Water consumption of corn for grain depending on the predecessor and fertilizers used using strip-til technology

. In the Volgograd region, 3-year field experiments were carried out on chernozem soils of cultivating corn for grain using the resource-saving Strip-til technology. The two-factor experiments made it possible to establish the optimal precursor for corn for grain and fertilizer application rates. The crop predecessor was taken as factor A (A1 - winter wheat, A2 - corn for grain, A3 - sunflower), and the use of fertilizers was taken as factor B (B1 - N 50 P 16 K 16 , B2 - N 32 P 32 K 32 ). The maximum yield was noted for the predecessor winter wheat against the background of fertilizers N 50 P 16 K 16 - 6.12 t/ha, in the variants for all predecessors when applying fertilizers, more economical water consumption was established, moisture was spent most efficiently to create 1 ton of yield in the variant with the predecessor winter wheat against the background of fertilizers N 50 P 16 K 16 - 443.51 m 3 /t. Ineffective moisture consumption was established for the predecessor sunflower on an unfertilized background - 973.67 m 3 /t.


Introduction
Corn plays a significant role in world agriculture; in some countries, this crop is the main food product, and already occupies sown areas that exceed those sown with grain.In the Volgograd region in 2020, the area sown with corn for grain increased by 25% and amounted to 89.5 thousand hectares; on the contrary, the gross harvest decreased compared to the previous year and amounted to 280 thousand tons.Low yields are primarily associated with the prevailing unfavorable weather conditions during the growing season, as well as low moisture reserves in the soil formed during the autumn-winter period.Stable demand for corn is observed among importers, in particular Iran, however, along with quantitative requests, strict requirements for grain quality are imposed: fat content, fiber content, residual pesticide content [1].To maintain crop yields at the level of meeting the demands of both importers and local processing enterprises, it is necessary to improve soil cultivation technologies [2][3][4][5], sow zoned highly productive hybrids, observe crop rotation, in particular sowing corn for grain only after good predecessors.As ways to increase productivity, it is necessary to use combinations of fertilizers [6], the method and period of their application [7][8], and treat seeds before sowing with growth stimulants.Alternative ways to increase the quantitative indicators of germination of seeds of agricultural crops, stimulate the growth and development of plants and, as a result, safety, are pre-sowing treatment of seeds by electrophysical methods [9][10][11] such as electromagnetic fields of various frequencies and wavelengths, ultraviolet and infrared radiation, corona discharge currents, electric pulse fields, which are an alternative to the use of pesticides and are safe for the surrounding flora and fauna [12][13].Conducted studies on the effect of pre-sowing treatment in an electric field on sunflower seeds confirm the hypothesis about an environmentally friendly way to increase crop yields.The key to cultivating corn for grain in a risky farming zone, taking into account a changing climate, reduced or uneven precipitation, longer periods of lack of precipitation and high temperatures, is to search for an integrated combination of agricultural practices for tillage, fertilization and alternation of predecessors.The gross harvest must be increased not through additional input of sown areas, but through increasing yields.When growing corn for grain, as well as other agricultural crops, an important economic indicator is profitability, which reflects the profit received compared to costs.With classical tillage, more than 30% of costs are spent on fuel, depreciation of equipment and wages to workers.The introduction of minimum tillage reduces tillage costs, reduces overall costs and increases profitability [14][15].

Materials and methods
The experiments were carried out in the Mikhailovsky district of the Volgograd region on the territory of Reconstruction LLC in 2021-2023.The two-factor experiment was carried out using the split plot method, in triplicate.
Factor A is the precursor of the crop (A1 -winter wheat, A2 -corn for grain, A3sunflower), factor B is the use of fertilizers (B1 -N50P16K16, B2 -N32P32K32).The registration area of the plot is 160 m 2 .The soil at the site of the experiments is southern chernozem, humus content is 4.65%, total nitrogen is 83.2 mg/kg, exchangeable potassium is 385 mg/kg, available phosphorus is 42.4 mg/kg.The seeding rate is 60 thousand seeds/ha.The experimental scheme is presented in Figure 1.
Corn was sown using the Strip-till system; for this purpose, the soil was prepared in the fall -strips were cut with an Ortman cultivator, 25 centimeters wide, while simultaneously applying fertilizers.Before tilling the soil, weeds were destroyed with herbicide.For sowing, a Gaspardo row-crop seeder was used, row spacing was 80 cm, seed placement depth was 7-8 centimeters.During the growing season, the herbicide Ballerina was used against weeds.Corn harvesting was carried out when grain moisture reached no more than 22% using an Akros combine harvester with an Orosh corn header.
Conducted meteorological observations showed that precipitation over the years of the research was uneven and differed significantly: in 2021 -195 mm fell, in 2022 significantly less than the previous year -134 mm, in 2023 -230 mm, which can be considered the most wet year for three-year observations.Assessing the growing season based on the hydrothermal coefficient, 2021 and 2023 are considered dry years, and 2022 is very dry. Figure 1 shows a diagram of the field experiment.

Results and Discussion
The yield of corn, like other agricultural crops, depends on the quality of the seeds, the quality of seedlings, and the climatic conditions that develop during the growing season.
Obtaining complete and friendly shoots is possible subject to compliance with the established deadlines for a certain climatic zone, the actual heating of the soil to the depth of seed placement, reserves of productive moisture in the arable soil layer, air temperature and the amount of precipitation during the period from sowing to germination.Climatic conditions according to the years of research that developed during the period after sowing and obtaining seedlings are presented in Table 1.The recommended dates for sowing corn in the Volgograd region are set from April 20 to May 10; during this time interval, the soil at the seeding depth warms up to an optimal temperature of 10-12 o C. Earlier sowing in insufficiently warmed soil leads to an increase in sowing-emergence time; with late sowing and lack of precipitation, the available moisture in the arable layer decreases, which does not have a favorable effect on the consistency of seedlings.Sowing work in 2021 was carried out on April 15, in 2022 -on May 10, in 2023 -on May 18.A significant difference in sowing work over the years of research, especially in 2021, was associated with the inability of equipment to enter the field due to weather conditions.
In 2021, the period of full germination occurred on the 12th day, with the sum of positive temperatures being 277 o C; in 2022-2023, the sowing-germination period was 10 days, with the sum of positive temperatures being 205 and 226 o C.
Field germination varied both according to the years of research, which differed in meteorological conditions, and according to the factors studied.Table 2 shows the field germination rates of corn depending on the predecessor and fertilizers used.
Analyzing the data in Table 2, the highest germination rate is observed in control, and for all studied factors in 2021.Differences in field germination can be clearly seen by the factor of predecessor alternation; the leader in this indicator was the predecessor -winter wheat 55.3-55.7 thousand, according to the predecessor -corn for grain -field germination was not significantly lower (54.9-55,0 thousand), in the variant with its predecessorsunflower -the lowest field germination was noted, in the range of 54.6-54.7 thousand.
The results of field germination in 2022 and 2023, relative to 2021 for all predecessors, were lower, which indicates a significant influence of weather conditions (average temperature during the sowing-germination period, amount of precipitation during the study period) and timing of seed sowing.The density of plant standing and preservation for harvesting according to the research options repeated the dynamics similar to that of seed germination.
The Volgograd region belongs to the regions included in the zone of risky agriculture, the climate is characterized by dry and windy weather during the growing season, the absence of precipitation for a long time or the precipitation does not fall evenly in the form of short-term downpour, as a result, rain moisture does not have time to be absorbed into the soil.Therefore, the issue of resource conservation, in this context of productive moisture reserves, is relevant for agricultural producers in the region.The reserves of productive moisture for the spring sowing period consist of the available moisture in the soil after harvesting the predecessor, precipitation in the form of snow and rain in the autumn-winter period.
The yield of a crop depends, in part, on the soil moisture available to plants; water consumption reflects how much moisture the plant consumes to form plant mass and yield.Table 3 shows the consumption of productive moisture on average for three years of experiments.The average three-year indicators of productive moisture before harvesting were the highest in the winter wheat option with N50P16K16 fertilizers -254 m 3 /ha, the minimum supply of productive moisture was obtained in the option with the predecessor sunflower without fertilizers -130 m 3 /ha.The minimum total water consumption was established in the variant with the predecessor winter wheat when applying fertilizers N50P16K16 -2695 m 3 /ha; for the predecessor corn for grain and sunflower, water consumption was higher by 48 and 32 m 3 /ha, respectively.During growth and development, the moisture consumed by the plant is used to form the crop; the yield is directly dependent on water consumption.In the variants with fertilizer application, the water consumption coefficient was lower than in the control for all predecessors, this indicates a more economical consumption of moisture to form a unit of yield.The greatest amount of moisture was spent on the formation of the crop in the variant according to the predecessor sunflower -704.65 m 3 /t, the minimum moisture consumption for the formation of 1 ton of the crop was in the predecessor winter wheat -440.36 m 3 /t.The maximum moisture consumption for the formation of one ton of crop in the amount of 973.67 m 3 /t was according to its predecessor -sunflower, without applying fertilizers.

Conclusion
A three-year study of growing corn for grain using the strip-til system using various predecessors with the use of fertilizers allows us to draw the following conclusions:  Field germination according to the years of research depended on temperature and soil moisture; germination was slightly higher than the predecessor of winter wheat. The maximum yield was noted for the predecessor winter wheat against the background of N50P16K16 fertilizers -6.12 t/ha, in the variants for all predecessors when applying fertilizers, more economical water consumption was established, moisture was spent most efficiently to create 1 ton of yield in the variant with the predecessor winter wheat against the background fertilizers N50P16K16 -440.36 m 3 /t.

Table 1 .
Duration of corn germination depending on hydrothermal conditions.

Table 3 .
Water consumption of corn depending on the factors studied.