Agronomic Services

Crop Fertilization Based on North Carolina Soil Tests

Table 1.1 Relationship between soil test index and yield
Soil Test Index		Crop Response to Nutrient Application *
Range	Rating	P	K	Mn	Zn	Cu
0–10	very low	high	high	high	high	high
11–25	low	high	high	high	high	high
26–50	medium	medium	medium	none	none	none
51–100	high	none	low/none	none	none	none
100+	very high	none	none	none	none	none
* Crop response to phosphate (P2O5) and potash (K2O) decreases as the soil test index approaches 50.
Hardy DH, Tucker MR, Stokes CE. 2013. Crop fertilization based on North Carolina soil tests. Raleigh (NC): North Carolina Department of Agriculture and Consumer Services, Agronomic Division. Circular No. 1.