大型喷灌机施肥的水肥损耗利用机制与调控方法

Continuously moving sprinkler machines (CMSM), including center pivot and linear move sprinkler systems, are playing increasingly important role in irrigation of intensified farmlands in China. We have not yet taken full advantages of chemigation through the CMSMs in reducing labor input and improving fertilization efficiency in China due to lacking of sufficient researches on loss mechanism of water and fertilizers during the spray process and crop response to the nutrients fertigated through sprinkler machines. The challenging situations of rural labor shortage and unceasingly enhancement of agricultural mechanization as well as severe loss of nutrients resulted from conventional fertilization methods represent great requirements for utilization of fertigation using CMSMs. The objectives of the current proposal are to: (1) evaluate the performance of fertigation systems and the losses of water and nutrients during the spray process through experiments and simulations based on principles of energy balance and mass balance; (2) investigate the influence of design and operation parameters of sprinkler fertigation systems and management practices of water and fertilizers on losses of water and nutrients, transport and transformation of water and nutrients fertigated in soil, and crop uptake for typical sprinkled crops of winter wheat and maize; (3) establish a couple model of water and nutrients dynamics and crop growth under sprinkler fertigation and gave recommendations for optimizing the management and operation parameters of CMSMs. The results obtained will be helpful to quantify the losses and utilization of water and nutrients under fertigation through CMSMs and a contribution to enhancing precision management of water and nutrients for intensifying farmlands.

大型喷灌机在我国集约化农田灌溉中正在发挥着越来越重要的作用。然而，由于缺乏对喷灌施肥水肥损耗利用机制和作物响应特征等问题的研究，大型喷灌机在施肥灌溉上的优势未能发挥。当前面临的劳动力紧缺、农业机械化程度不断提高以及传统施肥方式水肥损失严重等问题都对利用大型喷灌系统施肥提出了迫切需求。项目拟采用盆栽、田间试验和模拟相结合的方法，研究大型喷灌机条件下水肥喷洒性能及损耗机制，构建基于能量平衡和质量守恒原理的喷灌水肥损耗估算模型，提出大型喷灌机施肥灌溉性能评价方法；以典型喷灌作物小麦、玉米为对象，研究大型喷灌机技术参数、施肥运行参数及水肥管理措施对水肥损耗、运移转化和作物吸收利用的影响，揭示水肥亏缺反馈与调控机制；构建大型喷灌机施肥灌溉水肥动态和作物生长耦合模拟模型，提出运行管理参数确定方法。预期结果对探明大型喷灌机施肥条件下的水肥损耗和利用机制、实现集约化农田施肥灌溉精准调控与管理具有重要意义。

喷灌施肥灌溉过程中的肥液蒸挥发漂移损失、冠层截留损失和叶面灼伤风险是限制大型喷灌机施肥灌溉技术发展的主要因素。为了量化大型喷灌机条件下各过程的水肥损失量及其影响因素，并建立喷灌施肥调控方法，本项目一方面通过对圆形喷灌机施肥灌溉系统水力性能的测试量化了肥液的蒸挥发损失量，另一方面通过室内和田间试验研究了作物冠层截留肥液量，以及作物对肥液浓度、氮肥追施次数的响应特征，得到的主要结论如下：.（1）圆形喷灌机施肥灌溉时，肥液浓度均匀系数为98%，灌水量均匀系数为80%~85%，施肥量均匀系数为78%~86%，说明肥液浓度均匀性主要依赖于施肥系统注肥稳定性，而施肥量均匀性主要依赖于喷灌机灌水均匀性。.（2）不考虑蒸挥发漂移损失和冠层截留损失有效性的条件下，肥液与养分的蒸挥发漂移损失率分别为5.1%和1.5%，冬小麦生育期内最大肥液冠层截留量为0.64mm，夏玉米为0.58mm，冬小麦和夏玉米喷灌施肥由氨挥发产生的养分损失率分别为1.2%~2.9%和2.8%~11.3%，叠加计算后得到的冬小麦和夏玉米的喷灌施肥肥液损失率分别为6.5%~8.3%和5.3%~8.0%，养分损失率分别为4.9%~6.7%和5.0%~7.7%。.（3）喷施不同浓度的氮磷钾肥液后，植株叶片SPAD、光合能力Fv/F0和Fv/Fm值分别平均增加了1.22、1.57和1.11倍，且氮肥促进作用大于磷钾肥。与促进叶片光合能力增大的肥液浓度相比，促进叶片SPAD值增加的肥液浓度范围更大。 .（4）尿素喷施浓度对夏玉米株高、SPAD的影响较小，对LAI的影响较大。与肥料撒施的地面灌溉处理相比，2017和2018年喷施尿素处理的玉米产量分别提高0.1和1.1t/hm2，玉米大喇叭口期尿素喷施浓度宜控制在0.146%以内，证明了喷灌施肥的可行性，验证了基于测土配方施肥技术推荐玉米施氮量的可行性。.（5）基于测土配方施肥技术推荐小麦施氮量后，氮肥施用量和氮肥追施次数对冬小麦产量和吸氮量的影响在土壤基础肥力较低的田块更为明显。籽粒和秸秆吸氮量随氮肥施用量的增加显著增加，产量随氮肥追施次数的增加而增大。从提高作物产量和减少喷灌施肥养分损失量的角度出发，适宜推荐2~3次的氮肥追施次数。