Soil: Field & Row Crops
Samples are collected from the top 12 inches of soil with a soil probe. A shovel can be used if care is taken to assure a good vertical representation of the 0 to 12 inch profile.
Results will vary widely if soil amendment or fertilizer injection bands become part of the sample. It is best to avoid these bands or take a high number of random samples.
Nutrients are often better evaluated by petiole or leaf samples because root-depth and position of residual fertilizer levels vary, changing the amount of nutrients available to the plant. Tissue sampling will determine what the plant is absorbing; see Plant Tissue.