INCREASING CROP PRODUCTION THRU NPK FERTILIZER

 

Fertilizer use in Pakistan is grossly imbalance and more skewed towards nitrogen use


By Dr. B. Y. Khalid,
Engro Chemical Pakistan Ltd
Nov 17 - 23, 2003

Soil is a storehouse of plant nutrients and intensive cropping has led to the depletion of these nutrients and thereby limiting economic crop production. The depleted nutrients are supplied through fertilizers to sustain increasing crop production to meet the demand of the growing population of the world and Pakistan is no exception. This fact is substantiated by the healthy growth in fertilizer use in Pakistan over the last four decades. The level of growth in fertilizer use in itself is the testimony to the role the fertilizers have played in increasing crop production. The use of fertilizers in Pakistan has witnessed a steady increase over the last four decades (Table 1), starting with 31 tons nutrient (1kg/acre) in 1960-61 to 2513 nutrient tons (47 kg/acre) in 1999-2000. Our fertilizer usage is still low as compared to other countries (Table 2), Indian Punjab 69, Egypt 123, Korea 189, China 135 nutrients in kg/acre. We need not follow the suite irrationally and fertilizer use has to be optimum and balanced for increasing crop production to feed growing population of the country. But it remained somehow more focused on the use of nitrogenous fertilizers mainly due to widespread nitrogen deficiency and promotional efforts by private and public sectors.

Nitrogen (N) is the most important nutrient element for plant growth and is widely deficient in our soil. Climatic conditions in our country do not allow organic matter to accumulate and thus the level of N remains low in most of the cropped area of Pakistan. Hence the additions of N fertilizers are required for good crop production. For sustaining good crop yield, the general principle calls for the replenishment of the nutrients equivalent to what is removed by the plants. Promotional efforts and follow up by private sector companies and the government have resulted in farmer awareness about N fertilizers and most of the farmers are using adequate amount of N fertilizers. But there is room for further improvement as our N use is lower than many countries of the world. However some of the progressive farmers are using higher levels of N making the fertilizer use more irrational.

Table - 1
Fertilizer use in Pakistan

Year

Total Nutrient
(000 tons)

Kg/acre

1960 - 61

31

0.8

1970 - 71

283

7

1980 - 81

1,080

23

1990 - 91

1,893

36

1999 - 00

2,804

49

Phosphorus (P) is the second most important plant nutrient. Soil fertility evaluation of different area in Sindh and Punjab has indicated that 70-80% of our soils are deficient in P. Moreover, the efficiency of phosphatic fertilizers in our soils is 20-30% provided the phosphatic fertilizer used is granular, has high P content and water solubility is above 80%. The P availability to plant may still be lower if these conditions are not met. The use of phosphatic fertilizer has been low and the NP ratio has increased from 3.06 in 1991-92 to 3.81 in 1999-00. The situation in case of Kharif crops (cotton & rice) is worst and it increased from 4.33 to 4.95 in the same period. Thus the use of phosphatic fertilizers in kharif crop appears to be inadequate and we are mining our soils in relation to phosphorus as the application of phosphatic fertilizers is much less than what is removed from the soils by the crops.

Table 2
Fertilizer Use in Different Countries (Kg per acre)

Country

Nitrogen

Phosphorus

Potash

Total

China

83

31

21

135

Japan

53

64

44

161

Holland

165

28

32

225

Korea

93

44

52

189

Egypt

105

15

3

123

Indian Punjab

54

14

0.8

69

Pakistan

39

10

0.3

49

Flower and fruit shedding, and delayed flowering is commonly observed in some crops and low levels of P in soil can be one of the factor contributing to this syndrome. Since P deficiency symptoms are difficult to recognize in time during the growing season, the correction of P deficiency in crops remains unattended and this takes its toll in crop production. Again the role of low P in low crop yield is difficult to isolate due to crop complexities and it normally remains unnoticed. Hence the safest and cost effective method for P management in our soils is to go for soil testing. Soil testing services are available with Government and private sector soil laboratories.

Table 3
Nutrient Removal by Crops in Kg/acre (Production of 1 ton)

Crop

Nitrogen

Phosphorus

Potassium

Wheat

25

9

33

Rice

20

11

30

Cotton

62

14

60

Sugarcane

1.2

0.5

1.4

Maize

20

8

20

Potassium (K) is another important nutrient element and is required by plant in quantities almost equal to nitrogen (Table-3). But our soils have good supplies of K due to parent material and supplemented by canal irrigation water. Analytical results indicate that 20% of our soils are deficient. If the soils are deficient in K or at marginal level, good crop production is not possible. To avoid this loss and to achieve optimum crop production, we must know K level of the soil through soil analysis, and K fertilizer must be used if available K levels are low. We are removing huge quantities of K from our soils through intensive cropping, and the addition of K thru fertilizers is very low (0.3 Kg K2O/ acre). Thus, we are intensively mining our soil in relation to K, and K reserves in our soils are declining. The depletion of K reserves can lead to drastic situation and the loss may become irrepairable. Hence, we need to monitor the depletion of K reserves in the soil and we must devise mechanism to maintain K levels within the desired limits to avoid any catastrophe in future.

OPTIONS FOR IMPROVING NPK FERTILIZER USE

It is evident from above discussion that fertilizer use in Pakistan is grossly imbalance and more skewed towards N use. Certainly creating awareness among the farmers is very important but this has to be coupled with the availability of NPK fertilizer which can be easily used by the farmers. In USA and Canada sophisticated equipment is used to develop map for nutrient removal by the crops and different fertilizers are blended and applied according to the soil map thus making available the required nutrients on the basis of crop needs. This approach requires expansive equipment which is difficult for most of our farmers to afford. Another approach is to go for crop specific blended NPK fertilizers fortified with required micro nutrients and this appears to be the logical path way to address this problem.

Experts and FAO Consultants in the past recognized the significance of this approach and recommendations were made to put up NPK blending plants. A Bulk Blending NPK plant was installed in 1992 at Kissan but due to some operational problem this facility not only remained under utilized but no one followed the suite. Perhaps the bulk blended NPK fertilizers have certain inherent problems which affected the acceptance of this approach by the farmers. The modification to this approach, which is based on the production of homogenous granulated product, has found large scale acceptance in China, India, Malaysia, Thailand and other countries of this region. Substantial tonnage of different grades of NPK fertilizers are being used in these countries. Hence we can follow this approach to develop crop specific NPK fertilizers which can be easily used by the farmers. This has to be followed by strong research and development support for market development and for modification of desired NPK blends to take care of fertility trends in those areas. Soil and tissue testing should be an integral part of the program.

By using crop specific NPK fertilizers, the farmers will be relieved from the burden of collecting different fertilizers and making crucial decision about their ratios during mixing. At time the availability of these fertilizers and their proper mixing is impediment to the use of these fertilizers. Moreover the appreciation of K fertilizers by the farmers is poor as the impact of K is not generally very pronounced as compared with N and P fertilizers. The use of micro nutrients required in small amount is another challenge for the farmers. Hence the responsibility of developing crop specific NPK blends is taken over by expert agronomist. The concept of all nutrients in one bag and in each granule ensures efficient utilization of these nutrients. The enhancement in fertilizer use efficiency can be translated into higher yields and greater profitability.

IMPACT OF NPK FERTILIZERS ON CROP YIELD

The use of NPK blended fertilizers have been instrumental in increasing crop production in different countries and the approach is based on sound scientific validations. In some of the countries of our region-China, India, Malaysia, Thailand and Korea-NPK blended fertilizers have been used by farmers on different crops and higher yields and favorable value cost ratio have been reported. The investigations about the response of NPK fertilizer on different crops were undertaken in Pakistan, during the period 1993-98 under the coordination of Pakistan Agricultural Research Council, Islamabad. These trails were conducted jointly by different agricultural research institues and fertilizer companies of Pakistan. In these trials both types of NPKs; SOP and MOP based were used to investigate the impact of these sources on crop yield and quality of the produce. With the use of NPK fertilizers the wheat yield increased by 27-30% compared to control. This increase has been 75-77% for paddy, 39-42% for maize, 60-65% for cotton and 73-75% for sugarcane. The results of these trials have clearly indicated that both sources of NPK are equally good and these can be used to enhance crop production. Perhaps the MOP based NPK appears to have an edge as the increase in crop yield has been higher in most of the trials with MOP based NPK. These finding have been confirmed by the trials done by Engro Chemical Pakistan (ECPL), with potato, sugarcane, pea, paddy and maize. Application of NPK fertilizers also improved fruit production and quality of citrus. The NPK fertilizer marketed by ECPL during the last rabi season was extensively used by the potato growing farmers and yield increase of 10-25 % has been reported. Besides the increase in yield the quality and size of tubers also improved which resulted in higher price of the produce. Farmers used the NPK fertilizer on bigger blocks of more than 150 acres and obtained substantial increase in potato yield from these areas. Sugarcane production also exhibited increase of 29-38%. Pea crop has shown unexpected very high increase in pod yield (86-127%). This could be exceptionally high response to K in NPK due marginal levels of K in those soils. These are preliminary result and need further confirmation, however, it is quite evident that NPK fertilizers have improved the yield of these crops undoubtedly.

IMPACT OF NPK FERTILIZERS ON OUR SOILS

The use of NPK fertilizers improved the availability of these nutrients in the soil therby making more of these nutrient available to plants. Some apprehensions have been expressed about the use of MOP based NPK for the accumulation of chloride in soils with their use. This has been advocated that such accumulation would be detrimental to plant growth and this will lead to decline in soil productivity. Although these doubts have no support from scientific data generated from field trials in different countries, it was felt appropriate to undertake investigation with local set of conditions. Ayub Agricultural Research Institute, Faisalabad, initiated long term field trial to investigate the impact of MOP based NPK on soil. These trials were maintained for 12 years during 1985-97 and fertilizers were applied every year. The results clearly indicated that chloride being an essential plant nutrient is mobile in soil and the danger of chloride acumulation from normal use of MOP based NPK is uncalled. This is why most of the countries use MOP as K fertilizer and its use is more than 95% of the total K use. SOP being expansive as compared to MOP is used for special crops. Even in India the use of MOP as K is more than 95% and no ill effect has been observed with its use over the last two decades. Hence no adverse effect on plant growth is expected from MOP based NPK fertilizers and such fertilizers can be used with out any concern.

CONCLUSION

It is quit logical to conclude that the required increase in crop production can be attained with the proper and balanced fertilizer use and this can be achieved through crop specific NPK fertilizers fortified with required micro nutrients along with other growth regulators if needed. This has become more important in the present situation of declining water avails. This will also improve the profitability of the farmers by harvesting more and better quality produce for internal and external markets. This requires large scale promotional efforts with greater zeal and commitment coupled with sound research and development efforts. Government and private sector have to take up the challenge jointly so that the required resources are made available and the message is taken to each and every corner to create awareness about proper and balance use of fertilizers.