Chemical properties
The main building blocks of plants are:
- The carbon (C) that comes from the air (Co2).
- Hydrogen (H) and oxygen (O) from water.
- Nutrients that are derived from organic and mineral components. Plant nutrients include:
- Major elements: N, P, K.
- Secondary elements: Ca, Mg, S.
- Trace elements: Fe, Zn, Cu, B, Mo, Mn.
If one of these essential nutrients is missing, all the other nutrients present are useless. This is the law of the minimum, or the law of limiting factors of Justus Liebig.
Crop yields are proportional to the amount of nutrient that is lowest in the soil. The lack of an assimilable element in the soil reduces the effectiveness of the other elements, and consequently, decreases the yield of crops. This law of the minimum of Justus Von Liebig is commonly illustrated by the image of the barrel whose shortest stave determines the maximum level of filling of the barrel.