明其对土壤氮素释放与利用的影响，为进一步提升干旱区滴灌农田氮肥利用率提供理论依据。通过试验，PPM与氮肥配施处理显著提高了滴灌小麦株高、生物量和氮素的吸收利用，其中高分子材料与100%尿素配施（PN100）处理下第一年和第二年的籽粒产量均比正常施氮（N100）处理显著增加14.26%和14.02%，高分子材料与80%尿素配施（PN80）处理与N100处理相比产量不变，但PN80显著提高了氮肥利用率。PPM与氮肥配施显著提高了土壤团聚体稳定性，降低了土壤容重，延缓了土壤氮素的转化过程，在小麦成熟期不同处理较CK显著增加了表层土壤（0-20cm）全氮含量10.73%-17.93%、碱解氮含量17.65%-47.06%、硝态氮含量58.16%-119.08%和铵态氮含量9.28%-33.12%，同时抑制了土壤硝态氮和铵态氮向更深土层的淋洗。PPM通过调控了土壤中碳代谢和核苷酸相关的代谢途径，显著上调了氨基酸生物合成相关途径中代谢物Dihydroxyacetone phosphate和2-Phospho-D-glyceric acid，刺激了土壤微生物（Proteobacteria、Actinobacteria）产生更多的氨基酸，优化了微生物和线虫群落与土壤特性的关系，进而调控了土壤氮素转化过程，减少了土壤氮素损失。 15N桶栽试验研究表明，与单施氮肥（N100）处理相比，PN100显著提升土壤中的15N吸收率19.38%，并且降低了15N损失率8.16%，表明PN100能够提高小麦对氮肥的利用。室内模拟试验表明温度增加促进了PPM材料的水解，提高了养分释放率。土壤培养试验表明不同施氮处理均显著提高土壤氮素矿化率，且PN100处理在含水量25%条件下土壤氮素矿化量最高。PPM与氮肥配施后，改善了土壤理化特性，减缓了肥料养分释放，降低了土壤中硝态氮和铵态氮的损失，调控了不同土壤微生物对PPM的响应，同时通过代谢组学和相关性分析也证明PPM与氮肥配施调控了相应代谢物表达进而促进土壤氮素转化，提高小麦产量。