Proper use of fertilizers on soils of low natural fertility makes it possible to grow a wider variety of crops

By Dr.S.M.Alam and M.A. Khan
Mar 01 - 07, 1999

Fertilizer is a kingpin in enhancing crop production. It is also a key to securing the food need of a country. No country has been able to increase agricultural productivity without expanding the use of chemical industry. Balanced fertilization means application of essential plant nutrients, particularly the major nutrients, N, P and K in optimum quantity through correct method and time of application in right proportion. It is essential to encourage the use of nitrogenous, phosphatic and potassic fertilizers, so as to achieve the desirable consumption ratio of 4:2:1 to maintain the soil health and to sustain the crop productivity. With the use of unbalanced ratio of these fertilizers the coefficient of fertilizer use has considerably gone down thus adversely affecting the acreage yields of economical crops.

The loss of soil fertility in many developing countries poses an immediate threat to food production. Agricultural soils lose their fertility by plant nutrient exhaustion a real and immediate threat to food security and to the lives and livelihood of millions of people. The loss of fertility reduces yields and affects water holding capacity leading to greater vulnerability to drought, a fertile and productive resource for the farmer and the entire ecosystem. The farmer's main objective is to maintain the productivity of his soil. An excessive use of fertilizer which is not utilized for crop production can pollute the environment. For this purpose, it is very important to consider as to what is the crop requirement for various nutrients and what is their actual use. An IFA world fertilizer manual has revealed that for producing 5 tons of rice grain/ha, 304 kg nutrients (111 kg N. 35.5 kg P205 and 148 kg K20/ha) are required. For producing St/ha of wheat grain, 367.7kg nutrients (139.6kg N,41.2kg P205 and 188 kg K20) are needed. For producing 8.8 ton of grain yield per hectare of wheat and rice in rice-wheat system 663 kg nutrients (235 kg N. 92kg P205 and 336kg K202) are required. Of all farm inputs fertilizer has been one of the most profitable. Fertilizer responsive plants, the rapid development of weedicides and pesticides, narrow rows, sophisticated fertilizer placement implements, the low cost of fertilizer and efficient soil testing service have all contributed to the economic response and the continuous popularity of fertilizers all over the world. Without commercial fertilizers, world populations would probably that of soon exceed food supply with fertilizers and other modern necessities such as improved seed, better insecticides and more effective fungicides, the critical population pressures can be delayed perhaps indefinitely. The relatively low cost of fertilizers as compared with the cost of other farm inputs, such as land, wages and farm machinery have also contributed towards increasing fertilizer consumption.

The proper use of fertilizers on soils of low natural fertility makes it possible to grow a wider variety of crops. Widening the selection of crops, can result in the use of more vigorous, efficient and valuable cropping systems. The net result of the liberal use of fertilizers is greater efficiency in the utilization of land, labour and water. It has been a traditional practice to supply fertilizer to sow crops just prior to or at the time of planting. Nitrogen is readily lost in the water that percolates through the soil. The nitrogen lost in percolating waters is almost entirely in the nitrate form loss in the ammonium form is negligible, because clay and humus particles absorb the ammonium ion. There is some possibility of losses of nitrogen by leaching immediately after urea fertilizer is applied to the soils.

Fertilizers and their use in Pakistan

The most important constraints to crop growth are those caused by inefficient and imbalance use of plant nutrients in form of fertilizers. The fertilizers constitute the most important scientific breakthrough in feeding the growing populations of Pakistan.

Food and Agriculture Organization (FAO) of the United Nations has estimated that contribution of fertilizer in increasing crop productivity is about 50 per cent. Studies in Pakistan show that contribution of fertilizers through crop production ranges between 30 to 50 per cent under a given soil climatic conditions. Fertilizer production and consumption in the country showed an outstanding growth over a period of time. The production of all fertilizer products during 1997-98 was 3,894 thousand tons as compared to 4,017 thousand tons during 1996-97. Product-wise urea production during 1997-98 was 3,284 thousand tons (3,285 thousand tons in 1996-97). followed by CAN (316 thousand tons) and NP(293 thousand tons). Total fertilizer nutrient availability during 1997-98 was 2,948 thousand tons. Nitrogen availability was 2,234, phosphate 657 and potash 56 thousand nutrient tons. Product-wise urea availability was 4026, DAP 1205, and NP(23:23)307 thousand tons. The gap between production and consumption was met through imports. The imports, during 1997-98, of all sorts of fertilizers were 1,227 thousand tons as compared to imports of 1,576 thousand tons in 1996-97. During 1996-97, product-wise imports were urea 265, DAP 870, TSP 34, MOP 16, AS 39 and SOP 3 thousand tons.

The year 1997-98 has shown significant buoyancy in the fertilizer consumption. The consumption of all nutrients during 1997-98 was 2659 thousand tons, compared with 2413 thousand tons in 1996-97. Of this N was 2088 thousand tons, phosphate 551 thousand tons and potash 20 thousand tons, respectively. The consumption of urea increased from 3.6 million tons in 1396-97 to 3.8 million tons in 1997-98. The consumption of DAP showed significant improvement from 699 thousand tons in 1996-97 to 1016 thousand tons in 1997-98. The consumption, during 1997-98, of other products was CAN 314, NP 302, TSP 26, AS 17, NPK 12, SOP 14 and MOP 19 thousand tons respectively. The increase in fertilizer consumption and improvement in N:P ratio during 1997-98 can be attributed to variety of factors such as increase in procurement price of wheat, balanced supply/demand of urea and DAP fertilizer products, credit availability, stability in urea and DAP fertilizer prices and favourable weather in Rabi 1997-98. The NP ratio was improved and stood at 3:g in 1997-98.


With the use of various inorganic fertilizers, agriculture contributes about 25 per cent to Gross Domestic Product and is the largest source of foreign exchange earnings. Crops, mainly sugarcane, cotton, rice and wheat, make a vital contribution to the overall growth and earnings. This improvement can be attributed to comprehensive package by the concerned ministry. The following measures may improve the agricultural productivity of the commodities:

i) Adequate supply of seed of recommended varieties to ensure timely sowing.

ii) Use of recommended doses of fertilizers.

iii) Adequate weed control.

iv) In case of late sowing, suitable varieties and higher doses of fertilizer be used.

v) Adequate supply of fertilizers, well before sowing time, be ensured.

vi) Timely application of plant protection measures.

vii) Honesty and dedication of farmers and other related personnel.