Improving N management through intercropping alleviates the inhibitory effect of mineral N on nodulation in pea

Background and aims Symbiotic N-2 fixation is essential in the development of sustainable agriculture, but the nodulation of legumes is usually inhibited by N fertilization. Here, the intercropping of maize and pea in strips under various N managements was used as a means to alleviate the inhibitory effect of mineral N on pea nodulation and N-2 fixation and to improve system performance. Methods N natural abundance (delta N-15) analysis was employed to quantify N-2 fixation in the 3 years (2012 to 2014) of field experiment in Hexi Corridor of Northwestern China. Four N management systems with N rate of 0 kg N ha(-1) (the control), 90 + 45 kg N ha(-1) (base N plus topdressing N), 90 + 90 kg N ha(-1), and 90 + 135 kg N ha(-1) were implemented in the maize/pea strip intercropping to form different ratios of base N to top-dressing N. Results Intercropped pea improved nodule biomass per plant by 99 %, increased nitrogen derived from the atmosphere (Ndfa) by 35 %, and promoted above-ground plant tissue N accumulation by 35 % as compared with sole pea, averaged across the four N treatments. Compared to the highest N fertilizer treatment, a reduction of topdressing to 45 kg N ha(-1) increased the nodule biomass of intercropped pea by 116 %, Ndfa by 35 %, and grain yield by 6 %. Conclusions Adaptation of suitable N management in cereal/legume intercropping systems will allow an effective conversion of atmospheric N-2 into crop available N and thus maximizing the system productivity.