Effects Of Mixed Cropping On Growth,Nutrient Uptake Of Chinese Milk Vetch With Ryegrass And Soil Phosphorus Conversion

Mixed cropping of Chinese milk vetch and ryegrass is an efficient planting mode in the production of green manure in the south.Compared with monoculture,it could make more full use of resources,get more biomass,accumulation of nitrogen,phosphorus and potassium,it could also provide nutrients and fertility for the post-season crops after returning to the field.In this experiment,ryegrass and Chinese milk vetch were used as research materials,we studied the effects of mixed cropping of Chinese milk vetch and ryegrass on the growth,nutrient uptake and soil phosphorus availability through soil culture and root box test,and explored the mechanism of mixed cropping of Chinese milk vetch and ryegrass,which provided the basis for the high efficient utilization of soil nutrient resources and the improvement of green manure production efficiency.The main results were shown as follows:(1)The effect of mixed cropping of Chinese milk vetch and ryegrass on the growth of mixed ryegrass was greater than that of the mixed vetch,and the biomass of the mixed system of Chinese milk vetch and ryegrass showed a mixed system advantage,especially under the phosphorus application it was more evident.(2)The mixed cropping of ryegrass and Chinese milk vetch promoted the accumulation of phosphorus uptake in ryegrass,and showed a mixed system advantage about the phosphorus uptake,especially a higher phosphorus uptake showed under the low phosphorus level.Compared with monoculture,the phosphorus uptake of the mixed system was increased by 20.4% at the low phosphorus level,while the phosphorus uptake in the mixed cropping system increased by 18.6% at the normal phosphorus level.The mixed system enhanced the nitrogen and potassium uptake remarkably,and the increase of nitrogen and potassium uptake in mixed ryegrass were more than the decrease of mixed Chinese milk vetch,which showed an advantage of nitrogen and potassium uptake in the mixed system,especially under the phosphorus application it was more evident.Compared with monoculture,the nitrogen uptake of the mixed system increased by 28.6% at the low phosphorus level,and the nitrogen uptake of the mixed system increased by 31.6% at the normal phosphorus level.Compared with monoculture,the potassium uptake of the mixed system increased by 24.5% at the low phosphorus level and 38.6% in the mixed system at the normal phosphorus level.(3)Compared with monoculture ryegrass,mixed cropping of ryegrass and Chinese milk vetch improved the available phosphorus content in the rhizosphere soil.In the mixed system,the available phosphorus content in the root zones was significantly higher than that in monoculture ryegrass and Chinese milk vetch.The contents of Al-P and Fe-P in the rhizosphere soil of mixed cropping reduced to transform into the active state,and the activation ability of Al-P and Fe-P of the mixed system was higher than that in monoculture ryegrass and Chinese milk vetch.(4)The mixed cropping of Chinese milk vetch and ryegrass could promote the increase of acid phosphatase activity in the mixed cropping rhizosphere soil,and has the tendency to reduce the rhizosphere soil p H,maybe it was the important reason for the high absorption ability for the mixed system.