Effects of combined application of slow-release fertilizer and nitrogen fertilizer on nitrogen uptake, utilization and yield of maize under tillage modes

Abstract Objective To explore the improvement of water use efficiency(WUE), dry matter accumulation(DMA), nitrogen absorption and utilization and maize yield under the two tillage methods of slow release fertilizer(S) and urea(U), aiming to screen the appropriate tillage method and appropriate fertilizer ratio for high and stable yield of maize. Method The maize variety Qiangsheng 388 with strong drought resistance was selected as the experimental material, and a two-factor random block design was adopted from 2022 to 2023, with two tillage methods: rotary tillage (R) and rotary tillage + subsoiling (R+S). The combination of slow release fertilizer(S) and urea(U) was used as a sub-area, and 6 treatments were set: CK (no fertilization); U (100% nitrogen fertilizer); S (100% slow-release fertilizer); UNS1（U：S=2:8）； UNS2（U：S=3:7）； UNS3（U：S=4:6）. Soil moisture, dry matter accumulation, nitrogen uptake and utilization and yield of maize plants were measured at different growth stages. Result (1) From 2022 to 2023, as the fertility period progresses, the accumulation of DMA and nitrogen under all treatments under tillage methods showed an increasing trend. In 2022, the accumulation of DMA and nitrogen in the R tillage method UNS2 was the best, which were 24898.5 and 275.25 kg·hm-2, respectively, which were 2.0% and 3.88% higher than those of the R+S tillage UNS2 treatment, respectively. In 2023, UNS2 under R+S tillage was the best, which were 24056.34 and 260.81kg·hm-2, 2.52% and 1.85% higher than UNS2 under R tillage, respectively. (2) In 2022, the yield of R tillage UNS2 treatment was the largest, which was 14712.78 kg·hm-2, which was 4.06% higher than that of R+S tillage UNS2 treatment. In 2023, the yield of R+S tillage UNS2 treatment was 13901.88 kg·hm-2, which was 2.20% higher than that of R tillage UNS2 treatment. (3) In 2022, the nitrogen utilization rate, nitrogen fertilizer utilization rate, nitrogen absorption efficiency and nitrogen harvest index of UNS2 under R tillage were the best, which were 0.13%, 4.05%, 1.36% and 4.55% higher than those under UNS2 under R+S tillage, respectively. In 2023, all indicators of R+S tillage UNS2 treatment were also the best, which were 0.34%, 2.21% , 0.25% and 2.35%, higher than those of R tillage UNS2 treatment, respectively. (4) In 2022, the WUE of R tillage UNS2 treatment was 36.28 kg·hm-2·mm-1, which was 4.66% higher than that of R+S tillage UNS2 treatment. In 2023, the WUE of R+S tillage UNS2 treatment was 34.63 kg·hm-2·mm-1, which was 2.73% higher than that of R tillage UNS2 treatment. Conclusion This study showed that the R+S tillage effect in 2023 was better than that in 2022, and it was also better than that of R tillage treatment in 2023. UNS2 treatment could significantly improve the DMA, nitrogen uptake and utilization, WUE and yield of maize, and the optimal fertilization ratio was the most suitable fertilizer ratio.