Application of fertilizer in balanced amount is different from area to area and also according the crop. Through soil testing farmers can know how much and what kind of fertilizer to use for each crop. Fertilizer dose is further refined and is possible on the basis of type and variety of crop and available water and its quality, organic manures and crop residues. Soil tests indicate that most of the Pakistani soils have medium to low available phosphorus and potassium status 60 per cent medium whereas, nitrogen continues to be deficient worldwide. Pakistani soils are 47 per cent deficient in zinc (Zn), 12 per cent deficient in copper (Cu) and 4 per cent deficient in manganese (Mn).
In most of the agro-ecological regions boron (B) and molybdenum (Mo) are becoming deficient and limiting factors for crop production. In recent years increase in sulfur (S) deficiency has been observed particularly under intensive cropping system. The sulfur (S) deficit is more distinct in oil seeds, legumes and heavily fertilized crops like rice and wheat. In fact, deficiency ratio of sulfur (S) is increasing so quickly that it will become one of the major yield limiting aspects in future. It has been observed that it is said that the developers are more concerned with the barriers in production high yielding cultivars but they do not have concerned with the quickly altering situation of plant nutrient deficiency and they do not seem to concern with the essential role of fertilizers in food security.
Since in such a situation where besides major nutrients the micro nutrients e.g. sulfur, boron, zinc, manganese, iron and copper are also becoming diminishing factors. Now it is not possible to think about sustained food security without involvement of balanced and integrated use of nutrients applied synthetically. The hazard of nutrient deficiency is becoming more prominent under areas where intensive cropping systems are being practiced. Due to the application of unbalanced fertilizers there are symbols of yield stagnation and less response of crop to fertilizers and other inputs.
Green manure with legumes and other source of biological nitrogen fixations such as Azolla and Blue Green Algae can add to some extent of the nitrogen to the crop but there are several technological, economical and management problems in their adoption. At best they can be relied upon for 30-60 kg nitrogen annual supply under good management. The efficiency of biofertilizers depends on crop, region and management practices and unless there is a reliable system of quality and storage system, transport and management practices in the field.
It is fact that the awareness of balanced use of fertilizers is developing, but intensively use of nitrogen, phosphorus and potassium is a matter of our great concern. The current situation of phosphorus and potassium is more troublesome in Pakistan.
The decreasing efficiency of fertilizers use and of soil productivity are also getting great concern. It has been observed that annually more nutrients are robbed by the soil in the form of biomass than what amount we are providing to soil in the form of fertilizers and in the form of manures. Then there is loss of nutrients, which is decreasing about 10 million tons of nitrogen, phosphorus and potassium annually. This imbalance will increase many times when we try to double the productivity. If this ratio of nutrient loss continues, the sustainability of high production and agriculture industry will be hard to achieve task.
It is not only concern with the huge amounts of fertilizer which matters but also depend on the efficiency and management practices which also help to determine the economics or benefit/cost ratio which are also matter of great concern. Thus the key to national food security lies in balanced use and integrated supply and management structure. Balanced use of fertilizer is also essential to enhance the economics and profitability of fertilizer use, which provides benefits to farmer in the form of incentives for efficient use of balanced fertilizer. It mainly increases the quality of the crop which is of much concern and improves the demand in the international market as well as for Pakistani market. Now it needs hardly to be stressed that several false concepts about use of fertilizer degrading the soil quality are associated with unbalanced and imprudent use of nitrogen base fertilizers only.
There is no single source of plant nutrient which can meet the requirement of crop either it is chemical fertilizer or green manure. Moreover, the exact type of nutrients demanded by the crop cannot be obtained from a single source. This implies that integrated use of plant nutrients is necessary mainly for two purposes (1) to increase fertilizer use efficiency by which nutrient supply to soil will increase (2) to practices balanced use of fertilizers. In addition balanced use of different sources of plant nutrients helps to improve their efficiencies and ultimately increase crop productivity.
Efforts should be made to improve extension services and should educate farmers to adopt the practice of balanced use of fertilizers. Some of fertilizer companies and their associations have come forward to educate the villagers through publication of literature about use of balanced fertilizers for higher crop yield in their regional languages. Time has come that farmers, researchers and other related communities should come forward and play their role in this respect. The sustainable way for improved crop yield and soil productivity is to judiciously use of synthetic fertilizer and manure should also be used with chemical fertilizers. Many activities are being planned and promoting awareness about use of balanced fertilizers. It is expected that all these efforts would lead to desire awareness among farmers community and as a result use of balanced fertilizer would become a reality in future.
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