December 22, 2003	Monday	Shawwal 27, 1424

All living plants absorb a number of elements in balanced quantity for excellent growth along with higher production. Such plants obtain these nutrients from the soil through well developed root system, in the form of solution in varying quantities; translocated through stem to leaves and other parts of the body for various functions.

A few of these elements are required in larger quantities; called macro nutrients which are nitrogen (N), phosphorus (P2O5) and potassium (K2O). Whereas, on the other hand there are a number of nutrients which are required in lesser quantities named micro nutrients. The nature has provided all of them in abundance in the soil, but owing to continuous growing of various crops year after year and even more than one crop per year, has greatly depleted the reserve.

The atmospheric nitrogen is the main source of supply of N, which goes into the soil through rain water; leguminous plants also fix atmospheric nitrogen into the soil through nodules present on the roots, addition of organic matter and chemical fertilizers are other major source. These fertilizers are urea, ammonium sulphate, ammonium sulphate nitrate and combination of nitrogen and phosphorous in the form of diammonium phosphate (DAP), nitrophos (NP) and only phosphatic forms like triple super phosphate (TSP) and single super phosphate (SSP). Potassium is the third element required by plants in larger quantities. This is usually supplied from potassium sulphate or potassium chloride. The former is preferable under our soil conditions. Our soils are invariably deficient in nitrogen and phosphorous. Soils where sugar cane, potato and rice have been grown may become deficient in K.

The yield of a crop is primarily dependent upon the interaction of biological potential with environmental conditions. While the environment is absolutely a complex phenomenon comprising fluctuation in weather conditions through growing season, competition with obnoxious weeds, prevalence of insects and diseases, application of irrigation, supply of nutrients in balanced form and over top of this dissemination of crop growing technology to the cultivators play a vital role in crop production.

There has been tremendous increase in the application of fertilizers over the period of ten years {1991- 99} from 1,865,000 nutrient tons to 2,804,000 nutrient tons, an increase of 66 percent, without making any noteworthy dent in the yield of almost all the crops. Besides many other reasons, apparently the fertilizer is not applied in balanced doses at proper stage. If they are applied in balanced dosages at required time and with appropriate method of application, it is just possible that we may simultaneously be able to reduce the quantum of fertilizer use per unit area along with substantially increase in crop yield. Now let us have a glance at the fertilizer consumption of some of the important countries of the world and its trend. In 1980-81 Holland used 790 kg of fertilizer per hectare which declined to 550 kg in 15 years, in both cases it is highest in the world; Germany was using 470 kg which declined to 240 kg; Japan has slight increase to 400 kg from 372; in case of the USA it almost remained the same but with slight decreasing tendency but in case of Pakistan it considerably increased from 53kg to103 kg for the same period equal the US. By now the fertilizer consumption must have climbed by another fifty percent from 1995 to date. World over the declining trend in the fertilizer use indicate growing awareness raising crops with lesser and lesser fertilizer utility as these chemicals are supposed to have dreadful effect on human body; therefore, organic produce fetches higher price. What worries now is that pesticides use in the country increased at much greater pace, even highly poisonous pesticides are used on vegetables and fruit. Tomato, cucumbers, okra, cauliflower, “Kharbuza” and even green pepper are one of the highly sprayed. It is high time that the ministry of food, agriculture and livestock, must come to the rescue of the consumers with proper legislation so that pesticides may not be sold without proper prescription of a competent authority at the same time the growers may properly be educated to control the insects with lesser or no insecticide.

The fertilizer is added to the crop in four different ways such as broadcast, drilling or band application, with irrigation water or foliar application. The broadcast method is most prevalent and primitive with much higher losses. In this case fertilizer is mostly applied by the growers hours ahead of irrigation. Owing to high temperature in summer when the day temperature sores beyond 40 C, an active volatilization process takes place leading higher losses of nitrogen in the air. The drilling or banding of fertilizer along the plant row in dry soil also lead to losses, but not equal to broadcast. The third is application along with irrigation water; however the losses are minimal but distribution is most uneven, hence crop growth and yield is not attractive. The foliar application meets minor needs of crop and in case of macro nutrients it has to be repeated off and on. It has been proven that drilling fertilizer in “Tar Wattar” conditions shall be a better option as nutrient shall dissolve in no time and will be readily available for utilization by the plants. This method of fertilizer application has to be popularized amongst the farmers. The other major element needed by plants is P2O5. Although a lot of research has been conducted on this element yet there is a great deal unknown about it. The phosphorous is not mobile like nitrogen but remains in the soil where it has been applied. The most appropriate and desired technique is to drill or band it along the plant row; so that the roots may penetrate into it for its utilization. Unlike nitrogen it remain reserve in the soil; therefore, it is taken up by the following crop. Since P2O5 remains reserve in the soil for a long time; therefore, some scientists advocate building up its reserves in the soil at cheaper rates as compared to much higher cost latter on. Of course it merely depends upon the financial condition of farmer.

The micronutrients includes calcium (Ca), magnesium (Mg), sulphur (SO2), iron (Fe) copper (Cu), zinc (Zn), boron (B), manganese (Mn) and Molybdenum. All these elements are essential for the formation of chlorophyll, synthesis of nucleic acid, protein, and carbohydrates. The enzymes and auxin activity is enhanced due to adequate supply of nutrients and thus yields are increased. Any of these elements may either be deficient in minute quantity which may be called hidden hunger. In such cases the plants may not exhibit any obvious deficiency symptoms; however, the yield will be curtailed. When there is an acute shortage of one or more elements in larger quantities the plants in such cases show visible deficiency signs, discoloration of leaves , having stunted growth, few and small fruits or grains.

In order to determine the availability of macro and micro elements in the soil, the soil samples may got be analyzed from the soil and water testing laboratories, established by the department of Agriculture Research, Punjab, at each district head quarter or some fertilizer companies may have such facilities as well. Although the analysis cost is higher but for the benefit of farming community the soil and water samples are tested at very nominal rates. The soil must be tested frequently after passage of few years to know the fertility status. It is strongly felt that farmers are not properly reaping any advantage from these facilities, therefore, they may be educated and made aware to avail such facilities to generate maximum yield.

As for as condition of micro nutrients is concerned, more than three decades ago zinc was found to be deficient in rice growing areas of Punjab. It was observed that it becomes unavailable due to more moisture in the soil. It however, becomes available when the soil is dried or the roots of nursery plants are dipped in zinc sulphate solution or soil application. The premature dropping of kinno was attributed to be due to lack of supply of magnesium. Boron and zinc are believed to be deficient in some parts of cotton zone. Their deficiency leads to lesser and smaller bolls resulting in low yield of seed cotton and poor quality lint. It is imperative to apply these elements in sufficient quantities. Some of the seasonal ornamentals like petunia show cholorosis which can be overcome by spraying ferrous sulphate solution.

In our country wheat is mostly sown after cotton or rice. The seed cotton, paddy and wheat grains are removed either for personal consumption or sold in the market. Whereas, wheat straw is mostly fed to the animals, rice straw for packing or other purposes, and cotton sticks in some cases are used as fuel and in others burry them in to the soil. The burying of sticks not only adds organic matter to the soil in order to return partially some macro and micro nutrients to maintain the fertility level. For better crops not only all the cotton sticks buried into the soil but green manure may also is added. The addition of organic matter has many advantages for which the farmers may be encouraged to practice, hence each piece of land be green manured after 3-4 years. The farmyard manure and animal dung may not be used as fuel but may be utilized to enhance the soil fertility. The land is in fact more than a bank for the farmers which give 3-5 times or even higher return over the investment. Therefore, the maintenance of soil health is of supreme importance for sustained higher crop yields.