The University of Missouri Extension Soil Testing labs analyzed about 34,000 soil samples in 2000. The data has value as a broad assessment of the nutrient status of soils throughout the state of Missouri. Crops grown in Missouri generally require a pH s of 5.4 or more for non-limiting growth. Neutralizable acidity is determined by the Woodruff Buffer Method. 24 Table 4.
Soybean is the second most frequently tested field crop.
Corn stalk nitrate tests are done at the black layer stage to evaluate prior growing season N management practices. Click here to view UMC Guide G9131. The most common problem observed was K deficiency. While some corn samples that were submitted from Northwest part of the state had high K testing soils, they still showed K deficiency. Moisture stress and compaction likely resulted in reduced uptake of K in these fields.