Agronomic and Economic Benefits of Pea/Maize Intercropping Systems in Relation to N Fertilizer and Maize Density

Intercropping has been shown to increase crop yields and improve land utilization in many cases but it is unknown how the interspecies relationship is enhanced with improved crop management schemes. In this study, we investigated the effect of different maize densities and N rates on the growth, crop yields and economic benefits of pea (Pisum sativum L.)/maize (Zea mays L.) intercropping. The results indicated that total yields of pea/maize intercropping were higher than the yield of maize alone, and that pea/maize intercropping improved land use efficiency significantly compared to sole crops, the partial land equivalent ratio (LER) of maize and pea with high planting density increased from 0.98% to 9.36% compared to low planting densities during 2012 and 2013. The pea strips provided significant compensatory effects on the growing maize after the earlier-sown, shorter-seasoned pea was harvested. The crop growth rate (CGR) of the intercropped maize was 18.5% to 216.9% greater than that of sole maize after pea harvest, the leaf area index (LAI) of pea/maize intercropping was 6.9% and 45.4% greater compared with the weighted average of sole maize and sole pea in 2012 and 2013, respectively. Net returns and benefit to cost ratios of pea/maize intercropping were increased with an increase of maize planting density. A low rate of N fertilizer was coupled with increased maize plant density, allowing interspecific facilitation to be fully expressed, thus improving the land utilization rate and increasing economic benefits. Overall, our findings show that a higher density of maize and lower N application can be used to increase grain production with no adverse effects on the growth components of either pea or maize crops. It could be considered an advanced farming system for agricultural sustainable development in the oasis region of northwest China.