The role of inorganic fertilizers and their management practices

Nutrient management is the key issue in sustainable soil fertility. N, P, K fertilization aims not only for a high economic return of the investment through optimized yield and quality, but also for minimum environmental hazards. The basic concept underlying integrated plant nutrition systems, is the maintenance and possible increase of soil fertility for sustaining enhanced crop productivity through optimal use of all sources of plant nutrients, particularly inorganic fertilizer, in an integrated manner and as appropriate to each specific ecological, social and economic situation. Much research has established the importance of fertilizers in increasing the fertility of soil and in influencing its productivity. It has been observed that applying fertilizers causes many changes in the soil, including chemical changes, that can positively or negatively influence its productiveness. Only a fraction of the fertilizer applied to the soil is taken up by the crop, the rest either remains in the soil or is lost through leaching, physical wash-off, fixation by the soil, or release to the atmosphere through chemical and microbiological processes. The critical information on the relative merits of different fertilization practices such as method of fertilizer placement, time and rate of application and type of fertilizers, is essential. Results from different field and laboratory experiments which helped to achieve maximum efficiency, in the most economical and sustainable way of fertilizer use to reduce the nutrient losses and production costs to the farmers and prevent environmental pollution are presented in the paper.