Improving Nitrogen Availability and Crop Productivity Using Bioameliorants in Maize–Soybean Intercropping on Suboptimal Land

Suboptimal land conditions, characterized by limited nutrient availability and poor soil physical properties, restrict the growth and productivity of maize-soybean intercropping systems. Bioameliorants containing beneficial microorganisms, such as mycorrhizae, offer a sustainable strategy to enhance soil fertility and nutrient uptake efficiency. This study evaluated the effects of different bioameliorant compositions on nitrogen availability, plant growth, and yield in maize–soybean intercropping on suboptimal land. A randomized complete block design with four replicates tested five treatments: F0 (control, no bioameliorant), F1 (10% compost + 10% rice husk charcoal + 10% manure + 70% mycorrhizal biofertilizer), F2 (15% each of compost, manure, charcoal + 55% biofertilizer), F3 (20% each + 40% biofertilizer), and F4 (25% each component). Results showed that the balanced F4 bioameliorant markedly improved nitrogen availability, soil health, and yields in maize–soybean intercropping on sandy soils. These findings highlight its potential as a sustainable strategy to enhance productivity, reduce reliance on chemical fertilizers, and strengthen agroecosystem resilience on suboptimal land. The optimized F4 formulation therefore represents a practical approach to improving nutrient availability and plant performance in maize–soybean intercropping systems under marginal soil conditions.