Keywords. Nitrogen, serozem, fertilizer, plants, humus, phosphorus, soil.

Introduction. Development of methods for the effective use of nitrogen fertilizers for plants, including whitish wormwood, is not only of scientific, but also of practical importance, as it provides high yields of the plants of higher quality, as well as reducing environmental pollution.

The transformation of nitrogen fertilizers in irrigated typical gray and gravel gray soils, as well as its use by plants, depending on the mode of nitrogen nutrition, has not been studied enough. [1,2]

Research methods. In this regard, in 2009-2017. both vegetational and field experiments were conducted on conditionally irrigated gravelly and typically sierozem soils of the Farish district of the Jizzakh region. The area of ​​each plot is 480 m2. The plant layout is 60×25×1 with a density of 66680 bushes per hectare. The repetition of vegetation experiments 10, and field-4-fold. Soils for vegetation experiments were taken from the field experiments taking into account genetic horizons. The soil moisture in the vessels was maintained at the level of 70% capillary moisture capacity.Layout of plants in field experiments Artemisia leucodes Schrenk 60×25×1,soil moisture in the vegetation experiments was maintained at the level of 70% of PPV. The filling of the vessels was carried out in the autumn with soil taken from the field experiment (horizon 0-50 cm) taking into account its genetic horizons.

Results. The results of research in vegetation experiments have established that the content of nitrogen compounds of fertilizers depends on soil differences. In the first half of the growing season (before mass budding), the magnitude of nitrogen immobilization from fertilizer applied on a typical gray soil (or the transition of inorganic nitrogen to an organic form in the body of microorganisms) occurs more intensively than in gravelly gray earth.The application of manure enhances this process on typical gray earth, which is associated with the different content in these soils of the mass of organic residues, as well as the ratio C: N.Due to the immobilization of nitrogen, the content of inorganic compounds available to plants in the early phases of plant development and budding decreases, especially under gravelly gray earth conditions.

With the introduction of manure, the content of inorganic nitrogen of fertilizers, unused by plants of nitrogen fertilizer (at the end of its growing season) on gravelly gray soil, decreases even more when applying manure more than on typical gray soil.Based on the literature data and the results of our research on the balance and nitrogen conversion of fertilizers in the soil-plant system, it can be argued that in typical sierozem with a high content of organic matter and a wide C: N ratio, in the initial period of plant development more demanding nitrogen is applied than gravelly sierozem.Studies have shown that with the onset of the flowering phase and maturation, the availability of nitrogen in typical serozem plants is higher than in gravelly serozem, which is explained by the release of previously absorbed nitrogen by soil microorganisms.This makes it necessary to study the effectiveness of the timing of nitrogen fertilizers, taking into account the biological characteristics of nitrogen transformation and soil conditions.

Conclusions. Research has shown that Artemisia leucodes Schrenk grown on gravelly gray soil with full fertilizer, especially with manure, contributes to more seed formation and the formation of greater biomass. The value of biomass is more on typical sierozem than on gravelly sierozem.

Literature.1.Abzalov A.A. The use of sulfur as an important factor in obtaining an environmentally friendly product of medicinal plants J.Vestnik of agrarian science of Uzbekistan. № 1-2, 2009. 54-60с.