Managing Soil Nutrients in an Era of Fertilizer Price Volatility
Fertilizers are inherently sensitive to price shocks. They are energy-intensive to manufacture, rely on complex global supply chains, and are often sourced from regions with geopolitical risk. As a result, periodic fertilizer price spikes should be viewed not as anomalies, but as an expected part of modern farm management. Proactive fertility planning that anticipates these disruptions can help farms remain resilient when prices rise suddenly.
The foundation of any strategy to manage fertilizer price volatility is regular soil testing. Testing every field at least once every three years allows producers to identify which fields have an immediate economic need for fertilizer and which fields can tolerate nutrients being withheld temporarily. This information becomes particularly valuable when fertilizer prices are high, as it enables more strategic allocation of limited fertility dollars.
Fields with soil test phosphorus (P) and potassium (K) levels in the optimum range, which is 30-50 ppm P and 100-150 ppm K (or 200 ppm K for forages) on a Mehlich 3 extract, can often produce a crop without additional fertilizer inputs in the short term, since recommendations in this range are designed for maintenance rather than yield response. During periods of high fertilizer prices, these maintenance applications can be reduced or even eliminated. However, caution is warranted when soil test levels are near the lower end of the optimum range. Variability within fields means that some areas may still have below optimum nutrient levels and remain responsive to fertilizer, even if the field average appears adequate. This risk is typically greater for potassium than for phosphorus, as soil test P tends to be more buffered than K. Looking ahead, raising soil test levels toward the middle of the optimum range when fertilizer prices are lower can provide a valuable buffer, allowing maintenance applications to be skipped when prices are high without sacrificing crop performance.
Farms with access to manure are particularly well positioned to protect themselves from fertilizer price shocks. Operations with moderate to high volumes of liquid manure can significantly reduce, or even eliminate, the need for commercial nitrogen fertilizers by switching from broadcast application to injection. Immediate incorporation through low disturbance injection reduces nitrogen losses and increases the fertilizer replacement value of manure. A Penn State Extension article comparing the value of manure injection versus broadcast application across manure sources highlights the economic benefits of immediate incorporation and is worth revisiting.
Manure management strategies can be further optimized by prioritizing applications on fields with the lowest soil test levels. Fields that are already excessive in phosphorus or potassium may be better candidates for manure export, particularly when working with poultry litter, which is easier to transport than liquid manure. In cases where logistics allow, exporting manure to nearby crop farms can generate revenue while reducing nutrient accumulation on the home farm.
The Penn State Extension Manure Economic Value Calculator is a useful tool for evaluating pricing of both manure exports and imports. By incorporating current fertilizer prices, soil test-based nutrient recommendations, manure nutrient analyses, and nitrogen availability factors, the calculator estimates the break-even cost of manure relative to commercial fertilizer. A recent example from importing poultry litter to Penn State’s research farm at Rock Springs illustrates the value of this approach. Poultry litter transported from Snyder County to Centre County was delivered at a cost of $38 per ton. Based on fertilizer recommendations for soil tests at the bottom of the optimum range, a 190-bu/acre corn yield goal, and a two-ton-per-acre application rate of the poultry litter with no incorporation, the total nutrient value of the poultry litter was estimated at $165.32 per acre, with an annual fertilizer replacement value of $115.27 per acre. The resulting break-even price of the manure in this scenario was $57.64 per ton. Using the imported manure at $38 per ton instead of purchasing fertilizer to meet the nutrient recommendations led to a savings of $39 per ac, while also contributing to long-term soil fertility, organic matter, and overall soil health.
Finally, nitrogen management decisions should be refined using available diagnostic tools, particularly when fertilizer prices are elevated. Penn State Extension's recently developed nitrogen recommendation tool for corn evaluates how soil organic matter, cover crop residues, fertilizer prices, and corn prices affect the economic optimum nitrogen rate. Even approximate estimates of soil organic matter and cover crop residues entered into the tool can help give a relative sense of how much N to reduce when fertilizer costs increase based on various yield response scenarios. For manured systems, the pre-sidedress soil nitrate test (PSNT) remains an excellent in-season tool to determine whether additional nitrogen is needed, potentially avoiding unnecessary sidedress applications and saving costs during the growing season.
In an environment where fertilizer price volatility is likely to persist, farms that take a strategic, soil test–driven approach to nutrient management are best positioned to remain profitable. Regular soil testing, targeted fertilizer use, effective manure management, and the use of diagnostic tools allow producers to respond thoughtfully rather than reactively to price spikes. By building fertility buffers when prices are lower and relying on data to guide decisions when costs increase, farms can protect both short-term cash flow and long-term soil productivity.
