Proper collection procedures for plant parts can be obtained from agricultural Extension agents, N.C. Department of Agriculture regional agronomists, or a qualified crop consultant. Table 2 gives sufficient guidelines for small grains. No figures are given for nitrogen because this nutrient is very mobile. Tests can be conducted but have little predictive value. Recommended rates are based on research and observation of many field trials.
Sulfur is quite mobile in soils with sandy surface layers.
Although a surface soil sample may indicate low sulfur levels, adequate sulfur may still be within reach of most root systems. Therefore, a sulfur soil test has unreliable predictive value. Taken from information furnished by N.C. Department of Agriculture, Agronomic Division.