Optimal Nitrogen Practice in Winter Wheat-Summer Maize Rotation Affecting the Fates of 15N-Labeled Fertilizer

Abstract

Lower nitrogen recovery efficiency (NRE) and negative environmental impacts caused by excessive nitrogen (N) fertilization threaten the sustainability of agriculture. Efficient and appropriate fertilization practices are extremely important to achieve higher crop yield with minimum N loss. A field microplot experiment was conducted in a wheat-maize rotation system in Shaanxi province, at North China Plain, using the 15N isotope tracer technique to qualify the different annual N managements in terms of crop yield, NRE, N distribution in plant-soil, and N losses to optimize the N management. The experiment included four N treatments: conventional practice with 510 kg ha−1 annually in four applications (N1), and three optimized N treatments, reducing N rate to 420 kg ha−1, adjusting topdressing fertilizer times and using slow-release fertilizer (SRF) (N2, N3, N4). The results showed that the grain yield and N uptake did not differ significantly among treatments. N from fertilizer taken up (Ndff) by wheat was not affected by N management; however, in maize, Ndff performed differently. Optimized treatments significantly decreased the Ndff as compared to N1 treatment. Furthermore, NRE of wheat and annual nitrogen recovery efficiency (annual NRE) did not differ among treatments in 2016 but significantly increased in 2017 compared to N1. Annual NRE in 2017 was similar to that obtained for wheat. For maize, optimized N managements decreased the NRE in N3 and N4 treatments of two years. Potential losses in wheat were also similar amongst treatments, but in maize, N3 and N4 had lower residual N in the soil’s top 60 cm but resulted in higher potential losses than N1 and N2. Overall, our results demonstrate that applying 420 kg N ha−1 annually in three applications and combining SRF and urea are effective to sustain crop yield, improve the efficiency of N usage by maize, and reduce N losses in this region.

Optimized nitrogen fertilizer application strategies under supplementary irrigation improved winter wheat (Triticum aestivum L.) yield and grain protein yield

“…This suggested that a major portion of the nitrogen that accumulates in the wheat grains at harvest originates from the degradation of proteins in senescing and falling vegetative segments ( Bouchet et al, 2016 ). The application of fertilizer in appropriate proportions can results in greater nitrogen accumulation in the vegetative parts until anthesis ( Liang et al, 2020 ). Similarly, we report that the N3 treatment significantly increased the nitrogen accumulation of wheat plants during anthesis.…”

Nitrogen fertilization affects maize grain yield through regulating nitrogen uptake, radiation and water use efficiency, photosynthesis and root distribution

“…In the past four decades, global maize production has greatly increased (FAO, 2018) mainly due to application of nitrogen (N) fertilizers. Worldwide, N fertilizer has widely been excessively applied to achieve higher grain yields (Cui et al, 2009;Meng et al, 2016;Liang et al, 2020). For example, the average dose of N fertilizer applied by the farmers was field conditions.…”

Effects of Shallow Groundwater Depth and Nitrogen Application Level on Soil Water and Nitrate Content, Growth and Yield of Winter Wheat

“…In addition, from the perspective of actual production, our study showed that, with the increase in groundwater depth, both yield and its growths decreased from no significant difference under low to middle N application (150-240 kg/ha) to significantly decreased under high N application (300 kg/ha), indicating that the deeper groundwater depth would obtain the great potential of reduction N application. Particularly in recent years, a large amount of fertilizer has been applied, and groundwater was overexploited on the NCP to get high yields, which have resulted in a much lower groundwater table (>1.5 m) [39,56], and a thicker vadose zone year by year, leading to a large amount of seasonal nitrogen residue in the soil and the next crop is planted with high background nitrogen content [39,[57][58][59]. Therefore, it is feasible to reduce the N application by 20% on the NCP, based on our study, without the influence of crops yield.…”