Nutrient Removal Rates Crucial in Fertilizer Decisions
When planning for next year's crop rotation, farmers need to factor in the nutrient removal rates from this year's harvest. The crops being harvested now will be gone by next year, taking valuable nutrients with them.
The Tri-State Fertilizer Recommendations suggest that phosphorus (P) and potassium (K) can be stored in the soil for years, but it takes time to build up these nutrient levels once they are depleted. According to the recommendations, crops are removing less P and K per bushel of yield than in previous years.
Farmers need to calculate the removal amounts by multiplying the removal rate per bushel by the actual yield achieved. For example, a 150-bushel-per-acre corn crop will remove 52 pounds per acre P2O5 and 30 pounds per acre K2O. A 49-bushel-per-acre soybean crop will remove on average 39 pounds per acre P2O5 and 56 pounds per acre K2O.
Greater yield means more total nutrients are removed from the soil, leading to a gradual decrease in soil test P and K levels over time if no fertilizer is added. However, nutrient grain removal and soil nutrient depletion are not directly related, and other factors such as soil texture and mineralogy can influence how quickly nutrients are removed or replenished.