再生水地下滴灌技术参数对土壤氮磷转化和吸收的影响及调控

The nutrients in the reclaimed wastewater and the changed soil quality could impose considerable effects on the transformation and crop uptake of nitrogen and phosphorus in the soil irrigated with reclaimed wastewater. However, the mechanism of the effects of reclaimed wastewater irrigation on the transportation and transformation of nitrogen and phosphorus remains to be unclear. Besides, researches on the technical parameters, water and nutrient management of the subsurface drip irrigation with reclaimed wastewater are still rare. Pot experiments will be conducted to reveal the effects of irrigation water quality (reclaimed wastewater and groundwater) on the soil physical and chemical properties, enzyme activity, and transformation of nitrogen and phosphorus in soil. The effects of technical parameters of subsurface drip irrigation on the growth of tomato and the availability of nitrogen and phosphorus in the soil irrigated with reclaimed wastewater will be evaluated through field experiments conducted in a sunlight greenhouse. The optimized subsurface drip irrigation technical parameters and regulation measures would thus be put forward in the present study. The expected results of this project will add new knowledge to the regulation theory of reclaimed wastewater irrigation and will be a contribution to enhancing the efficiency and safety of reuse of wastewater for irrigation.

再生水灌溉条件下，灌溉水中的营养元素及再生水灌溉自身的环境效应会对土壤氮磷转化及吸收产生影响。针对再生水灌溉对氮磷在土壤中的迁移转化及吸收影响机制的认识不清晰，以及制定再生水地下滴灌技术参数及水肥调控措施的依据不足等问题，本项目拟开展盆栽试验，对比研究灌溉水质（再生水和地下水）对土壤理化性质、酶活性、土壤氮磷形态及分布特征的影响，揭示土壤-作物系统中氮磷迁移转化和吸收过程对再生水灌溉的响应机制；同时开展日光温室番茄试验，研究地下滴灌技术参数和水肥管理措施对作物生长和养分有效性的影响，提出优化的再生水地下滴灌技术参数与管理措施。预期研究结果对丰富再生水灌溉技术理论、实现再生水灌溉的高效安全利用具有重要意义。

本项目以再生水灌溉条件下养分高效利用为目标，采用盆栽试验和大田试验相结合的方式开展研究，探讨了再生水灌溉对氮磷在土壤中的迁移转化及吸收的影响机制。盆栽试验重点在于机理探讨，评价了灌溉水质、滴灌带埋深及施磷方式对氮磷分布及动态的影响机理；大田试验重在对盆栽试验结论进行验证，评价再生水灌溉水肥管理措施对水肥动态和作物生长的影响。.项目获得的主要结果如下：（1）再生中含有的营养元素在灌溉过程中能够对土壤氮、磷形成补充，但在灌水量较小的情况下，其带入的氮、磷对土壤氮磷的分布及动态变化影响较小；（2）再生水灌溉能一定程度上增加土壤酶活性，但灌溉水质对土壤酶活性的影响未达到显著水平；（3）当磷肥以基肥方式施入土壤时，能使表层土壤速效磷含量明显增高；当以追施方式分次施入土壤时，更能提高土壤剖面中速效磷含量，土壤剖面中速效磷呈随距滴头距离增加而减小的趋势。磷肥追施条件下，地下滴灌能够明显改变土壤剖面速效磷分布，提高速效磷在土壤中分布均匀性；（4）磷肥追施措施可以有效促进作物生长及产量形成，其对玉米株高、叶面积指数及产量的影响在α = 0.1水平上达到显著，滴灌带埋深为15 cm时，作物生长及产量优于地表滴灌处理。但是，当滴灌带埋设位置较深时（如30 cm）时，随滴灌系统进入土壤中的磷肥较难满足上层根系对速效磷的吸收，在一定程度上降低了施入磷肥对作物生长的促进作用。为了提高再生水灌溉条件下氮磷利用效率，建议采用地下滴灌磷肥追施方式。本研究结果对丰富再生水灌溉技术理论、实现再生水灌溉的高效安全利用具有重要意义。