Water and radiation use in maize–pea intercropping is enhanced with increased plant density

Crop management to improve water use is a well-established strategy for the effective use of limited natural resources in intercropping systems. Here, maize (Zea mays L.)– pea (Pisum sativum L.) strip intercropping with three maize densities (D1: 45,000, D2: 52,500, and D3: 60,000 plants ha⁻¹) was compared to sole maize with three maize densities and sole pea. Soil water extraction and water difference were determined through soil water content over depth and across rows in intercropping, measured six times during the growing season. Land equivalent ratio (LER), radiation use efficiency (RUE_GY for grain yield, and RUE_BM for biomass), and water use efficiency (WUE) were calculated to compare intercropping with sole cropping. A soil water supplement potential from intercropped maize strips to intercropped pea was observed during the pea independent growth and co-growth with maize periods, which declined as the growing season progressed and with increased maize density. After pea harvest, the potential of compensatory soil water for maize existed from the pea strips, which was greater with increased maize density. Maize–pea intercropping produced 23–38% greater total yield than corresponding sole crops, as the LER ranged from 1.23 to 1.38. Maize–pea intercropping with D3 attained the greatest grain yield, RUE_GY, RUE_BM, and WUE among three maize density treatments, and was 10, 9, 17, and 14% greater than that of corresponding sole maize. Increasing maize density increased grain yield, radiation and water use efficiency, and LER, indicating that the intercropping advantage was improved with increased maize density.