Optimized Nitrogen Rate, Plant Density, and Regulated Irrigation Improved Grain, Biomass Yields, and Water Use Efficiency of Maize at the Oasis Irrigation Region of China

Abstract

Nitrogen is a key factor in maize (Zea mays L.) grain and biomass production. Inappropriate application with sub-optimum plant density and irrigation can lead to low productivity and inefficient use. A two-year field experiment was conducted to determine which nitrogen rate, plant density, and irrigation level optimize grain, biomass yield, and water use efficiency. Three nitrogen rates of urea (46–0–0 of N–P2O5–K2O) (N0 = 0 kg N ha−1, N1 = 270 kg N ha−1, and N2 = 360 kg N ha−1), with three maize densities (D1 = 75,000 plants ha−1, D2 = 97,500 plants ha−1, and D3 = 120,000 plants ha−1), and two irrigation levels (W1 = 5250 m3/hm2 and W2 = 4740 m3/hm2) were investigated. The results show that both grain and biomass yields were affected by the main factors. The interaction between nitrogen rate and irrigation level significantly (p < 0.001) affected grain yield but not biomass. It was observed that the grain yield increased correspondingly with nitrogen rate and plant density, while it decreased as the irrigation level increased. Water use efficiency was significantly (p < 0.001) affected by the main factors and their interactions. Nevertheless, water use efficiency was highest at (5250 m3/hm2) × 270 kg N ha−1; × 360 kg N ha−1 × 120,000 plants ha−1 and increased from 62% to 68%. In addition, the highest biomass yield was recorded at 5250 m3/hm2 × 270 kg N ha−1; × 360 kg N ha−1 × 120,000 plants ha−1 while the interaction of either irrigation level with 0 and 270 kg ha−1 or 97,500 and 120,000 plants ha−1 yielded the lowest water use efficiency. Thus, optimized nitrogen rates, plant density, and alternate irrigation levels can support optimum grain and biomass yields. It can also improve nitrogen and water use efficiency in maize production.

Appropriate dense planting with N fertilisation increased maize grain yield and soil organic carbon

“…The interaction of N fertilisation rate and PD effectively improved the GY and HI, in line with the results of Asibi et al (2022). In the present study, a larger GY was recorded at a higher PD and a higher N fertilisation rate.…”

“…Nitrogen affects the crop GY via influencing KN and TKW. In the present study, GY and its components were significantly increased at the N application levels (N1 220 kg ha −1 N and N2 290 kg ha −1 N), consistent with the results of Asibi et al (2022). However, no difference of GY and its components was observed at the N1 and N2 application levels.…”

“…Differently, Shi et al (2016) showed a higher GY when maize was sown at a higher PD and soil was applied with a lower N fertilisation rate. Moreover, Belete et al (2018) found that GY was directly related to the N fertilisation rate and the GY was lower in the first year, while Asibi et al (2022) reported a lower GY in the second year, the main reason being irrigation. However, the results of current experiment showed no difference of GY during two experimental years, which might verify the effect of water, since no difference in the precipitation and irrigation between the two experimental years was recorded.…”

“…It has been shown that a high PD would contribute to the increase of maize GY (Xu et al, 2017). Generally, the appropriate PD will correspondingly promote the dry matter accumulation and GY and the suitable increased N fertiliser rates can promote the growth of maize, so as to obtain a higher dry matter accumulation and GY (Asibi et al, 2022). The higher GY can be attributed to a higher KN and TKW.…”