Bulgarian Journal of Soil Science

81-89

Authors: Kameliya Petrova

Dystric/eutric Cambisols diagnostic features from TEFR Petrohan were investigated in the present study, which morphologically corresponded to Podzols. Diagnostic horizons were investigated to establish presence or absence of podsolization process and to classify the soil type according to the modern requirements of WRB, (2006, 2007; 2014). Humus forming process insitu, clearly expressed in the Ah horizon, acidification, degradation of clay minerals, formation of E horizon, which is clay-poor with increased content of sand, accumulation of Fe and other mobile elements in Bw horizon were established. The metamorphic Bw horizon had some diagnostic properties, which met these of spodic horizon. This horizon is specific for the Podzols. The content of organic carbon in it was less than 0.5 %. Cambisols properties are predominant.It was established that the soil-forming process in the investigated Cambisols is directed to podsolization process.

104-118

Authors: Marija Galic, Milan Mesic, Aleksandra Percin, Ivana Sestak, Zeljka Zgorelec

This field study shows how different crops and soil treatments with different nitrogen fertilization levels affect sulphur balance. Sulphur deposition, leaching through soil and water seepage, availability and uptake by crops, effects on crop yield and losses were investigated. The research was conducted on a field trial from 1996 to 2014 in temperate continental climate on Stagnosols. The soil was treated 10 times with mineral nitrogen fertilizers in an ascending doses from 0 to 300 kg N ha-1 and additional two 250 kg N ha-1 treatments, one with phosphogypsum and one with zeolite tuff and CaCO3. Drainpipes and lysimeters were installed to collect water samples and measure the effects of N doses, amendments and precipitation on sulphur losses. Average annual sulphur losses were from 4.9 to 68.7 kg ha-1 through drainage water, and from 1.5 to 24.9 kg ha-1 through lysimeter water. Depending on a crop, year and yield, average crop losses ranged from minimal 2.8 kg ha-1 in winter wheat up to 17.6 kg ha-1 in oilseed rape. Average total S content in soil varied from 882 to 1764 kg ha-1. Overall agroecosystem S balance between input and output, calculated for all crops and all treatments was positive only in the treatment with phosphogypsum for winter wheat, corn and oilseed rape. Water shortage in 2011 caused positive S balance for soybean in other treatments too, not only in the treatment where phosphogypsum was applied.

134-142

Authors: Zorintsa Mitreva, Veselin Pankov

Areas facing natural constraints represent a serious obstacle for Bulgarian farmers and to a great extent limit their development. In this regard, it is necessary to look for alternative options for optimal use of these areas so that they are as efficient as possible despite the limitations they have. The paper presents the basic requirements of lavender in terms of climatic and soil conditions. There is also a soil and climate characterization of a village located in area of high altitude - the land of the village of Borika, Sofia in order to be able to indicate which soil types in the Borika land are best suited for lavender growing.

4 - 12

Authors: Tsetska Simeonova, Maya Benkova, Lyuba Nenova, Irena Atanassova

The cationic and anionic composition, i.e. K +, Na+ , Ca2+, Mg2+, Cl- , NO3 -, phosphates,SO4 2- and dissolved organic carbon (DOC) in soil solutions of Technogenic soils (Technosols)from the area of Maritsa-Iztok coal mine basin in Bulgaria was analyzed and links with overburden strata were discussed. Two sites are located at the Mednikarovo village with humus and non- humus reclamation under grass vegetation. The other two are situated near the village of Obruchishte (non-vegetated and pine-vegetated). The sites differ in their textural composition, physico-chemical and hydro-physical properties. It was found that major cations and anions in the soil solutions at Mednikarovo site did not exceed the maximum permissible concentration limits (MPCL) for drinking water, while in solutions from the Obruchishte Technosols, composed of black clays intermixed with coal ash maximum permissible concentrations of sulphate (250 mg.l -1), phosphate (0.5 mg.l-1 ), calcium (150 mg.l-1 ) and magnesium (80 mg.l-1 ) were exceeded and may pose a threat to contamination of surface and sub-surface water of reclaimed soils.

27 - 33

Authors: Alexander N. Sadovski

The paper traces the emergence and development of the problem of scheduling irrigation as a scientific and practical issue at the Institute of Soil Science "N. Poushkarov" for half a century. The main participants in this process and the leading scientific publications are noted.

48 - 62

Authors: C.M. Ahukaemere, N.S. Obasi

Land capability classification (LCC), fertility capability classification (FCC) and land suitability evaluation of some soils of Ebonyi State were carried out for cassava, yam and maize cultivation. Land capability and fertility capability classes were obtained using the method of United State Development of Agriculture (USDA) while suitability evaluation was done using the Food and Agricultural Organization of the United Nations’ (FAO) conventional method. Four (4) pedons were investigated, two from Akaeze (Asu river group)and two from Abakaliki (Asata nkporo shale) . Results of LCC showed that sites 1 and 2 (Asu river group) were classified as class II soils while sites 3 and 4 (Asata nkporo shale) were classified as class IV soils. According to FCC results, the major classes obtained were SM,g,k for site 1, A,g,k for site 2 and SA,e,k,r for sites 3 and 4 respectively. The results of land suitability evaluation showed that despite climatic factors and topography, there was no highly suitable (S1) land for maize, yam and cassava cultivation. Total nitrogen and organic carbon contents of pedons 1, 2 and 4 were marginally (S3) suitable for the production of yam and cassava while the nitrogen and organic carbon contents of pedon 3 were currently not suitable (N1) for yam and cassava cultivation. Soil texture, pH, ECEC and available phosphorus made the 4 sites moderately suitable (S2) for cassava and yam cultivation. Also, the acidic condition of the soils made all the sites moderately suitable for maize production. From the results of the aggregate suitability ratings, the major constraint for yam, cassava and maize cultivation in the sites was soil fertility (f) resulting from low organic carbon and total nitrogen contents of the soils. Though not optimum for the cultivation of the crops evaluated, the soils can still produce increased and sustainable crop yield if the appropriate husbandry practices are adopted, with particular reference to organic and nitrogen fertilizer application.

89-98

Authors: Metodi Teoharov, Biser Hristov

The article discusses the relationship between soils, land modern man and his concern and responsibility for sustainable land management. The main problems, which limit the rational use and protection of land are analyzed and also on the first place among them the improper and unfair distribution of fertile soils and lands, and the resulting problems on a different nature – geographic, demographic, ecological, food consumption and social onece The significance of the triadic paradigms "soil-land-people", "capital-labor-science" and "wisdom-harmony-prosperity" is noted as well as the maxims that oblige us to work on them. It is also emphasized that soils in Bulgaria are subject to natural, anthropogenic and technogenic pressures. Problems are outlined which are related to arable land, recommendations, guidelines and critical assessments of the soil scientists and the European institutions (European Parliament and European Commission on Agriculture and Development of Rural Areas) concerning the organization and management of soil and land resources.

106-111

Authors: Radoslava Lazarova, Ivanka Yordanova, Donka Staneva

The content of natural radionuclides 40K, 235U, 238U, 232Th and 226Ra in soils from two regions of past uranium mining in Bulgaria were determined and analyzed and results of radiation monitoring summarized. Soil samples from three other regions in the country: North Bulgaria - plane region (around “Kozloduy” Nuclear Power Plant and the Danube River) – 40 samples; semi-mountainous - (Sofia field) – 5 samples and South Bulgaria – mountainous (Rhodope massif) – 25 samples, were analyzed for comparison. Evaluation of possible radiation hazard to the population in the respective regions was made by calculatingthe average radium equivalent activity (Raeq) and the external hazard index (Hex). It was found that content of natural radionuclides in the studied soils, both plain and mountainous, is within normal background levels and is not hazardous to the population.

123 - 132

Authors: Biser Hristov, Ivona Nikova, Nataliya Andreeva

The loess in the Danubian plain is rich of nutrients and there is situated the south border of so called ―corn belt of Europe‖, where are the most fertile soils of Balkan Peninsula. There are five main typical soil types spread over loess - Chernozems, Phaeozems, Kastanozems, Regosols and Calcisols. There is also a big diversity in the content of basic nutrient elements – it varies between low and high content of organic carbon and mobile forms of nitrogen, phosphorous and potassium. As a whole there is shortage of phosphorus in all soil types. Soils over loess are characterized by a surface layer that is rich in organic matter, minerals and nutrients with abundant natural grass vegetation and high fertility soil types such as Chernozems, Phaeozems and Kastanozems. Eroded and shallow soils such as Regosols and Calcisols have low quantities of major nutrient elements as mobile nitrogen, phosphorus, and total organic matter, consequently their fertility is low.

4-17

Authors: Metodi Teoharov

The present study includes a detailed analysis on the past, present and future of the soil science in the Bulgaria and over the world. Soil science entered in the cycle of scientific discipline serving practice when in 1883 the famous Russian scientist V.V.Dokuchaev established regularities of soil formation. Since then it has emerged as an important branch of biological science and it has become a science of undoubtedly great for public importance. There are different periods how it was developed in Bulgaria and it the rest of the world. In third period is examined Vernadski‟s concept of the Noosphere and relationship with soil science and how „‟the thoughtful layer of the planet” can repairs the consequences of the Technosphere and Anthropocentris.

32-41

Authors: Vladimir Ilinkin, Simeon Bogdanov, Antonia Goleva

The paper presents results from an investigation on soils located in the Ludogorie region. Rendzinas (Rendzic Leptosols, FAO, 2006) have been studied. They are situated in the Lower forest vegetation zone (0–600 m a.s.l.) of the Moesian forest vegetation area. Soil samples have been taken from seven soil profiles. The study covers an area of 3000 m2 . The factors of soil formation have been characterized. Soil physical and chemical properties have been investigated. The results have been processed by a statistical programme. The arithmetic means (M) and standard deviations (±SD) have been calculated. The studied soils are characterized by favourable physical properties, e.g. water-resistant crumb and granular structure, porosity and bulk density Their low supply of plant available water is due to the high permeability of the parent material. The tendency of calcium to form complex insoluble compounds with humic substances (Knežević & Košanin, 2010) is a prerequisite for reduced accessibility of N and humus, although are not in low contents. The calcium content is naturally higher given the specific features of the parent material. Antagonism between the ions of Ca and К, Ca and Mg (Jorova, 1995) is a prerequisite for reduced accessibility of К and Mg, although, soil texture with a predominant presence of silt and clay, allows for higher nutrient content than that of other primitive soils.

53-74

Authors: Md Toufiq Iqbal

Biochar is a carbon-rich co-product resulting from pyrolysis process. Biochar amendment to soil can improve productivity of wheat plant. Therefore, the utilization of biochar in improving yield of wheat in Bangladesh was investigated in this study. Soil pH decreased 0.8 units and organic matter increased 0.67% after 159 days of incubation for the biochar amendment. Several yield parameters was similar between Bangladesh Agricultural Research Council (BARC) recommended fertilizer and half of BARC recommended fertilizer plus rice straw added treatment. This study also found that the combination of rice straw biochar with half of BARC recommended fertilizer gave better effect than single application rice straw biochar as well as gave the highest yield of wheat in the same treatment. Rice straw biochar can have the potential to decrease dependence on chemical fertilizer for wheat production. Therefore, utilization of biochar is a viable option to improve yield of wheat in Bangladesh.

104-111

Authors: Biser Hristov

The paper deals with physico-chemical properties of Regosols in Bulgaria. Ten soil profiles are studied in North and South part of the country. These soils are spread mainly on unconsolidated rocks (regolith), slopes and eroded terrains in semi-arid areas. Sediments in these areas are manly alkaline with good sorption capacity. Regosols are moderately acidic to slightly alkaline soils. Exchangeable Ca2+ is almost equal to the soil cation exchange capacity. The amount of exchangeable Ca2+ is between 8 to 26 mequ/100g. Regosols have high base saturation from 75 to 100 %

122-139

Authors: Venera Tsolova, Ivona Nikova, Biser Hristov, Kalin Ruskov, Alexandar Zdravkov

The content of Si, Al, Fe, Ti, Mn, Mg, Ca, Na, K, S, P, C, Cu, Pb and Zn were determined in order to reveal geochemical patterns of soils in the Bobov dol valley, Bulgaria. Since the Bobov dol Thermal-electric Power Plant (TPP) is situated in the valley this paper pays attention to the geospatial distribution of Cu, Pb, and Zn due to their diverse vital significance. Elements assemblages and geospatial distribution pathways are also discussed in the light of the past 40 years of operation of the Thermal Power Plant. According to the results obtained the average content of Cu (27.04 mg kg-1 ), Pb (21.96 mg kg-1 ) and Zn (57.95 mg kg-1 ) is higher than the average content of elements in local soil parent rocks: Cu (20.03 mg kg-1 ), Pb (6.07 mg kg-1 ) and Zn (46.60 mg kg-1 ). Compared to the precautionary threshold concentrations adopted for assessing the soil contamination in Bulgaria the elements contents are lower including their maximum values. However, the geoaccumulation indexes reveal an initial stage of contamination of soils with Pb. Lead tends to follow a separate mode of geospatial distribution which is controlled by both the geogenic factors and the aerosol emissions of TPP. Copper accumulation is more strongly affected by technogenic depositions and dominated in urban and technogenic zones under the form of oval spots. Konyavska Mountain is the domain of Zn revealing an altitudinal gradient of distribution. Its accumulation proceeds slowly in topsoil, but still, Zn is the most abundant element in studied soils from the Bobov dol valley. The petrogenetic pattern of geochemical suits still predominated in studied soils wherein the iron has the greatest affinity for studied elements. Soil medium reaction (pH) and organic carbon do not control the processes of distribution and accumulation of Cu, Pb and Zn. The lack of statistical correlation with organic carbon resulted from the siliciclastic nature of soil parent rocks and also reveals the prevailing geogenic origin of studied elements.

147-153

Authors: Zornitsa Mitreva, Veneta Krasteva,Veselin Pankov

Method is developed for the field rating of main soil characteristics that define the suitability for growing emmer and einkorn wheat. Soil texture of the fallow land, depth of the humus horizon, depth of the soil profile, texture differentiation of the soil profile, soil reaction, humus content and groundwater level have been evaluated. The method is harmonized with the officially accepted in Bulgaria parametric methods of the system of field ratings and the categorization of the agricultural lands. The end result is an evaluation of the soil conditions and a soil rating.

170-186

Authors: Zornitsa Popova

Water distribution could be quite non-uniform along the furrow length under surface irrigation. This “down field” disuniformity is usually combined with “inter-row” nonuniformity of irrigation water and nitrogen fertilizer distribution. Spatial variation of application depth and nitrogen (N) fertilization rate in the furrow plot produces yield, drainage and nitrogen losses. In addition to that, due to year-to-year variability of climate, regional irrigation depths range significantly (from 0 to 360 mm/season in the studied field). The objective of this paper is to study the impact of global nonuniformity of irrigation water and N fertilizer distribution within a furrow plot on yield, water and nitrogen losses when climate variability is taken into account. Six maize vegetation seasons with contrastive probability of exceedence of irrigation depth PI are considered. Irrigation water is distributed according to six scenarios for “downfield” and “inter-row” non-uniformity by using the validated FURMOD model (Popova, 1990; 1992; Popova and Kuncheva, 1996). Nitrogen fertilization broadcast corresponds to two scenarios of lateral non-uniformity. The validated CERES-maize model (Jones and Kiniry, 1986;Gabrielle et al, 1995; Popova et al.1999; 2001- b; Popova and Kercheva, 2005) is applied with the different “climate-irrigation nonuniformity-fertilization nonuniformity” scenarios to simulate water&nitrogen cycle and crop growth on a daily basis in 30 representative points along “median”, “high intake” and ”low intake” furrows of the set. It is established that yield, water and nitrogen losses vary over uniformity scenarios and studied 30-year period. Combination of non-uniform irrigation/N-fertilization with the high irrigation demand seasons (having probability of exceedance PI<11%) causes losses of yield by 2 to 14.5 % of potential maize productivity, irrigation water (up to 40-45% of applied depth) and nitrogen (up to 10-12% of N-rate). Model runs show that poor distribution uniformity of irrigation water and N fertilizer should be maintained especially in the case of high irrigation requirements. Different strategies aiming at reduction of heterogeneity sources of “inter-row” and “down-field” uniformity of water distribution and fertilizer broadcast are recommended.