INVESTIGATIONAL ALLOWANCES

Subpart 1. Primary plant nutrients. A commercial fertilizer is deficient if the analysis of any plant nutrient is below the guarantee by an amount exceeding the values in the following schedule, or if the overall index value of the fertilizer is below 97 percent. Guaranteed percent Nitrogen percent Available Phosphate percent Potash percent 04 0.49 0.67 0.41 05 0.51 0.67 0.43 06 0.52 0.67 0.47 07 0.54 0.68 0.53 08 0.55 0.68 0.60 09 0.57 0.68 0.65 10 0.58 0.69 0.70 12 0.61 0.69 0.79 14 0.63 0.70 0.87 16 0.67 0.70 0.94 18 0.70 0.71 1.01 20 0.73 0.72 1.08 22 0.75 0.72 1.15 24 0.78 0.73 1.21 26 0.81 0.73 1.27 28 0.83 0.74 1.33 30 0.86 0.75 1.39 32 or more 0.88 0.76 1.44 For guarantees not listed, calculate the appropriate value by interpolation. The overall index value is calculated by comparing the commercial value guaranteed with the commercial value found. For example, when using a 2:2:1 ratio, assuming that the nitrogen and phosphorus are valued at twice the amount of potash: 10.0 units N x 2 = 20.0 10.0 units P 2 O 5 x 2 = 20.0 10.0 units K 2 O x 1 = 10.0 Commercial Value Guaranteed = 50.0 10.1 units N x 2 = 20.2 10.2 units P 2 O 5 x 2 = 20.4 10.1 units K 2 O x 1 = 10.1 Commercial Value Found = 50.7 Overall Index Value = 100(50.7/50.0) = 101.4% Subp. 2. Secondary and micro plant nutrients. Secondary and micro plant nutrients are deficient if any plant nutrient is below the guarantee by an amount exceeding the values in the following schedule: Plant Nutrient Allowable Deficiency Calcium (Ca) 0.2 unit + 5% of guarantee Magnesium (Mg) 0.2 unit + 5% of guarantee Sulfur (S) 0.2 unit + 5% of guarantee Boron (B) 0.003 unit + 15% of guarantee Cobalt (Co) 0.0001 unit + 30% of guarantee Molybdenum (Mo) 0.0001 unit + 30% of guarantee Chlorine (Cl) 0.005 unit + 10% of guarantee Copper (Cu) 0.005 unit + 10% of guarantee Iron (Fe) 0.005 unit + 10% of guarantee Manganese (Mn) 0.005 unit + 10% of guarantee Sodium (Na) 0.005 unit + 10% of guarantee Zinc (Zn) 0.005 unit + 10% of guarantee The maximum allowance when calculated under this subpart is one unit (one percent). Subp. 3. Analytical procedures. Sampling equipment, procedures, preparation, and analysis must be those adopted by the Association of Official Analytical Chemists. In cases not covered by those methods, or in cases where methods are available in which improved applicability has been demonstrated, the commissioner may adopt appropriate methods from other sources.