After reading this article you will learn about the importance of balanced supply of fertilizers to soil.
Nitrogen being ‘the motor of plant growth’ will usually show its efficiency soon after application – the plants develop a dark green colour and grow more vigorously. However, unbalanced, excess nitrogen in cereals/rice may result in lodging, greater weed competition and pest attacks, with substantial losses of cereal or paddy production (in other crops it will decrease quality, particularly storage ability).
In addition, the nitrogen not taken up by the crop is likely to be lost to the environment. Where the financial resources of the farmer are limited or no credit facilities are available and if his tenure of the land is insecure, and urea, for example, is offered on the market at a comparatively attractive price per unit of nitrogen, the farmer-expecting an immediate and evident returnâ€”will supply his crops exclusively with nitrogen. In the short term this is a logical decision.
Consequently, most of the increase in world nitrogen consumption has been accounted for through the use of urea. Such one-sided or unbalanced preference may be justified on soils rich in plant-available phosphate, potassium and all other necessary secondary and micro-nutrients. However, higher yields will also take up greater amounts of the other nutrients from the soil.
Thus increased yield through application of nitrogen alone deplete the soils of the other plant nutrients. It is evident that without the application of phosphorus and potassium, nitrogen efficiency declined, whereas when all nutrients were applied together phosphorus and potassium efficiency increased steadily, thereby indicating interactions between these nutrients.
Therefore, conditions must be made as favourable as possible in the rhizosphere for optimum uptake of plant nutrients. An effort should be made to keep the soil pH at an optimum level by liming or application of gypsum (on alkaline soils), and to supply organic matter, water and a balanced fertilization.
It has been demonstrated that primary, secondary or micro-nutrients which are the most deficient in the soil limit the yield and/or affect the equality; they cannot be substituted by any other nutrients.
Therefore, for good agricultural practices, balanced fertilization primarily means a supply of nitrogen, phosphorus and potassium in line with soil reserves, the requirements and expected yield of the crop, with the addition of secondary and micro-nutrients where necessary.