The Effects of Soil Drying Out and Rewetting on Nitrogen and Carbon Leaching—Results of a Long-Term Lysimeter Experiment

Holger Rupp,Ralph Meissner,Nadine Tauchnitz

doi:10.3390/w13182601

Abstract

As a result of global climate change, heavy rainfall events and dry periods are increasingly occurring in Germany, with consequences for the water and solute balance of soils to be expected. The effects of climate change on nitrogen and carbon leaching were investigated using 21 non-weighable manually filled lysimeters of the UFZ lysimeter facility Falkenberg, which have been managed since 1991 according to the principles of the best management practices and organic farming. Based on a 29-year dataset (precipitation, evaporation, leachate, nitrate and dissolved organic carbon concentrations), the lysimeter years 1995/96, 2018/19, and 2003/04 were identified as extremely dry years. Under the climatic conditions in northeastern Germany, seepage fluxes were disrupted in these dry years. The reoccurrence of seepage was associated with exceptionally high nitrogen concentrations and leaching losses, which exceeded the current drinking water limits by many times and may result in a significant risk to water quality. In contrast, increased DOC leaching losses occurred primarily as a result of increased seepage fluxes.

Highlights

IntroductionGermany is one of the countries that have been strongly affected by extreme weather events in the recent past
In a modification of the common procedure, a value is considered an outlier if it exceeds 1.0·interquartile range (IQR) above the upper quartile (Q3) or below the lower quartile (Q1)
As a result of lysimeter and field experiments, we have found that dissolved organic carbon (DOC) increased with decreasing

Summary

Introduction

Germany is one of the countries that have been strongly affected by extreme weather events in the recent past. Summer droughts (especially with higher summer temperatures) are likely to occur more often [2,3]. Potential evaporation is subject to change and will, on average, increase due to expected higher temperatures. Extreme weather events affect the soil water balance and seepage-linked solute fluxes in the soil [4,5]. As already predicted by the IPCC [8], increased evaporation combined with less precipitation in summer can lead to lower groundwater tables, which may in turn amplify the impact of summer droughts in groundwater fed ecosystems. Climate change can result in significant changes (increase or decrease) in water cycle components due to changes in temperature and precipitation

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Results

Conclusion