In recent years, several varieties of almost all crops with high-yield and high-quality potentials have been developed for cultivation. However, these varieties can grow and perform to their maximum genetic potentials, only if they are cultivated in the productive soils.
The soil can be productive only if it is fertile and healthy. The soils can be fertile and healthy only if they are supplied with all the essential macro and micronutrients in sufficient amounts and desirable proportions, besides being free from any toxic substance.
Very small dosages
Although the micronutrients of iron, manganese, zinc, copper, boron, molybdenum and chlorine are required by plants in very small amounts, they are as much essential and important for the normal growth of the crops as the major nutrients of carbon, oxygen, hydrogen, phosphorous, potassium, calcium, magnesium and sulphur required by the crops comparatively in large quantities at percentage levels.
Limiting nutrient
The growth and yield of a crop will be limited to the amount of the nutrient that is available to the crop in the least amount, as dictated by the Law of minimum concept.
If one micronutrient needed at the least level becomes deficient, the crop cannot grow normally, even if all the other nutrients are supplied in sufficient amounts.
As we have been cultivating high yielding varieties of different crops under intensive agriculture over the years, the reserves of many of the micronutrients have been depleted in the soils as they have not been replenished through the appropriate manure – fertilizer schedules including the micronutrients too.
A situation has arisen that the fertility and productivity of our arable lands cannot be restored without suitable balanced fertilization programmes.
Rectify deficiency
The growth and the yield of the crop will be limited to the amount of the nutrient present and available to the crop in the least amount irrespective of the availability of all other nutrients in relatively higher amounts.
Unless we rectify the deficiencies of micronutrients, continuous application of major nutrients alone cannot improve the performance of the crops under cultivation.
Dr. K. Kumaraswamy
Formerly Professor of Soil Science & Agricultural Chemistry, TNAU Coimbatore
