Maja Manojlović

Long-term effects of agronomic practices on the soil organic carbon sequestration in Chernozem

The study was based on data from selected long-term field trials established at the Experimental Fields of the Institute of Field and Vegetable Crops, Novi Sad (Serbia). The effect of tillage systems on SOC concentration and SOC stock was most pronounced at 0–10 cm depth. In a 0–40 cm soil layer, in a 7-year period, no-till (NT) sequestrated 863 kg SOC ha−1 yr−1 more compared to moldboard plow tillage (PT), while the effects of disc tillage (DT) and chisel tillage (CT) were not significantly different. Unfertilized three-crop rotation (CSW) compared to two-crop rotation (CW) enhanced SOC storage in a 0–30 cm soil layer by 151 kg C ha−1 yr−1 in a 56-year period. Within fertilized treatments, SOC concentration was highest under continuous corn (CC). Mineral fertilization (F) non-significantly increased the SOC stock compared to no fertilization in corn monoculture in a 32-year period. The incorporation of mineral fertilizers and harvest residues (F + HR) and mineral fertilizers and farmyard manure (F + FYM) sequestered 195 and 435 kg C ha−1 yr−1 more than the unfertilized plot, respectively, in a 0–30 cm soil layer, in a 35-year period. Irrigation did not significantly affect SOC sequestration.

Fertilization Economy in Organic Lettuce Production

In a field experiment on a farm registered for organic production, we studied the economic profitability of the application of different organic materials (farmyard manure, FYM; guano, G; soybean meal, S, and forage pea meal, P) in lettuce production. The highest fertility costs per unit of N were found with the P treatment (6.22 € kg N−1), and the lowest with the FYM treatment (0.8 € kg N−1). Due to the application of organic materials, the highest additional profit was made with the FYM treatment (1289 € ha−1), and the lowest with the P treatment (729 € ha−1). If the farm does not have manure at its disposal, with current market prices, the economically most sound application is soybean meal and forage pea meal.

Chemical speciation and bioavailability of Cd, Cu, Pb and Zn in Western Balkan soils

Abstract Three thermal power plants in Serbia, Croatia and Bosnia of the Western Balkan region were expected to be metal polluting sources, and this study was performed to investigate the bioavailability and chemical speciation of trace metals in soils and soil water extracts, respectively. Surface (0–15 cm) soil samples along with maize and grass samples were collected at a gradient from the pollution source. The chemical speciation of metals was conducted using the Windereme Humic Aqueous Model (WHAM)/Model VI for water, whereas the Diffusion Gradient in Thin Films (DGT) technique was used to estimate plant availability. The chemical speciation indicated that more than 99% of all four metals in soil water extracts were complexed to fulvic acid. This is connected to relatively high soil pH (> 6.5) and high contents of soil organic matter in these soils. The accumulation of trace metals by DGT was not correlated to plant uptake. This is connected to the very low partitioning of free ions in solution, but also to the low variation in metal solubility and metal concentration in plant tissue between sites. In spite of active thermal power plants located in the areas, hardly any differences in concentration of soil metals between sites were seen and the partition of metals in soil waters was insignificant. The latter indicates that these soils have a large metal-retaining capacity. The only significant soil chemical variable affecting the variation in metal solubility was the soil pH. In a time with large infrastructure and industrial expansion in these areas, this investigation indicates the importance of protecting these high-quality soils from industrial use and degradation. High industrial activity has so far had insignificant effect on soil quality with respect to bioavailability of trace metals in these soils.

Status of selenium in sheep and dairy cow blood in Western Balkan countries

Abstract The main goal of the study was to assess the selenium (Se) status of sheep and cows in some of the Western Balkan countries. A total number of 105 sheep and 160 cow blood samples (from 21 and 39 farms, respectively) were collected and analyzed for Se in the whole blood (WB). Samples have been analyzed using inductively coupled plasma mass spectrometry. The results showed that 85.6% of sheep and 45.6% of cows had inadequate (≤100 ng/mL) level of WB-Se concentration. The WB-Se concentration was significantly higher in both Se supplemented sheep and cows than in those without any Se supplementation. The WB-Se concentration was inadequate at all farms without Se supplementation. Therefore, Se should be supplemented to the animal feed or Se-biofortified feed used to ensure adequate level of Se in cows and sheep in all the Balkan countries.

The sensitivity of water extractable soil organic carbon fractions to land use in three soil types

ABSTRACT Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are highly associated with SOC in the silt and clay fraction (<53 µm) and were slightly associated with SOC in the macroaggregate classes. The WEOC fractions were highly and positively correlated with the SOC and mean weight diameter.

Performance of legume–grass mixtures in the West Balkan region

ABSTRACT Three perennial legumes (alfalfa, red clover and birdsfoot trefoil) and four cool-season perennial grasses (orchardgrass, tall fescue, Italian ryegrass and red fescue) were grown in legume–grass combinations and in pure stands of individual species, at three locations in the West Balkan region (Novi Sad, Banja Luka and Pristina) in the period from 2012 to 2015. The study evaluated dry matter yield, legume–grass–weed proportion and forage quality. High annual forage yield of legume–grass mixtures can be obtained with proper selection of species and an appropriate legume–grass ratio. However, high and stable yield, particularly in the case of grasses, depends on the amount and schedule of precipitation as well as the cutting time. The mixtures and legume pure stands achieved better forage production both per cutting and on the annual basis and had better forage quality than grass pure stands.

Microbiological Activity in the Soil of Various Agricultural Crops in Organic Production

Summary The purpose of this study is to investigate the microbial activity and the number of different groups of microorganisms in the soil under organic agricultural systems. A range of analyses was conducted on soil samples taken from calcareous chernozem soils managed under organic (7 sites) and conventional agricultural systems (1 site). Laboratory measurements were performed in the Laboratory of Microbiology, Faculty of Agriculture, Novi Sad. The total number of bacteria, actinomycetes, fungi, aminoheterotrophs and azotobacters was determined using the dilution method. Soil dehydrogenase activity was measured spectrophotometrically. The greatest number of the Azotobacter sp. bacteria was recorded in the soil devoted to pumpkins (132.61 × 102) and in the soil devoted to apples (126.39 × 102). The greatest number of aminoheterotrophs (1786.05 × 106) and the total number of bacteria (1370.82 × 106) and actinomycetes (235.45 × 104) were determined in the soil devoted to carrots. Fungi were more abounded in the soil devoted to chard (36.82 × 104) than in the soil devoted to other plants. The research results show that the soil devoted to wheat in organic production indicated a greater number of aminoheterotrophs, total bacteria, actinomycetes and fungi, whereas only the number of Azotobacter sp. was greater in the soil devoted to wheat in the conventional agricultural system. The highest dehydrogenase activity level was determined in the soil devoted to radishes, whereas the lowest dehydrogenase activity level was determined in the soil devoted to apples.

A field screening test for the assessment of concentrations and mobility of potentially toxic elements in soils: a case study on urban soils from Rome and Novi Sad

The increasing demand for environmental pollution control results in the development and use of new procedures for the determination of dangerous chemicals. Simple screening methods, which can be used directly in the field for a preliminary assessment of soil contamination, seem to be extremely advantageous. In our laboratory, we developed and optimized a rapid test for a preliminary evaluation of both the concentration and the mobility of some potentially toxic metals in soils. This screening test consists of a single extraction of the soil sample with a buffer solution, followed by the titration of the extracted solution with dithizone to determine the contents of bi-valent heavy metals (such as Pb, Cu, Zn, and Cd). This screening method was then directly applied in the field during the sampling campaign in the framework of an Italian–Serbian collaborative project, finalized in the study of metal availability in soils. The results obtained in the field with the rapid test were compared with those obtained in the laboratory following the conventional procedure commonly used to evaluate metal bioavailability (diethylenetriaminepentaacetic extraction). Moreover, selected samples were analyzed sequentially in the laboratory using the standardized BCR three-step sequential extraction procedure. The screening test gave results conceptually in good agreement with those obtained via the BCR procedure. These preliminary data show that the proposed screening test is a reliable method for the preliminary rapid evaluation of metal total concentrations and of potential metal mobility in soils, supporting sampling activities directly in the field.

Copper and zinc concentration in soil and plants used for feed on different locations in Serbia

In 2013 an investigation was conducted on 15 different localities on the territory of Serbia (12 on territory of Vojvodina province and 3 in west Serbia - Kolubara count) in order to overview content of copper and zinc in soil and plants. The total and available content of Cu and Zn were determined and compared to the limits concentration in order to determine the level of the supply with these elements in soil and their effect on the plants quality. In the examination of the plant material only plants used for feed (alfalfa, pasture and grassland) were considered. In the aboveground plant mass the content of Cu and Zn was determined and put in correlation with soil content of analyzed elements. Soil samples showed that content of the available Cu was high in all locations, while the content of Cu in plant material was insufficient on three locations. The concentration of available Zn in soil was sufficient on almost all locations, but the analysis showed that the plants was insufficiently provided with Zn on the most locations, thus certain agricultural methods need to be applied in order to increase its content in plants.

Aggregate stability and sealing risk of solonetz under different land use regimes

Solonetz is a type of alkaline soil which covers about 3.75% of the Province of Vojvodina, Serbia. In order to investigate the potential implementation of efficient agricultural production on this soil, we investigated the stability of structural aggregates and sealing risk (crusting hazard) in the surface layer (0-20 cm) of solonetz exposed to different land use. Four classes of stable aggregates (8000-2000, 2000-250, 250-53 and <53 μm) were obtained and the risk of sealing was calculated. The results show relatively stable structure in the surface layer of the investigated solonetz soils, but also a high risk of sealing. Solonetz under native vegetation showed higher aggregate stability and lower risk of sealing compared to solonetz exposed to long term tillage. Such soils can be recommended for establishing protective forests or cultivation of shallow rooted plants under condition that appropriate chemical properties of the surface horizon are monitored and cultivation practices against risk of sealing are implemented. Also further interdisciplinary study of these alkaline soils is recommended bearing in mind its high prevalence and variability of their properties.