The impact of mineral nutrition on winter barley yields while using mustard as a precursor crop

Abstract

The influence of supplying mineral nutrition on yield and indicators of quality of winter barley grain using mustard as a precursor crop has been examined. Studies have shown that under the conditions of Steppe in the south of Ukraine, the application of mineral fertilizers while growing mustard has a positive effect on the yield of winter barley, increasing it by 0.46-1.35 t per ha compared to the control. Winter barley of the "Dev'yatyi Val" cultivar provides a higher level of yield compared to the "Dostoynyi" variety while using mustard as a precursor crop. The highest economic performance was obtained on the basis of N40Р40К40 application before sowing with subsequent fertilization of crops with nitrogen (N30) during early spring on partially frozen soil. When using this option, the level of profitability of "Dev'yatyi Val" cultivar amounts to 99.2%, which is 14.9% higher compared to the margins of the "Dostoynyi" variety. The level of productivity of various crops, including winter barley, depends on the choice of the optimal precursor crop. It is established that the use of the appropriate precursor crop provides an opportunity to significantly increase the barley grain yields even in the case of rather arid conditions of the Ukrainian steppe. The influence of precursors on the productivity of winter barley is primarily determined by the reserves of productive moisture in the soil that have remained there after a harvest. Recently, especially in zones of risky agriculture, less widely known alternative oilseeds, such as mustard, flax, safflower, camelina and sesame, are becoming all the more popular. Mustard is considered to be the most "hyped" of the abovementioned plants - it's a promising, 100% marketable crop, mainly because the physiology of the plant allows it to be used as an optimal precursor that can improve agrophysical and phytosanitary properties of soil. In order to realize the high genetic potential of modern varieties of winter barley, it is necessary to introduce modern agricultural technologies, an important component of which is the use of mineral fertilizers that affect the quantity and quality of the crop. Fertilizers are one of the most important factors to effectively manage both yield and quality of grain. Along with the fertilizers, micronutrients that are essential for plants' survival, can also get into the soil. Despite its high adaptability, barley is a species, which responds particularly strongly to the levels of fertilizer in soil, namely that an increase in the growth of grain from the use of mineral fertilizers can be as high as 50%. This responsiveness of barley to fertilizers is one of the important conditions for its further expansion in sown areas. Barley is highly sensitive to mineral fertilizers, especially when applying them to partially frozen soil, when there is enough moisture and the elimination of stressful winter conditions positively affects the further growth and development of plants thus ensuring increased yields. However, depending on different soil and climatic conditions, the doses of mineral fertilizers may differ, plus there is also a need to review and re-evaluate the effectiveness of fertilization of winter barley, taking into account significant changes in weather conditions during its cultivation. Studies that examine the impact of precursor crops on the yield of winter barley were conducted in field conditions from 2016 to 2020 on the basis of the "Agrotechnics of grain crops" laboratory at the Institute of Oilseeds of NAAS. Various cultivars of winter barley ("two-handed") were sown with regard to its physiological properties – "Dostoynyi" (registered in 2006) and "Dev'yatyi Val" (registered in 2014), which in recent years have dominated the northern part of the steppe zone in terms of sown areas. Sowing was carried out with a selection seeder SCS-6-10 with a sowing rate of 4.5 million pieces of similar seeds per hectare. Depth of seed wrapping – 5–6 cm. Sowing method – solid row. The size of the test area is 18 m2 (12×1.5). Repetition of the experiment was threefold. Plant protection measures have been carried out while taking into account the economic threshold of harmfulness. The soil of the experimental plot is of the ordinary chernozem type, medium-strength and low-humus, with humus content in the arable layer up greater than 30 cm – 3.5%, available nitrogen – 7.2–8.5, mobile phosphorus – 9.6–10.3, exchangeable potassium – 15.2–16.9 mg per 100 g of completely dry soil and pH level of soil solution at 6.5–7.0. Mineral fertilizers were applied according to the layout of the experiment: using control (without fertilizers); N40R40K40 (ANP fertilizer) minus the background (for pre-sowing cultivation); background + N30 on partially frozen soil; background + N60 on partially frozen soil. The given technology of growing winter barley is one generally accepted in the southern part of the Ukrainian Steppe. Harvesting was carried out by direct combining with a self-propelled combine "Sampo-130". Yield was determined by the method of continuous threshing of the entire area of the test plot at the moment of full maturity of the grain. Bunker harvest from each plot was weighed directly in the field, and after weighing, average samples weighing 1 kg were taken. The yield was established after the purification of grain and conversion to standard 14% humidity, determined by the thermostatic/weight technique. The growth and development of winter cereals was significantly affected by weather conditions. During the five years of plant vegetation (2016-2020), the average moisture reserves in a meter layer of soil averaged 134.7 mm, in the stem elongation phase – 95.1 mm, earing – 54.7 mm, phase of full maturity – 17.8 mm. The aim of the research was to study the influence of nitrogen mineral fertilizers on the productivity of winter barley while using mustard as a precursor crop under the conditions of the southern Ukrainian steppe. The analysis of biometric parameters of "two-handed" winter barley plants has shown that when applying mineral fertilizers at a proportion of N40R40K40 plant, height in the earing phase increases by an average of 5.0-9.6 cm (5.7-10.7%), whereas in case of application of N40Р40К40 before sowing, which is followed by fertilization with N30 on partially frozen soil, the height increases by 10.4–14.5 cm (12.6–17.3%) on average. The optimal development of winter barley plants in the earing phase was ensured by the application of N40P40K40 followed by fertilization with N60 on partially frozen soil which amounted to 12.5–15.5 cm in height (15.1–20.9%) compared to the unfertilized control. Winter barley of the ''Dev'yatyi Val" cultivar has higher figures in terms of growth and development in the earing phase compared to the "Dostoynyi" cultivar. Improving the nutritional background had a positive effect on the rate of productive tillering. The use of N40P40K40 provided a value of the tillering coefficient that was close to the control (1.5-1.6). The highest tillering coefficient of winter barley cultivars (2.1 and 2.3) was obtained after application of N40R40K40 before sowing followed by fertilization with N60 on a partially frozen soil. The absolute dry weight of 100 plants has increased by 21.6–96.9% in case of the "Dostoynyi" cultivar and 12.6–109.0% in the case of ''Dev'yatyi Val" cultivar according to the application doses. The yield of barley largely depended on the dose of the fertilizer. According to the research results, the yield of winter barley was 3.58–4.93 t per ha in case of the ''Dev'yatyi Val" cultivar and 3.34–4.65 t per ha in case of the "Dostoynyi" cultivar. "Dev'yatyi Val" provides the higher level of yield compared to the "Dostoynyi" cultivar. When grown by way of N40R40K40 application with subsequent fertilization with N30 in early spring on partially frozen soil, both varieties of winter barley formed a yield of 4.83–4.47 t/ha combined. The maximum yield (4.93–4.65 t/ha) of winter barley cultivars was obtained by application of N40R40K40 before sowing with subsequent fertilization with N60 in early spring on partially frozen soil (Table 2). Increasing the dose of nitrogen fertilization provided an increase in grain yield by 0.46–1.35 t/ha compared to the control without fertilizers. The obtained experimental data show that the grain quality of winter barley during the research period significantly depended on the use of nitrogen fertilizers. The highest protein content of 9.83% in the grain of winter barley varieties was obtained in the plots by way of pre-sowing application of N40P40K40, followed by fertilization with N60 on partially frozen soil. With a decrease in the proportion of mineral fertilizer to N30, the protein content in the grain of the "Dostoynyi" cultivar decreased to 8.36% and "Dev'yatyi Val" figures saw a fall of up to 9.53%, moreover, without the use of fertilizers, these figures were the lowest and amounted to only 6.38-6.80% and 7.22–9.01%, respectively. As the dose of fertilizer increased, the weight of 1000 grains also increased. Thus, in the variant without fertilizers (control) the weight of 1000 grains of the "Dostoynyi" cultivar was 38.0 g, and through the increase of mineral nutrition, this figure also increased by 3.1% and 5.7%, depending on the cultivar. The weight of 1000 grains of the "Dev'yatyi Val" cultivar after the pre-sowing application of N40P40K40 followed by fertilization with N30 and N60 on partially frozen soil was higher by 1.2 and 2.8% respectively against the control without fertilizers. Analyzing the economic indicators in the cultivation of winter barley using mustard as a precursor crop, it should be noted that mineral fertilizers were the main factor that most significantly affected the productivity of this crop and, consequently, the economic efficiency of its production. The cost of growing 1 ha of winter barley, depending on the level of mineral nutrition, ranged from 9508 to 13402 UAH. In the experiment, the highest indicators of economic efficiency were determined for the cultivation of winter barley of the "Dev'yatyi Val" cultivar. It was established that the maximum net profit of 12506 UAH/ha was obtained by way of pre-sowing application of N40Р40К40 with subsequent fertilization with N30 on partially frozen soil. It should be noted that when using this option, the cost of growing "Dev'yatyi Val" winter barley grain amounted to 2611 UAH/t, the level of profitability of 99.2%, which is higher than the margins of the "Dostoynyi" cultivar by 14.9%. Cultivation of "Dev'yatyi Val" by way of pre-sowing application of N40R40K40 followed by fertilization with N60 on partially frozen soil resulted in a net profit of 12234 UAH/ha, the cost of grain – 2611 UAH/t, profitability – 91.3%, which is higher than the level of profitability of the "Dostoynyi" cultivar by 10.9%. The minimum value of the level of profitability of grain production (68.0–78.7%) of the cultivars under study was in those cases where mineral fertilizers at the proportion of N40R40K40 were applied in the background without fertilization.