Humic acids optical properties of rendzina soils in diverse environmental conditions of Serbia

This study examined the impact of climate, altitude and landforms on humic acids (HA) optical properties (E-4/E-6, Delta logK, RF indexes) in Serbian Rendzina soils. HA humification degree of calcareous and decarbonated Rendzinas under natural vegetation (forest and grassland, separately) decreased with altitude increasing. This particular rule was not manifested in arable Rendzinas. HA humification degree in Rendzinas on flat positions (hilltop and footslope) is significantly higher than in Rendzinas on slope sides. Humification degree of HA is the highest in Rendzinas in eastern Serbia (in the vicinity of Negotin), followed by central Serbia (Sumadija) and Srem, southeast and finally, southeast and southwest Serbia. With respect to the climate change foreseen for the end of this century, i.e. increase of precipitation and temperature variance among the regions in Serbia, also an increase in variance of quality of humic acids in Rendzinas on different altitudes and regions can be expected

Influence of environmental conditions on carbon and nitrogen content in Serbian rendzina soils

Organic matter in Serbian Rendzina soils dependence on altitude and geographic regions was investigated. There was no regular dynamics of carbon and nitrogen content nor in C/N ratio, probably because of slight climatic variation among altitudes and regions, thus negligible differences in vegetation, organic litter and decomposition dynamics. Predicted climatic changes, uneven for regions, will exert a complex influence on soil C and N storage. These results should be used as a base for future monitoring of C and N content in Serbian Rendzina soils and their dependence on climate

Humus composition of rendzina soils in different environmental conditions of Serbia

This paper shows organic matter composition (humic acids, fulvic acids, humins) and fractions of humic (free and bounded with mobile R2O3 (HAI), bounded with Ca (HA2), and bounded with clay and stabile R2O3 (HA3)), and fulvo acids (free and bounded with mobile R2O3), bounded with HA1 bounded with HA2, and bounded with HA3), in Rendzina soils on different altitudes (151-1210 m), landforms (hilltop, flat or very gentle slope; foot slope, very gentle slope, south, southwest; slope 45-80 degrees, south, southeast, southwest; slope 20-60 degrees, north, northwest, northeast), and regions (Srem, west, central, east and southeast Serbia). Differences in temperature and water regimes of Rendzinas on various altitudes are not so prominent to have a significant impact on organic matter composition. Landform has more significant impact, with average higher content of HA on slopes, and FA on flat positions, which could be attributed to reduced wetting of soils on slopes. Exposition had no significant impact on humus composition. Differences in soil moisture among regions are more pronounced than differences in soil temperature. Differences in soil organic matter composition among Rendzinas from various regions are small and do not follow pattern of humidity change. Still, organic matter of Rendzina from most humid western region has the least favourable HA/FA ratio, while at the driest east and southeast regions content of humin is the greatest

Uticaj procesa izluživanja i načina korišćenja rendzina na stepen humificiranosti huminskih kiselina

The humification degrees of humic acids extracted from calcareous and decarbonated Rendzinas under different land use were characterized upon their optical properties, to evaluate the influence of carbonate leaching (decarbonation) and different land uses. Decarbonation influenced the humification degree of humic acids positively. Base leaching and acidification of decarbonated Rendzinas led to a decrease in humification degree of humic acids. In calcareous Rendzinas, the humification degree of humic acids was in descending order: grassland>arable land>forest land, and in decarbonated Rendzinas: arable land>grassland>forest land. The humification degree of humic acids was higher in the calcareous forest and grassland Rendzinas compared to decarbonated Rendzinas, analogously in decarbonated arable land compared to calcareous arable land Rendzinas. Differences in the humification degree of humic acids among various land uses that emerged between calcareous and decarbonated Rendzinas indicate the dominant influence of soil chemical characteristics (carbonate content and pH value) compared with the quantity and quality of the organic litter input.Prema domaćoj klasifikaciji, rendzine su zemljišta sa moličnim A horizontom koji postepeno prelazi u rastresiti karbonatni C horizont. Primarno su karbonatna, i njihova evolucija teče u pravcu izluživanja pa zatim posmeđivanja. Najčešće su pod prirodnom šumskom i travnom vegetacijom, manji deo njih se obraduje. U ovom radu su ispitivane optičke osobine huminskih kiselina zemljišta tipa rendzina, a istraživanja su imala za cilj praćenje posledica izluživanja i promene načina korišćenja ovog tipa zemljišta u Srbiji na stepen humificiranosti huminskih kiselina. Priprema rastvora huminskih kiselina za VIS spektroskopiju izvedena je metodom Kononove. Karakterizacija optičkih osobina huminskih kiselina je data preko optičkih indeksa: E4/E6, ΔlogA i RF. Rezultati su obrađeni u programu StatSoft, Inc. Statistica, Version 8. Proces izluživanja je pozitivno uticao na stepen humificiranosti huminskih kiselina u rendzinama (najveći je pri neutralnoj reakciji). Dalja debazifikacija i acidifikacija izluženih rendzina uticala je negativno, odnosno dovela do smanjenja stepena humificiranosti huminskih kiselina. Stepen humificiranosti huminskih kiselina u karbonatnim rendzinama se kretao travnjak>njiva>šuma, a u izluženim rendzinama njiva>travnjak>šuma. Huminske kiseline karbonatnih rendzina pod šumom i travnjakom su imale veći stepen humificiranosti u poredenju sa izluženim rendzinama pod šumom i travnjakom. U izluženim rendzinama pod njivom stepen humificiranosti huminskih kiselina je bio veći nego u karbonatnim rendzinama pod njivom. Razlike u stepenu humificiranosti huminskih kiselina prema načinu korišćenja koje su se pojavile između karbonatnih i izluženih rendzina ukazuju na dominantan uticaj hemijskih karakteristika zemljišta na osobine huminskih kiselina u poredenju sa količinom i kvalitetom organskih ostataka koji dospevaju u zemljište

Classification of Rendzina soils in Serbia according to the WRB system

According to soil classification system used in Serbia (Škorić, Ćirić and Filipovski, 1985) Rendzina is a soil type within the order of automorphic soils and the class of humus-accumulative soils with an Amo-AmoC-C-R profile, which is developed on parent rock containing more than 20% of calcareous material. Rendzinas are divided onto subtypes - according to the parent material: (i) marl, marly limestone and soft limestone, (ii) loess and loess like sediments, (iii) dolomite sand, (iv) moraine; on varieties - according to stadium of evolution: (i) calcareous, (ii) decarbonated, (iii) brunified, (iv) colluvial, and forms - according to texture and coarse fragments content. Throughout the world, the term Rendzina (and Pararendzina) is used to denote soils formed on different calcareous parent material and it generally corresponds with Rendzic Leptosol of the WRB soil classification system. Rendzinas on marl, marly limestone and soft limestone is the most widespread subtype in Serbia, and the aim of this study was to precisely classify it according to the WRB 2015 system. Total of 29 Rendzina soil profiles from different parts of Serbia were studied. Field and laboratory investigations (soil depth, colour, coarse fragments, texture, structure, pH, soil organic carbon, base saturation) were determined using methods recommended by the WRB system (except for base saturation, where BaCl2, pH 8.1, was used instead of NH4OAc, pH 7). According to soil classification system used in Serbia, from total of 21 soil profiles on soft limestone, 16 were calcareous variety (form: 8 loamy, low or medium skeletal and 1 clay, medium skeletal); 13 decarbonated variety (loamy, low skeletal); and 2 colluvial variety (loamy, low skeletal); and 8 profiles on marl of which 7 were calcareous variety (loamy, low or medium skeletal), and 1 profile was decarbonated variety (loamy, low skeletal). According to WRB 2015 system, investigated Rendzinas were classificated to RSG of Leptosols (12 profiles), Regosols (10 profiles) and Phaeozems (7 profiles). Leptosols include Rendzinas with A-R soil profile, where continuous rock (10 profiles on soft limestone and 2 profiles on marl) starting ≤15-25 cm from the soil surface. For calcareous Rendzina variety, combinations of the principal qualifiers were: Rendzic, Rendzic Calcaric, and Skeletic Calcaric. The decarbonated variety matched the diagnostic criteria for the Eutric principal qualifier. The supplementary qualifiers for Leptosols were Loamic or Clayic, Aric and Humic. Renzinas deeper than 25 cm, usually with A-AC-R soil profile, having a mollic diagnostic horizon were classified to RSG of Phaeozems. For calcareous Rendzinas variety, combinations of the principal qualifiers were: Rendzic Calcaric or Rendzic Skeletic Calcaric. The decarbonated Rendzinas variety only matched criteria for the Leptic principal qualifier. Loamic and Aric supplementary qualifiers were added to Phaeozems. RSG of Regosols includes Rendzinas thicker than 25 cm, usually with A-AC-R soil profile, when surface horizon does not match diagnostic criteria of a mollic horizon (in slightly crushed samples a Munsell colour value of ≥3 moist, and ≤ 5 dry, and a chroma of ≥4 moist). Surface horizons were more than 20 cm deep (except for 2 profiles) and had over 0.6% (1.1-4.6%) soil organic carbon. For calcareous Rendzinas variety combinations of the principal qualifiers were: Leptic Calcaric or Leptic Skeletic Calcaric. For Colluvial Rendzinas variety (all calcareous) combination of the principal qualifiers was: Leptic Colluvic Calcaric. Loamic and Aric and/or Humic supplementary qualifiers were used for Regosols. Soil depth caused the first differentiation between Leptosols and Phaeozems, and soil (moist) colour caused the second differentiation between Phaeozems and Regosols. Somewhat brighter soil colour of Rendzina/Regosols is a result of low soil organic matter content and/or high content of calcaric material in the fine earth

Uticaj načina korišćenja na vodne karakteristike planosola (južna Mačva i Pocerina, Srbija)

Water holding capacities and saturated hydraulic conductivity of Planosols in south Mačva and Pocerina (Serbia) were compared to assess how different types of land use (forest, arable and grassland) influence soils endangered by stagnating water. These changes came from decrease of total porosity and changes in pores size distribution in arable and grass land compared to forest land. Changes of water characteristics of arable and grassland Planosols compared to forest Planosols were statistically most significant in illuvial horizon Btg (absence of root network and fauna activity). It is important to emphasize: (i) surface A horizon of arable and grass land compared to forest showed insignificant increase of plant available water and significant decrease of saturated hydraulic conductivity (ii) significant decrease of saturation and macro porosity increased the risk of oxygen deficiency in Planosols in wet periods of year in this order: arable land > grassland > forest.Cilj rada je utvrđivanje promena u vodnim kapacitetima i vodopropusnosti planosola na području Mačve i Pocerine zbog pretvaranja šuma u travnjake i njive. Promena načina korišćenja značajno je uticala na vodne kapacitete, ali ne i na vodopropusnost. Generalno u poređenju sa šumama, u njivama i travnjacima je došlo do smanjenja MVK i povećanja vrednosti PVK, LVK i VV. Navedene promene su posledica smanjenja ukupne poroznosti i promene diferencijalne poroznosti. Promene u njivama i travnjacima su najznačajnije u Btg horizontu (odustvo korenovog sistema i faune), zatim u A horizontu (smanjenje korenovog sistema, aktivnosti faune i sadržaja humusa), a najmanje u Eg horizontu (manja promena poroznosti zbog nestrukturnosti). Sa agroekološkog aspekta je važno istaći da u A horizontu njiva i travnjaka u poređenju sa šumama povećanje KPV i smanjenje SHC nije značajno; značajno smanjenje MVK i makroporoznosti povećava rizik od nedostatka kiseonika u vlažnom delu godine ovim redom: njive > travnjaci > šume

Humic acids in the environment

Humic acids, belonging to the humic substances, are the most reactive organic compounds in water, soil and sediments. They are known for their role in processes related to soil structure, biology, and chemistry, as well as for their effects on the behavior of environmental pollutants. The effects of humic acids on the environment are strongly influenced by their composition and structure. Humic acids are used in various fields, especially in agriculture, environmental remediation and medicine. Agricultural fertilizers containing humic acids as additives are often used to improve plant growth and soil fertility. The content of heavy metals, metalloids, radionuclides and various organic pollutants can be reduced by adsorption, complexation, and redox processes involving humic acids. Owing to the ability of humic acids to form composites with inorganic and organic oxides, pollutants are adsorbed and removed from water. In addition, the composites formed exhibit pronounced antibacterial activity in water. Various organic pollutants such as pesticides, microplastics and antibiotics can also be removed from soil and water by adsorption on the composites or humic acids. Various viruses with positively charged glycoproteins can be bound by the negatively charged humic acids, defining them as antivirally active. Currently, the humic acids are isolated from various matrices such as coals, peat and organic wastes. Due to the increasing requirements for the commercial applications of humic acids, their production and utilization are significantly important and trendy tasks. The humic acid production with the higher yield is the focus of research toda

Land use impact on soil structure of Pseudogleys in southern Mačva and Pocerina, Serbia

The impact of various types of uses of Pseudogley soils in southern Mačva and Pocerina on theiraggregate distributionand stability was studied on soil samples collected from profiles under forest, meadow and arable land, at three localities. The aggregate composition and stability were determined by Savinov’smethod. The soil structure was assessed by using Revut’s coefficient of soil structure (Ks) and Vershinin’s coefficient of soil aggregate structure (KA). The results show that the studied Pseudogley soils are characterized by an unfavorable structure, while the type of land use has a significant impact on the aggregate composition and stability, especially in surface Ah and Ahp horizons, where these differences are the most pronounced. The most favorable aggregate composition and highest wet-stability are found in Pseudogley profiles under forest vegetation. The aggregate distribution of meadow profiles was intermediate and of arable land the poorest. Statistical analysis of the collected data shows that Ks values, determined by dry sieving, were the highest in forest profiles (2.261.21 on average), while the values for meadow were 1.591.09 and of arable land 1.140.62. The values of KA, used to assess the aggregate stability to water, also show that forest Pseudogleys have the highest average values (2.051.03), followed by meadow (1.96 0.99) and cultivated soils (1.931.22). The results of correlation analysis indicate that Ks is negatively correlated with clay, pH value and base saturation, but positively correlated with soil humus (r=-0.77, -0.70, -0.81 and 0.79, respectively, p<0.01). Conversely, KA is negatively correlated with humus and positively correlated with clay, pH value and base saturation (r=-0.21, 0.82, 0.69 and 0.69, respectively, p<0.01)

Self-aggregation of soil humic acids with respect to their structural characteristics

The main goal of this work was to estimate the influence of carboxyl and phenolic groups, as well as aromatic, aliphatic and polysaccharide components, on the soil humic acids (HA) self-aggregation process. Soil HAs (leptosol and regosol) were separated using base resin getting fractions with different functional group contents. Blocking of carboxyl groups was performed using the esterification procedure to estimate the participation of each functional group in the HA aggregation. The presence of HA structural components was evaluated by potentiometric titration and ATR-FTIR. The aggregation was monitored at pH 3 using dynamic light scattering. Results indicated that the higher group content, the HA aggregation is less pronounced. A significant positive correlation of aliphatic C and aggregate size revealed their dominant influence in the HA self-aggregation. A lower abundance of aliphatic C in HA fractions could be considered as not sufficient to start the process. An increase of aromatic C in esters likely pointed out to its participation in hydrophobic bonding and, consequently, more pronounced aggregation. The relation of HA self-aggregate size with carboxyl and phenolic group, as well as aliphatic C, at low pH, could be considered universal regardless of the structural characteristics of the original or modified HA forms

Land degradation neutrality in Serbia

Land degradation neutrality (LDN) is defined as a state whereby the amount and quality of land resources necessary to support ecosystem functions and services and enhance food security remain stable or increase within specified temporal and spatial scales. This concept is a part of sustainable development goal 15 of the UN Agenda for Sustainable Development. Target 15.3 aims to combat desertification, restore degraded land and soil, including land affected by desertification, drought and floods, and strive to achieve a land degradation-neutral world by 2030. The achievement of this target is measured through indicator called “Proportion of land that is degraded over total land area”. United Nations Convention to Combat Desertification (UNCCD) endorsed SDG target 15.3 and the concept of land degradation neutrality as a strong vehicle for the implementation of the Convention. Countries are invited to formulate voluntary targets to achieve LDN. UNCCD provide guidance for formulating national voluntary targets and facilitate utilization of the UNCCD indicator framework. Republic of Serbia has ratified Convention in 2007 and actively works on LDN target setting process. This paper aims to present: (a) the basic principles of LDN concept, (b) global datasets provided by UNCCD, (c) SWOT analysis for the country, and (d) to discuss possible national datasets and further activities related to LDN. Indicator “Proportion of land that is degraded over total land area” is measured by means of three subindicators: land cover, land productivity and soil organic carbon. This indicator framework could be broaden with national indicators by decision of the country. Country has been provided by global data on land cover from European Space Agency (ESA). Land productivity dynamics (LPD) dataset was prepared by Joint Research Centre of the European Commission, while soil organic carbon (SOC) dataset was provided by ISRIC. Watershed boundaries are provided from FAO GAUL network. Net area change as a result of comparison between two periods for land covers change and SOC, while LPD is obtained as a trend for the 15 years period. ESA land cover data are given for the two epochs, around 2000 and 2010. These data indicate the loss of 3,800 ha of forests and their conversion to croplands or shrubs. National datasets on land cover exist but their utilization is constrained with the necessity to have dataset for two period of time and to have regular acquisition of future data which are necessary for further analysis and monitoring. Land productivity dynamics data indicated that 5% of the Serbian territory has negative trends in land productivity for the period 1998-2013. There are no national data on LPD obtained according to LDN concept. Soil organic carbon for the country indicates average content of 82.2 t/ha. National data on SOC stocks exist in the databases of relevant institutions but the problems in their utilization are related to the fact that they are sometimes very old, rarely geo-referenced, and obtained by various analytical and terrain procedures. Hence, global data on SOC stocks do not present real country situation, while national SOC stocks data should be systematized to be confident. Indicator analysis at watershed level has recognized the watersheds of Great Morava, Tisa, Sava 3 and South Morava and Nisava rivers, as four watersheds which present 50% of degraded areas according to the proposed methodology. These watersheds should be prone to detailed analysis of around 20 potential hotspots are found in the country. LDN baseline is not yet decided on a country level. Global land cover and land productivity dynamics data will be used until we obtain national data for these indicators. SOC national data should be systematized and used instead of global data. Further activities in LDN target setting process are related to the establishment of LDN baseline, analysis of land degradation trends and drivers, and suggestion of possible national voluntary targets and associated measures at the country, local and/or watershed level. The inclusion of national indicators should be further discussed. LDN concept should be strongly lead by the Government of Republic of Serbia. Hence, Serbian UNCCD NAP document should be finalized, adopted by the Government and LDN embedded into the NAP