Application of fertiliser by using proper methods and at appropriate time is important for crop production. Nitrogenous fertiliser should be applied in split doses. While slow releasing, phosphorus and potassium should be applied at the time of sowing or planting. Broadcasting fertilisers should be applied by placement method or through fertigation. During application of fertilisers, following considerations should be taken in account:
Soil Factors – The coarse texture soils are poorer in available nutrients than fine texture soils. Hence, it is necessary to apply nitrogenous, phosphatic and potassic fertilisers in coarse soils more frequently than in fine texture soils. Higher the soil fertility. the lower is the response of crops to fertiliser. Soil reaction is important in selection of right type of phosphatic fertiliser. Efficient use of fertilisers by the crop is more in the higher organic matter status of soil.
Climatic Factors – These include temperature, rainfall, evaporation, and length of day and growing season. The rate of nitrification is slower in a cooler climate that in a warmer climate. Hence, more ammonical nitrogenous fertilisers will be needed in a cool climate. In region of high rainfall, higher fertilizer is required because of higher yield potential, leaching and loss of soil and fertilisers nutrients. In arid region, soil moisture is the limiting factor in fertiliser use. If soil moisture is conserved efficiently, fertiliser becomes very effective.
Reclamation of problem soils
Problematic soils viz. acidic, saline and alkaline soils can be converted into proper condition for raising the crop satisfactorily and economically, by adopting special measures. Acidic soils can be corrected by liming. Saline and alkaline soils can be reclaimed by improving drainage, scrapping off surface soils and using gypsum, sulphur, molasses and adopting agronomical measures viz. green manuring, adding organic manures, mulching and suitable crops rotation.