Effect of long-term fallow and cultivation on soil fertility in rice-based cropping system

A long-term field experiment was conducted to investigate the effect of fallow and cultivation on soil fertility in rice-based cropping system.The results showed that organic matter and total nitrogen content in fallowed soil were significantly higher compared to cropped soils.The difference decreased with the soil depth.Potentially mineralizable N in the upper 15cm of fallowed soil was greater than that of cropped soils.Cropped soils which were continuously applies to pig manure,crop straw or other organic fertilizers had equivalent or much more available P in comparison to fallowed soil,while cropped soils without any fertilizers or with only mineral fertilizers had much less available P than fallowed soil.No differences between fallow and cultivation were observed in non-exchangeable K content in the depth from 15 to 30cm of soils.Fallowed soil had more non-exchangeable K in the top 15cm of soil compared to cultivated soils.Exchangeable K content of fallowed soil in the whole plow layer was higher than that of cultivated soils. A slight lower pH was found in fallowed soil in comparison to cropped soils.