Modern man has developed several methods to jack up agricultural production, of which the use of chemical fertilizers has been gaining popularity in many countries.

The world consumption of chemical fertilizers has more than trebled since 1957 which bears testimony to this fact. Though there has been adequate chemical fertilizers consumption, only about 15% of the world is used by farmers in the Third World. Asia’s annual fertilizer consumption is about 17%.

Fertilizers, coupled with improved inputs to crop productions, have played a significant role in increasing agricultural production. However, it is difficult in modern production systems to identify their individual roles because inputs interact.

Actually, in highly developed agricultural systems, the large increase in agricultural output is due to interactions among inputs. Experiments that test one factor, such as increasing quantities of nitrogen, show how much nitrogen is needed for maximum output under these conditions. Separate experiments may test necessary quantities of phosphate or potash.

The maximum benefit from nitrogen will only be reaped when a particular crop has sufficient phosphorus, potash and water. Responses to nitrogen will be greater in the presence of phosphorus than without phosphorus and vice versa. To get benefits from fertilizers, their applications should be timed.

For example, the International Research Institute (IRI) in the Philippines discovered that split application, first held just after transplanting and the second half in the beginning gave rise to 1 to 1.5 tons more rice per hector than with just one application. IRI’s data also showed that fertilizer efficiency increased about 68% when it was applied to 10cm deep.

The practice of using only one kind of chemical fertilizer in a piece of land should be discouraged to reduce adverse effects. For example, if nitrogenous fertilizers are used continuously for some years on a piece of land, the soil becomes acidic and hard.

If phosphate and potash fertilizers are used continuously for some years in any piece of land separately, plants will not grow luxuriantly.

The use of lime should be encouraged to reduce the adverse effects of chemical fertilizers.

However, the quantity of lime that should be used in a patch of land depends on the acidity and the nature of the soil. If we used fertilizers in this way, our agricultural production will be increased.