Model-Based Estimation of Irrigation Water Demand for Different Agricultural Crops Under Climate Change, Presented for the Federal State of Brandenburg, Germany

Abstract

In the Federal State of Brandenburg, the average temperature is expected to increase by about 4.4 °C by 2100 due to climate change. In addition, precipitation is expected to decrease by about 200 mm, consequently the climatic water balance deficit will increase to 420 mm. Brandenburg is mainly characterised by morainic sandy soils with a low soil water storage capacity. All this will limit the amount of plant-available water during spring and summer months, increasing the cropping risk, especially for spring crops, and reducing crop yields as well as yield stability. This paper outlines the ZUWABE model for estimating the irrigation water demands of agricultural crops, which was developed in ZALF Müncheberg, Germany. It can be used for spatial simulation under past, present and future climate conditions. For all agricultural fields throughout the Federal State of Brandenburg, irrigation water demands were calculated for winter wheat, oats, winter barley, spring barley, sugar beets, oilseed rape, silage maize, potatoes, clover-grass-mix, lucerne-grass-mix, triticale and winter rye. The simulation runs were carried out for five climate levels (1975, 2000, 2025, 2050 and 2075) using climate data from WETTREG 2010 under the A1B emission scenario. The paper presents and discusses the averaged results for Brandenburg as well as for the five productivity classifications of arable land in Brandenburg separately. Four crops (winter wheat, sugar beets, potatoes and silage maize) are used to show and explain the spatial results for Brandenburg. At all climate levels, the irrigation water demand was the lowest for oilseed rape, and was the highest for the clover-grass mix and silage maize.