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Abstract

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

Soil acidifcation is caused by natural paedogenetic processes and anthropogenic impact 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-specifc 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 (RMSEpH: 0.37); the soil texture was predicted by a combination of apparent electrical resistivity measurements and natural soil-borne gamma emissions (RMSEclay: 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 refection measurements (RMSESOM: 6.4 g kg−1). Second, to address the high within-feld 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 workfow was applied to a 25.6 ha test feld 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 feld 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.



Bönecke, E.; Meyer, S.; Vogel, S.; Schröter, I.; Gebbers, R.; Kling, C.; Kramer, E.; Lück, K.; Nagel, A.; Philipp, G.; Gerlach, F.; Palme, S.; Scheibe, D.; Zieger, K.; Rühlmann, J. (2020). Guidelines for precise lime management based on high‑resolution soil pH, texture and SOM maps generated from proximal soil sensing data. Precision Agric 22, 493–523 (2021). https://doi.org/10.1007/s11119-020-09766-8