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Khamidov Muxamadxan, doctor of agriculture scientific, professor Тashkent institute of irrigation and agricultural mechanization engineers Jurayev Umid, doctor of Ph D., Kadirov Zayniddin, assistant, Saksonov Umidjon, student,
Bukhara branch of Тashkent institute of irrigation and agricultural mechanization engineers
E-mail: buhtimi@mail.ru
REDUCTION OF MINERALIZATION OF COLLECTOR-DRAINAGE WATER BY THE BIOLOGICAL METHOD AND USE OF THEM IN THE IRRIGATED AGRICULTURE
Abstract: This article presents the results of the research work on the use of different methods of irrigation to economize irrigation water. Particular attention is related on the decrease of the salinity of drainage water in the Bukhara region using biological method by growing water plants Lemna minor.
Keywords: Lemna minor, biological method, mineralization, drain-drainage, algae, water scarcity, irrigation, dry residue, chlorine ion, salt regime, productivity, and cotton.
The lack of water resources is increasing in all countries of Central Asia, including the Republic of Uzbekistan [1]. Currently, 54-55 billion m 3of water resources are consumed in the Republic of Uzbekistan, of which 92% are used in irrigated agriculture.
The average annual discharge of irrigated lands in the Bukhara region is 4.2-4.6 billion m 3 of which almost 50% (1.9-2.3 billion.m 3) is carried to the collector-drainage network [2]. Mineralization of collector-drainage water ranges from 2 g/l to 15 g/l. In the period of water shortage, their direct re-use in irrigated agriculture can increase soil saliniza-tion, which will adversely affect the growth and development of plants and reduce the resulting yield to 30-80%.
Objective: to develop scientifically based technologies for the effective use of collector-drainage water in the Bukhara region. In this case, the desalting of saline waters is carried out mainly due to biological methods. Namely, algae with a special tendency to the absorption of salts contained in water. First of all, this plant Lemna is small (Lemna minor). This plant has an amazing salt tolerance and a need for salts in water. Salt for this plant is the staple food.
Research methodology
Research methods are based on the recommendations of the Uzbek Scientific Research Institute of Cotton-growing "Methods of conducting field experiments" (UzNIIKh, 2007) and the German Research Center for Agricultural Technology Leibniz.
To realize the idea, a pool was dug along the Yulduz
collector at the research site, where drainage water was discharged and where the growing of Lemna minor algae was supposed to provide the desired effect of desalinization of moisture.
Studies on the establishment of the effect of cotton irrigation with biological purified water from the basin were carried out according to the recommendations of the Bukhara branch of the Cotton Research Institute. Norms of mineral fertilizers are taken N250, P175, K100 kg/ha [3].
The experiments were conducted in one tier, in 5 variants and in 3 replications. The mineralization of the Yulduz collector water used for irrigating cotton was by the amount of dense residue, 3.9 g/l, Cl -0.374 g/l, SO4-1.348 g/l, HC03-0.476 g/l, Ca-0.228 g/l, Na-0.367 g/l and Mg-0.412 g/l. When growing Lemna minor in the reservoir capacity at the collector, by the end of the growing season the mineralization decreased, the amount of dry residue was 2.8 g/l, the Cl content of the ion was 0.291 g/l, and S04-1.084 g/l, HC03-0.246 g/l and Ca--0.174 g/l, Na-0.311 g/l, Mg-0.284 g/l. In order to establish the effect of irrigation on the salt regime from a meter-thick layer of soil (0-30, 30-70, 70-100 cm), after each irrigation and irrigation of each variant, soil samples were taken, and at the beginning and at the end of the growing season, it was determined Cl content; Cl; HC03; S04; and the amount of dry residue.
Section 11. Agricultural sciences
Results of experience and their discussion
The growth and development of cotton, yield, time for opening of the bolls and its quality is mainly determined by the irrigation time, quantity, irrigation pattern, duration of irrigation, irrigation and irrigation rates.
For a number of years on the experimental fields, cotton irrigation was carried out on the basis of the adopted scheme for the Bukhara region. At the same time, the duration and norms of irrigation according to options were determined depending on the level of soil moisture. In all cases, the calculated layers for determining the irrigation rate were in the period before flowering 0-70 cm, in subsequent period's 0-100 cm [4]. The irrigation rate of cotton is determined by the formula Academic Kostyakov.
m = 100-h-riPmax P per) + m3/ ha
here: Pmax - the maximum soil moisture,%; f3per - The personal moisture in the soil,% Y by weight of dry soil; - volume mass of the soil to be moistened, g/cm3; h - depth of the layer to be moistened, m; P - precipitation during the autumn-winter period, m 3/ha; jU - coefficient of use of precipitation.
The amount ofwater supplied to each field was measured by the "Chipoletti" watersheds established at the entrance to the temporary irrigator of the experimental field.
On the experimental fields, the smallest irrigation rate was observed in option 1 (irrigation with river water). In this variant, according to the scheme 1-3-1.5 irrigations were carried out, the irrigation rate was 4595 m3/ha. In the experimental field in option - 5 there was the largest irrigation rate (irrigation with drainage water). In this variant, relative to 1 experimental field, 284 m3/ha more water resources were consumed, the irrigation rate was equal to 4879 m3/ha. In variant 2 of the studies, that is, when cotton was irrigated with river water mixed with biologically purified drainage water, the irrigation rate was 4640 m3/ha. If in the 3-variant research (irrigation of cotton with the addition of drainage water to the river water), the irrigation rate was 4730 m3 / ha, in the 4-variant with irrigation scheme 1-3-1, the irrigation rate in relation to the 3-variant was 85 m 3/ha less, with a total water supply of 4655 m3/ha.
During the years of research, the cotton variety "Bukha-ra-6" to maintain pre-irrigated soil moisture of70-75-65% of HB, irrigation was carried out according to the scheme 1-3-1. The average rate of each irrigation was 688-1216 m3/ha, the irrigation rate was 4595-4879 m 3/ha, and the duration of irrigation was 14-22 hours, the time between irrigation was 16-22 days (Fig. 1).
Figure 1. Irrigation of cotton with biologically treated drainage water
We have analyzed the accumulation of salts in the soil during the growing season. Before sowing seeds during the experiment, the salt composition was analyzed in the laboratory.
Analysis of the results of the arable layer (0-30 cm) showed that if the amount of Cl was 0.009%, HCO3 was 0.029%, SO4 was 0.049%, then the dense residue in the soil was 0.153%. In the soil layer of 0-100 cm, the amount of these salts, respec-
tively, was: Cl-0.012%, HC03-0.033%, and S04-0.048% and the amount of dense residue - 0.128%. At the end of the growing season, it can be stated that the values of all salts in the soil have increased, with the exception of only HC03, which has decreased in comparison with the initial position. Ifwe analyze the change in the amount of chlorine (Cl), then when irrigating with river water in variant 1 in the topsoil (0-30 cm), the
amount of chlorine was 0.014%, then in the subsoil (30-70 cm) relative to the initial result, the amount of chlorine increased by 0.003%, and it was equal to 0.014%, in the layer of 0-100 cm at the end of the growing season was 0.015%. In variant 2 of studies, i.e., with river water irrigation mixed with biologically purified drainage water in the topsoil (0-30 cm), the amount of chlorine was 0.015%, and in the 0-100 cm layer, this amount became 0.015%. Or, compared with the 1-variant, the amount of chlorine increased by 0.001-0.002%. In the 3 variant of the experiments, by the end of the growing season, the amount of chlorine became equal to 0.018% in the topsoil, 0.016% in the separable layer, and 0.017% in the 0-100 cm layer. In the 5 th variant, when watering cotton only with drainage water, the greatest amount of salts was observed in the soil. In this variant, in the topsoil the amount of chlorine was 0.034%, and in the separable layer 0.031%, in the 0-100 cm layer, 0.031%.
When studying the effect of irrigation water quality on the amount of dense soil residue, if at the beginning of the growth period on the arable layer is equal to 0.153%, in the subsoil layer by 0.136%, and in the 0-100 cm layer it is equal to 0.128%, then at the end of the growth period, 1-variant, the amount of dense residue in the topsoil relative to the growth phase increased to 0.079%, and amounted to 0.232%. And in the subsurface layer, this value is equal to 0.193%. In the 2 variant of experiments in the topsoil, the amount of dense residue is 0.241% ha, and in the 0-100 cm layer it is equal to 0.178%. In the 3-variant, i.e., with irrigation with the addition of drainage water to the river water, the dense soil residue in the arable layer relative to the initially obtained results increased to 0.091% and amounted to 0.244%, in the 0-100 cm layer it is 0.196%. When cotton was irrigated with biologically purified drainage water in the 4th variant, the amount of dense residue in the arable layer was 0.243%, and in the separable layer was 0.210%, in the 0-100 cm layer, the amount of dense residue
was 0.185%. In the 5th variant of the experiments, i.e., with cotton irrigation with drainage water, the amount of dense residue in the arable layer at the end of the growing season was 0.283%, in the separable layer 0.236%, and in the 0-100 cm layer increased to 0.244%.
According to the collection and repetition, the indicators of raw cotton harvest in case of irrigation with river water in variant 1 amounted to 41.8 centners per hectare. In variant 2, with irrigation by river water with mixed biologically purified drainage water, the yield was 40.1 c/ha, and in variant 3, i.e. under irrigation with the addition of drainage water to the river water, the yield of cotton relative to the 1- and 2-variants decreased by 4.6-6.5 c/ha, amounted to 34.1 c/ha. In the 4th variant, with irrigation with biologically purified drainage water, respectively, the yield was 32.3 c/ha, yields were increased by 4.2 c/ha relative to the 5 th option (irrigation with drainage water). In the 5th variant of our research, i.e. under irrigation with drainage water, cotton yield was 28.1 c/ha.
Conclusion:
1. In the conditions of water shortage, irrigation of agricultural crops causes great difficulties, in particular, to achieve a tolerable, and sufficiently justified yield requires additional labor costs.
2. In order to mitigate the shortage of water resources, prevent the deterioration of the ameliorative state and find additional sources to increase the water supply of irrigated lands in the Bukhara region, a technology has been developed for biological treatment of collector-drainage water from plants harmful to plants, in particular for cotton, salts. Lemna minor is able to effectively neutralize toxic salts in drainage waters up to 22-28%. The use of collector-drainage waters, purified by biological methods, for irrigation of cotton of the variety "Bukhara-6" yielded a yield increase of 4.2 c/ha than for irrigation of cotton only with drainage water.
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