Katrin Drastig

Relationship between irrigation water demand and yield of selected crops in Germany between 1902 and 2010: a modeling study

The demand for irrigation water is increasing worldwide, including regions in Germany with low precipitation and water-demanding crops. In this study, history of irrigation water demand (IWD) in the German nation states in relation to the yield of four crops (1) potato, (2) spring barley, (3) oat, and (4) winter wheat, during droughts between 1902 and 2010 was analyzed. The difficulties caused by the shifting borders of the German nation state over the past century were dealt with by dividing the data for the region into four time periods for the analysis. Low precipitation during droughts influenced crop yield in the German nation states. Analyses of droughts resulted in no clear conclusions; however, it appeared that after 1950, German nation states droughts had a negative influence on the yield of the four crops despite the important role irrigation played in German agriculture since 1960 in the German nation state. Lower yield because of weather conditions since 1950 was primarily attributable to the high-yield potential of improved crop varieties, for which yield potential is only reached under optimal growing conditions. In this study, the analysis of the modeled historical IWD in agriculture revealed the urgency with which the German crop production systems must adapt to extremes in a changing climate not only by improving irrigation systems via irrigation scheduling but also by greater higher diversification of crops.

Effects of nitrogen fertilization and irrigation on N2O emissions from a sandy soil in Germany

The aim of this study was to investigate the effect of supplemental irrigation on the amount of N2O emissions on a sandy soil in north-east Germany. N2O flux measurements were carried out over two vegetation periods from the emergence of plants to harvest. The level of N2O emissions was low, which is typical for sandy soils in north-east Germany. In both periods, irrigation had no increasing effect on N2O emissions. Relevant factors were the soil temperature and the soil water-filled pore space (WFPS), which were mainly influenced by weather conditions. This may indicate that nitrification was the main source of N2O emissions. In conclusion, this study has confirmed that sandy soils under weather conditions of north-east Germany generally have a very low potential for N2O emissions.

Nitrous oxide emissions from potato cropping under drip-fertigation in eastern Germany

In this article, a drip-fertigation system was compared to a control without irrigation concerning the amount of nitrous oxide (N2O) emissions under the climatic conditions of north-east Germany. The investigation was carried out at a field research station in the federal state of Brandenburg. The mean N2O emissions under drip-fertigation were significantly higher than under non-irrigation. The higher N2O emissions under drip-fertigation can be explained by a constantly higher water-filled pore space (WFPS). These higher values in WFPS were caused by the necessary nutrient supply in combination with additional water application in periods with frequent rainfall.