# NutrientDepletionEstimate

This feature is used to determine the amount of nutrients a crop has absorbed from the soil during a certain period. The values are expressed as kilograms.

To use this feature, you can select a farm field, a crop type and a period. The results will appear automatically in the result table. If you change the production period the results will adapt themselves.

You can use the results in the following way:

The concentration of the macro-nutrients in a fertilizer is given in percentage per weight units, e.g.: grams of the macro-nutrients (N, P2O5, K2O) per 100 gram of fertilizer (gr/100 gr).

• Nitrogen (N) – the concentration of nitrogen in a commercial fertilizer is expressed as the percentage of pure N in the fertilizer, as grams of N in 100 gr of fertilizer.
• Phosphorus (P) – the concentration of phosphorus in the commercial fertilizer is expressed as the percentage of phosphorus (pent) oxide (P2O5) in the fertilizer, as grams of P2O5 in 100 gr of fertilizer.

The relationship between pure phosphorus (P) and the oxide (P2O5) is: 1 Kg (pure) P = 2.3 Kg P2O5 (2.3 x the weight of P = the weight of P2O5).

• Potassium (Kali) (K) – the concentration of potassium in the commercial fertilizer is expressed as the percentage of potassium oxide (K2O) in the fertilizer.

The relationship between pure potassium and potassium oxide is: 1 Kg (pure) K = 1.21 Kg K2O.(1.21 x the weight of K = the weight of K2O).

The numbers that appear on a fertilizer’s formula express the concentration of the various nutrients (for both solid and liquid fertilizers) in percentage per unit weight. The world over, the main nutrients are listed in the following order: N-P-K (nitrogen, phosphorus, potassium).

• Nitrogen: The first number on the left represents the concentration of pure nitrogen (N) in the commercial fertilizer, in percentage units.
• Phosphorus: The second number represents the concentration of phosphorus (pent) oxide (P2O5) in the commercial fertilizer, in percentage units. In order to calculate the concentration of pure P (in %), multiply that number by 0.44.
• Potassium: The third number represents the concentration of potassium oxide (K2O) in the commercial fertilizer, in percentage units. In order to calculate the concentration of pure K (in %), multiply that number by 0.832.

So now that we calculate the amount of pure N of P or K that exists in a fertilizer, and the nutrients used by the plant during the last crop period, we can calculate exactly the amount of fertilizer that we will have to use in order to restore the nutrient balance in the soil, so that our plant will not go under a nutrient deficiency period.