Judicious nutrient management is critical to help reduce environmental effects of excess crop nutrients in the soil and maximize profit. Nutrient management is an important component of the relay cropping system.
Each crop has different requirements although it may not be convenient or economical to apply nutrients to each crop. Excess nitrate can leach into groundwater while phosphorus can be carried in runoff to surface water where excess levels can enhance algae growth, and in turn reduce oxygen for fish and other aquatic organisms.
For the same yield level (60 bushels per acre), each crop removes a different amount of each nutrient in grain.
- Soybean removes the greatest amounts of all three nutrients since concentrations of nitrogen, phosphorus, and potassium are much greater than with the other crops.
- Nitrogen, phosphorus and potassium applications are recommended when the soil test levels fall below the critical level.
- Potassium is usually very high in Nebraska soils and only a few soils would require more. Nitrogen is not normally applied to soybean.
- All three crops would require adding phosphorus if the soil test level falls below the critical level. The recommended amount of phosphorus applied for each crop is lower than the crop removal since soil provides some of the phosphorus needed for each crop.