“多花黑麦草→水稻”轮作系统根茬养分释放规律

Nutrient release regulation of stubble in the Italian ryegrass–rice rotation (IRR) system

在“多花黑麦草(Lolium multiflorum)→水稻(Oryza sativa)”轮作系统中,通过研究水稻和黑麦草根茬的养分释放动态规律,旨在探讨该轮作系统的土壤培肥机理。结果表明,1–30 d是水稻和黑麦草根茬降解最快的时期,19.12%的水稻根茬和38.89%的黑麦草根茬在这一时期降解。水稻根茬的降解率随气温的变化呈现先下降后增加的趋势,而黑麦草根茬在夏季高温时降解率显著降低。“稻→草”轮作期间,水稻和黑麦草根茬的营养元素释放率差异显著(P<0.05),黑麦草中的氮、磷、钾必需营养元素的释放率显著高于水稻根茬(P<0.05),而水稻根茬的钙、镁主要营养元素的释放率显著高于黑麦草(P<0.05)。对降解前后的土壤分析表明,水稻降解后土壤全氮含量显著高于降解前(P<0.05),而黑麦草降解后全氮含量最高,显著高于水稻降解后(P<0.05);土壤全磷含量随水稻、黑麦草的降解逐渐降低但未出现显著差异(P>0.05);土壤全钾含量在水稻根茬降解后显著增加(P<0.05),而在黑麦草根茬降解后则显著降低(P<0.05)。研究结果揭示了水稻和黑麦草轮作过程中两类根茬养分的释放规律以及对土壤的影响,可为“黑麦草→水稻”轮作的系统培肥原理提供理论支持。

The dynamic release of nutrients from rice(Oryza sativa)and Italian ryegrass(Lolium multiflorum)stubble was studied to explore the soil fertilization mechanisms in the Italian ryegrass–rice rotation(IRR)system.The results showed that the fastest degradation of rice and Italian ryegrass stubble occurred during the first 30 days:19.12%of rice stubble and 38.89%of Italian ryegrass stubble degraded during this period.The degradation rate of rice stubble showed a tendency of first decrease and then increase with the change in air temperature.The degradation rate of Italian ryegrass stubble decreased significantly at an increasing temperature in summer.The release rate of nitrogen,phosphorus,and potassium in Italian ryegrass was significantly faster than that of rice(P<0.05)during the rotation period.The release rate of calcium and magnesium in rice was significantly faster than that of Italian ryegrass(P<0.05).Soil analysis before and after degradation showed that the total nitrogen content of rice degraded soil was significantly higher than that of the control soil(before degradation)(P<0.05).The total nitrogen content of Italian ryegrass degraded soil was the highest,and significantly higher than after rice degradation(P<0.05).Soil total phosphorus content decreased with the degradation of rice and Italian ryegrass stubble,but there was no significant difference with the pre-degradation content(P>0.05).Soil total potassium content increased after the rice stubble degradation(P<0.05)but decreased after the Italian ryegrass stubble degradation(P<0.05).The results demonstrate the nutrient release mechanisms of two kinds of stubble and their effect on the soil nutrient content during rice and Italian ryegrass rotation.This study can provide theoretical support for fertilization methods in the Italian ryegrass–rice rotation system.