Effects of nitrogen fertilization and root interaction on the agronomic traits of intercroppedmaize, and the quantity of microorganisms and activity of enzymes in the rhizosphere

Aims To elucidate the mechanisms of the beneficial effects of below-ground root interactions in maize plus legume intercropping system, Methods A pot experiment was conducted using root separation techniques. Results It is shown that root interaction and nitrogen fertilization increased chlorophyll content and improved plant characteristics of maize, and the effect of root interaction was significant (p<0.05). Compared to a full root separation treatment, no root separation increased the leaf and grain nitrogen contents, and economic and biological yields per maize plant by 9.3 %, 6.0 %, 14.0 %, and 6.5 %, respectively. Root interaction and nitrogen fertilization enhanced the numbers of bacteria, fungi, actinomycetes and Azotobacteria and the activities of urease, invertase, acid-phosphatase and protease in soil. Correlation analyses revealed that the quantity of microorganisms and the activity of the aforementioned enzymes were all positively or significantly (p<0.05) positively correlated with chlorophyll content, plant height and economic and biological yields per maize plant. Conclusions The findings demonstrate that root interactions are important in improving the soil microecological environment, increasing microbial quantity and enzyme activity in soil, and enhancing crop yield.