甘肃引黄灌区枸杞-豆科牧草复合系统水盐分异特征及互馈机制研究

In view of the current problem of lower water and land use efficiency due to the increasing aggregation of salt on the land surface for higher soil evaporation under a single Lycium barbarum L. or leguminous forage cropping conditions in Gansu Yellow River Irrigation District of Northwest China, the field experiments will be conducted to research on the spatial-temporal variation feature of water and salt of Lycium barbarum L. interplanting with leguminous grass and its driving mechanism under different salt and water interaction conditions for Lycium barbarum L. interplanting with leguminous grass. The experiment were designed by four irrigation water gradient(75-85%,65-75%,55-65%,45-55% of field capacity, respectively) and three salinity gradient(2.0-5.0g/kg,5.0-7.0g/kg,7.0-10.0g/kg). In order to reveal the temporal and spatial variation law of water and salt, drive mechanism and mutual feedback mechanism, the difference of water and salt among soil, Lycium barbarum L. and leguminous grass will be found, and establishing differentiation function in complex systems and interaction effect function. Based on the comprehensive analysis of the above problem, the spatial-temporal variation feature and feedback mechanism of water and salt in Lycium barbarum L. and leguminous grass combined system is formed. The results can provide a theoretical basis and technical support for critical value of salt and water by revealing water and salt action mechanism, drive mechanism and feedback mechanism on the condition of the intercropping pattern of Lycium barbarum L. and leguminous grass, also can provide a scientific basis for higher the efficient use of water and land resources.

针对甘肃引黄灌区枸杞或豆科牧草单作条件下，棵间蒸发量大引起林草耕作层盐分聚集，导致水土资源浪费的实际问题，采用大田试验，以枸杞间作豆科牧草(枸杞间作紫花苜蓿、枸杞间作红豆草、枸杞间作毛苕子、枸杞间作箭筈豌豆、枸杞单作)为研究对象，选取不同盐渍化程度土壤实施水分调控，分析水、盐在土壤、枸杞、豆科牧草三者间的时空变化、运移、分配规律，对比不同枸杞-豆科牧草复合系统下水盐分配规律的差异，确定适宜的水盐时空分异指标和关键驱动因子，建立复合系统分异函数、互作效应函数，揭示复合系统水盐时空分异规律、驱动机理、互馈机制。研究成果为明确枸杞-豆科牧草复合系统水盐协同和互馈关系、构建驱动因子指标体系、解析驱动机理、确定水盐临界阈值等问题提供理论依据和技术支撑，通过研究土壤-林草间、林-草间、水-盐间的互馈机制消减盐害，实现水土资源的高效利用提供科学依据。

针对甘肃引黄灌区枸杞生产中棵间蒸发量大、盐渍化土壤利用率低、水土资源浪费严重等实际问题，基于种间竞争互补、水分调控、林草消盐效应等理论，采用大田试验、室内分析和数值分析相结合的方法，以枸杞间作豆科牧草（枸杞||紫花苜蓿、枸杞||红豆草、枸杞||毛苕子、枸杞||箭筈豌豆、枸杞||大豆和枸杞单作）为研究对象，开展种植模式、种植模式×水分调控、水分调控×盐分调控等研究，分析了种植模式、水分及盐分调控对土壤环境，林草生理生长、产量、品质和水分利用的影响，确定了适宜的土壤水热盐时空分异指标和关键驱动因子，建立了复合系统互作效应函数，揭示了复合系统水热盐时空分异规律、驱动机理和互馈效应。结果表明，种植模式、种植模式×水分调控、水分×盐分调控对土壤水分、温度、盐分的影响远大于结构因素引起的变异，且种植模式、水分调控、盐分调控间存在一定的交互效应；水平方向0－60cm是枸杞||苜蓿系统中地上部分生长的高强竞争区域，苜蓿应在距离枸杞树行60cm外开始种植。在种植模式方面，间作多年生豆科牧草较间作一年生豆科牧草更有利于枸杞生长，在一年生豆科牧草中，间作毛苕子和箭筈豌豆的效果优于间作大豆；与枸杞单作相比，枸杞‖苜蓿和枸杞‖红豆草的产量分别提高15.38%和14.05%，水分利用效率分别提高13.14%和12.57%。在种植模式×水分调控方面，枸杞产量表现为单作高于间作，枸杞单作在轻度水分亏缺条件下产量较高，枸杞||苜蓿和枸杞||红豆草均在充分灌水时产量较高，且苜蓿和红豆草均在间作后第三年产量最高。在水分×盐分调控方面，充分灌水效果优于其他水分调控，中度及以上盐渍化土壤不利于间作系统中林草的生长，枸杞单作盐分呈累积状态，枸杞||红豆草时非盐化、轻度及中度盐渍化的脱盐率分别为34.85%、8.82%和14.20%。研究成果可为明确枸杞||豆科牧草复合系统土壤水热盐协同与互馈关系、解析驱动机理、确定水盐临界阈值等问题提供理论依据和技术支撑，为甘肃引黄灌区水土资源高效利用提供科学依据。