Effect of cover crops and application of nitrogen fertilizer on tuber yield and nitrogen use efficiency of potato (Solanum tuberosum L. cv. Sante)

Inclusion of cover crops in crop rotations has several benefits such as supplying nitrogen for the next crop. To investigate the effect of cover crops and different levels of nitrogen fertilizer on tuber yield, yield components, and different nitrogen efficiency indices of potato, a filed experiment was conducted as split plots arrangements in randomized complete block design with three replications in 2018-19 and 2019-20 growing seasons at the agricultural research farm of Faculty of Agriculture and Natural Resources, Razi University, Kermanshah, Iran. The main plots was assigned to cover crop at four levels including; rye, vetch, mixed (vetch + rye) and control (no cover crop) and the sub-plots was nitrogen fertilizer application at four levels including; 0 (control), 33, 66, and 100 percent of the recommended fertilizer level based on the soil test. The results showed that treatments had significant effects on tuber yield and yield components, plant height, the number of main stem per plant, nitrogen use indices and tuber nitrate content. Vetch and mixed treatments along with application of 66 percent of nitrogen fertilizer led to the 13 and 8 percent increases in potato yield when compared with application of 100 percent of nitrogen fertilizer without cover crop, respectively. Maximum tuber yield obtained in vetch with application of 66 percent of nitrogen fertilizer (35.42 ton.ha-1) and the least tuber nitrate (31.92 mg.kg-1) wasmeasured in control (without nitrogen fertilizer). Application of nitrogen fertilizer had a significant negative effect on nitrogen use efficiency as the highest nitrogen use efficiency (94.78 kg.kg-1) was obtained by inclusion of vetch as cover crop and without application of nitrogen fertilizer. In conclusion, our findings showed the positive effect of cover crops along with application of optimum level of nitrogen fertilizer on tuber yield potato, plant height and number of main stem per plant. This can be considered as a crop management package that leads to the reduction of application of chemical fertilizers, prevents its adverse effects on environment and more economic benefits for farmers.