Comparative effects of biological and mineral nitrogen fertilization on Soybean – corn intercropping performance

Intercropping is a viable method to achieve a high land equivalent ratio (LER) and increase production in a given area under sustainable agricultural practices like bio-nitrogen (N) fertilization. A 2-year field study was conducted at the Agricultural Experiments and Research Station of the Faculty of Agriculture, Cairo University, Giza, Egypt, from 2023 to 2024 to compare the effects of bio-N- fertilization and chemical N application on soybean and corn plants in both sole and intercropping systems. The study included two cropping systems (2:2 intercropping and sole cropping of corn and soybean), N-fertilization treatments (N-0 for corn and soybean, 238 kg N/ha for corn under both intercropping and sole cropping, and 53.55 kg N/ha for soybean under intercropping and 107.1 kg N/ha under sole cropping, biological N-fertilization was used for corn grains by treating soil with bioferilizer compound “cerialin”, and biological N-fertilization was used for soybean seeds by inoculating seeds with Bradyrhizobium japonicum . Three replicates of each treatment were used in a split-plot design. Corn grain yield and shelling percentage increased when soybeans and corn were intercropped, but soybean productivity decreased. Corn yields and shelling percentages improved with intercropping. Biological N-fertilization treatments resulted in higher grain yields. Intercropping with biological N-fertilization increased grain yield per plant and LER by utilizing soybeans to fix atmospheric N and provide natural N to corn. Aggressivity of soybean was positive for N-0 or biological N fertilization, indicating that soybean is a dominant component under mineral N-fertilization. Intercropping soybeans with corn had higher net benefits, ranging from 1429.81 to 1624.93 USD per hectare.