Alabama row crop producers will find research-based nutrient recommendations for the maintenance of their row crops throughout the growing season in the PDF linked below. Nutrient Recommendations for Alabama Row Crops is a shorter portion of an earlier publication titled Nutrient Recommendations for Alabama Crops—which encompassed many Alabama-grown crops—updated by Audrey Gamble, an Alabama Cooperative Extension System soil scientist.
The tables contained in the PDF highlight recommendations by crop based on soil test rating (low, medium, high, etc.) for P and K. Auburn University Soil Testing Recommendations use research-based tables to calculate recommended P and K to the nearest 10 – 30 pounds of P₂O₅ (phosphate) and K₂O (potash). Comments growers will find printed on the soil test report are also included for each crop.
The following information is contained in recommendations in this publication:
- N rate. Each crop is assigned a standard, annual N rate based upon research conducted throughout Alabama. However, comments given with each crop may modify this rate based upon yield potential, soil, time of application, cropping system, etc.
- P requirement level. There are only two levels. Level 1 is for those crops with a low P requirement, such as peanut. All other crops fall in level 2.
- K requirement level. Crops are divided into three classes based on their K requirements. These classes are (1) low K requirement (ex. peanuts), (2) medium K requirement (ex. soybeans and corn and other grasses), and (3) high K requirement (ex. cotton).
- Mg Ratings and Mg Codes. Magnesium is rated either high (above the critical value) or low (below the critical value) based on the soil group. There are three Mg recommendation codes for different crops.
- Ca ratings. Extractable Ca is calibrated only for peanuts. All other crops are not expected to respond to direct Ca applications if the soil is properly limed but receive at rating based upon that for peanuts.
- Lime recommendation code. Crops vary in the amount of acidity they can tolerate and still make top yields. They are divided into six classes based on the pH ranges in which they produce best.