Unveiling the effects of crop rotation on soil pH mapping: a soil sample grouping strategy

We explored the effects of incorporating crop rotation on digital mapping of soil pH. Facing the challenge of quantifying the extent to which crop rotation affects soil pH mapping accuracy, we introduced the soil sample grouping strategy. We hypothesized that grouping soil samples by crop rotation could built optimized sub-models for different rotations and achieve a higher accuracy than simply incorporating crop rotation. To test this hypothesis, we selected a typical acidic soil region in Southern China where the agricultural landscape is highly heterogeneous due to intensive and diversified cropping systems. Specifically, the objectives of this study are (1) to explore the effectiveness of simply incorporating crop rotation in mapping soil pH and (2) to verify whether and to what extent the soil sample grouping strategy and separate modeling for different crop rotations could further improve digital mapping of soil pH.