Guidelines for precise lime management based on high-resolution soil pH, texture and SOM maps generated from proximal soil sensing data

• Published in: Precision agriculture Vol. 22; no. 2; pp. 493 - 523
• Main Authors: Bönecke, Eric, Meyer, Swen, Vogel, Sebastian, Schröter, Ingmar, Gebbers, Robin, Kling, Charlotte, Kramer, Eckart, Lück, Katrin, Nagel, Anne, Philipp, Golo, Gerlach, Felix, Palme, Stefan, Scheibe, Dirk, Zieger, Karin, Rühlmann, Jörg
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.04.2021; Springer Nature B.V
• Subjects: Acidic soils; Acidification; Acidity; Agricultural production; Agriculture; Algorithms; Alkalies; Anthropogenic factors; Antimony; Atmospheric Sciences; Best management practices; Biomedical and Life Sciences; Chemistry and Earth Sciences; Computer Science; Crops; Electrical resistivity; Emission measurements; Farmers; Guidelines; High resolution; Human influences; Life Sciences; Lime; Liming; Optical reflection; Organic matter; Organic soils; pH effects; Physics; Remote Sensing/Photogrammetry; Sensors; Soil acidification; Soil chemistry; Soil lime; Soil maps; Soil organic matter; Soil pH; Soil properties; Soil Science & Conservation; Soil texture; Soils; Statistics for Engineering; Texture; Workflow; Germany; Soil organic matter; Soil pH; Soil texture; Variable rate soil liming; Soil sensing; Site specific soil management
• DOI: 10.1007/s11119-020-09766-8
• ISSN: 1385-2256

Soil acidification is caused by natural paedogenetic processes and anthropogenic impacts but can be counteracted by regular lime application. Although sensors and applicators for variable-rate liming (VRL) exist, there are no established strategies for using these tools or helping to implement VRL in practice. Therefore, this study aimed to provide guidelines for site-specific liming based on proximal soil sensing. First, high-resolution soil maps of the liming-relevant indicators (pH, soil texture and soil organic matter content) were generated using on-the-go sensors. The soil acidity was predicted by two ion-selective antimony electrodes (RMSE pH : 0.37); the soil texture was predicted by a combination of apparent electrical resistivity measurements and natural soil-borne gamma emissions (RMSE clay : 0.046 kg kg −1 ); and the soil organic matter (SOM) status was predicted by a combination of red (660 nm) and near-infrared (NIR, 970 nm) optical reflection measurements (RMSE SOM : 6.4 g kg −1 ). Second, to address the high within-field soil variability (pH varied by 2.9 units, clay content by 0.44 kg kg −1 and SOM by 5.5 g kg −1 ), a well-established empirical lime recommendation algorithm that represents the best management practices for liming in Germany was adapted, and the lime requirements (LRs) were determined. The generated workflow was applied to a 25.6 ha test field in north-eastern Germany, and the variable LR was compared to the conventional uniform LR. The comparison showed that under the uniform liming approach, 63% of the field would be over-fertilized by approximately 12 t of lime, 6% would receive approximately 6 t too little lime and 31% would still be adequately limed.