南方红壤区旧村复垦农田生产力障碍机制及精准调控

There are more people and less land in the red soil region of southern China, and the agricultural development faces the severe situation of insufficient cultivated land. Old village reclamation is a feasible and effective measure to ensure food security in this region. In the past, most of the researches on soil improvement of old village reclamation were carried out in northern China, and most of them were single studies on soil improvement measures or planting patterns. However, there was still a lack of study on obstacle mechanism and precise regulation of productivity of farmland reclaimed from old villages in red soil region of southern China. The farmlands reclaimed from old villages in Fujian Province, which were located in the red soil region of southern China, were selected in this project. Comprehensive combination of laboratory and field experiments, questionnaire survey of farmers and model simulation was used. DSSAT model was used to estimate the productivity of reclaimed farmland in the study area firstly, then the productivity difference between the reclaimed and control farmland was identified, and the influence degree and mechanism of the obstacle factors were analyzed. The DSSAT model was adopted to simulate the improvement effects of different combination plans of multiple factors, such as soil improvement measures (biochar + oyster shell powder) and tillage management measures. Several relatively optimal combination plans were preliminary screened out, and then the comprehensive screening of the optimal improvement plans for the productivity of the reclaimed farmland was implemented by combination of laboratory experiments and field application, providing scientific support for precisely and rapidly improving the soil fertility and crop yield of the reclaimed farmland and ensuring food security in the red soil region of southern China.

我国南方红壤区人多地少，农业发展面临耕地不足的严峻形势。旧村复垦是保障该地区粮食安全可行且有效的措施。以往对旧村复垦土壤改良的研究基本都在北方地区，且多是土壤改良措施或种植模式等少数影响因素的单一研究，尚缺乏南方红壤区旧村复垦农田生产力障碍机制及精准调控的研究。本项目以南方红壤区的福建省旧村复垦农田为研究对象，综合采用室内和田间实验、农户问卷调查和模型模拟相结合的方法，利用DSSAT模型估算研究区旧村复垦农田的生产力，明确旧村复垦农田和对照农田的生产力差异，解析各障碍因素的影响程度及机制。采用DSSAT模型模拟不同改良措施（生物炭+牡蛎壳粉）和耕作管理措施等多因素组合方案的改良效果，初步筛选出若干较优的组合调控方案，再通过室内实验验证和野外田间应用相结合的方法综合筛选出旧村复垦农田生产力的最佳调控方案，为精准、快速提高旧村复垦农田土壤肥力和作物产量，保障我国南方红壤区粮食安全提供科学支撑。

我国南方红壤区人多地少，农业发展面临耕地不足的严峻形势。旧村复垦是保障该地区粮食安全可行且有效的措施。针对南方红壤区旧村复垦后土壤板结、养分状况差和生产力低下等问题，本项目综合采用室内和田间实验、农户问卷调查和DSSAT模型模拟相结合的方法，发现旧村复垦农田土壤的各指标值普遍低于对照农田。DSSAT系统模拟发现旧村复垦农田土壤的颗粒组成、土层厚度、有机质含量、CEC、全氮及灌溉水量是影响水稻产量的主要障碍因素。室内盆栽以及水分和溶质运移等实验结果表明生物炭和牡蛎壳联合施用能明显提高水稻的株高、鲜重和干重，以及旧村复垦农田土壤的pH、有效磷、速效钾和有机质含量，显著降低复垦农田土壤的黏粒和粉粒含量。添加较高含量的生物炭可以显著提升旧村复垦农田土壤的水分保持能力，而生物炭和牡蛎壳的联合施用可以显著提升旧村复垦农田土壤的保肥能力。野外验证实验结果表明各改良措施可以显著提高建阳和德化基地复垦土壤的pH、交换性钙、电导率、速效磷和有机质含量，显著降低土壤容重，提高旧村复垦农田的水稻分蘖数、鲜重、株高、叶面积指数、地上生物量和产量，其中低量生物炭+高量牡蛎壳+化肥处理为建阳基地旧村复垦农田的最优改良方案，生物炭+牡蛎壳+有机肥处理为德化基地旧村复垦农田最优改良方案。上述结果能为我国南方红壤区旧村复垦农田土壤肥力和作物产量的精准快速提升提供科学支撑。

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