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сельскохозяйственные науки
MICROBIOLOGICAL CHARACTERISTICS OF CERTAIN MAJOR TYPES OF _SOIL IN BULGARIA_
Tsveta Hristeva1, Svetlana Naumova2
'Tobacco and Tobacco Products Institute, Agricultural Academy, 4018 Plovdiv, Bulgaria 2Institute of Biodiversity and Ecosystem Research, BAS, 1000 Sofia, Bulgaria Correspondence to: Tsveta Hristeva e-mail: zveta_h@abv. bg
ABSTRACT
The objective of this study was to characterize and assessed by quantitative microbiological parameters the present biological condition of some of major soil types occurring in Bulgaria. The work summarizes the results of the analyses of 70 samples collected in the period 2001-2012 from 30 sites all over the country. The soils presented belonged to: chromic luvisols in various stage of erosion; eroded humic cambisols; gleyic colluviosols; rendzinas; eutric fluvisols; gleyic phaeozems and eutric vertisols. Samples were collected in spring and summer from the humus horizon at depth of 0 -20 cm, from arable and non-arable areas, under different plant cover. Samples were processed according to the standard techniques and subjected to conventional chemical and microbiological analyses. The set of microbiological parameters was designed to comprehensively characterize the biological condition of the soil through microbial communities structure, trophic groups diversity, and their potential to perform the major transformations of carbon and nitrogen compounds in the soil. The results divided the studied soils into three groups: Gleyic colluviosols and Rendzinas were densely populated; Humic cambisols and Eutric fluvisols were moderately populated, followed by Chromic luviols; Gleyic phaeozems and Eutric vertisols were sparsely populated. Differences between arable and non-arable areas have been established. The results obtained can be used for diagnosis of the soil quality.
Key words: trophic groups of soil microorganisms; microbiological characteristics; soil types
INTRODUCTION
Serious environmental problem worldwide is the trend towards reducing the quality of soils and their natural fertility. In the modern agricultural systems, subject to the principles of sustainable agriculture paying increased attention to the quality of soil as a natural resource and a major production area (2, 5). Indicative of soil fertility are organic matter content and stocks of nutrients for plants. The fertility depends on many factors, but the main determinant of its creation, preservation and enhancement are soil microorganisms. Soil mi-crocenoses are important structural element of each ecosystem. The quantity of soil microorganisms of different ecologo - throphic groups is an important biological characteristic of soils and constitutes an integral part of modern environmental studies. Various basic biological processes related to the transformation of nutrients and important for soil fertility are depending on the activity and the normal functioning of micro-ceno-ses (1, 6, 7). In the specific physicochemical properties of a soil are formed a specific microbial communities and the ongoing processes are depending on the quantities of numerous trophic groups of microorganisms involve with similar physiological functions and performing the same biochemical processes in the soil. The contemporary understanding is that the microbiological indicators are more informative about changes in the quality of soil from the agrochemical indicators, which are more stable and remain longer, unchanged. When building systems for diagnosis and prognosis of changes in the quality of the soil, for the essential criterion has been recomended microbiological component (2, 8, 6, 9)
The objective of this study was to characterize and assessed by quantitative microbiological parameters
the present biological condition of some of major soil types occurring in Bulgaria
MATERIALS AND METHODS The present work covered the results of the analyses of 70 samples collected in the period 2001 - 2012 from 30 sites all over the country. The soils presented belonged to eutric vertisols (Northern and Southern Bulgaria); chromic luvisols in various stage of erosion (Sredna Gora, Rhodopes and Middle Struma - Ossog-ovo Provinces); eroded humic cambisols (Central and Western Rhodopes, Belassitsa Mountain,); gleyic col-luviosols and rendzinas (the Rhodopes Yaka in the Northern Chernatitsa Ridge); eutric fluvisols and phaeozems (Plovdiv Region); eroded and gleyic haplic chernozems. The determination of the types of soils have been made according to Koinov at al. (4). Samples were collected in spring and summer from the humus horizon at depth of 0 - 20cm, from arable and non-arable areas, under different plant cover (mainly tobacco). Samples were processed according to the standard techniques and subjected to conventional chemical and microbiological analyses (viable counts in various specific media). The set of microbiological parameters was designed to comprehensively characterize the biological condition of the soil through microbial communities structure, trophic groups diversity, and their potential to perform the major transformations of carbon and nitrogen compounds in the soil. The microbiological analyses were executed according to Koh's method -culture of diluted soil suspensions on specific for every trophic group microorganisms nutrient media, in three replications (3). The most probable number technique is used to estimate microbial population sizes per gram absolute dry soil (MPN/g a.d.s), with confidence level 0.05. The microorganisms of the following trophic groups were counted: autochtons - on soil extract agar
and oligotrophs - on diluted soil extract agar (connected to the humus complex); carbophils - on meat-peptone stock agar; aerobic nitrogen fixing from genus Azoto-bacter - on Ashby agar; mineral nitrogen consuming organotrophs - on starch-ammonium agar, Actinomy-cets - on starch-ammonium agar and microscopic fungi - on Chapek agar were also estimated. Two structural indices were calculated - oligotrophy index and nitrogen immobilization-mineralization index, which enlighten the accessibility of nutrients and the direction of nitrogen transformations in soil.
Agrochemical analysis of soil samples have been made - total organic carbon % (by Turin); total nitrogen content % (by Kjeldahl) and soil reaction pHH2o (by potentiometry).
0,30-r
0.25--
The statistical analysis of the data has been carried out with SPSS Statistics, using multivariate Spearman's rank correlation and cluster-analyses, using weighted pair-group average approach with Euclidian distances.
RESULTS AND DISCUSSION Clustering of the objects studied by similarity based on abiotic parameters (altitude, content of total organic carbon, total nitrogen; soil reaction) was not revealed, including of soil type (fig.1)
Resemblance by Euclidean Distance Abiotic parameters data:
30 sites, TO samples, 4 abiotic parameters (normalized)
ft, ri
X
IL
r
1
£
£
Samples
Fig. 1. Grouping the soils of abiotic parameters
The soil samples were collected from cultivated and uncultivated areas. Crops of arable land were mainly tobacco, tomato and sunflower. The vegetation cover on uncultivated land was mainly natural grass, and forest at soil type - humic cambisols.
The average data for the content of total organic carbon and total nitrogen have been showed trends to decrease at all surveyed soil types in arable land.
Table 1.
Average data of the agrochemical indicators
Soil type vegetation total organic carbon, content (%) total nitrogen content (%) pH (H20)
Eutric vertisols- arable land tobacco 3.40 0.188 7.26
Eutric vertisols - non-arable natural grassy 3.94 0.162 6.50
Chromic luviols - arable land tobacco 1.49 0.101 6.85
Chromic luviols - non-arable natural grassy 5.55 0.2795 7.81
Humic cambisols - arable land potatoes 4.06 0.210 6.76
Humic cambisols - non-arable forest /natural grassy 5.52 0.353 6.72
Gleyic colluviosols - arable land tobacco 2.01 0.123 7.52
Gleyic colluviosols non-arable natural grassy 2.62 0.154 7.72
Rendzinas- arable land tobacco 1.51 0.1845 7.7
Rendzinas - non-arable natural grassy 3.41 0.213 7.92
Eutric fluvisols - arable land tobacco 1.75 0.101 7.22
Eutric fluvisols - non-arable natural grassy 2.48 0.143 7.81
Gleyic phaeozems - arable land sunflower 4.6 0.250 7.87
Gleyic phaeozems - non-arable natural grassy 5.32 0.432 8.18
Not observed trend in changes in the values of soil reaction (Table 1). The impact of anthropogenic factor is with strength 25.34% on the content of total organic carbon and with 20.22% on the content of total nitrogen, but not statistically significant (Fexp = 4.41 and F exp. = 3.30 < F tab. 95% = 4.67).
The average values of the microbiological param- Gleyic colluviosols and Rendzinas were densely popu-eters separating investigated soil types in three groups: lated; Humic cambisols and Eutric fluvisols were moderately populated, followed by Chromic luvisols;
Fig. 2. Average population density in the microbial communities in the different soil types -MPN/g a.d.s.
Gleyic phaeozems and Eutric vertisols were sparsely populated (fig. 2).
In thus grouped soils were observed some differences between the distribution of the different trophic groups microorganisms into the microbial communities (table 2). At all soil types with the highest proportion are authochtones and oligotrophic microorganisms, which is normal for soil micro-cenoses. Autochtones there are preponderance in soils with the highest population density (Gleyic colluviosols and Rendzinas). There was an increase in the proportion of assimilating mineral nitrogen microorganisms and disbalance in the biological equilibrium between them and carbophils microorganisms, i.e. in those soils the processes to immobilization of nitrogen are intensified. Numeric expression violations in nitrogen balance are high levels of mineralization-immobilization index. At the soil type with the lowest micro-bial population density - Gleyic phaeozems are disturbed the equilibrium ratios between autochtones/ oligotrophic microorganisms and between carbophils/ assimilating mineral nitrogen also. This is an indication for reducing the content of easily digestible nutrients increased level of destruction and accelerated immobilization processes. With this type of soil is registered
the highest relative gave to microscopic fungi. The share of actinomycetes is relatively high, which is also an indicator of depletion of easily degradable and rapid mineralization of organic compounds hard degradable. In microbial communities at another soil type with low population density - Eutric vertisols the shares of groups of microorganisms show prevailing processes of nitrogen immobilization. Very high percentage of oligotrophic microorganisms was reported in microbial communities formed under soil type - Eutric fluvisols and also increase to some extent at soil type Chromic luviols which is an indication for the reduction of organic matter and destructive changes in these soils types. The shares of the other trophic groups of microorganisms at the different soil types vary. Actinomy-cetes were with highest levels in soils types - Gleyic colluviosols, Chromic luviols and Eutric vertisols, and with lowest in soil type - Humic cambisols. Bacteria aerobic nitrogen-fixing of the genus Azotobacter (Az. chroococcum) were with highest share in soils types -Chromic luviols, Humic cambisols and Gleyic colluvi-osols. They were with lowest in soil type - Eutric ver-tisols.
soil type Relative share of trophic groups of microorganisms (%) Microbiological indices
Au Ol Mf Ac Car AmN Az OI MII
Chromic luviols 24.54 23.39 0.015 4.24 16.19 11.29 6.22 1.50 0.61
Humic cambisols 44.49 29.31 0.013 0.88 15.33 5.46 4.46 0.66 0.36
Gleyic colluviosols 50.34 20.03 0.009 4.94 4.40 15.91 4.36 0.40 3.62
Rendzinas 51.06 18.18 0.005 1.10 19.33 1.39 2.33 0.36 0.38
Eutric fluvisols 16.19 48.69 0.001 1.53 20.86 9.39 2.12 2.90 0.45
Gleyic phaeozems 35.36 40.58 0.093 3.41 1.29 11.16 1.45 1.15 1.61
Eutric vertisols 26.06 14.30 0.006 1.81 13.15 43.11 0.90 0.55 3.32
Table 2.
Relative shares of trophic groups of microorganisms (%) in microbial communities and values of microbiological indices (Au -autochtons; Ol - oligotrophs; Mf - microscopic fungi; Ac - Actinomycetes; Car- carbophils; AmN - assimilating mineral nitrogen; Az - Azotobacter)
Table 3.
Quantities of of investigated trophic groups of microorganisms (MPN/g a.d.s) depending on the condition of the soils areas - arable or non-arable ((Au -autochtons; Ol - oligotrophs; Mf - microscopic fungi; Ac - Actinomycetes; Car- carbophils; AmN - assimilating mineral nitrogen; Az - Azotobacter)_
soil type Au Ol Mf Carb Assm.MN Az Ac
Chromic luviols - arable 338917851 558969652 114331 211303087 127510738 75513724 54386285
Chromic luviols - non-arable 152072172 166960064 214507 129654019 105586923 51138241 31486059
Humic cambisols- arable 1477464 7366008 73163 14742348 5304146 508201 731629
Humic cambisols - non-arable 877957134 578284751 250788 299691750 106667691 203280 17229785
Gleyic colluviosols - arable 1312359612 575996514 376178 182151569 701361835 186627330 173587861
Gleyic colluviosols - non-arable 7285714286 2469387755 51020 97297297 10270270 48648649 357142857
Rendzinas - arable 225248327 228864499 176582 188812122 179594815 58147415 56163143
Rendzinas - non-arable 6293917512 1646627012 64362 1967788039 323191165 96300502 14509090
Eutric fluvisols - arable 133489509 571107888 66835 205476098 78798871 39964589 19414646
Eutric fluvisols - non-arable 286451455 600647157 116246 407392474 231250000 7146939 14919355
Gleyic phaeozems- arable 26355308.6 37766900 65727 4253591 10372191 1069034 2842044.6
Gleyic phaeozems - non-arable 61348315 32808989 179775 18522727 12386364 2558139 4767442
Eutric vertisols - arable 20430108 73333333 43011 18494624 13548387 2365591 6021505
Eutric vertisols- non arable 413533835 164765526 65188 200501253 714285714 7593985 25062657
Variations in the quantities of the different trophic groups of microorganisms depending on the condition of the soils areas - arable or not arable have been observed without statistically proven (table 3). Generally, in all soil types, except Chromic luvisols, the average population density in the microbial communities is higher in not arable areas. At soil type Chromic luvisols the trend in the studied trophic groups of microorganisms was to increase their number, with the exception of microscopic fungi in arable areas. At Humic cambisols only the numbers of Az. chroococ-cum were higher in arable areas, . The quantities of
groups involved with the transformations of nitrogen and especially assimilating mineral nitrogen, and the microscopic fungi were higher in cultivated areas at soil type Gleyic colluviosols. At Rendzinas number of acti-nomycetes and microscopic fungi were more in arable, also.
Detected is a statistically significant relationship between abiotic and microbiological parameters (Rho 0.370 at a level of significance 0.1%) which confirms the potential of the test-microbiological parameters in determining the properties of the soils and the direction of flowing of the processes there (fig.3).
Fig. 3. Multivariante Spearman's rank correlation between abiotic and quantities of throphic groups of soil microorganisms
CONCLUSIONS
1. The results divided studied soil types, depending on the population density in microbial communities into three groups: Gleyic colluviosols and Rendzinas were densely populated; Humic cambisols and Eutric
fluvisols were moderately populated, followed by Chromic luviols; Gleyic phaeozems and Eutric vertisols were sparsely populated.
2. Differences between arable and non-arable areas have been established. In cultivated areas in Gleyic
colluviosols, Rendzinas, Chromic luviols and Eutric fluvisols have been observed reduction of organic matter and strengthened immobilization processes
3. Detected is a statistically significant relationship between abiotic and microbiological parameters in soil. The results obtained can be used for diagnosis of the soil quality.
References
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РОСТ И РАЗВИТИЕ ЖИТНЯКА ГРЕБНЕВИДНОГО НА ЗЕМЛЯХ КОРЕННОГО УЛУЧШЕНИЯ В ЗАВИСИМОСТИ ОТ РАЗЛИЧНЫХ ПРИЕМОВ _ПОВЕРХНОСТНОГО УЛУЧШЕНИЯ_
Бахралинова Айжан Сагидуловна
Докторант PhD КАТУ имени С.Сейфуллина, г. Астана Куришбаев Ахылбек Кажигулович Д.с.-х.н., профессор КАТУ имени С.Сейфуллина, г. Астана Серекпаев Нурлан Амангельдинович Д.с.-х.н., профессор КАТУ имени С.Сейфуллина, г. Астана
Стыбаев Гани Жасымбекович К.с.-х.н., доцент КАТУ имени С.Сейфуллина, г. Астана Ногаев Адильбек Айдарханович доктор PhD КАТУ имени С.Сейфуллина, г. Астана
АННОТАЦИЯ
Изучено влияние приемов поверхностного улучшения пастбищ на сроки наступления фенологических фаз житняка гребневидного, произрастающего на участке коренного улучшения возле поселков Бир-суат и Баймырза Енбекшильдерского района Акмолинской области. Рассматривались различные комбинации приемов поверхностного улучшения пастбищ, подразумевающие внесение аммиачной селитры в дозе 45 кг.д.в., суперфосфата простого в дозе 75 кг д.в. и их смеси, а также обработки дернины боронами John Deer 2600 и БИГ-3А. Наблюдения за прохождением фенологических фаз растений проводили ежедневно на каждой опытной делянке по методике проведения опытов на сенокосах и пастбищах. Было выявлено, что внесение аммиачной селитры в дозе 45 кг. д.в. в сравнении с контролем на 5-7 дней ускоряет наступление фазы кущения, но на 3-4 дня удлиняет периоды кущения-колошения.
ABSTRACT
The article shows the results of studying the influence of pasture's surface improvement methods on the dates and length of phenological phases of comb-shaped Wheatgrass grown in the radically improved area near to villages Birsuat and Baimyrza of Enbekshilder district of Akmola region. The article discusses various combinations of methods of surface improvement of pastures, implying the application of ammonium nitrate in the dose of 45 kg a.g., simple superphosphate in the dose of 75 kg a.g. and mixture of them, as well as treatment employing BIG-3A and John Deer 2600 harrows. Observation of the duration of phenological phases of plants was carried out daily on each experimental plot according to the method of conducting experiments on hayfields and pastures. It was found that the application of ammonium nitrate in the dose of 45 kg. a.g. in comparison with the control for 5-7 days accelerates the onset of tillering, but for 3-4 days extend periods of tillering-earing.
Ключевые слова: пастбище, поверхностное улучшение, житняк гребневидный, фенологические фазы.
Keywords: pasture, surface improvement, comb-shaped Wheatgrass, phenological phases.
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