Effects Of Continuous Cropping On The Growth Of Sorghum And The Soil Environment

Continuous cropping obstacle is a common cultivation problem in agricultural production.In general,sorghum is not suit for continuous cropping.Continuous cropping significantly affected the growth and yield of sorghum,which lead to soil environmental degradation.Currently,the study of continuous cropping obstacle mostly focused on facilities vegetables(tomato,cucumber),economic crops(soybean,peanut)and field crops(maize,wheat),there almost no research on sorghum continuous cropping obstacle.We set sorghum continuous cropping and corn/sorghum rotation positioning experiments during the period of 2011 and 2015 in Dongyang test base in Shanxi province.With the corn/sorghum as contrast,we study the effects on plant height,stem diameter,leaf area and grain yield of sorghum continuous cropping for 3,4 and 5 years separately,and study the effects on soil enzyme activity of different continuous cropping years.For further research of sorghum continuous cropping obstacle,we study the function diversity of rhizosphere soil microbes for continuous cropping 5 years with BIOLOG technology.The study aims to determine the effects of sorghum continuous cropping obstacle and it's influence on the soil environment.Here are the main results and conclusions:There is an obvious inhibition on the growth of sorghum when continuous cropping for 3 years,which is more remarkable for jointing stage.There's the same trend when continuous cropping for 4 and 5 years.The stem diameter,plant height,leaf area and biomass of continuous cropping for years accounts for 15.18%?21.67%?43.31%?40.30%of rotation.There's an significant difference of sorghum grain yield between the continuous cropping and rotation,the sorghum grain yield of continuous cropping account for 85.58%?84.48%?95.34%of rotation in 2011,2013,2015.It means that there's an obvious inhibition on the growth of sorghum when sorghum continuous cropping,and appropriate rotation can ease the obstacle of sorghum continuous cropping.When analyzing the rhizosphere microbial community functional diversity of sorghum continuous cropping and maize/sorghum rotation by using BIOLOG technology,the results shows that the average color change rate of continuous cropping flowering and maturity is significantly higher than that of rotation.It can be seen from the data of classification of carbon source,the sugars,amino acids,esters,alcohols,acids,and amine of sorghum continuous cropping increased by 26.47%,33.04%,46.56%,45.63%,47.36 and 3.97%compared with that of rotation.According to the results of principal component analysis,there's a significant differentiation of continuous cropping and rotation in flowering,because of the differences in variety of carbon metabolism especially the amino acids and carboxylic acid.And the significantly differentiation in mature stage is due to the differences in such as carbon source of sugar metabolism mainly.With the increase of the continuous cropping years,the activities of the Catalase,sucrase,urease,phosphatase showed a rising trend.The catalase activities in 2015 increased by 49.44%,57.77%than 2011,2013(P<0.05),and there's no significant difference between annual processing of rotation.In 2015,the activities of catalase increased by 53.23%than rotation.The phosphatase activities of continuous cropping and rotation have a rising trend with the increase of continuous cropping years.The impact of continuous cropping is much smaller than rotation.The phosphatase activities of continuous cropping in 2015 increased by 49.76%,18.14%than 2011,2013,and the rotation increased by 96.57%,32.88%.In 2015,the activities of phosphatase decreased by 12.05%than rotation.There both rising trend that when continuous cropping or rotation,but there's no significant difference between continuous cropping and rotation.