Effects Of Planting Italian Ryegrass On Soil Fertility And Microorganisms In Paddy Field

The effective use of winter fallow rice field in South China agriculture region is a urgent problem to be solved.Rice rotation technology can make full use of existing land resources and the coordinated development of feed crops.A series field experiments were conducted in ryegrass/rice rotation farmland in Jiangsu Province to understand the effects and difference of three cropping-patterns on soil fertility and microbial activity,in order to provide detailed information for the application and popularization of the ryegrass/rice rotation techniques.The experiment was set to investigate the changes of soil fertility and soil microorganisms after crop rotation,such as Italian ryegrass and wheat,with the winter follow/rice rotation as a control.After ryegrass harvested,three treatments were carried out with stubble,50%,100%ryegrass returning to field,with no-ryegrass returning to field as control,so as to find the suitable crop rotation and amount of ryegrass returning to field.The main results are as follows:1.The differences of soil fertility under different treatments were significantly different(P<0.05).After rice harvest,Thel pH decreased significantly in Italian ryegrass/rice treatment(P<0.05),While the pH increased in wheat/rice treatment and winter fallow/Rice in the control area;the soil organic matter content of Italian ryegrass/Rice treatment increased 5.31%(2014)and 9.91%(2015),while the total nitrogen,phosphorus,and potassium content in soil showed a slow increasing trend.The effects of ryegrass/rice rotation on soil fertility were not significantly different on soil fertility.2.The effects of ryegrass returning treatment on soil physical and chemical properties were significantly different(P<0.05).The study found that,after the rice harvest,with the increase amount of ryegrass returning to field,soil pH slowly increasing.With the increase of the amount of ryegrass returning to field,the soil fertility firstly increased and then decreased.The amount of 50%ryegrass returning treatment had significant effects on total nitrogen,phosphorus and potassium and the organic matter content of soil by 8.15%,14.17%,6.42%and 9.21%,respectively.3.Microbial changes under different treatments were significantly different.The changes ratio of soil microorganisms in different cropping rotations were as follows:winter fallow/rice rotation<wheat/rice rotation<ryegrass/rice rotation;the amount of 0%ryegrass returning<the amount of 100%ryegrass returning(or stubble returning)<the amount of 50%ryegrass returning.4.After the treatment of perennial ryegrass returning to field,the changes of rice production were significantly different(P<0.05).Agronomic traits in yield,plant height and tiller number with the increase amount of ryegrass returning to field firstly increased and then decreased;yield component factor such as spike number,spike weight and 1000 grain weight changes in 50%perennial ryegrass returning rate treatment increased greatly,with an increase of 61.38%,58.9%and 7.52%,respectively;with the increase amount of ryegrass returning ratio,the feeding quality related traits of rice straw such as crude protein,crude fiber content firstly increased and then decreased.