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Author: Drastig, Katrin × End date: 2024 × Start date: 2020 × DDC: 690 × Subject: AgroHyd Farmmodel ×

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    Agricultural water balance in the polder Scheidgraben (Brandenburg)
    (Berlin ; Heidelberg : Springer, 2022) Drastig, Katrin; Schmidtke, Lea; Jacobs, Helen; Recker, Martin
    A predicted increase in water demand for irrigated agriculture in the wake of climate change, and the threat of more extensive periods of drought, poses a challenge to the availability of groundwater resources in Germany. In this study, water availability and water withdrawal for agricultural irrigation are calculated for the polder Scheidgraben (Brandenburg). The agricultural water demand in the Scheidgraben polder is modeled using the AgroHyd Farmmodel. Climate data, soil data, plant-specific data and operating data of all farms in the polder are used as a data basis. In the dry years 2018 and 2019, more than 20% of the potentially available water in the Scheidgraben polder was used for irrigation. The use of water resources by agricultural water withdrawals in the area may increasingly be a problem in the future. In some regions of Brandenburg, region-specific calculations for water management are necessary due to a wide range of conflicts and thus steadily increasing challenges for water authorities.
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    Case Study of Effects of Mineral N Fertilization Amounts on Water Productivity in Rainfed Winter Rapeseed Cultivation on a Sandy Soil in Brandenburg (Germany) over Three Years
    (Basel : MDPI, 2021) Drastig, Katrin; Kreidenweis, Ulrich; Meyer-Aurich, Andreas; Ammon, Christian; Prochnow, Annette
    Detailed knowledge about farm management practices and related hydrological processes on water productivity is required to substantially increase the productivity of precipitation water use in agriculture. With this in mind, the effect of the nitrogen (N) fertilization level on water productivity of winter oilseed rape (Brassica napus L.) was analyzed using a modeling approach and field measurements. In this first study of interception loss and water productivity in winter oilseed rape, the crop was cultivated in a field experiment on a sandy soil in Brandenburg (Germany) under five nitrogen fertilization treatments with 0, 60, 120, 180, and 240 kg mineral N ha−1 a−1. Based on data from three vegetation periods the water flows and the mass-based water productivity of seeds were calculated on a daily basis with the AgroHyd Farmmodel modeling software. As recommended from the recently developed guidelines of the FAO on water use in agriculture, the method water productivity was applied and uncertainties associated with the calculations were assessed. Economic profit-based water productivity (WPprofit) was calculated considering the costs of fertilization and the optimal level of N fertilization, which was determined based on a quadratic crop yield response function. Mean water productivity of seeds varied from 1.16 kg m−3 for the unfertilized control sample to 2.00 kg m−3 under the highest fertilization rate. N fertilization had a clearly positive effect on WPprofit. However, fertilizer application rates above 120 kg N ha−1 a−1 led to only marginal increases in yields. Water productivity of seeds under the highest fertilization rate was only insignificantly higher than under medium application rates. The optimum N level for the maximal WPprofit identified here was higher with 216 kg N ha−1 a−1. The conclusion is that further research is needed to investigate the interaction between fertilization and other farm management practices.