Abstract. Spatiotemporal yield heterogeneity presents a significant challenge to agricultural sustainability efforts and can strain the economic viability of farming operations. Increasing soil organic matter (SOM) has been associated with increased crop productivity, as well as the mitigation of yield variability across time and space. Observations at the regional scale have indicated decreases in yield variability with increasing SOM. However, the mechanisms by which this variability is reduced remain poorly understood, especially at the farm scale. To better understand the relationship between SOM and yield heterogeneity, we examined its distribution between particulate organic matter (POM) and mineral-associated organic matter (MAOM) at the subfield scale within nine farms located in the central United States. We expected that the highest SOM concentrations would be found in stable, high-yielding zones and that the SOM pool in these areas would have a higher proportion of POM relative to other areas in the field. In contrast to our predictions, we found that unstable yield areas had significantly higher SOM than stable yield areas and that there was no significant difference in the relative contribution of POM to total SOM across different yield stability zones. Our results further indicate that MAOM abundance was primarily explained by interactions between crop productivity and edaphic properties such as texture, which varied amongst stability zones. However, we were unable to link POM abundance to soil properties or cropping system characteristics. Instead, we posit that POM dynamics in these systems may be controlled by differences in decomposition patterns between stable and unstable yield zones. Our results show that, at the subfield scale, increasing SOM may not directly confer increased yield stability. Instead, in fields with high spatiotemporal yield heterogeneity, SOM stocks may be determined by interactive effects of topography, weather, and soil characteristics on crop productivity and SOM decomposition. These findings suggest that POM has the potential to be a useful indicator of yield stability, with higher POM stocks in unstable zones, and highlights the need to consider these factors during soil sampling campaigns, especially when attempting to quantify farm-scale soil C stocks.

中文翻译：

---

子田产量稳定区中颗粒物和矿物相关有机物组分的控制和丰度的变化

摘要。时空产量异质性对农业可持续发展工作提出了重大挑战，并可能限制农业经营的经济可行性。土壤有机质（SOM）的增加与作物生产力的提高以及随时间和空间的产量变异性的缓解有关。区域尺度的观察表明，随着 SOM 的增加，产量变异性降低。然而，人们对减少这种变异性的机制仍然知之甚少，特别是在农场规模上。为了更好地了解 SOM 与产量异质性之间的关系，我们在美国中部的 9 个农场的子田范围内检查了颗粒有机物 (POM) 和矿物相关有机物 (MAOM) 之间的分布。我们预计，最高的 SOM 浓度将出现在稳定的高产区，并且这些区域的 SOM 池中的 POM 比例相对于田间的其他区域更高。与我们的预测相反，我们发现不稳定产量区的 SOM 显着高于稳定产量区，并且不同产量稳定区 POM 对总 SOM 的相对贡献没有显着差异。我们的结果进一步表明，MAOM 丰度主要是通过作物生产力和土壤特性（例如纹理）之间的相互作用来解释的，而土壤特性在稳定区域之间存在差异。然而，我们无法将 POM 丰度与土壤特性或耕作系统特征联系起来。相反，我们假设这些系统中的 POM 动态可能是由稳定屈服区和不稳定屈服区之间分解模式的差异控制的。我们的结果表明，在子田规模上，增加 SOM 可能不会直接提高产量稳定性。相反，在时空产量异质性较高的田地中，SOM 储量可能由地形、天气和土壤特征对作物生产力和 SOM 分解的交互影响决定。这些发现表明，POM 有可能成为产量稳定性的有用指标，不稳定地区的 POM 储量较高，并强调在土壤采样活动期间需要考虑这些因素，特别是在尝试量化农场规模的土壤碳储量时。