Optimizing the split of N fertilizer application over time increases grain yield of maize-pea intercropping in arid areas

Productive cropping systems like cereal-legume intercropping might contribute to feeding the ever-growing population. However, intercropping systems require adapted nitrogen (N) fertilizer management that better match temporal and spatial N supply with crop demand. On the basis of field experiment conducted in northwestern China from 2012 to 2014, the study evaluated three N management practices in maize (Zea mays L.)-pea (Pisum sativum L.) intercropping on yield performance. All three treatments (N1, N2, and N3) received the same amount of fertilizer N prior to planting and at the pre-tasseling stage of maize, while they received different ratios of fertilizer N at jointing (45, 90, and 135 kg N ha⁻¹ for N1, N2 and N3, respectively) and at 15 d post-flowering (135, 90, and 45 kg N ha⁻¹ for N1, N2 and N3, respectively). The N1 treatment was superior to other treatments as it achieved a mean N nutrition index (NNI) near 1 and extended the duration of N accumulation by 3.6 d for pea and 9.0 d for maize. This treatment also improved the nodulation advantage of intercropped pea, enhanced compensatory intensity of intercropped maize, and increased yield components of pea and maize, compared to N3 (current farmer practice). Consequently, grain yield of pea and maize in intercropping with N1 was increased by 6 and 14 %, respectively, compared to N3. The optimized NNI and improved grain yield allow us to conclude that the N1 treatment with jointing top-dress N at 45 kg N ha⁻¹ and 15 d post-flowering top-dress N at 135 kg N ha⁻¹ can be used as an efficient N management practice for maize-pea intercropping.