应用耕作指数评价耕作措施对双季稻田土壤质量的影响

Assessment of Tillage Effects on Soil Quality for Double-Rice Paddy with Tilth Index

【目的】采用耕作指数(TI)定量评价了耕作措施对双季稻田土壤质量的影响,旨在为选择合理的土壤耕作措施提供依据。【方法】试验始于2005年,在湖南省宁乡县设免耕(NT)、旋耕(RT)和翻耕(CT)3个处理,测定了2007、2008年水稻收获期0—20 cm土层有机质(SOM)、土壤容重(BD)、全氮(TN)及pH等理化性状指标,利用目的线性回归模型计算TI。【结果】有机质含量和土壤容重对双季稻田土壤质量影响显著,水稻产量与土壤有机质含量显著正相关(R2=0.45),与土壤容重显著负相关(R2=0.67);可通过测定有机质含量和土壤容重计算得到TI,TI=0.40 SOM'+0.60 BD',且与水稻产量呈显著正相关(R2=0.67),可作为选择耕作措施的依据。试验中3个耕作处理土壤质量均有不同程度的改善,TI变化表明试验期间NT处理初期土壤质量较差(TI=0.79),但其TI增加最快,免耕能有效地改善土壤质量。【结论】利用目的线性回归模型计算TI能够较准确的定量描述不同耕作措施下双季稻田土壤质量。免耕有利于土壤质量的改善。

【Objective】 Improvement of soil quality is very meaningful for increasing land productivity and ecological environment.In this study,tilth index（TI） was used to evaluate the soil quality of double-rice paddy under different tillage systems in order to provide a basis for selecting reasonable tillage.【Method】 No-tillage（NT）,conventional tillage（CT） and rotary tillage（RT） were carried out in 2005 at the Ningxiang County,Hunan province.Soil organic matter（SOM）,bulk density（BD）,total nitrogen（TN） and pH of 0-20 cm soil were measured to calculate TI,and soil samples were collected at rice harvest time in both 2007 and 2008.TI was calculated by a proposed regression model.【Result】 Rice yield had a significant negative correlation with bulk density（R2=0.67） and positive correlation with soil organic matter（R2=0.45）.TI increased linearly with increasing rice yield（R2=0.67）.TI could be easily determined through measured SOM and BD of the soil,TI = 0.40 SOM＇ ＋ 0.60 BD＇,the proposed regression model showed the value of TI was a good indicator for optimum rice yields,as well as an evaluation of the soil quality.In this study,soil quality of all the three tillage treatments was obviously improved,the change of TI showed that NT didn＇t have a better soil quality at early period of experiment,but the tendency of soil quality improvement was more significant than CT and RT,therefore long-term no-till and straw returning may be a good choice.【Conclusion】 The value of TI,which was calculated through the proposed regression model,could be a good indicator for rice yields,as well as an evaluation of the soil quality.Soil quality of NT increased the fastest in all the three tillage systems.