Maize/soybeans intercropping increases nutrient uptake, crop yield and modifies soil physio-chemical characteristics and enzymatic activities in a subtropical humid region based in Southwest China

In China, the high use of nitrogen fertilization for agricultural production and intensive mono-cropping systems have adversely affected the agricultural ecosystem and environment. Therefore, to improve the sustainable agricultural production system, farming systems need to be adjusted within the country. Consequently, a two-year (2021–2022) field experiment was conducted on the maize/soybean intercropping practices with/without nitrogen (N) fertilization (i.e., N 0 ; 0 N kg ha − 1 and N 1 ; 225 N kg ha − 1 ) to know whether such cropping system can improve the nutrients uptake and crop yields, soil physio-chemical properties, and soil enzymes, which ultimately results in enhanced crop yield. The results revealed that maize intercropping treatments (i.e., N 0 MI and N 1 MI) had higher crop yield, biomass dry matter, and 1000-grain weight of maize than mono-cropping treatments (N 0 MM, and N 1 MM). Nonetheless, these parameters were optimized in N 1 MI treatments in both years. For instance, N 1 MI produced the maximum grain yield (10105 and 11705 kg ha − 1 ), biomass dry matter (13893 and 14093 kg ha − 1 ), and 1000-grain weight (420. and 449 g) of maize in the year 2021 and 2022, respectively. Conversely, soybean intercropping treatments (i.e., N 0 SI and N 1 SI) reduced such yield parameters for soybean. Also, the land equivalent ratio (LER) and land equivalent ratio for N fertilization (LER N ) values were always greater than 1, showing the intercropping system's benefits in terms of yield and improved resource usage. Moreover, maize intercropping treatments (i.e., N 0 MI and N 1 MI) and soybean intercropping treatments (i.e., N 0 SI and N 1 SI) significantly (p < 0.05) enhanced the nutrient uptake (i.e., N, Fe, P, K, Ca, and Zn) of maize and soybean, however, these nutrients uptakes were more prominent in N 1 MI and N 1 SI treatments of maize and soybean, respectively in both years (2021 and 2022) compared with their mono-cropping treatments. Similarly, maize-soybean intercropping treatments (i.e., N 0 MSI and N 1 MSI) significantly (p < 0.05) improved the soil-based N, K, P, NH 4 , NO 3 , and soil organic matter, but, reduced the soil pH. Such maize-soybean intercropping treatments also improved the soil enzymatic activities such as protease (PT), sucrose (SC), acid phosphatase (AP), urease (UE), and catalase (CT) activities. This indicates that maize-soybean intercropping could potentially contribute to higher and better crop yield, enhanced plant nutrient uptake, improved soil nutrient pool, physio-chemical characteristics, and related soil enzymatic activities. Thus, preferring intercropping to mono-cropping could be a preferable choice for ecological viable agricultural development.