Humus state of chernozem at different ways of tillage in the agrosystems of the left-bank forest steppe of Ukraine

Abstract

The contemporary condition of soil cover in Ukraine is characterized. The attention is focused onto widespread degradation processes in soils. The causes that determine the development of these negative processes are considered. The contemporary informational support for the condition of soil cover in Ukraine is estimated. In general, the current available information is of narrow-departmental nature, obtained by different methods and non-correlated monitoring programs. As a rule, it is stored in under-structured databases, incompatible with other information systems; mainly recorded on paper media unusable with modern technologies, whereby such information resources are diffi cult to be compiled together. These disadvantages are strong constraints against consistent usage of materials for evaluation, forecast and management of changes in the soil cover. The Soil Observation program should thereby be combined with Agrochemical Passportization and ecology-ameliora- tive monitoring; in other words, the application of innovative soil-agrochemical methodology is considered. Each individual type of surveys shall complement the others, and taken altogether, they shall constitute a con- sistent Information System, capable of solving the problems of assessing the condition, forecasting, manage- ment, usage and protection of soil resources. The monitoring procedures should be conducted on the basis of a new soil concept in line with unifi ed programs and methods, so as to meet European approaches to the maxi- mum extent. Such a technical composition enables getting information on present-day processes in soils, and is the only combination that actually helps us to “ecologize” our knowledge of soils, which is the leading trend in the scope of global soil-science. Thus obtained results will serve as a State-owned tool which would subse- quently facilitate the use and protection of soil resources all over the country, to be involved in a united global soil-information scope. The attention is focused onto social signifi cance of the information on soils and their fertility in terms of land resources optimization, as well as the formation of sustainable land use in Ukraine. Aim. To demonstrate the long-term effect of different ways of tillage of typical low-humus chernozem on the change in humus content and composition and the direction of transformation processes of organic fertili- zers. To study the changes in the structure of energy reserves in group and fractional composition of humus in typical low-humus light-loamy chernozem of the Forest-Steppe of Ukraine. Methods. Field, laboratory, microbiological, computational, mathematical and statistical. Results. It was determined that in conditions of long-term subsurface tillage the most effi cient humus accumulation occurs in the 0–20 cm layer of chernozem with simultaneous increase in its content in the lower part of the processed layer without any accumulation differentiation. Surface tillage leads to expressed differentiation in humus accumulation in the 0–20 cm layer of soil (0.005 % per year). When 6 t/ha of humus are replaced by 7 t/ha of by-products the intensity of humus accumulation is decreasing regardless of the way of tillage, but humus accumulation was found to be the most effi cient for subsurface tillage. The application of subsurface tillage leads to the increase in the ratio of C HA : C FA , which is conditioned by the increase in the humifi cation of plant remains of by-products in the 0−20 cm layer of soil by 110–112 % – for subsurface tillage, and by 105 % – for surface tillage. Conclusions. It was established that systematic subsurface tillage of typical chernozem of the Left-Bank Forest-Steppe of Ukraine leads to the structuring both of the total reserves of energy С org , and its quality content, aimed at the increase in the intensity of the processes of humifi cation and accumulation of organic carbon, and the decrease in miner- alization. The ratio of energy reserves С org of humic acids to fulvic acids in the 0−30 cm layer of chernozem is 1.85−1.87 regardless of the way of tillage, which testifi es to the repeatability of humus accumulation, but the total reserves of energy С org was higher for subsurface tillage (+ 31 Teracalorie/ha) compared to deep plough- ing. As for the surface tillage, the energy enrichment was at the level of deep ploughing.

State of water-stable soil structure in the Central Forest-Steppe under agrogenic and postagrogenic maintenance

“…The structure of chernozem-type soils, optimal for the development of plants, may be stable to different moisturization conditions and ensure the consistency of maintaining the pores of the soil matrix, creating the favorable air-and moisture exchange regime between the roots and soil environment (Degtyarev et al, 2020). The waterstable aggregate structure is formed by macro-and microaggregates, and the water stability of aggregates is determined by the content of organic carbon in the aggregates and has a direct effect on the structural state of soil and its physical properties (Degtyarev et al, 2020;Demidenko et al, 2014;Medvedev et al, 2003). The decrease in humus composition and negative changes in soil absorption complex is one of the reasons for the unfavorable transformation of the structural state of arable chernozems -a phenomenon of common incidence (Medvedev, 2010;Sinchenko, 2019).…”

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“…The structure of chernozem-type soils, optimal for the development of plants, may be stable to different moisturization conditions and ensure the consistency of maintaining the pores of the soil matrix, creating the favorable air-and moisture exchange regime between the roots and soil environment (Degtyarev et al, 2020). The waterstable aggregate structure is formed by macro-and microaggregates, and the water stability of aggregates is determined by the content of organic carbon in the aggregates and has a direct effect on the structural state of soil and its physical properties (Degtyarev et al, 2020;Demidenko et al, 2014;Medvedev et al, 2003). The decrease in humus composition and negative changes in soil absorption complex is one of the reasons for the unfavorable transformation of the structural state of arable chernozems -a phenomenon of common incidence (Medvedev, 2010;Sinchenko, 2019).…”

Chernozems of Ukraine: past, present and future perspectives

“…Demyanyuk et al 2018), dynamics of the soil organic matter (e.g. Mamontov 1975;Kravchenko et al 2012;Demydenko and Velychko 2015) and transformation of the soils due to agricultural activity (Gninenko and Kizyakov 1983;Poznyak 1990;Filon 1996;Demyanyuk et al 2018).…”