The efficiency of the use of mineral fertilizers on dry meadows of Prykarpattia

Goal. To determine the patterns of formation of productivity of sown cereal grass and feed quality indicators depending on the doses and ratios of mineral fertilizers on sod-podzolic soils of Prykarpattia. Methods. General scientific -- hypotheses, inductions and deductions, analogies, generalizations; and special -- field, laboratory, mathematical and statistical, computational and comparative. Results. Of the mineral elements, nitrogen had the greatest effect on grass productivity and chemical composition. With the introduction of the total dose of N75 with uniform distribution of nitrogen under each of the 3 slopes on different backgrounds of phosphorus-potassium fertilizers, the productivity of cereal grass increased by 2.82 - 3.06 t/ha of dry weight, with the introduction of N150 -- by 3.33 - 4.93 t/ha, or respectively 1.8 - 2.1 and 2.5 - 2.9 times. With the introduction of N75, the content of crude protein in the dry mass increased by 2.9 - 3.2%, with the introduction of N 150 -- by 4.2 - 5.4%, or 1.2 and 1.4 times, respectively. The application of nitrogen fertilizers also increased the content of protein, calcium, magnesium, feed units, metabolic energy, dry matter digestibility, the supply of feed unit with digestible protein, and decreased the content of nitrogen-free extractives and potassium. Conclusions. The dependence of the productivity of cereal agrocenosis on sod-podzolic soils of the Carpathian region on doses and ratios of N, P, K of mineral fertilizers is described by a polynomial of the 2nd degree. The most influential mineral element in terms of increasing productivity and improving feed quality is nitrogen. It provides the highest payback of 1 kg of fertilizer by increasing the yield of dry mass, which for the application of N75 is 38 - 41 kg of dry weight, which is 4 - 5 kg more than at the application of N150. Nitrogen fertilizers improve the uniform distribution of the crop on the slopes and increase the content of crude protein. Yield increase from the application of P60, K90, P30K45 or P60K90 on different nitrogen backgrounds is 0.28 - 1.34 t/ha with a payback of 1 kg of active substance 5 - 14 kg of dry weight.

Key words: nitrogen, cereal grassland, potassium, mathematical model, productivity, crude protein, chemical composition of feed, phosphorus.

Introduction

Fertilizers are one of the decisive means of increasing the productivity of meadow grasses on hayfields and pastures, as well as increasing the profitability of land reclamation and other activities. They can be effectively used on all types of meadows. But, first of all, they are highly effective, as noted by P.S. Makarenko [1], VG Kurgak [2], on sufficiently moistened lands (floodplain and lowland meadows, normal land and irrigated areas of meadow pastures), where valuable meadow grasses from the group of cereal mesophytes predominate.

Various methods are used to determine fertilizer doses, including balance-calculation, economic- mathematical, chemical diagnostic method, which is based on chemical analysis of plants, and the method, which is based on the recommendations of research institutions [2-4]. The main criterion for determining the doses of fertilizers for hayfields and pastures, when using any method is the experimental data: they are taken as a basis for developing recommendations for fertilizer application. For an approximate determination of nitrogen doses, it is proposed to use the calculated way, based on the average possibility of herbs, to effectively use 2.5 kg N per day.

According to the economic-mathematical method, doses and ratios of basic nutrients are optimized with the help of special mathematical models of productivity, which in a concise form contain information for certain soil and climatic conditions and types of onions, on the quantitative relationship between doses and ratios of nutrients and yields of meadows.. In addition, they provide an opportunity to solve a number of other tasks: to plan (predict) yields and agro-technological (economic and energy) efficiency of fertilizers, machines and methods of their application [5], to develop standards for onions and pastures in mineral fertilizers, etc. [2].

Research conducted by L.M. Derzhavin and IA Rubanov [6], proved that the best functions of "harvest- fertilizer" are functions degree 0.5 and square. For practical use, successful, in our opinion, is a classical model using a quadratic mathematical function (polynomial of the second degree), which with sufficient accuracy allows not only to determine doses, predict yields depending on them, but also on the basis of predicted yield to assess the quality of mineral application fertilizers [5, 7].

Despite the significant amount of research on the study of fertilizer doses, until recently experimental data using modern methods of planning and modeling experiments with fertilizers on natural forage lands in the Carpathians of Ukraine are still insufficient. Therefore, these questions were the purpose of our research.

The purpose of the work. To establish regularities of formation of productivity of sown cereal grass and forage quality indicators depending on doses and ratios of mineral fertilizers on sod-podzolic soils of Prykarpattia.

Materials and methods of research

A study to determine the productivity of cereal grass and chemical composition of feed from doses and ratios of nitrogen, phosphorus and potassium we conducted in a three- factor field experiment on poor in humus and nutrient content sod-podzolic surface gleyed soil during 20172019 in the dendrology "Druzhba" SHEI "Precarpathian National University" (Tysmenets district of Ivano- Frankivsk region). Coverless sowing of a mixture of cereal grasses from meadow thyme, thistle and meadow fire was carried out in the summer of 2016.

The use of stands is triangular. The first mowing was carried out in the phase of earing cereals buddingbeginning of flowering legumes, otav - 30-35 days after the previous mowing.

Phenological observations and crop accounting in each slope on the accounting plots were performed according to SSTU 8044: 2015 [8]; productivity indicators on the yield of 1 ha of dry mass, feed units, crude protein and metabolic energy - according to sStU 8044: 2015 [8] and SSTU 8066: 2015 [9]. In the dry mass of plant mass indicators of chemical composition of feed and in vitro digestibility - by infrared spectroscopy, nutritional value and energy of feed - by calculation according to SSTU 8066: 2015 [9] and SStU 4674: 2006 [10].

The experiment was carried out according to an abbreviated scheme, which is recommended when planning experiments [2, 3] Mathematical processing of research results was performed by methods of variance and regression analysis according to Dospekhov BA [12].

Research results

Analysis of the results of our studies conducted during 2017-2019 to study the doses and ratios of NPK mineral fertilizers showed that on sown cereal grass in the first year of use, the proportion of meadow thyme was 7-9%, foxglove 20-23% and meadow fireweed. 55-58%. Over the years, and to the greatest extent against the background of the introduction of N150, the share of stokolos bezzostogo increased, and meadow bonfire decreased by 31-40%.

Nitrogen was the most effective mineral nutrient in terms of its effect on productivity (Table 1). For example, the application of its total dose of N75 (25 + 25 + 25) on different backgrounds of phosphorus-potassium fertilizers, the productivity of cereal grasses for an average of three years increased from 2.53-3.47 t/ha to 5.35-6, 53 t/ha of dry mass or 2.82-3.06 t/ha or 1.8-2.1 times, and for the application of N150 (50 + 50 + 50) - up to 7.46-8.80 tons/ha or 4.93-3.33 t/ha or 2.5-2.9 times. Thus, the highest productivity of grass feed was obtained when N150 was applied. However, the payback of 1 kg of nitrogen fertilizers with dry matter yield was higher than the application of N75, which ranged from 38 to 41 kg, which is 3-5 kg more than the application of nitrogen at a dose of N150.

Phosphorus and potassium fertilizers had much less effect on the productivity of sown cereals. The increase in yield from the use of phosphorus at a dose of P60 on different nitrogen backgrounds ranged from 0. 28 to 0.56 t/ha with a payback of 1 kg of active substance 5-9 kg of dry weight. The increase in yield from the introduction of potassium at a dose of K90 on different nitrogen backgrounds was equal to 0.42-0.74 t/ha with a payback of 1 kg of active substance 5-8 kg of dry weight. With the combined application of phosphorus and potassium in doses of P60K90 and P30K45 on different nitrogen backgrounds, the productivity of sown grass increased by 0.60-1.34 t/ha of dry mass with a payback of 1 kg of their active substance from 6 to 14 kg. Higher payback rates were for the introduction of P30K45. Slightly larger increases in dry matter yield from the application of phosphorus and potassium fertilizers and the payback of 1 kg of these fertilizers by dry weight were against the background of nitrogen fertilizers.

The intermediate position of payback between the use of only nitrogen fertilizers or only phosphorus and potassium fertilizers was occupied by the joint application of nitrogen with phosphorus and potassium fertilizers. In this case, the payback of 1 kg of active substance fertilizer ranged from 18 to 27 kg. The greatest productivity was at the combined introduction in the maximum investigated doses N150P60K90. In this case, the yield from 1 ha of dry matter was 8.80 t/ha, which is 3.5 times more than the option without fertilizer.

mineral fertilizers soddy podzolic

1. The effect of doses and ratios of NPK fertilizers on the productivity of cereal grass (2017-2019 yy.)