耐盐深根作物秋葵与暗管结合改良盐碱地作用机制研究

Saline-alkali land is an important reserve arable land resource in China. To improving heavy saline-alkaline land by subsurface pipe can effectively increase the area of arable land, which is of great significance to China's food security. However, there is a lack of freshwater resources in the region and there is a gradient-improving process under rain-fed conditions. In the initial stage of soil salinity improvement, soil salt is relatively heavy, the general crop is difficult to grow normally, and it is difficult to get economic income. Thus, people's enthusiasm for subsurface pipe investment is lower. The soil nutrient is also lost along with the drainage of pipes. The developed root systems with salt-tolerant and deep-rooted crops can not only provide channels for drainage, but also increase the efficiency of drainage and salt leaching, as well as increase soil nutrients and obtain economic benefits. In this study, simulated container were used to study the mechanism of root density, morphology, and the effect of continuous planting years on the effect of salt drainage under subsurface pipes using. And a study on mechanism of combined effects of salt-tolerant and deep-rooted crop okra planting and salt-drainage on the soil quality is established. Then, we hope to establish a methods for compensating soil nutrients under the interaction between deep-rooted crop planting and underground pipes. And field validation is carried out for economic and ecological evaluation. This study is to provide a new model for heavy saline-alkaline soil improment and provide theoretical guidance for the promotion and application of salt-tolerant, deep-rooted crops and dark pipe combined with improved saline-alkali land.

盐碱地是我国重要的后备耕地资源，环渤海重度盐碱地暗管改良可以有效增加耕地面积，对我国粮食安全具有重要意义。但该区域缺乏淡水资源，在雨养条件下存在一个梯度改良的过程。重度盐碱地改良初期土壤盐分较重，一般作物难以正常生长，难以形成有效的经济收入，降低了人们对暗管投入的积极性。暗管排水的同时土壤盐分也随之淋失，耐盐深根作物有发达的根系不仅可以为排水提供通道，提高排水淋盐的效率，也能增加土壤养分，并获得经济效益。本研究通过模拟箱模拟暗管排水与深根作物种植试验，研究根密度、形态、连续种植年限对暗管排盐效果影响的机制。明确耐盐深根作物秋葵种植与暗管排盐结合对土壤质量的影响机理，构建深根作物种植与暗管相互作用下对土壤养分的补偿机制，进而开展田间验证，从经济、生态学角度开展评价。旨在为重度盐碱地雨养条件下暗管改良盐碱地初期提供一种新的改良模式，为耐盐深根作物与暗管结合改良盐碱地推广应用提供理论指导。

滨海中重度盐碱地是我国重要的后备耕地资源，改土适生与植物适应盐碱地是盐碱地综合利用的两个方面。阐明暗管改良与植物适生改土之间的互作关系，将为滨海盐碱地综合开发利用提供重要理论支撑，对保障我国粮食安全具有重要意义。本项目采用模拟箱控制性试验的方法研究了耐盐植物秋葵适生种植与暗管排水技术相结合的生态、生产效果，明确了土壤肥盐调控对改土适生与植物适生改土相结合模式的促进作用机制。研究结果表明，秋葵根重密度与根系垂直分布密切相关。在秋葵根重密度为116 μg cm-3，秋葵可以显著提高暗管排水技术在改良滨海盐碱地时的排水效果。根重密度为 136 μg cm-3，秋葵可以显著提高暗管排盐效果。同时种植秋葵可以提高暗管排水技术的改碱效果；通过分析秋葵生长指标、产量、土壤含盐量、土壤速效磷含量、暗管排水量和排盐量等的变化，揭示了连续种植年限对暗管排盐效果的影响机制，提出了滨海盐碱区深根作物秋葵与暗管排水结合改良盐碱地条件下的最佳土壤养分补偿方案。施肥显著改善秋葵农艺性状，使株高、茎粗、产量增加。施肥有效补偿了土壤养分，与初始值相比，全氮含量增加，速效磷和速效钾均高于不施肥处理。施肥增加了暗管排水量与暗管排盐量，显著降低土壤含盐量，以0-20 cm土层效果最好。施肥能平衡滨海盐土氮磷养分并改善秋葵农艺性状，增加暗管排水量，促进暗管排盐，并降低土壤电导率与含盐量，加快盐碱地的改良速度。以有机肥和化肥一起施用效果最佳。在此基础上以秋葵产量和经济效益为指标，评价了深根作物秋葵与暗管排水结合改良盐碱地的经济效益，中重度盐碱地种植秋葵可以实现收入约850元/亩。因此，在我国北方滨海中重度盐碱地上采用暗管工程改良与植物适生改良的方法，可以有效提高脱盐改碱效率，缩短改良时间，增进农民改良意愿。本项目为中重度盐碱地雨养条件下暗管改良盐碱地初期提供了一种新的改良模式，为滨海盐碱区农业的可持续发展提供了理论指导。