Effects Of Cassava/peanut Intercropping On Micro-ecology In Soil And On The Nutrition Utilization

Cassava/peanut intercropping is an endemic collocation model in tropical and subtropical regions,which can make full use of land resources and increase the farmers’economic income.The study about cassava/peanut intercropping system is transferring from the aboveground part to the underground part.This study set field experiment of three treatments:cassava monoculture,peanut monoculture and cassava/peanut intercropping,and the aim is to systematically study the effect of cassava/peanut intercropping on the aboveground and underground part.The underground part includes that the effects of cassava/peanut intercropping on the amount of microorganism,enzyme activity and nutrient in rhizosphere and non-rhizosphere soil,and analyze their correlation.The aboveground includes that the effects of cassava/peanut intercropping on the growth,nutrient uptake and yield.This study explains the effects of cassava/peanut intercropping on efficient nutrient utilization mechanism from micro-ecological perspective.The main results are as follows:1.Microbe amount:Both monoculture and intercropping,with the extension of growth period the amount of bacteria and fungi in both cassava and peanut rhizosphere soil followed the trend of multiplying first and then dropping to the original value.Obviously,the amount of bacteria and fungi reached the peak value in the cassava root expanding stage and peanut pod setting stage,individually.While with the extension of growth period,the amount of bacteria and fungi in both cassava and peanut non-rhizosphere soil rose gradually.When compared with the cassava or peanut monoculture,the intercropping B/F value in rhizosphere soil were higher in the middle and later periods,which can induce cassava and peanut rhizosphere soil to be bacteria type.During the common stage of cassava and peanut,cassava/peanut intercropping can induce the non-rhizosphere soil to be fungi type,but after harvesting the peanut,cassava/peanut intercropping can induce the non-rhizosphere soil to be bacteria type,which was helpful to maintain the soil fertility.2.Enzyme activity:When compared with cassava or peanut monoculture,cassava/peanut intercropping increased the activity of urease,acid phosphatase and sucrase in cassava rhizosphere soil,but only increased the activity of urease and phosphatase in peanut rhizosphere soil and decreased sucrase in peanut rhizosphere soil.Cassava/peanut intercropping increased the activity of urease,acid phosphatase and sucrase in the non-rhizosphere soil.3.Soil nutrition content:When compared with cassava or peanut monoculture,cassava/peanut intercropping decreased pH value in cassava and peanut rhizosphere soils,but slightly increased pH value in the non-rhizosphere soil;Cassava/peanut intercropping increased the oranic matter content and effective phosphorus content in cassava and peanut rhizosphere and non-rhizosphere soils;Cassava/peanut intercropping increased effective potassium content in cassava rhizosphere soil,but reduced the available potassium content in non-rhizosphere soil;Cassava/peanut intercropping had the trend to increase alkaline hydrolysis nitrogen content in cassava and peanut rhizosphere soils,but during the common stage of cassava and peanut,cassava/peanut intercropping decreased the alkali-hydrolysable nitrogen content in non-rhizosphere soil,but after the peanut harvested,alkali-hydrolysable nitrogen of intercropping cassava in non-rhizosphere soil had the trend to recovery.4.Correlation analysis:Some factors of soil microorganism,enzyme activity and fertility factors were closely related to each other,but the acid phosphatase activity and phosphorus content did not reach significant correlation and the urease activity and alkaline hydrolysis nitrogen content did not reach significant correlation.5.Aronomic traits and fresh yield:For cassava,during the common stage of cassava and peanut,the height,stem diameter,fresh yield of intercropping were lower than cassava monoculture.But after the peanut harvested,the height,stem diameter,fresh yield of intercropping had a tendency to reply;For peanuts,the height and stem diameter of intercropping were higher than peanut monoculture,and along with the growth period,peanut intercropping increased the aboveground fresh yield in the pod-pin stage and podding period,while increased the root fresh yield in the harvesting stage.Meanwhile,intercropping slightly increased the yield of 100-pod weight(left)and 100-kernel weight of peanut.The above results shows a phenomenon that during the common period of cassava and peanut,peanut was a dominant species,because it had stronger competition ability for resources and production advantage,while cassava was a subordinate species,it would grow fast after peanut harvested.6.Plant nutrition content:Cassava’s root formation stage is peanut’s podding period.Druing this stage,the nitrogen,phosphorus and potassium content of intercropping in cassava leaf,stem and root were lower than cassava monoculture,but after harvesting peanut,or peanut harvested,the nitrogen,phosphorus and potassium uptake content of intercropping in cassava root,stem and leaf were relatively higher than cassava monoculture,of which the absorption of potassium in stem is the most obvious.The results shouwed that during the common stage of cassava and peanut,cassava’s seedling stage is peanut’s exuberant growth stage.The nutrition competitive is intense between cassava and peanut and cassava is at a competitive disadavantage,but after the peanut harvested,the absorption of nitrogen,phosphorus and potassium in intercropping cassava had a tendency to recover.7.Middle and micro elements:When compared with cassava or peanut monoculture,cassava/peanut intercropping can reduce the calcium content in cassava leaves,increase the calcium content in cassava stem and root,increase the calcium content in peanut leaf,stem,root and shell,increase the magnesium content in peanut leaf,and increase the zinc content in cassava and peanut leaf,stem and root,increase manganese content in peanut leaf,stem and root,but reduce the content of manganese in peanut shells.