Grain yield, and nitrogen uptake and translocation of peanut under different nitrogen management systems in a wheat-peanut rotation

Better N fertilizer management is essential for improving crop productivity and reducing N losses to the environment. However, few studies have reported N absorption, use, and balance in a wheat (Triticum aestivum L.)-peanut (Arachis hypogaea L.) relay intercropping system. This study aimed to determine the effects of different N application rates and ratios at different maturation stages on the yield and N use of peanut in this system. Nitrogen (300 kg ha(-1)) was applied the day before sowing and at jointing, booting, and anthesis in peanut at the following ratios: 50-50-0-0 (N1), 35-35-0-30% (N2), and 35-0-35-30 (N3) (control: 0 kg ha(-1)). Nitrogen isotope-labeled urea was used under the same conditions in microplot. Peanut pod yield increased by 19.0 and 24.8% under the N2 and N3 treatments, respectively, compared with the N1 treatment. Applying N at three stages and withholding N until booting improved the N derived from fertilizer in peanut, promoted the distribution of N-15 to pods, and increased pod yield. The N-15 experiment revealed that N uptake at different growth stages of peanut was 20.7 to 30.4% higher under N3 than under N2, increasing N harvest index and apparent N recovery efficiency compared with N2. The N3 treatment also significantly increased the N recovery efficiency and the agronomic N use efficiency and reduced the apparent N loss. Therefore, applying N fertilizer as in the N3 treatment could be appropriate for wheat-peanut relay intercropping systems in China.