Nitrogen fertilization and nitrate leaching into groundwater on arable sandy soils

authored by: Kai Köhler, Wilhelmus H.M. Duynisveld, Jürgen Böttcher
Abstract: Nitrate leaching depending on N fertilization and different crop rotations was studied at two sites with sandy soils in N Germany between 1995 and 2000. The leaching of NO₃^- was calculated by using a numerical soil-water and N model and regularly measured N_min values as input data. Also the variability of N_min values on the sandy soils was determined along transects. They reveal the high variability of the N_min values and show that it is not possible to confirm a significant N_min difference between fertilizer treatments using the normal N_min-sampling intensity. Nitrate-leaching calculations of five leaching periods showed that even strongly reduced N-fertilizer applications did not result in a substantially lower NO₃^- leaching into the groundwater. Strong yield reductions of even more than 50%, however, were immediately measured. Mean NO₃^- concentrations in the groundwater recharge are >50 mg L^-1 and are mainly due to mineralization from soil organic matter. Obviously, the adjustment of the N cycle in the soil to a new equilibrium and a reduced NO₃^--leaching rate as a consequence of lower N inputs need a much longer time span. Catch crops are the most efficient way to reduce the NO₃^- concentrations in the groundwater recharge of sandy soils. Their success, however, strongly depends on the site-specific development possibilities of the catch crop. Even with all possible measures implemented, it will be almost impossible to reach NO₃^- concentrations <50 mg L^-1 in sandy soils. The only way to realize this goal on a regional scale could be by increasing areas with lower nitrate concentrations in the groundwater recharge like grassland and forests.
Organisation(s): Institute of Soil Science
Section Soil Biophysics
External Organisation(s): Federal Institute for Geosciences and Natural Resources (BGR)
Type: Article
Journal: Journal of Plant Nutrition and Soil Science
Volume: 169
Pages: 185-195
No. of pages: 11
ISSN: 1436-8730
Publication date: 04.2006
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Soil Science, Plant Science
Sustainable Development Goals: SDG 2 - Zero Hunger
Electronic version(s): https://doi.org/10.1002/jpln.200521765 (Access: Unknown)