How to Identity Soil Fertility
The capability of soil to provide and coordinate nutrient substance and environmental conditions for plants’ normal growth is called soil fertility.
When it comes to formula fertilization, the first need is to realize the soil fertility. Soil fertility is the comprehensive performance of physical, chemical, biological and environmental factor. 
By now there is not an exact quantity index to express soil’s fertility, nor one or several factor numbers to generalize soil fertility, so it is usual to consider the yield of crops on the soil without any fertilizer, also called blank yield, as the comprehensive index of soil fertility.
Generally, the higher the blank yield is, the higher the soil fertility will be, and vice versa.
After knowing the fertility of the soil and lack elements or nutrients of the crops and soil, we can supplement the absent nutrients from mixed fertilizers. How to get the mixed fertilizer with exact formula? It is easy and fertilizer mixing plant is to help solve this problem. Generally, there are a lot of this kind of machines, but their capacity and precision are so different that the whole equpments may affect a factory’s benefit and crop yield, which means too much for both the owner of factory and a farmer. To get qualified mixed fertilizer and benefit, choose a set of excellent fertilizer equpiments.
Previsou Popularization of Science on Slow and Controlled Release Fertilizer