Effects of Tillage System and Plant Residue on Nitrogen Uptake and Use Efficiency in Corn and Bean Intercropping Systems

In order to investigate the N uptake and N utilization efficiency and nitrogen harvest index in corn and bean intercropping under the influence of tillage systems and residues of wheat an experiment was performed using split- split plots based on a randomized complete block design with three replications in agricultural research field of Shahrekord during growing season of 2016–2017. The tillage systems with three levels (conventional, minimum, and no tillage) and four levels of crop residue (0, 30, 60, and 90% of straw yield of wheat) and five intercropping patterns including corn monoculture, bean monoculture, corn and bean ratio with 2:2, 3:1 and 1:3 were considered as main, sub and sub-sub plots, respectively. The results showed that the highest nitrogen content in seed and biomass of both crops under conditions of use of 60% of plant residues, no- tillage systems and their monocultures. Agronomic use nitrogen efficiency in intercropping was lower than their monocultures. The highest N utilization efficiency was obtained in 3: 1 and 2: 2, indicating a clear superiority of intercropping than monoculture. Therefore, intercropping corn and bean can improve the nitrogen utilization efficiency. By decreasing nitrogen fertilizer application, it can play an important role in the long-term sustainability of agro-ecosystems production.