稻蟹生态种养模式对稻田土壤肥力及生产效益的影响

试验通过对稻蟹生态种养田连续多年进行定位监测，探讨不同种植方式对稻田土壤基本理化性质以及生态系统经济效益的影响。试验设置在辽河三角洲中心地带，处理为稻蟹种养处理（CR）和单一稻田处理（FP），13年内连续监测土壤基本理化生物学性质、水稻与河蟹的产量，计算其经济效益。结果表明，相对于单一种稻模式而言，稻蟹生态种养模式土壤物理化学性质得到明显改善，尤其在最初的3 ~ 4年内变化显著，后续的10年内变化较小，达到了相对稳定的状态。总的来说，土壤容重降低了0.05 g cm?3，土壤孔隙度增加了2.1%。土壤有机质含量从25.5 g kg?1提高到了28.4 g kg?1，增加了2.90 g kg?1；土壤全氮含量增加了0.19 g kg?1，速效氮磷钾含量分别增加了21.2 mg kg?1、2.23 mg kg?1、29.0 mg kg?1；土壤微生物量碳增加了128%。从氮肥利用率来看，CR处理比FP处理氮肥利用率提高了10.3%，增幅显著。从水稻及河蟹经济效益来看，水稻产量无显著差异，稻米品质优化促使稻米价格上涨13.8%，加之河蟹的产出，每公顷纯经济效益增加18269元，实现了稻蟹双收的目的。综上所述，稻蟹生态种养模式不但使土壤性质得到明显改善，提高了氮肥利用效率，还保证了水稻产量和河蟹的经济效益，是兼顾经济效益和生态效益的最佳生态种养模式。

Effect of Rice-Crab Co-Culture System on Soil Fertility and Economic Benefits

In order to explore the effects of different planting methods on the physical and chemical properties of paddy soil and the economic benefits of rice-crab co-culture system, a continuous positioning monitoring system for 13 years, with the treatments of rice-crab cultivation (CR) and single rice field (FP), built in the central area of Liaohe River Delta, was applied to investigate the basic physical, chemical and biological properties of soil as well as the yields and benefits of rice and crab. Compared with FP, the soil physical and chemical properties of CR were significantly improved, especially in the first 3-4 years. In the following 10 years, the changes of them were small, reaching a relatively stable state. Generally, soil bulk density decreased by 0.05 g cm?3 and soil porosity increased by 2.1%. Soil organic matter increased from 25.5 g kg?1 to 28.4 g kg?1, increasing by 2.90 g kg?1. Total nitrogen increased by 0.19 g kg?1. Moreover, the available nitrogen, phosphorus and potassium increased by 21.2 mg kg?1, 2.23 mg kg?1 and 29.0 mg kg?1, respectively. Soil microbial biomass carbon increased by 128%. In terms of nitrogen use efficiency (NUE), NUE of CR treatment was significantly increased by 10.3% higher than that of FP treatment. From the economic benefits of rice and river crab, there was no significant difference in rice yield, but the rice price increased by 13.8% due to the optimization of rice quality. Combined with the output of river crab, the net economic benefits per hectare increased by 18269 yuan, realizing the goal of double harvest of rice and crab. In conclusion, the rice-crab co-culture mode not only improved the soil properties and NUE, but also ensured rice yield and economic benefits of river crab, which was the best ecological planting and breeding model with both economic and ecological benefits.