Soil application of herbicides for pre-emergence (PRE) weed control is vital for grain sorghum production. Many soil-applied herbicides can be adsorbed or bound to the soil reducing the amount available for weed control. Extent of adsorption is strongly correlated to soil physical properties of organic matter (SOM) and texture. To overcome adsorption, the rate of herbicide to be applied is dependent on SOM and texture levels. These properties can vary within one field, making it difficult to follow label recommendations and achieve adequate weed control with a uniform rate. Variable rate applications (VRA) can be utilized to maximize herbicide effectiveness by applying the right rate in the right place. In 2016 and 2017, herbicide algorithms were developed for two different tank-mixes to be applied at five locations across Kansas. A Veris MSP3 system was utilized to collect and develop interpolated maps of SOM and of EC values that were correlated with soil texture classes to develop soil texture maps. Three algorithms were evaluated in the field for each tank-mix: based only on SOM (alg-SOM), on SOM and texture (alg-SOMtex), or on a flat rate. Rates for each tank-mix were based on the maximum usage rate (MUR) allowed for each herbicide. VRA based on SOM reduced the amount of herbicide applied while resulting in similar weed control compared to the flat rate. VRA based on SOM and texture greatly reduced the amount of herbicide applied but also resulted in reduced weed control compared to the flat rate at several locations. These findings prove that accurate SOM and texture data at high resolution combined with herbicide algorithms can be utilized by producers for effective VRA of soil-applied herbicides.

在土壤中施用除草剂以控制芽前 (PRE) 杂草对于高粱生产至关重要。许多土壤施用的除草剂会被吸附或结合到土壤上，从而减少了可用于控制杂草的数量。吸附程度与土壤有机质 (SOM) 的物理性质和质地密切相关。为了克服吸附，除草剂的施用率取决于 SOM 和质地水平。这些特性在一个领域内可能会有所不同，因此很难遵循标签建议并以统一的比率实现充分的杂草控制。通过在正确的位置应用正确的比率，可以利用可变比率应用 (VRA) 来最大限度地提高除草剂的有效性。2016 年和 2017 年，开发了用于两种不同桶混的除草剂算法，用于堪萨斯州的五个地点。Veris MSP3 系统用于收集和开发与土壤质地类别相关的 SOM 和 EC 值的插值图，以开发土壤质地图。在现场针对每种罐混合评估了三种算法：仅基于 SOM (alg-SOM)、基于 SOM 和质地 (alg-SOMtex) 或基于统一速率。每个桶混的比率基于每种除草剂允许的最大使用率 (MUR)。基于 SOM 的 VRA 减少了除草剂的施用量，同时与固定率相比产生了类似的杂草控制。基于 SOM 和质地的 VRA 大大减少了除草剂的施用量，但与几个位置的统一比率相比，也导致杂草控制减少。