Part 1, Section 2: Soil Fertility Management
Soil Fertility Management
FERTILIZER MATERIALS
Fluid fertilizers
Fluid fertilizers are becoming more and more common. The latest fertilizer statistics for Pennsylvania indicate that nitrogen solution (UAN) is the most common source of nitrogen used in the state. Multinutrient fluid fertilizers also are becoming more popular. The fluid fertilizers may be categorized into two groups: clear solutions and suspensions.
In clear solutions, nutrients are dissolved completely in water. The major advantage is in handling. The disadvantages are the generally higher price and lower possible analysis compared to dry fertilizers, especially when the material contains potassium.
Suspension fertilizers are fluids in which the components’ solubility has been exceeded and in which very fine undissolved particles are kept from settling out by the inclusion of clay. Again, the major advantage of these materials is in handling. Suspensions also can be formulated at much higher analyses than can the clear solutions. Analyses similar to those for dry materials are possible. The major disadvantage of suspensions is that they require constant agitation, even in storage. Furthermore, suspension fertilizer cannot be used as a carrier for certain other chemicals.
The bottom line in comparing fluid fertilizers with dry fertilizers on the basis of amount of plant food, is that they are equal in agronomic effectiveness when each is used properly.
Remember, when making calculations of fluid fertilizers, that the analysis is given as a weight percentage, not on a volume or “per-gallon” basis. Most fluids weigh between 10 and 12 pounds per gallon. The following is an example to illustrate the calculations.
One gallon of the 10-34-0 liquid weighing 11.68 pounds per gallon contains:
11.68 × .10 = 1.17 lb N
11.68 × .34 = 3.97 lb P2O5
It would take a little less than 9 gallons of this liquid to equal 100 pounds of a dry material with the same analysis. For comparing fluids on a price-per-ton basis, divide the weight per gallon into 2,000 to get the number of gallons per ton.
In the above example, the calculation is:
2,000 ÷ 11.4 = 175 gallons per ton
This conversion can be used to compare a liquid priced in dollars per gallon with a solid priced in dollars per ton.