Yield of soybean and corn intercropping and quality of mixed silage in farming-pastoral ecotones with nitrogen fertilization
The effect of nitrogen fertilization and its rate of application on the agronomic traits,crop yield,and mixed silage quality of farming-pastoral ecotones that use intercropping has yet to be determined. To address this,maize and soybean intercropping systems were evaluated using a two-factor random block design. Herein,the main factor was maize and soybean intercropping (M2S3),maize monoculture (MM),and soybean monoculture (SS),while the secondary factor was comprised of three nitrogen levels:N1 (0 kg·ha−1),N2 (150 kg·ha−1),and N3 (300 kg·ha−1). Therefore,,nitrogen application was found to change the agronomic traits and yield of soybeans,increasing the fresh yield by 12.97%~14.79%. Soybean intercropping had a significant effect on plant height,bottom pod height,and number of main stem nodes (P<0.05). The application of nitrogen improved plant height,ear height,stem diameter,and the maize yield,while intercropping had a significant impact on stem diameter and yield,but no effect on plant or ear height (P>0.05). Reducing the nitrogen level achieved the same results as constant nitrogen application. Secondly,nitrogen application increased the crude protein content by 6.36%~6.63% and the crude fat content by 7.11% of mixed silage,but had no significant impact on the crude ash or starch content. The acid detergent fiber and neutral detergent fiber contents showed a decreasing trend with nitrogen application,and the nutritional components achieved better results under N2 treatment. A comprehensive analysis of agronomic traits,yield,and nutritional components revealed that nitrogen applied at a rate of 150 kg·ha−1 under intercropping mode was the most suitable for soybean and corn crops. The results suggest that a ratio of 4∶6 and 2∶8 for soybean and corn mixed silage,respectively,would be optimal for high-yield,efficient cultivation,and high-quality feed in farming-pastoral ecotones.