Maize/faba bean intercropping with rhizobial inoculation in a reclaimed desert soil enhances productivity and symbiotic N2 fixation and reduces apparent N losses

Abstract

Although intensive modern agriculture, featured with high inputs of chemicals, contributed to global food production, simultaneously caused a series of serious issues, such as loss of biodiversity, soil degradation, and environment risk. The objective of our study is to integrate various inherit biological potentials of cropping system to gain higher productivity with lower external inputs. Field experiments were conducted over a two-year period (2008-2009) with five fertilizer-N application rates (0, 75, 150, 225 and 300 kg N ha−1) to study the influence of fertilizer N application on the productivity and N utilization of a Rhizobium-inoculated maize (Zea mays L.)/faba bean (Vicia faba L.) intercropping system on a reclaimed desert soil (Sierozems). Average grain yields of faba bean and maize with inoculation increased by 50.0 and 19.6 %, respectively, and reached a maximum land equivalent ratio of 1.78 with zero fertilizer N application in 2009 compared with sole crops. The nodulation of intercropped faba bean was significantly higher with Rhizobium inoculation, especially with an optimum N application rate of < 150 kg N ha−1. Average %Ndfa and Ndfa increased by 42.5 and 86.6 %, respectively, based on interspecific interaction and inoculation. The average apparent N recovery of the intercropping system with inoculation increased by 146.5 % at 75 kg N ha−1 relative to the weighted mean values of sole crops. Intercropping saved fertilizer N compared to sole crops suggested by a fertilizer N equivalent ratio (NFER) > 1. Furthermore, intercropping with rhizobium inoculation saved more fertilizer N than that without rhizobium inoculation. After the faba bean harvest, intercropped maize made better use of the nitrogen taken up to grow faster than sole maize. At the maize harvest the intercropping system showed higher grain yield and N acquisition in the aboveground parts and lower Nmin accumulation in the soil profile, an effect that declined with fertilizer N application. The results therefore indicate that Rhizobium-inoculated maize/faba bean intercropping on the reclaimed desert soil with a moderate fertilizer N application rate enhancede productivity, biological N2 fixation and apparent N recovery with lower environmental risk.