Abstract
Nitrogen is one of the main factors that shapes soil fertility and the productivity of crops, although its abundance can also cause damage to the environment. The aim of this study is to evaluate the influences of different forms of nitrogen fertilizers, soil temperature, and precipitation on the changes of nitrogen compounds (N-NH4+, N-NO3−, and Nmin) in two soil layers. Two pot experiments are performed, involving simulated precipitation levels of 10- and 20 mm. Urea and ammonium nitrate fertilizers are used for fertilization. The soil samples are stored in pots in a climate chamber at different temperatures of 5, 10, 15, and 20 °C. After seven days, the changes of nitrogen compounds (N-NH4+, N-NO3−, and Nmin) in 0–15 and 15–30 cm soil layers are analyzed. This study shows that the amount of N-NH4+ nitrogen in the soil depends on the fertilizer form and soil temperature. In the temperature range of 5–20 °C, significantly more N-NH4+ nitrogen is present in urea-fertilized soil. The migration of N-NH4+ into the deeper 15–30 cm soil layer at both the 10- and 20-mm simulated precipitation levels is negligible. The N-NO3− contents in the 0–15 cm soil layer in the temperature range of 5–20 °C are 1.7–2.3 times lower in the urea-fertilized soil than in the ammonium nitrate-fertilized soil at a 10-mm simulated precipitation level and 1.6–2.2 times lower at 20 mm. The Nmin contents in soil are directly dependent on the fertilizer form and soil temperature for both levels of simulated precipitation.
Highlights
Anthropogenic activities have doubled the amount of reactive nitrogen circulating on Earth, leading to excess nutrient transfer to freshwater ecosystems and causing the eutrophication of freshwater and marine aquatic ecosystems [1,2]
The data from this study define the variation of N-NH4 + nitrogen and N-NO3 − contents in the arable layer of soil of a certain temperature when fertilizing with different forms of nitrogen fertilizers at the precipitation levels of 10 and 20 mm
In the 0–15 cm soil layer, under the simulated precipitation level of 10 mm, the experimental findings show significantly higher amounts of N-NH4 + nitrogen in the urea-fertilized soil compared with the ammonium nitrate-fertilized soil (Figure 1)
Summary
Anthropogenic activities have doubled the amount of reactive nitrogen circulating on Earth, leading to excess nutrient transfer to freshwater ecosystems and causing the eutrophication of freshwater and marine aquatic ecosystems [1,2]. The adoption of more stringent environmental standards and increasing nitrogen fertilizer prices oblige researchers, fertilizer manufacturers, and agricultural producers to look for rational and sustainable solutions to reduce nitrogen emissions [5,6,7], which is directly related to nitrogen losses from mineral fertilizers. Mineral nitrogen losses from the soil are caused by the unbalanced and untimely fertilization of crops, improper choices for fertilizer forms, and other factors [8,9,10,11,12]. It has been documented that the changes of Agronomy 2020, 10, 2011; doi:10.3390/agronomy10122011 www.mdpi.com/journal/agronomy
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