Radik A.Mindibayev,Marat G.Ishbulatov,Khalil M.Safin,Aidar G.Baikov,Florid M.Davletshin

Federal State Budgetary Educational Establishment of Higher Education“Bashkir State Agrarian University,”50-letiya Octyabrya Str.,34,450001,Ufa,Russia

Keywords

Abstract

1 Introduction

A characteristic feature of the current state of agricultural land in the Republic of Bashkortostan is a change in the state of the general ecological situation for the worse due to the imbalance of energy and mass transfer in the “soil-plant –environment” system and a decrease in humus due to insufficient compensation of nutrient losses by the introduction of organic and mineral fertilizers. The initially low content of phosphorus and mineral nitrogen in available forms in the soils under consideration,as well as a significant decrease in indicators such as air-heat exchange and biological activity of soils,are also typical of Agricultural land in the Republic(Zaripova et al.,2009).

Similar problems are diagnosed throughout the world. For example, Yuan et al. (2019) note that when studying the assessment of the effect of reduction of vegetation on soil humus and nutrient reserves of soils of pasture lands in China,a change in the granulometric composition and structural state of soils is observed. The decrease in nitrogen and phosphorus content, the increase in soil pH,the degree of soil compaction have been established. Such a decrease is also noted by scientists of the Bashkir State Agrarian University as a result of mechanized processing of sloping arable lands(Rakhimov et al.,2018,Uskov et al.,2014).

Arteaga et al. (2017) believe that the loss of organic carbon reserves from the soil and its emission into the atmosphere as a result of anthropogenic activities should be considered as a problem that goes beyond the ecological and socio-economic context,and soil degradation is only one of its many consequences. At the same time,the carbon content in the soil naturally depends on the interaction of several biotic and abiotic factors,the management methods often lead to deterioration in its physical, chemical and biological properties and, thus,an increase in the level of mineralization and a decrease in carbon reserves. This study was conducted in the municipality of San Jose del Rincon,Mexico.

In Turkey,conclusions about the current situation resulting from the anthropogenic impact were made electronic,and a map of anthropogenic biomes was compiled using ArcGIS Desktop software. Based on the results obtained, we can say that over the past 200 years, the natural habitat has changed significantly, vegetation has suffered,and land degradation has become faster due to human activities(Curebal et al.,2015).

Electronic soil maps of agricultural land are also made in the Republic of Bashkortostan. In the central agricultural regions of the republic, this work is completed. In this work, the scientists of the Bashkir State Agrarian University also take an active part(Ishbulatov et al.,2018c,Spitsov et al.,2016).

As Medvedev and Plisko (2018) note, soils that have been arable for a long time are typical polygenetic formations since anthropogenic factors played a significant role in their formation along with natural ones.With mechanical, chemical, and reclamation effects, natural soils lose their inherent structure, properties, and regimes. The increasing anisotropy, spatial heterogeneity, predominant descending, and ascending moisture flows are lost, new types of horizontal and vertical soil profiles are formed. The density, the ability to reverse the properties and regimes as the primary condition for counteracting degradation processes are changing. The significant changes occur in finely divided mineral and organic parts. As a result of anthropogenic evolution in a relatively short historical period,a new body is formed–anthropogenically transformed soil,which becomes a 4-dimensional body of nature, since its parameters change in space and time. This fact requires reflection in the classification of soils and making adjustments to the study,management of their fertility, and use. Possible scenarios of further anthropogenic evolution of soils are discussed: degradation, balance, and “smart” outdegradation transformation.

In experiments conducted in Northern Iran, the effect of the remnants of logged wood on the physical and chemical properties and microbiological activity of the soil was studied. The soil samples were taken at depths of 0-15 and 15-30 cm. The results showed that the remnants of the wood had a positive effect on the state of the soil: moisture increased by 5%,a decrease in pH was by 2%,an increase in the content of organic substances -by 2%and microbiological activity improved by 10%(Moghimian et al.,2020).

The beneficial effects of introducing agricultural waste into the soil have been noted by many scientists around the world. Scientists from China Yang et al. showed that as a result of the introduction of straw into the soil,a change in the C/N ratio and microbial diversity is noted and recommends that the straw burial depth not exceed the depth of more than 20 cm(Yang et al.,2020).

Crop residues are an essential source of organic carbon in the soil,according to Wang et al.The use of no-till compared to dump plowing contributed to the conservation of carbon by 14.5%(Wang et al.,2020).

The study of the modern territory of Bashkortostan as a geographical object began in the XVIII century by such scientists as Pallas, Lepekhin, and Rychkov. The study of the soil cover of the territory was not given importance, so the description of the soils was carried out as one of the elements in the composition of general geographic studies. The study of the territory was subsequently continued by Eversman,who in 1840 published a work entitled“The Natural History of the Orenburg Territory,”which provided a reasonably accurate description of the territory of modern Bashkortostan. In 1895-97,the first county soil maps of the lands of the Ufa province were prepared on a scale of 1: 420000. The data for compiling these maps were obtained from a survey of local historians, and specific land field survey. In the latter case, soil samples were taken for subsequent analysis of the humus content for each land use(Veleckij,1899).

In 1955-56, the soil science laboratory of the Institute of Biology of the Bashkir Branch of the USSR Academy of Sciences was engaged in in-depth studies of gray forest soils of Bashkortostan(Tajchinov,1963).

The considerable work on the soil survey of agricultural land was carried out by the land management department of the Ministry of Agriculture of the Bashkir Autonomous Soviet Socialist Republic. Based on the soil detachments of this department,the Bashkir land-management expedition was subsequently organized,which grew into the Bashkir branch of the Volgogiprozem Institute(Mindibaev,2005). Soil maps were compiled on a scale of 1: 25000 for all farms of the republic and 1: 100000 in administrative regions. However,since the late 90s of the latest century, such work has been discontinued. As a result, agricultural production ceased to receive relevant data on the state of fertility, which led to the inefficient use of agricultural land. Updating and correcting soil maps at the present stage based on digital technologies is carried out by the“VolgoNIIgiprozem”Institute and the Bashkir State Agrarian University (Ishbulatov et al., 2019). The work started in 2016 and continues to the present. The soil maps in 33 municipal districts of the republic were surveyed and updated. The completion is planned in 2021. The results will be used primarily in the drafting of inter-farm and on-farm land management and state cadastral valuation of agricultural land.

The research aims to study the dynamics of soil fertility of agricultural lands of the Northern forest-steppe on the example of the Askinsky district as a result of anthropogenic impact.

2 Methods

The general landscape of the study area is characterized by the watersheds of the Bui(left bank tributary of the Kama) and the Bystryi Tanyp (right bank tributary of the Belaya). On the western part of the territory is the lowland between the confluence of the Belaya and Kama rivers(Fig.1). The remaining parts of the territory are represented by dissections of the right-bank tributaries of the Bystryi Tanyp and the left-bank tributaries of the Buya River.Altitudes fluctuate at the level of 150-200 m and in the river valleys 120-130 m in the Baltic altitude system.

The climate of this territory is characterized as moderately humid and moderately warm. The continental climate is determined by the location of the republic on the border of Europe and Asia.It is far from the seas and oceans. Although the climate is sharply continental, it is generally favorable for agricultural production. The minus temperature is set in early November and lasts until the first decade of April. The average temperature in July is 17.5,and January minus 15 degrees. Annual precipitation exceeds 600-600 mm. The total number of days with temperatures above plus 10 degrees is enough for the ripening of field crops.

The underlying rocks are the rocks of the Artinsky tier of the lower part of the Perm system. They consist of conglomerates,sandstones, limestones,dolomites,and sandy shales. These rocks are covered by an insignificant cover of relatively young Quaternary formations, which are represented by diluvial sediments and eluvial formations,and alluvium on the floodplain.

Regular adjustments are made to soil maps made in previous years to show the level of fertility of agricultural land. In the northern forest-steppe zone of the Republic of Bashkortostan, studies on soil fertility were carried out in the 70s and 90s. The field soil surveys, updating the soil register of the territory based on field and laboratory surveys, processing the data obtained are carried out according to the “Methodology for compiling large-scale soil maps using aerial photographs” and the All-Union instruction on soil surveys and compiling large-scale soil maps for land use(Mindibaev,2005).

Currently, the soil survey is carried out not for agricultural enterprises, but municipalities, in the context of rural settlements. The work is divided into three stages: 1) preparatory, 2) field 3) cameral. At the first stage,the selection of analytical and graphical materials is carried out with the study of materials from previously performed works by the Bashkir branch of the “Volgogiprozem” Institute. It is necessary to use topographic surveys performed in recent years on a scale of 1: 10000 and 1: 25000, as well as in the presence of aerial photographs of the studied areas and satellite images. When analyzing these materials,it is possible to establish land use with changes in soil cover that have occurred as a result of anthropogenic activities. The separate soil contours with no changes are observed. If necessary,places for additional sampling are determined(Ishbulatov et al.,2018b).

Fig.1 Geographical location of the study area.

Soil surveys are carried out in municipal districts to update old paper soil maps and clarify the current state of soil cover in the republic. The fieldwork is carried out using a planned route survey of the territory of rural settlements. Sections are laid at predetermined points, and soil samples are taken along genetic horizons for agrochemical analysis, and the degree of soil stoniness and erosion is also specified. When performing the adjustment work, the main sections and half-holes are laid along the contours of previous surveys, to clarify the boundaries of the soil contours – digging. The main sections were laid down to determine the complete characteristics of the soil type and to elucidate the changes that have occurred in the soil contour since the last years of the survey, as well as for diagnoses requiring clarification and newly selected contours not previously displayed on the soil map. On the recommendation, semi-holes are laid to clarify the characteristics of the common subtypes of soils and to identify changes in the soil profile. The diggings are recommended to be laid to clarify the boundaries of the soil contours. Of all the main sections and several digging,we take soil samples for analysis by current instructions and recommendations for soil surveys. Each newly selected or changed contour should be provided with a cut, half-hole, or digging. On reclaimed lands, the occurrence depth and salinity of groundwater, and the occurrence depth of salts are also determined(Ishbulatov et al.,2018a).

The field stage is carried out by route inspection, according to the coordinates of the previously designated points; sections are laid out with a description of all genetic horizons for the subsequent determination of the name of the soil. For each section, coordinates and a description of the terrain are determined -the site and its condition, soil surface condition, erosion with an indication of the macro relief, mezzo relief, and microrelief indicating the steepness of the slopes. The field name of the soil is also determined. The power of genetic horizons is measured in each section,the color,humidity,structure,granulometric composition of each horizon,the degree of compaction,the presence of new formations and inclusions,and the transition to the next horizon are determined. The sections are laid before the appearance of parent rocks and underlying rocks. Soil sampling is done over genetic horizons. When sampling for analysis,they are guided by the following requirements:

a) obtaining soil characteristics of those areas where changes in soil properties can be expected as a result of economic activities;

b) obtaining the full characteristics of the studied soils of additionally modified or distinguished contours at the level of type,subtype or variety;

c) for selective control of the initial definitions of soil varieties, deepening their characteristics, including analytical ones.

Soil samples are also taken for agrochemical analysis. In case of doubt on the refinement of the soil contours,half-holes and ditches are laid.

3 Results

In the annual state (national) report, “On the state and use of land in the Republic of Bashkortostan in 2018”,it is noted that the land fund for this zone amounted to 2932.82 thousand hectares,including 1400.76 thousand hectares of agricultural land. The area of arable land is 693.48 (49.51% of the agricultural land), hayfields 272.37 (19.44%), and pastures 428.7 (30.6%) thousand ha (Federal Service for State Registration, Cadastre,and Cartography, 2019). At the same time, the plowing of agricultural land for the period from 1996 to 2018 decreased from 65.6%to 49.51%. The reason for the decrease is the measures for tinning the degraded arable land and its transfer to fodder lands carried out by the management of the republic.

The distinctive effect on the soil formation process in the Northern forest-steppe was exerted by the uniqueness of the climate and vegetation. According to our research, in the soil cover of the territory, the most widespread are automorphic soil types such as light gray forest, gray forest, and dark gray forest soils. In the floodplains of rivers and streams,more dynamic floodplain-alluvial soils are developed.

As a result of the survey of agricultural land soils in the redistribution of the MP,the Askinsky district laid more than 260 soil sections. Soil samples were taken from all sections for genetic horizons for agrochemical analysis.

When conducting a field soil survey of agricultural lands on the territory of the Askinsky district, the three types above of soils were revealed,and 5 of the common subtypes were subsequently identified from them(Fig.2). In the soil cover of the region, the most widespread are forest-type soils(light gray forest,gray forest, dark gray forest). They are ubiquitous and make up the principal background in the soil cover of the region.

The results of the field soil survey of agricultural lands of the municipal district Askinsky are shown in Table 1.

Based on the materials received,an updated digital soil map of agricultural land will be compiled.

As a result of a field soil survey using the example of the Askinsky district, arable and other agricultural lands were overgrown with weeds and tree species(Figure 3).

A distinctive feature of the area under consideration is the almost complete cessation of agricultural activity.This process was influenced by the opportunities for more efficient use of forest resources. Currently, the bulk of the population is engaged in deforestation and the processing of forests.

As a result, there is natural restoration of soil fertility and a slowdown in erosion processes. As of 2019 agrochemical analysis of prevailing soils, there is a significant change in such a key indicator as to the humus content in the upper layer of the soil horizon. Concerning light gray forest soils, there has been a significant improvement over previous soil survey tours of 1972 and 1995. On gray forest soils,in 1995,there was humus state deterioration compared with 1972, and in 2019 a complete restoration of the level of 1972 is observed.Some other situation is observed about dark gray forest soils, which are subject to more intensive agricultural use. There is also an increase in the content of humus,but the level of 1972 has not yet been reached.

Fig.2 Section of prevailing soils: a) gray forest (agricultural enterprise Askinsky Village Council); b) light gray forest(agricultural enterprise Sul-tanbekovsky Village Council;c)dark gray forest(agricultural enterprise Arbashevsky Village Council).

Table 1 Soil area by humus content,thickness of the humus horizon and erosion category.

4 Discussion

Fig.3 Example of overgrowing with woody vegetation.

A similar situation is observed in Nepal. The research results indicate a significant reduction in land degradation and forest restoration over the past 40 years. Dense forests increased by 1,471 ha (88%), while rare forests,meadows,and agricultural land decreased by 26%,77%,and 15%,respectively. These significant changes have had a positive impact on the ecological system due to the conversion of agricultural grassland and degraded forests to dense forests. As the authors note,dense forests provided a relatively higher delay in deposits(the rate of soil erosion decreased from more than 30 tons per ha per year to less than 15 tons per year),carbon reserves increased from 50 m3/ha to 100 m3/ha(Paudyal et al.,2019).

In recent decades,more attention has been paid to secondary forests,as their total area is increasing,and the ecological and economic benefits provided by forest ecosystems are gaining increasing recognition. Therefore,the Chinese government has given high priority to the implementation of its natural forest regeneration program,which includes the restoration of degraded secondary forests. Therefore,the question of how the ecosystem and their elements change in the process of restoration of secondary forests deserves study(Zeng et al.,2019). The research results showed that secondary broad-leaved forests could restore soil fertility.

The concerns over food security are pushing agriculture to intensify around the world. However, the agricultural intensification may impede the restoration of vegetation in natural ecosystems and could jeopardize the conservation of trees in agricultural landscapes and ecosystem conditions. The researches were conducted to study the patterns of natural regeneration of trees and factors affecting the restoration of the natural state in Southeast Australia in 2008–2014 (Sato et al., 2016). During this period, it was found that the proportion of plant residues supporting natural regeneration was stable. It was found that intensification of agriculture and irregular grazing of cattle adversely affects the restoration of natural soil fertility.

The need for constant updating of data on the state of soils is also confirmed by Kumar and Geeta(2009).According to their data,information obtained in the 1960s and 70s lose their relevance to characterizing the real state of soils. Therefore, at present, the primary attention is paid to the development of modeling approaches based on the use of new GIS and remote sensing methods as the best option.

Thus,to meet production and environmental needs on a large scale,the preparation and implementation of land management projects are required.

5 Conclusions

Everyone knows that the reason for the natural fertility of the soil is the intake and processing of plant organic matter by living soil microorganisms and agrocenosis. Thus,the soil annually gets back the matters that are taken from it for agricultural use,as well as new nutrients obtained from soil and atmospheric air by microorganisms.

It is known that stable soil humus is restored over a very long period;so many scientists believe that natural fertility cannot be restored. However,fertility is not only a product of humus but primarily a product of biomass returned to the soil. If the soil is given insufficient quantities of organic products, the process of restoration of the humus state of soils can accelerate in the soil. There is no need to make additional fertilizers.

The soil surveys conducted in the Askinsky district in 2019 clearly show that the natural restoration of fertility is possible. Based on the results of field and laboratory studies, digital soil maps of agricultural lands were compiled. The analysis of the data shows the change in soil contours by the following indicators: the thickness of the humus horizon, the content of humus,and the influence of erosion processes on the soil cover,the content of nutrients. Askinsky district is the area with the natural restoration of soil fertility compared to areas where agricultural production is intensively carried out, and crop rotation is not observed, resulting in a decrease in soil fertility.