LaMotte STH Outfit - Manual (Page 19)

19
Units of Measure
Test results are expressed in the following terms:
Parts per Million
(ppm)
Pounds Per Acre
(lb/acre)
Relative Amounts
from Very Low to
Very High
Nitrite Nitrogen Nitrate Nitrogen Ammonia Nitrogen
Calcium Phosphorus Magnesium
Sulfate Potassium Aluminum
Chloride Iron Manganese
Pounds per acre represent the number of pounds of soil in an acre to the
plough depth of 6-7 inches, or 2,000,000 lbs. Conversion from pounds
per acre to parts per million, or vice versa, may be accomplished by
means of the following formulas:
ppm x 2 = lb/acre
lb/acre x 0.5 = ppm
In the four nutrient tests which produce relative test results, the
following approximate quantitative values may be assigned to the
relative terms:
Approximate Value Expressed in ppm
Test Factor
Very
Low
(Low)
Low
(Medium
Low) Medium High
Very
High
Ammonia Nitrogen 5 10 40 100 150
Magnesium 5 10 25 80 150
Aluminum 5 10 30 80 125
Manganese NA 5 12 25 40
Fertilizer Application Rates
When interpreting soil test results to establish a fertilizer program, a number
of variables must be considered in addition to the values obtained in the
soil tests. These variables include the composition of the soil, drainage,
climate, previous fertilizer programs and soil test results, and the type of
plant to be grown. Consult local agricultural services for guidelines to
fertilizer application rates for the specifi c soils in your area.