Delineation of management zones in clover-grass for site-specific management of subsequent crops

Abstract Modern agriculture faces the challenges of food security with increasing world population and the need to protect natural resources. Organic farming is known as more environmentally friendly, but has a deficit of around 80% yield compared to conventional farming due to lower availability of nitrogen (N) fertilizer. Site-specific management based on subfields can improve the use efficiency of nitrogen, but organic agriculture lacks fast dissolving N fertilizer. Spatial differences must therefore even out strategically within the crop rotation. Between 2020 and 2023 a trial for management zone (MZ) delineation was developed on three organically farmed fields located in northwest Germany. The clover-grass period and the subsequent cereal crop were observed. During the clover-grass period, Unmanned Aerial Vehicle (UAV)-based images were recorded for calculation of the normalized difference red edge index (NDRE), which was used to divide the study sites into site-adapted management zones using a fuzzy-C-means clustering algorithm. On each of the three fields, a subfield with high productivity and one with low productivity were identified. The more productive subfield during clover-grass-period also had higher cereal yield on all fields. At one field, the high productive MZ was characterized by lower terrain elevation and higher clay content, while on other fields, the differences in yield might be due to land use history and soil depth. This research shows a promising approach to delineate management zones of clover-grass based on NDRE index and offers the potential of site-specific management withing the crop rotation.