Precautions To Be Taken While Preparing Fertilizer Mixtures
1. Do not mix the fertilizer containing ammonia like Amm. Sulphate with basically reactive fertilizers like lime, basic slag, Rock Phosphate and Calcium Cynamide as losses of ‘N’ may result through escape of gaseous ammonia.
2. Do not mix water soluble phosphatic fertilizer (Super Phosphate) with the fertilizer containing free lime (basic slag, Calcium Cynamide) as this coverts the portion of soluble phosphate into soluble phosphate.
3. Do not mix fertilizers which are easily soluble and hygroscopic like urea, Calcium Ammonium Nitrate with other fertilizers because they will form lumps. The fertilizer mixtures are made manually or in the factory, having the grades 6:12:0, 12:6:0, 9:9:0, 9:9:5, 15:5:5, 10:5:5, etc.
Formulation of FM: The quantity of fertilizers for fertilizer mixture can be calculated by
Q = M * T F
Where Q = Quantity of fertilizers to be calculated
M = Total quantity of mixture to be prepared.
T = Parts of nutrients in the fertilizer grade.
F= % of nutrients in the supplier fertilizer.
Unit value of fertilizers: One percent of N, P or K present in one tone of a fertilizer is treated as one unit. A unit is thus equal to 10kg.
The unit value of plant food in a fertilizer is the price of one tone of fertilizers divided by the percentage content of that particular nutrient.
Unit value = Price of 1 tonne fertilizers/ % of nutrient in the fertilizer
The fertilizer having a lower unit value will be cheaper than a fertilizer having a higher unit value. It is made use in determining the price of fertilizer mixtures containing N, P and K and in comparing the cost of 2 or 3 fertilizers providing same nutrient.