1. THE IMPACT OF AGROCHEMICALS ON CROP YIELD AND SOIL ECOLOGY (THE CASE OF THE KHOREZM OASIS)
Akhmad Hoji Khoresmiy
Presented at the SOAS conference ”Cotton Sector in Central Asia: economic policy and development challenges”, 3-4 November 2005
(English version)

2. Introduction
My data is the result of year-long investigations of the impact of agrochemicals (chemical fertilizers and pesticides) on the quality and fertility of meadow soils in the oasis of Khorezm, and of the effectiveness of fertilizers
The use of agrochemicals is the main agro-technical method for increasing the crop yield of cotton in Uzbekistan
70-90% of agricultural production in Uzbekistan relies on the use of agrochemicals
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3. Profitability and Crop Yield
Every unit of expenses procures units of profit.
The crop yield of cotton without fertilizers does not exceed mt/ha.
Crop yield increased by 150kg/ha. when organic fertilizers (kunjar) were used.
Crop yield increased by 170kg/ha. when mineral fertilizers (ammonium sulphate) were used.
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4. The main agrochemicals used in Uzbekistan
Purpose
Mineral (chemical) fertilizers
Provide plants with nutritious elements
Pesticides
Protect plants from pests and diseases
Herbicides
Destroy weeds
Defoliants
Accelerate defoliation and the ripening of fruits
Chemical ameliorators
Ameliorate acidic and saline soils
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5. Boosting the Crop Yield
During the Soviet period, the unlimited and unbalanced use of agrochemicals led to typical crop yields of mt/ha., and up to 4.2 mt/ha. in Khorezm
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6. Pesticides
Only 1% of used pesticides actually fight plant pests and diseases
From , kg/ha. of pesticides were used on the cotton fields of Uzbekistan (in Khorezm, it was even kg/ha.)
In the 1990s, 85,000 tons of pesticides were used annually in Uzbekistan
Due to financial difficulties, the use of pesticides has gone down by about 15-20% to 50,000 tons per year
Official figures do not show the real use of pesticides as farms buy them independently.
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7. Residue of Pesticides in Soils
In 1990: 0.72 kg/ha. (republican average); 1.36 kg/ha. (Khorezm)
As a comparison:
Russia – 0.04 kg/ha.
USA – 0.01 kg/ha.
When the share of pesticides in soil exceeds 0.1 mg/kg, the ecological balance of the soil is disturbed.
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8. Results of the Use of Agrochemicals
Where agrochemicals have been applied in high doses for many years, the share of humus has decreased by a factor of 5.7 – 10.2 % to a level of less than 2% (it should not be less than 3-4%).
The share of heavy metals (from pesticides) has doubled or trebled
The quantity and mass of macro – and micro organisms has gone down 2-3 times
The fertility and productivity of soils has decreased by 25-30%
Diseases: the oasis of Khorezm has one of the worst public health records in Uzbekistan
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9. Heavy Metals
Fluorine, cadmium, nickel, chromium, mercury, lead and other metals
Heavy metals are considered protoplasmic toxins
Cadmium, mercury and lead suppress the process of ‘phosphatasis’ in plants (an aspect of plant metabolism that involves phosphorus)
Iron, copper and cadmium produce cracks in cell membranes.
Fluorine and chromium slow down the process of photosynthesis (the respiration and growth of plants)
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10. Conclusions and Recommendations
Transition to a combination of mineral and organic fertilizers. As a result, the economy of the cotton sector as well as the ecology and fertility of soils would be improved significantly.
When local fertilizers are used, the crop yield of cotton initially does not exceed mt/ha. In the 4th - 5th years, the crop yield increases to mt/ha., reaching mt/ha. after 7-8 years. That is similar to the results achieved with mineral fertilizers.
The share of nutritional elements (N, P, K) is considerably higher in soils where agrochemicals and mineral fertilizers have been applied in high doses. On the contrary, the share of humus is higher in soils where local fertilizers (manure) have been applied instead of agrochemicals.
A transition to the cultivation of organic cotton is both necessary and profitable.
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