Impact of Human Activity and Climate on Nitrogen in Agriculture

Abstract

High concentrations of gases containing nitrogen in the air and different nitrogen forms in soils, plants and water pose a threat both to the environment and to human health. Here I review the impact of various factors on the content of nitrate, nitrite, ammonium, organic and total nitrogen, urease and nitrate reductase in soils and plants. I also review impacts on ammonia, nitrous oxide, nitrogen dioxide and nitric oxide in the atmosphere. The strongest effect on concentrations of gases is the type of animals producing the gases. A weaker dependency is the distance from a farm, and the lowest effect is the type of plant species. The highest concentration of NH3 and N2O came from cattle (56.1 and 42.3 mu g m(-3)), whereas the lowest - from camels (0.3 and 0.5 mu g m(-3)), respectively. The following dependency prevailed: the longer the distance from animal farms, the lower the concentrations of ammonia. Higher emissions of ammonia (92.0%) and nitrous oxide (74.8%) were found to come from urea in a crop field, whereas lower from calcium ammonium nitrate applied to grassland (1.6% of NH3) and from ammonium salts used in a crop field (0.1% of N2O). Similar tendencies were observed for NO. Total emission of ammonia was the highest when resulting from the spreading of waste (36%), whereas the lowest volatilization from grazing / outdoors (8%). The older the animals, the higher the NH3 loss. The highest organic nitrogen concentration was noted after the application of pig slurry manure (3.5%) and the lowest after applying cattle and pig farmyard manure (FYM) (2.3%) above ryegrass field. The highest amounts of net nitrogen were found in Melilotus alba, whereas the lowest in Poa pratensis. A total nitrogen concentration also depended on the type of crops. Its level was higher in Vicia faba (48.71%) and the lowest in grained winter rye cereals (14.96%).