It has been studied the effectiveness of using for medicinal plants (lobed morel, calendula, valerian, rhaponticum carthamoides) and cotton plant of slow acting carbamideformaldehyde fertilizer (CFF). It has been determined by researches that owing to low leaching into the ground waters and low gaseous losses of CFF use on meadow soil and low-salted bright grey earth with regard to typical grey earth turned to be more effective than carbamide.

Introduction. The nitrogen fertilizers (carbamide and ammoniac nitre) used nowadays for medicinal and agricultural plants in wide scales have the number of disadvantages. For example, both ammonia and ammoniac fertilizers after some time (during 5-7 days) after putting into the soil turn into nitrate forms.

For prevention the environment's contamination by remains of nitrogen tocks and increasing the effectiveness of nitric fertilizers was tested the effectiveness of using slow acting CFF for cotton plant and some medicinal plants.

Subjects and methods of research. The experiments were held in special constructed lisimetric installations, vegetative vessels and field conditions. Vegetative vessels and lisimeters were filled with typical grey earth, low-salted bright grey earth and meadow soil. The area of each lisimeter was equal to 1 m².

Soils for filling the lisimeters and vegetative vessels were taken from the places taking into account the genetic layers where the field experiments were held. The level of ground waters in lisimeters was near to natural conditions. In certain time the lisimetric waters were gathered and determined the content of different nitric compounds in them. Besides, were determined the remained in soil and used by plant the content of nitrogen and values of its gaseous losses. The experiments were conducted at the agrochemistry chair of the Tashkent State Agrarian University and also at the ecology and microbiology chair of the Tashkent Pharmaceutical Institute. The content of total nitrogen was determined according to Kjeldal-Iodelbauer, nitrates - Granwald-Lyage. At experiments for cotton plant the nitric fertilizers were put into the soil calculating 200 kg per ha. The enrichment of nitric fertilizers by stable isotope of nitrogen 15N made up 20%. At the experiments with medicinal plants the amount of put into the soil nitric fertilizers made up: artichoke prickly-150 kg/ha, Valerian and calendula - 100 kg/ha, cotton plant - 200 kg/ha.

The results of research. The research results determined that at the conditions of typical grey earth by introducing different forms of nitric fertilizers the value of nitrogen's use by cotton plant was 28-41 (in per cent in accordance with the introduced to the soil). At applying carbamide the value of this indicator made up 4.5%, and at applying CFF-28-31%. In the second year of experiments the amount of using carbamide's nitrogen by cotton plant made up 9% and at the applying CFF or CFF urea - 48.0-53.3%. Consequently, the amount of using nitrogen both carbamide and CFF by cotton plant was nearly equal. It should be noted that in using CFF the content of residual nitrogen in the soil was two times more than at carbamide applying. In the second year of experiments the amount of applying CFF nitrogen was more than at carbamide applying. In general, the nitrogen losses at introducing CFF to the soil were less than carbamide using. The low-salted bright grey earth according to the balance differs sharply from the typical grey earth. In this soil in the first and second years of experiments the cotton plant used more СFF than carbamide. Thus, for two years the use of carbamide's nitrogen by the cotton plant made up 33.5% and CFF (70% from the year norm) together with carbamide (30%) this value made up 49.1-52.4%. So, at applying CFF together with carbamide the amount of the used nitrogen by cotton plant was by 18.9% more than at only carbamide applying. In the second year of experiments the amount of the remained nitrogen in the soil independently from soil types hardly changed. According to the fact that at introducing СFF to the soil the intensity of nitrification process was running slow, the amount of used nitrogen of this fertilizer by the cotton plant was more than at applying carbamide.  The similar data were obtained on the meadow soil as well. It is important to note, that analogical results were obtained from the obtained by us medicinal plants (Valerian, rhaponticum carthamoides, calendula lobed morel and etc.).

Conclusion: 1. In the conditions of typical grey earth at applying carbamide and CFF separately the use of nitrogen by the cotton plant, artichoke prickly and valerian, rhaponticum carthamoides, calendula, lobed morel were similar to each other. At joint use of СFF with carbamide (70% as CFF before sowing and during flowering process and 30% as carbamide at the phase of budding) the use of nitric fertilizers by the cotton plant, artichoke prickly, valerian, rhaponticum carthamoides, calendula lobed morel was more than at their introducing to the soil separately. 2. In view of low leaching into the ground waters and low gaseous losses the applying CFF on meadow soil and low-salted bright grey earth in comparison with typical grey earth is more effective fertilizer than carbamide.