Nitrogen Fertilizer

Nitrate and nitrite are two ions largely diffused in the environment because they take part in the nitrogen cycle. Moreover, a great part of atmospheric nitrogen may be oxidized to nitrite and nitrate by microorganisms in plants, soil or water. The more stable form of oxidized nitrogen is nitrate ion, but, through microbial activity, it can be reduced to nitrite ion which is more chemically reactive. Nitrate and its salts are widely used, especially as inorganic fertilizers, and for many other purposes such as oxidizing agents, explosives, in the chemical industry and as food preservatives. This book discusses the agricultural uses, management practices and environmental effects of nitrogen fertilizers.

This award-winning publication gives the most in-depth information available on nitrogen fertilization of walnut orchards. Discusses the variables that make nitrogen management of each orchard a unique challenge; and provides the tools that let you manage your orchard efficiently and economically. Chapters discuss concepts of fertilization, nitrogen budgeting, choosing and using nitrogen fertilizers, and fertilizing young trees.

The improvement in global crop production over the past several decades has been associated with increased use of nitrogen (N) fertilizer. However, on average, less than 50% of the nitrogen added to croplands globally is harvested as crop product. Inefficient use of N fertilizer by crops will result in substantial agricultural nitrogen losses, posing threats to human and ecosystem health. Crop production must increase dramatically to meet the growing demand for food and biofuels projected for 2050. To boost crop yield with lowered environmental cost, the use of high-potential crop cultivars and efficient nitrogen fertilizer management are required. Recent advances in N management practices, such as enhanced-efficiency fertilizer use, improved manure management and machine deep placement of fertilizer have opened up new strategies to achieve improved crop production with N use reduction. A better understanding of the key crop traits and regulatory processes in response to N fertilizer managements will facilitate the increase in crop yield, N use efficiency while minimizing impacts on the environment.

Intensively managed agricultural soils are a major source of the greenhouse gas nitrous oxide (N2O), mainly due to the use of mineral nitrogen fertilizers which stimulate microbial processes in soils that form N2O. While oxidized N fertilizer forms can be subject to denitrification, reduced N forms must first be oxidized by nitrification to become available for denitrification. Because the contribution of these processes to N2O emissions depends on the prevailing soil conditions, the choice of the N fertilizer form has the potential to mitigate N2O emissions from fertilized soils. The present study focused on comparing amid-, ammonium- and nitrate-based mineral fertilizers with regard to nitrogen transformation dynamics and N2O production under controlled as well as field conditions. For this two distinct methodological approaches to measure N2O emissions were evaluated and deployed. Furthermore, the effects of soil pH and the alkalizing hydrolysis of urea were investigated. It was shown that especially under aerobic conditions the N fertilizer form can significantly affect N2O production in soils, and that nitrite dynamics are important especially for nitrification-derived N2O emissions. Thus, the careful consideration of the N fertilizer form can be a measure to mitigate emissions from farmland.