Effect of temperature and precipitation on nitrate leaching from organic cereal cropping systems in Denmark

Abstract

a b s t r a c tThe effect of variation in seasonal temperature and precipitation on soil water nitrate (NO 3 N) concentration and leaching from winter and spring cereals cropping systems was investigated over three consecutive four-year crop rotation cycles from 1997 to 2008 in an organic farming crop rotation experiment in Denmark. Three experimental sites, varying in climate and soil type from coarse sand to sandy loam, were investigated. The experiment included experimental treatments with different rotations, manure rate and cover crop, and soil nitrate concentrations was monitored using suction cups. The effects of climate, soil and management were examined in a linear mixed model, and only parameters with significant effect (P < 0.05) were included in the final model. The model explained 61% and 47% of the variation in the square root transform of flow-weighted annual NO 3 N concentration for winter and spring cereals, respectively, and 68% and 77% of the variation in the square root transform of annual NO 3 N leaching for winter and spring cereals, respectively. Nitrate concentration and leaching were shown to be site specific and driven by climatic factors and crop management. There were significant effects on annual N concentration and NO 3 N leaching of location, rotation, previous crop and crop cover during autumn and winter. The relative effects of temperature and precipitation differed between seasons and cropping systems. A sensitivity analysis revealed that the predicted N concentration and leaching increased with increases in temperature and precipitation.

Nitrogen leaching: A crop rotation perspective on the effect of N surplus, field management and use of catch crops

“…N leaching at the plot scale was mainly determined by the effects of catch crop, main crop and year, as also discussed by Jabloun et al (2015). A significant relation between N surplus and leaching was nonetheless found for green manure in OGM/+CC (Fig.…”

“…In particular, OGL/+CC/+M had an average of 9 kg N ha −1 y −1 higher leaching than OGL/+CC/−M, equal to 13% of the average yearly manure N input. This effect was not reported for the previous cycles of the experiment (Askegaard et al, 2005;Askegaard et al, 2011;Jabloun et al, 2015). A less accurate methodology for N leaching measurement could be the reason behind this difference, as suction cups were previously installed just in selected plots.…”

“…In particular, two organic and one conventional crop rotations are tested, with and without use of animal manure, green manure and catch crops. N leaching has been one of the focus points from the beginning, and previous studies have investigated how different management factors affect it (Askegaard et al, 2005;Askegaard et al, 2011;Jabloun et al, 2015). The installation of ceramic suction cups in all plots in 2011 combined with a long-term management history (the organic systems ran for 17 years) provides a unique source of information.…”

“…This was related to their position in the crop rotation after legume crops (Jabloun et al, 2015) and the early harvest of potatoes (Neumann et al, 2012). The general effect of rotation underlines how the rotation with green manure (OGM) is the system with a higher risk of N leaching, especially from spring wheat, which follows green manure.…”

Socio-economic Impacts—Agricultural Systems

“…This in turn may increase the risk of nitrate leaching during periods of little or no crop cover with sufficient nitrogen uptake to prevent nitrate being leached in periods of precipitation surplus (Jabloun et al 2015). This may increase the risk of nitrate leaching to surface and groundwater systems (Stuart et al 2011;Patil et al 2012).…”