| The experiment was conducted in Zhao Wang Zhuang,Laiyang,Shandong province.Six treatments were assessed: relay intercropping of green bean and waxy maize with residues retention(G/MR-B);relay intercropping of broccoli and waxy maize with residues retention(B/MR-B);relay intercropping of green bean and waxy maize(G/M-B);relay intercropping of broccoli and waxy maize(B/M-B);green bean monoculture(G-B);broccoli monoculture(B-B),through the soil physical and chemical properties,soil water stable aggregates,soil organic carbon and Rhizosphere Soil Microbes The effect of two kinds of cropping patterns on the yield and quality of continuous cropping vegetable fields were investigated in order to alleviate the problems of continuous cropping barriers and provide a theoretical basis for providing good soil microecosystem,establishing efficient production model and realizing the cultivation system.The main results are as follows:1.Effects of interplanting maize and straw on Soil Environment1.1 Influence of soil physical and chemical propertiesThe content of soil bulk density was significantly higher than that of other treatments,which decreased by 15.88%,5.99% in 2016 and 13.32% and 9.96% respectively in 2017.The content of soil available phosphorus and available potassium decreased gradually with the growth stage.The results showed that intercropping and returning to field increased significantly compared with continuous cropping.With the growing period of vegetable growth,the nitrate nitrogen content in soil showed a trend of decreasing and increasing first,the planting period reached the maximum value,and the vegetative growth period decreased to the lowest.This period was a period of higher nitrogen requirement.Intercropping maize and straw returning can absorb more nitrate nitrogen,promote nitrogen fixation,and effectively absorb nitrogen nutrition.Soil ammonium nitrogen content reached its peak during the vegetative growth period.Maize can effectively reduce the content of inorganic nitrogen in the soil,so that the nitrogen in the soil can be effectively absorbed,and the effect of straw returning to ammonium nitrogen content is not high.1.2 Influence of soil aggregatesUnder different planting methods,soil water stable aggregates were mainly distributed in 0.25-0.5 mm and 0.5-1 mm grain levels,and the intercropping treatment was significantly higher than continuous cropping treatment,indicating that waxy corn could effectively improve the soil water stable aggregate structure,and straw returning to the aggregate structure was less.The soil aggregate content data showed that the changes of 0-10 cm and20-40 cm soil layers were roughly the same,which showed that the intercropping treatment and the intercropping non return field treatment were significantly higher than the continuous cropping treatment,and the large aggregate content in the 10-20 cm soil layer was the highest,and the set back field treatment was better than the intercropping treatment and continuous cropping treatment.Don't rise 5.6%,2.8%.It indicated that interplanting maize and straw returning could effectively improve the stability of soil structure.1.3 Influence of soil organic carbonSoil organic carbon content showed a slowly decreasing trend with the deepening of soil level.Along with the growth stage,it presents a trend of first increase and then decrease.The treatment of intercropping and returning to field reached the peak at vegetative growth stage,which was significantly higher than that of intercropping without returning to field and continuous cropping,66.5% and 69.3% respectively.The results showed that intercropping and straw returning could improve soil organic carbon content and make it play a role in soil accumulation.The SOC content of soil increased first and then decreased with the growth process,and the intercropping and intercropping treatments were higher than other treatments.In 2016,the content of the soil easy to oxidize organic carbon reached the peak in the vegetative growth period.The treatment and the intercropping treatment were higher than the continuous cropping treatment by 44.1%-86.7%.Intercropping maize and straw returning can effectively increase the accumulation of readily oxidized organic carbon,while continuous cropping reduces its effective content.1.4 Influence of the rhizosphere soil microorganismThe average color change rate(AWCD)of Biolog analysis could prove the utilization of soil microbial community to substrate carbon source,and the AWCD value of each sample increased slowly with time.Soil microorganisms have higher utilization capacity of carbohydrates,amino acids and carboxylic acids,and their utilization rate for polymers,amines and other species is weak.The results of principal component analysis showed that the variance contribution rate of first principal components and second principal components were 43.63%,67.26%(2016),50.80% and 67.10%(2017)respectively.The negative direction of the non returning field treatment in the PC1 axis was applied to the positive direction of the PC1 axis.Therefore,intercropping is more conducive to the utilization of carbon sources by microorganisms.The difference in the abundance of the samples at the door classification level showed that the proportion of the actinomycetes in the waxy corn soil increased,and the proportion of the acid bacilli in the corn and straw returning soil showed a higher degree than that of the continuous cropping soil.Cluster analysis showed that the intercropping of waxy corn and waxy corn straw had a great influence on the structure of rhizosphere soil flora.2.Effects of interplanting corn and straw on Yield and quality of vegetablesDifferent cropping patterns changed crop yield to varying degrees,and crop yield was significantly higher than that of other treatments.In 2016,interplanting corn and straw returned to field could effectively increase the yield of broccoli.Intercropping waxy corn and waxy corn straw can significantly increase vegetable yield.The yield of G/MR-B and G/M-B increased by 19.9% and 15.9% respectively compared with G-B treatment.The yield of broccoli treated by B/MR-B and B/M-B increased significantly by 33.9% and 23.5%compared with B-B.In 2016,compared with continuous cropping,the content of nitrate decreased by 45.7% and 38.4%,respectively,while the content of vitamin C increased by4.7% and 8.8%,and the content of total phenol was increased by 18.4% and 53.9%,respectively.Therefore,maize intercropping and straw returning can reduce nitrate content,increase vitamin C and total phenol content,and effectively improve the quality of broccoli.To sum up the results,corn and straw returning to the field can improve soil environment to some extent,improve microbial diversity and activity,alleviate the continuous cropping obstacle of vegetables,and then improve the yield and quality of vegetables. |
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