水/沼液一体穴灌及其对设施土壤环境的影响机理研究

Superfluous irrigation, heavy fertilizers and pesticides usage are the main reasons for soil environmental deterioration in the traditional facilities. In this research, we put forward a new irrigation method, which combine the effect of water control and biogas slurry irrigation, take advantage of suitable water control can improve the crop quality and biogas slurry can better soil environment, hole-irrigation with water and biogas slurry integration. The method will change the traditional irrigation pattern of irrigating the water and biogas slurry respectively. Through field experiment and theoretical analysis, the project will research the effects of hole irrigation control parameters, such as the diameter of the hole, the distance between the holes, the quantity and concentration of biogas slurry, and the frequency of irrigation, on the moisture and nutrient distribution, physicochemical property, organic and heavy metal content of the soil and the plant physiological ecology indexes of the crop. The research will reveal the water and nutrient saving mechanism of the hole irrigation, and find out the internal relations among all factors and the functional relationship among the indexes of soil environment, explicit the influence mechanism of the irrigation method on soil environment of the facilities. The research will set up the comprehensive evaluation model based on the soil environmental index for greenhouse vegetable under the condition of hole-irrigation with water and biogas slurry integration. The outcomes can provide a new kind of water and biogas slurry irrigation method for farmers, and provide theory basis for biogas slurry use, which will be proved to maximizing the benefits for biogas slurry use, and promote the greenhouse soil used sustainable.

为解决传统设施农业中过量灌溉和大量化肥农药的使用造成土壤环境恶化的问题，本项目利用水可调质、沼液可改善土壤环境的特点，提出水与沼液一体化穴灌的方法。通过试验和理论分析，系统研究穴孔尺寸、穴孔间距、沼液灌溉量、沼液浓度、灌溉频次等控制参数对土壤水分、养分运动分布规律、土壤理化性质、有机质含量、重金属含量及植物生理生态指标的动态定量影响，揭示水/沼液一体穴灌的节水、节肥机理，确定适宜的灌溉技术参数；探明水/沼液一体穴灌中各影响因子内在联系及与土壤环境指标之间的函数关系，明确水/沼液一体穴灌对设施土壤环境的影响机理，建立以土壤环境指标为目标函数的评价指标体系。本项目研究成果为农民提供了一种新的水/沼液穴灌模式，对沼液资源效益最大化,促进其高值利用和农田土壤可持续利用提供理论依据。

科学合理的施用沼液，既使其能被广大农民所接受，又能实现节水、节肥及设施土壤环境的改善，进而提高设施土壤的可持续利用性是目前农村设施农业发展过程中一个亟待解决的科学问题。本项目将沼液和水一体化，结合现有的沼液穴灌技术，采用试验研究和理论分析相结合的方法，系统研究水-沼液一体穴灌合理技术参数、节水、节肥机理及对设施土壤环境的影响机制。研究表明沼液土壤水扩散率受到沼液浓度的影响最大，沼液穴灌形成的湿润体形状会逐渐由水平轴大于垂直轴的椭球体趋向于水平轴小于垂直轴的椭球体，Philip入渗模型能够准确描述沼液穴灌累积入渗量随时间的变化规律；土壤湿润体内铵态氮含量分布规律由穴孔向外可划分为铵态氮高含量区、铵态氮含量急降区和铵态氮低含量空白区，铵态氮含量随着土壤含水率的变化关系呈三次多项式（a<0）；随沼液配比浓度的增加，全氮和硝态氮吸附曲线逐渐向右偏移，运移吸附转折点对应时间随沼液配比及密度的增大而增加，而吸附转折点渗出液相对浓度（C/C0）随浓度的增加而减小；土壤对1:1（沼液:水）、1:2及1:4沼液配比吸附达到平衡时渗出液中硝态氮的含量均小于国家标准值（10mg•l-1）；随沼液配比的增加，平均孔隙水流速(V)及水动力弥散度（D）均减小，随土柱高度的增加平均孔隙水流速(V)逐渐较小，阻滞因子R逐渐增加；T1（1:4，沼液:水）和T2（1:6）的产量较CF（当地常规化肥处理）分别提高了3.04和0.72%（2016秋）、5.71和2.73%（2017春），T1和T2处理均能够实现化肥替代，综合番茄生长、产量、品质和氮素农学利用率等因素，建议番茄全生育期施用沼液适宜配比为1:4。项目研究可解决沼液穴灌技术在实际应用中遇到的实际问题，为设施土壤环境恶化问题提供解决途径，并对沼液资源效益最大化，促进其高值利用和农田土壤可持续利用提供理论依据。