Technical and technological Solutions for environmentally safe Irrigation with wide-reach Sprinklers

. It is known that sprinkling can cause surface runoff of irrigation water and water erosion of soils, which leads to deterioration of water-physical and agrochemical properties of soils, its fertility decreases. The purpose of the research was to ensure environmentally safe irrigation with wide-reach sprinklers by improving the designs of sprinklers and their placement along the pipeline. The developed sprinklers were equipped with sprinklers "Frigate" DMU-B463-90. Studies have shown that the volume of surface runoff of irrigation water during the irrigation season when watering with sprinklers with developed sprinklers was less, and as a percentage of the irrigation norm was: in 2020, when watering DM with sprinklers having a rotating deflector – 6.3%, when watering with a machine with sprinklers having a double deflector – 3.9%; in 2021 respectively – 6.6 and 4.1%, in 2022 – 6.0 and 3.9%. The conducted studies allowed us to recommend installing sprinklers with a rotating deflector or cascade versions at high irrigation rates in the end part of the machine.


Introduction
In the natural and climatic conditions of most regions of the Russian Federation, stable development of agricultural production is possible only with additional irrigation to natural humidity.Currently, sprinkling irrigation is carried out in Russia on an area of 4.5 million hectares.About 70% of this area is watered by wide-reach sprinkler machines (DM).
The disadvantage of this method is that under certain conditions, sprinkling can cause surface runoff of irrigation water and water erosion of soils, which leads to deterioration of the water-physical and agrochemical properties of soils, its fertility is significantly reduced.
The reason for the occurrence of surface runoff and water erosion are inconsistencies in driving modes, emergency stops when operating in automatic mode, especially characteristic of the DM "Frigate" of the "Soviet design" if there is no provision for disconnecting machines from the supply network when the last trolley stops or slips, leading to overflows.
With an increase in the degree of erosion, the agronomic properties of soils deteriorate.As a result of erosion, the humus content decreases, soil density increases, porosity, moisture capacity, water permeability decrease, biogenicity decreases.
The effect of droplets on the process of water erosion is determined mainly by the mechanical action of droplets.
Studies of scientists [1][2][3][4][5][6][7][8][9][10] have established that the average intensity of rain at the beginning of the DM "Frigate" varies from 0.05 to 0.10 mm/min and reaches 0.45 mm/min at the end of the car when calm and increases to 0.6...0.8 mm/min with wind.The average actual rain intensity varies along the pipeline from 1.5 to 2.6 mm/min.
Currently, the droplet size of 1 mm is considered environmentally appropriate [12][13][14][15].It is known that when watering the DM "Frigate" under the influence of drops, the structure is destroyed and a soil crust 4-6 mm thick is formed, which reduces water permeability by 25% [9].
It was found that with a specific precipitation power of 0.002-0.056W per 1 m 2 , soil erosion is not observed, and with an increase in this indicator from 0.056 to 0.12 W/m 2 , destruction and water erosion of the soil are insignificant [10].
Thus, rain with a specific energy not exceeding 0.12 W per 1 m 2 will be optimal for sprinkler machines, from the point of view of erosive action [10].
Currently, sprinklers in the form of deflector nozzles are one of the most promising areas.They form a fine-drop rain with a small height of the rain cloud rise.The radius of capture by rain reaches 6-18 meters, with an average intensity of 0.3-0.8mm/min [1][2][3][4].
The manufacture of sprinklers in the form of deflector nozzles made of polymer materials reduces their cost compared to metal ones.
The advantages listed above allowed us to conclude about the prospects of their use on wide-ranging DM forming fine-drop, wind-resistant and erosion-safe rain.
Currently, quite a lot of experience has been accumulated in the design of sprinklers.Nevertheless, there are no constructive versions of Russian-made sprinklers, depending on meteorological conditions, their location on the water supply pipeline of the machine, the culture being watered.
The purpose of the research is to ensure environmentally safe irrigation with wide-reach sprinklers by improving the designs of sprinklers and their placement along the pipeline.
Basic requirements for sprinklers:  Ensuring the quality of irrigation indicators. Low cost. Versatility and unification of individual elements of sprinklers for different operating conditions.

Materials and methods
The developed nomenclature range of sprinklers for wide-reach sprinklers includes the following types: with a smooth deflector, with a deflector with grooves, with a rotating deflector, with a double deflector, Figure 1.Sprinklers can be used for all types of wide-reach sprinklers of circular and frontal action, including Western production.
In particular, good results were shown in experimental studies of DM "Frigate".Watering was carried out by sprinklers "Frigate" DMU-B463-90.

Research results
The results of the studies were presented in Tables 1 and 2. The surface runoff with a single watering of a serial sprinkler machine in 2020 amounted to 9% of the irrigation norm, which is 2.4 times more than that of DM equipped with sprinklers with a rotating deflector and 4 times more than that of DM equipped with sprinklers with a double deflector.According to research results, in 2021, the volume of surface runoff of DM "Frigate" with serial sprinklers amounted to 9.2% of the irrigation norm, the volume of runoff for DM with sprinklers installed on them with rotating deflectors was 2.2 times less, and for DM with sprinklers with double deflectors was 3.8 times less.
Field studies in 2022 also showed that the volume of surface runoff when watering DM with serial sprinklers is higher than that of upgraded machines and the volume of runoff from the irrigation norm was 8.5%, and for machines with sprinklers having a rotating and double deflector, respectively, 3.6 and 2.2%.
The volume of surface runoff of irrigation water during the irrigation season when watering with sprinklers with developed sprinklers was also less, and as a percentage of the irrigation norm was: in 2020, when watering DM with sprinklers having a rotating deflector -6.3%, when watering with a machine with sprinklers having a double deflector -3.9%; in 2021, respectively -6.6 and 4.1%, in 2022 -6.0 and 3.9%.
Studies have shown that, on average, for the entire period of field research from 2020 to 2022, the volume of surface runoff compared to a DM equipped with serial sprinklers was reduced: when watering with a machine with sprinklers having a rotating deflector by 3.4 times, when watering with a DM equipped with sprinklers with double deflectors by 5.4 times.
With the surface runoff of irrigation water, the soil is also washed away -solid runoff.Together with solid runoff, nutrients and humus are removed from the soil.
The volume of solid runoff was determined using the conversion coefficient of the Shumakov B.B. nomogram.
Since the volume of solid runoff depends on the amount of surface liquid runoff of irrigation water, corresponding values were obtained showing that solid runoff when watering DM with developed sprinklers is lower than when watering with a sprinkler equipped with serial devices.
The obtained data on the removal of nutrients with the liquid phase of surface runoff show that when watering DM with serial sprinklers, nitrogen losses over three years of research amounted to 8.1 kg/ha.When watering a DM equipped with sprinklers with a rotating deflector -3.5 kg / ha, and when watering a DM equipped with sprinklers with a double deflector -2.1 kg/ha.E3S Web of Conferences 463, 02012 (2023) EESTE2023 https://doi.org/10.1051/e3sconf/202346302012Phosphorus losses when watering DM "Frigate" with serial devices amounted to 1.8 kg/ ha, and when watering DM with developed sprinklers -0.8 and 0.5 kg/ha, respectively, for sprinklers with a rotating deflector and with double deflectors.
Potassium losses, respectively, amounted to: 4.1; 1.8; 1.1 kg/ha.Thus, during the period 2020-2022, when watering DM with sprinklers having a rotating deflector, the removal of nutrients with a liquid phase of surface runoff was reduced by an average of 2.3 times; when watering DM "Frigate" with sprinklers with double deflectors -by 3.7 times.The removal of nutrients with solid runoff during irrigation with serial and upgraded DM was also determined using chemical analysis.
According to the data obtained on the removal of nutrients from solid runoff, when watering serial DM, humus losses for three years amounted to 789.7 kg/ha, nitrogen -58.2 kg/ha, phosphorus -16.1 kg/ha, potassium -255.5 kg/ha.When watering DM with sprinklers having a rotating deflector, humus losses amounted to 335.2 kg/ha, nitrogen -24.7 kg/ha, phosphorus -6.9 kg/ha, potassium -108.5 kg/ha.When watering the DM "Frigate" equipped with sprinklers with double deflectors, the loss of humus is 202.4 kg/ha, nitrogen is 14.9 kg/ha, phosphorus is 4.1 kg/ha, potassium is 65.5 kg/ha.
The results on the removal of nutrients from the soil with liquid and solid runoff for the entire research period (2020-2022) are shown in Table 3.
Watering the DM with the developed sprinklers prevented the removal of nutrients: humus -1043 kg/ ha, nitrogen -87 kg/ ha, phosphorus -23 kg/ ha, potassium -343 kg/ha.Thus, experimental studies have proved the high efficiency and environmental safety of improved sprinklers "Frigate".

Discussions
The conducted studies allowed us to establish that for DM "Frigate", in order to reduce the impact of rain, and also, based on the possibility of reducing the pressure at the entrance to the car, it is recommended to install sprinklers with a smooth deflector.And when working at high watering rates, install sprinklers with a rotating deflector or cascade versions in the end part of the machine.

Сonclusion
Equipping the machines with improved sprinklers, depending on the soil-relief conditions, made it possible, due to the reduction of the impact of rain on the soil, to increase the irrigation rate and, accordingly, to reduce the amount of runoff, especially in the end part of the machine.

Table 1 .
Surface runoff of irrigation water on average per irrigation.

Table 2 .
Surface runoff of irrigation water during the irrigation season.

Table 3 .
Removal of nutrients from the soil during the research period.