@inproceedings{KlingSchroeterVogeletal.2021, author = {Kling, Charlotte and Schr{\"o}ter, Ingmar and Vogel, Sebastian and B{\"o}necke, Eric and R{\"u}hlmann, J{\"o}rg and Gebbers, Robin and L{\"u}ck, Katrin and Schubert, Torsten and Gerlach, Felix and Philipp, Golo and Scheibe, Dirk and Zieger, Karin and Palme, Stefan and Kramer, Eckart}, title = {Optimization of soil pH and crop yield based on a precision liming strategy guided by proximal soil sensing: Results of three on-farm field trails}, series = {Landscape 2021 Diversity for sustainable and resilient agriculture, Online conference, 20.-22.09.2021}, booktitle = {Landscape 2021 Diversity for sustainable and resilient agriculture, Online conference, 20.-22.09.2021}, editor = {Leibniz-Zentrum f{\"u}r Agrarlandschaftsforschung (ZALF),}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:eb1-opus-7741}, pages = {292}, year = {2021}, abstract = {Soil acidity is a key factor for soil fertility as it simultaneously influences several yield-relevant soil properties and thus the productivity of agricultural soils. Besides natural pedogenetic processes, on agricultural land, soil acidification is amplified by the removal of the harvested biomass as well as by the application of acidifying fertilizers. Therefore, regular lime application on agricultural fields is inevitable to sustain soil quality and productivity. In Germany, the standard method for defining the lime requirement of a soil is the VDLUFA framework of the German Advisory Board for Agricultural Analytics. The VDLUFA method uses look-up tables that define the lime requirement according to soil texture, soil pH (CaCl2) and soil organic matter (SOM) content (LVLF et al., 2008). To determine these lime-relevant parameters, fields should be subdivided into subunits of 3 to 5 ha. Within a subunit, one mixed sample from 15 to 20 samples should form a composite sample for further reference lab analysis. However, a uniform lime requirement determined for subunits of 3 to 5 ha is often in contrast to the real soil variability observed in the field (Kling et al., 2019). In order to reflect the within-field soil variability, a few studies have demonstrated the use of high-resolution proximal soil sensing (PSS) data as tools for variable rate (VR) lime application (B{\"o}necke et al., 2020; P{\"a}tzold et al., 2020). However, there is a lack of studies that evaluate the feasibility and benefit of VR methods in on-farm field trails. Therefore, the aim of this study is to compare the performance of site-specific liming based on PSS to optimize soil pH and crop yield with that of commonly applied standard liming methods in Germany. To determine the effect and practicability of the VRA method, a multi-site-multi-year experiment was conducted between 2017 and 2020 on three sites in Brandenburg, Germany. The trial compared the effects on soil pH and crop yield of three lime management practices: variable-rate liming based on PSS data (VR-PS), uniform liming rate based on the VDLUFA standard method (UR), and no liming (ZR). Soil texture and soil pH were assessed with two mobile sensor platforms: the Geophilus system measuring apparent electrical resistivity (ERa) and Gamma-radiation and the Veris pH Manager (Veris Technologies Inc., Salina, KS, USA). Crop yields were obtained from revenue recordings of combine harvesters. Lime prescription maps were generated with an adapted and stepless VDLUFA algorithm, allowing a continuous CaO recommendation (B{\"o}necke et al., 2020). Based on these maps, management zones were delineated to perform lime spreading with state-of-the-art technique. In this study, we outline the conceptual framework of the VR liming approach and present first results from the on-farm field trials to verify the VR approach for an optimized soil acidity management as well as consider whether the higher economic revenue can compensate for added costs for mapping services and spreading technologies.}, language = {en} } @article{BoeneckeMeyerVogeletal.2020, author = {B{\"o}necke, Eric and Meyer, Swen and Vogel, Sebastian and Schr{\"o}ter, Ingmar and Gebbers, Robin and Kling, Charlotte and Kramer, Eckart and L{\"u}ck, Katrin and Nagel, Anne and Philipp, Golo and Gerlach, Felix and Palme, Stefan and Scheibe, Dirk and Zieger, Karin and R{\"u}hlmann, J{\"o}rg}, title = {Guidelines for precise lime management based on high-resolution soil pH, texture and SOM maps generated from proximal soil sensing data}, series = {Precision Agriculture}, volume = {22}, journal = {Precision Agriculture}, publisher = {Springer Nature}, issn = {1385-2256}, doi = {10.1007/s11119-020-09766-8}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:eb1-opus-4890}, pages = {493 -- 523}, year = {2020}, abstract = {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 (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 reflection measurements (RMSESOM: 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.}, language = {en} }