Study on yield, economic benefit, and key impact factors under the strip intercropping system of soybean and maize

China’s soybean is heavily dependent on imports, with insufficient production capacity constraining the development of the domestic soybean industry and posing risks to national food security. It is imperative to increase the integrated production capacity of soybeans to enhance the self-sufficiency of supply and demand. As a key agronomic technology promoted by the Ministry of Agriculture and Rural Affairs in recent years, soybean-maize strip intercropping plays a critical role in expanding soybean cultivation areas and increasing yields. This study is based on 1,012 valid questionnaires from a survey on soybean-maize strip intercropping in 19 provinces(municipalities and autonomous regions)across the country in 2024. It systematically analyzes the yields of soybeans and maize, planting costs and economic benefits, the land equivalent ratio, as well as the effects of planting row ratios, densities, and varieties on yields. Results showed that the national average yield of soybean was 1 642 and 6 916 kg∙hm⁻² for maize. The Huang-Huai-Hai Region had the total yield of soybean and maize with 9 905 kg∙hm⁻², which was higher than northwest and southwest regions by 13% and 45%, respectively. The average value of national land equivalent ratio was 1.55, ranging from 1.42−1.70. It was highest of 1.62 at Huang-Huai-Hai Region and 1.55, 1.56 in Southwest Region and Northwest Region, respectively. For the planting row ratios of soybean and maize, it was 6∶4 at Huang-Huai-Hai Region with the highest percentage of 39%. Under 6∶4 planting ratio of soybean and maize, soybean planting density was 128×10³−150×10³ plant∙hm⁻² with the highest percentage (40%) and 42×10³−105×10³ plant∙hm⁻² for its corresponding maize. In Northwest Region, it was 4∶4 with the highest percentage of 35%. Under 4∶4 planting ratio of soybean and maize, soybean planting density was 127.5×10³−150×10³ plant∙hm⁻² with the highest percentage (48%) and 37.5×10³−82.5×10³ plant∙hm⁻² for its corresponding maize. In Southwest Region, it was 3∶2 with the highest percentage of 60%. Under 3∶2 planting ratio of soybean and maize, soybean planting density was 105×10³−124.5×10³ plant∙hm⁻² with the highest percentage (36%) and 37.5×10³−67.5×10³ plant∙hm⁻² for its corresponding maize. For the cultivars of soybean, ‘Yundou 1’ had the highest percentage in Huang-Huai-Hai Region, followed by ‘Qihuang 34’ and ‘Jidou 12’. ‘Huangjinliang MY73’ had the highest percentage for maize cultivar in this region, followed by ‘Liangyu 99’ and ‘Denghai 605’. ‘Dongdou 339’ had the highest percentage for soybean cultivar in Northwest Region, followed by ‘Zhonghuang 13’ and ‘Qihuang 34’; ‘Youdi 919’, ‘Xianyu 1483’ and ‘Denghai 605’ were the first three maize cultivar in Northwest Region. ‘Qihuang 34’ had the highest percentage for soybean cultivar in Southwest Region followed by ‘Qiandou 12’ and ‘Diandadou 12’. ‘Chuandan 99’, ‘Xianyu 1171’ and ‘Chengdan 716’ were the first three maize cultivar in Southwest Region. This study supplies the important information for the further development and technology extension of the strip compound planting of soybean and maize.