Effect of Long-Term Nitrogen Addition on Wheat Yield, Nitrogen Use Efficiency, and Residual Soil Nitrate in a Semiarid Area of the Loess Plateau of China

Abstract

Nitrogen (N) fertilizer plays an important role in wheat yield, but N application rates vary greatly, and there is a lack of data to quantify the residual effects of N fertilization on soil N availability. A 17-yr experiment was conducted in a semiarid area of the Loess Plateau of China to assess the effects of N fertilization on spring wheat (Triticum aestivum L.) grain yield, N uptake, N utilization efficiency, and residual soil nitrate. Treatments included a non-N-fertilized control and annual application of 52.5, 105.0, 157.5, and 210.0 kg N ha−1 in the first two years (2003 and 2004). In the third year (2005), the four main plots with N fertilizer application were split. In one subplot, N fertilization was continued as mentioned previously, while in the other subplot, N fertilization was stopped. The concentration of NO3-N in the 0–110 cm depth soil layers was significantly affected by N application, with higher N rates associated with greater soil NO3-N concentration. With the annual application of N over 17 years, residual soil NO3-N concentration in the 100–200 cm soil layer in the last study year was significantly greater than that in the non-N-fertilized control and was increased with rate of N application. There was a significant positive relationship of soil NO3-N in the 0–50 cm and 50–110 cm soil layers at wheat sowing with wheat grain N content and yield. Wheat grain yield in the third year (2005) was significantly, i.e., 22.57–59.53%, greater than the unfertilized treatment after the N application was stopped. Nitrogen use efficiency decreased in response to each increment of added N fertilizer, and was directly related to N harvest index and grain yield. Therefore, greater utilization of residual soil N through appropriate N fertilizer rates could enhance nitrogen use efficiency while reducing the cost of crop production and risk of N losses to the environment. For these concerns, optimum N fertilizer application rate for spring wheat in semiarid Loess Plateau is about 105 kg N ha−1, which is below the threshold value of 170 kg N ha−1 per year as defined by most EU countries.

Durum Wheat Grain Yield and Quality under Low and High Nitrogen Conditions: Insights into Natural Variation in Low- and High-Yielding Genotypes

“…This is coherent because a large part of the additional N is driven to grain protein synthesis whereas yield increases were small (i.e., the concentration of N in the grain increases more than the yield). This result confirms previous reports made working with bread [33,39,43] and durum [44] wheat. Under both N treatments, high-yielding genotypes showed higher efficiency in the use of the applied N. This finding led us to hypothesize that NUE can be a trait under genetic control.…”

Elevated Carbon Dioxide and Nitrogen Impact Wheat and Its Aphid Pest

“…It has also been suggested that nitrate assimilation is suppressed under eCO 2 (Bloom et al, 2010). Nitrogen fertilizer application often improves wheat yield (Sudderth et al, 2005;Belete et al, 2018;Xu et al, 2020). We observed that greater N application rates significantly increased tiller number, aboveground dry biomass, leaf chlorophyll content and plant N content of wheat, in agreement with different studies on wheat and other plant species (Chaturvedi, 2005;Sudderth et al, 2005;Walker et al, 2017).…”

Efficiency of Nitrogen Fertilization of Winter Wheat Depending on Sulfur Fertilization

“…From an exclusively economic point of view, it is estimated that a 1% improvement of N efficiency in cereals could save over US$200 million in N fertilizer costs, worldwide [71]. Therefore, fertilizing crops with excessive N rates not only poses environmental hazards, which is gradually becoming a serious cause for concern, but also leads to economic losses [44,54,[71][72][73][74].…”