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Dominance of grass weeds in maize crop occurs due to a lack of selective herbicides for their control. With sulphonylurea herbicides this problem became under control, but a problem with selectivity was developed, particularly in maize seed crop. The effect of sulphonylureas and foliar fertiliser on maize lines was evaluated by visual estimation, grain yield, as well as the alterations in the content of antioxidants: free thiolic groups, phenolics and soluble proteins in the leaves. The proteins content did not vary significantly under the influence of herbicides, compared to the control, opposite to free thiolic groups and phenolics. The differences in the content of phenolics and thiolic groups in the treatments with herbicides plus foliar fertiliser indicated that herbicide stress was more rapidly overcome. Most of the genotypes expressed significant increase of grain yield in the treatments with foliar fertiliser, compared to control and analogous treatments with herbicides.

Crop productivity and soil fertility of arable lands largely depends on the applied fertilizer, including their composition, dosage and way of application. In the paper, a comparison of the fertilization values of different composite fertilizers was performed. The complex composite and different mixed fertilizers with fillers (lime and zeolite) were used in two experiments on two types of soil, Pseudogley and Cambisol. The grown crops were wheat and corn. The results showed no significant differences between applied fertilizers in terms of crop yield and nutrient uptake. Use of lime and zeolite as filler didn't result in increase of the fertilization effect of the applied fertilizers. The way of distribution of composite fertilizers influenced on the overall fertilization effect. Manual application of mixed fertilizers had better fertilization effect in comparison to mechanical spread, while use of complex fertilizers mechanically had better effect in comparison to blended mixed fertilizers.

Thallium (Tl) is a highly toxic element, even in small concentrations, to a range of organisms and in different environments. Therefore, our aim was to study (i) Tl geochemical fractionation by the means of the modified BCR sequential extraction procedure and (ii) the impact of redox potential (EH) alteration and principal factors such as iron (Fe), manganese (Mn), dissolved organic carbon (DOC), chlorides (Cl) and sulfates (SO4 2) on Tl (im)mobilization in periodically flooded arable soil (Serbia). Flooding was simulated using an automated biogeochemical microcosm system that allows systematical control of pre-defined redox-windows. Afterwards, EH was increased stepwise for approximately 100 mV from reducing (-205 mV) to oxidizing (530 mV) conditions. EH was automatically monitored at 10 minutes intervals. Total duration of the experiment was 914 hours. The sequential extraction revealed majority of pseudo-total soil Tl (0.15 mg kg-1 ) in the residual fraction (85.5 %), following by reducible (10.2 %), oxidable (3.8 %) and acid soluble (exchangeable) (0.5 %) fraction. The soluble Tl concentrations (0.024-0.116 μg l-1 ) were significantly affected by EH, having an increase with EH increase (r=0.75, p lt 0.01, n=30). Concentrations of soluble Fe, Mn, and Doc showed significant negative correlations with soluble Tl (r=-0.78, r=-0.73 and r=-0.91, respectively, p lt 0.01, n=30), whereas Tl correlated significant positive with SO42and Cl(r=0.89, r=0.81, respectively, p lt 0.01, n=30). Thallium mobilization was attributed to several simultaneous processes, involving the reductive dissolution of Fe-Mn oxides and gradual oxidation of Tl-bearing metallic sulfides. Our results imply that soluble Tl concentrations might increase when soil redox status evolves from reducing to oxidizing conditions. Due to high Tl toxicity at low doses, and increasing flooding events, our findings suggest that Tl should be included in future monitoring of plants and groundwater on the site or on similar sites. Talijum je veoma toksičan element i u niskim koncentracijama za razne organizme u okviru različitih delova životne sredine. Cilj rada bio je da se ispita (i) sadržaj talijuma u hemijskim frakcijama u zemljištu po modifikovanoj BCR proceduri i (ii) uticaj redoks potencijala (EH) i glavnih faktora, kao što su gvožđe (Fe), mangan (Mn), rastvorljiv organski ugljenik (DOC), hloridi (Cl -) i sulfati (SO4 2-) na (i)mobilizaciju talijuma u povremeno plavljenom obradivom zemljište (Srbija). Plavljenje zemljište je simulirano u laboratorijskim uslovima, uz korišćenje automatskog biogeohemijskog zatvorenog sistema koji dozvoljava sistematsku kontrolu definisanih redoks uslova. Nakon toga, redoks potencijal zemljište je postepeno povećavan u okvirima od po 100 mV od redukcionih (-205 mV) do oksidacionih (530 mV) uslova. Redoks potencijal je automatski meren u intervalima od 10 minuta. Ukupno vreme trajanja ogleda je bilo 914 sati. Hemijska frakcionacija je pokazala da se najveći deo ukupnog talijuma (0,15 mg kg -1) nalazi u rezidualnoj frakciji (85,5 %), a zatim u redukujućoj (10,2 %), oksidujućoj (3,8 %) i frakciji izmenljivo adsorbovanih elemenata (0,5 %). Redoks potencijal je značajno uticao na sadržaj rastvorljivog talijuma (0.024-0.116 μg l -1), koji se povećavao sa njegovim povećanjem (r=0.75, p lt 0.01, n=30). Rastvorljivi sadržaji Fe, Mn, i Doc su pokazali značajnu negativnu korelaciju sa rastvorljivim sadržajem Tl (r=-0.78, r=-0.73 i r=-0.91, redom, p lt 0.01, n=30), dok su utvržene značajne pozitivne korelacije između Tl i sulfata i hlorida (r=0.89, r=0.81, p lt 0.01, n=30). Mobilizacija talijuma može se dovesti u vezu sa nekoliko procesa koji se istovremeno odvijaju, a to su, između ostalih, rastvaranje Fe-i Mn-oksida u oksidacionim uslovima i postepena oksidacija metalnih sulfida koji sadrže Tl. Naša istraživanja ukazuju da sadržaji rastvorljivog Tl mogu da se povećavaju u kada se redoks potencijal menja od redukcionih ka oksidacionim uslovima. Naša istraživanja upućuju na neophodnost sistematskog praćenja sadržaja Tl u biljkama i podzemnim vodama, s obzirom na njegovu visoku toksičnost u niskim dozama, kao i učestalu pojavu plavljenja obradivih zemljišta.

Dynamics of labile fractions of soil organic matter under 36-years of application of mineral and organic fertilizer in Chernozem (Mollisol) in Ukraine were studied. "Light" fractions of SOM between various mineral and organic fertilization treatments were studied. Amount of total organic C increased in manured treatments; while amount of total N didn't change under any of the treatments. Labile N was correlated to soil mineral N, MBC and MBN, LFN and LFC, while labile C correlated to the total organic C, LFC and LFN. The pattern of mineralization and accumulation of SOM suggested that OC dynamics more related to long-term substrate addition, while N dynamics better reflects short-term substrate addition. Application of mineral fertilizer alone accelerated mineralization of SOM, especially of "light" fraction, while partial or complete replacement of inorganic by organic fertilizers has a significant impact on soil microbial community and soil capability to supply plants with nutrients for longer period.

A field study in western Serbia evaluated during two seasons (from 2005 to 2007) the effect of nitrogen (N) fertilizer application on Italian ryegrass (Lolium italicum Lam.) grown for seed and its competitive interaction with cleavers (Galium aparine L.) in the year after establishment. Increasing rates of N fertilizer (control, N-1-50, N-2-100 and N-3-150 kg ha(-1) N) and two ryegrass sowing rates (5 and 20 kg ha(-1)) were used. The increase of fertilizer N level improved competitive ability of ryegrass and affected the interspecific competitive interactions. The interaction between Italian ryegrass and cleavers was evaluated by measuring total nitrogen content (TNC) in the leaf during vegetation and seed yield at the end of vegetation period. The highest seed yield was obtained with 100 kg ha(-1) N in both experimental years as well as in ryegrass monoculture and ryegrass-cleavers mixture. Competition with cleavers decreased ryegrass seed yield.

Studies were carried out in pure stands of three grasses: cocksfoot, meadow fescue and perennial ryegrass, and lucerne, as well as their mixtures with different ratios of individual components. The trial was carried out on an experimental field of the Institute for Animal Husbandry (Belgrade, Serbia). Fertilization with N caused a significant increase of yield. The highest yields were determined in treatments with 100 kg N ha(-1), and the lowest in treatments without fertilization. Fertilization increased significantly the CP content, but without impact on other quality parameters. CP, NDF and ADF differed significantly in various crops.

During a three-year field experiment with Italian ryegrass forage in the first production year, a dynamics of crude protein content under the influence of different levels of spring nitrogen application was examined. Crude protein content decreased from stem elongation to flowering, but the changes had different intensity among years and treatments. The highest crude protein content during stem elongation was obtained using the highest nitrogen rate - 150 kg ha-1, even 100% higher than control treatment in 2006 and 2007. Differences among treatments decreased prior flowering, and all treatments hay yield was equable per year. The highest hay yield was reached in 2007. and it was influenced by spring nitrogen rates. U trogodišnjim ispitivanjima krme italijanskog ljulja prve proizvodne godine praćena je dinamika sadržaja sirovih proteina pod uticajem različitih nivoa primenjenog azota u proleće. Prema očekivanju, sadržaj proteina je opadao od fenofaze vlatanja do cvetanja, ali su promene bile različitog intenziteta po godinama, kao i među tretmanima. Najveći sadržaj proteina pri vlatanju je bio pri najvećoj primenjenoj dozi azota od 150 kg ha-1, čak dvostruko veći u odnosu na kontrolu tokom 2006. i 2007. godine. Razlike među tretmanima prihrane su se smanjivale do cvetanja, a i prinos sena svih tretmana je bio ujednačen po pojedinim godinama. Najviši prinos sena je ostvaren u 2007. godini i povećavao se s rastućim dozama azota.

In this paper were analyzed data from domestic production, import, turnover and quality control of mineral fertilizers in Serbia before and after 1990. The aim of analyze was to find reason and consequence of inadequate use of fertilizers for plant nutrition over the last years. According to this data average use of fertilize on our land (less than 80kg/ ha, active NPK matter), which is three times less then in other agricultural countries and third of use in Serbia before 1990, it can be conclude why production of many cultivated grass especially cereal grains is on low profitability range. In addition to increasing prices of fertilizers and unpromising position of agricultural producers, more reasons of reduction fertilizers use are: demagnification domestic production, import, turnover and very often unsuitable quality for our real requirement. U radu su analizirani podaci o domaćoj proizvodnji, uvozu, prometu i kontroli kvaliteta mineralnih đubriva u Srbiji pre i nakon 1990. godine, a sve u cilju tumačenja razloga i posledica njihove nedovoljne upotrebe u ishrani gajenih biljaka poslednjih godina. Prema tim podacima, sa prosečnom upotrebom đubriva na našim obradivim poljoprivrednim površinama (ispod 80 kg/ha, aktivne NPK materije), koja je za oko tri puta niža nego u razvijeno poljoprivrednim zemljama i oko 1/3 u odnosu na period pre 1990. godine u Srbiji ,može se zaključiti zašto su prinosi mnogih gajenih kultura, posebno žitarica, na donjoj granici rentabilnosti. Pored povećanja cena đubriva i nezavidnog ekonomskog položaja naših poljoprivrednih proizvođača, razlozi za ovakvo smanjenje upotrebe đubriva je i činjenica što je domaća proizvodnja istih drastično smanjena, a uvoz, promet pa i često kvalitet neusaglašen i neadekvatan našim stvarnim potrebama.

Italian ryegrass cv. Tetraflorum sown at different inter-row spacings and seeding rates was examined under agroecological conditions of Mačva. The study tested a hypothesis that Galium aparine growing in Italian ryegrass seed fields reduces the growth of established species and consequently decreases seed yield. Four established methods were tested: narrow and broad row spacings (20 and 60 cm) in combination with low and high seeding rates (5 and 20 kg ha-1). Control treatments were sprayed with the herbicide Starane-250 (1 l ha-1) to eradicate G. aparine. Italian ryegrass was affected by G. aparine in three of the four cultivation methods. In this experiment, seed yield reached 973 kg ha-1 in control treatments and 956 kg ha-1 in the presence of G. aparine. Italian ryegrass straw yield was in linear correlation with seed yield. Italian ryegrass seed quality was very high and the effect of experimental factors insignificant. U proizvodnji semena italijanskog ljulja prilepača (Galium aparine L.) predstavlja opasan korov koji dovodi do poleganja i neujednačenog sazrevanja semenskog useva. Ovaj rad testira hipotezu da prisustvo ove korovske vrste u semenskom usevu italijanskog ljulja (Lolium italicum L.) smanjuje rast gajene vrste što smanjuje prinos semena i biomase. Ogled je izveden na području Mačve, gde se često gaji italijanski ljulj a korovska vrsta G. aparine je veoma zastupljena. Istraživana je produkcija semena i biomase italijanskog ljulja u uslovima zakorovljenosti sa G. aparine pri četiri načina zasnivanja semenskog useva: uskoreda i širokoreda setva (20 i 60 cm) sa malom i velikom setvenom normom ljulja (5 i 20 kg ha-1). Kontrolne varijante su tretirane herbicidom Starane-250 (a.s. fluroksipir, 250 g l-1) u količini 1 l ha-1 radi praćenja produkcije ljulja bez korova. U tri od četiri tretmana gajenja italijanskog ljulja za seme, G. aparine je smanjivao prinos semena i slame italijanskog ljulja. U zavisnosti od načina i gustine setve, prinos semena se kretao od 653 do 973 kg ha-1 na kontrolnim varijantama, a na zakorovljenim od 628 do 956 kg ha-1. Prinos slame italijanskog ljulja na zakorovljenim i kontrolnim varijantama je bio u pozitivnoj korelaciji sa prinosom semena. Takođe, ostvaren je visok kvalitet semena ljulja, bez značajne razlike na tretmanima sa prilepačom u odnosu na varijantu gde je primenjivan herbicid.

The main objective of this study was to test the possibility to use the SPAD-meter as an appropriate tool for the fast estimation of a nitrogen status in both, Italian ryegrass (Lolium italicum L.) and catch weed (Galium aparine L.) that occurred as a predominate Italian ryegrass weed species. The measurements of the SPAD-units were conducted four times (from the stage of the Italian ryegrass stem elongation to the seed ripening stage, in two-week intervals) during the growing season, followed by the chemical analyses of nitrogen in the same leaf material. The high correlation between the leaf nitrogen content (expressed as a percentage per dry weight basis) and SPAD-units, were found in all treatments (varying from 0.75 lt Rxy≤0.90 to 0.90 lt Rxy≤0.99). Obtained results showed that method based upon using a SPAD chlorophyll meter was suitable for a quick estimation of the nitrogen status in plants. U ovom radu ispitivana je mogućnost korišćenja ručnog prenosnog SPAD (Spectral Plant Analysis Diagnostic) hlorofilmetra (SPAD-502) za brzo merenje sadržaja azota u usevu Lolium italicum L. i korovskoj vrsti Galium aparine L. Na osnovu korelacione analize utvrđeno je da postoji jaka do vrlo jaka pozitivna zavisnost (od 0,75 lt Rxy≤0,90 do 0,90 lt Rxy≤0,99) između sadržaja azota u biljkama određenog standardnom hemijskom (Kjeldahlovom) metodom i procene njegovog sadržaja dobijenog na osnovu SPAD očitavanja. Dobijeni rezultati ukazuju da je metoda zasnovana na korišćenju SPAD hlorofilmetra podesna za brzu procenu obezbeđenosti biljaka azotom.

The investigation was based on two pot experiments with lettuce and strawberry, aiming to assess the uptake of heavy metals (cobalt [Co], chromium [Cr], lead [Pb], cadmium [Cd], nickel [Ni], arsenic [As]) from coalmine tailing soils subjected to different amelioration measures (application of liquid fertilizers combined with different organo-mineral materials - zeolite material, peat material, coal dust and poultry manure processed by flies' worms). The results obtained indicate the problem of high Cr and Ni accumulation in above ground parts of plants (leaves and fruits). The question of Cr mobility within substrates and plants stayed open. Concentrations of Ni and Cr in lettuce and strawberry are below the levels allowed for animal food, but could influence daily human intake. Further work should focus on the mobility of heavy metals within treated tailings and their uptake by different plant species.

Investigation about effect of high amounts of nitrogen and source of nitrogen on maize organic production was conducted on Agriculture faculty experimental field in Radmilovac. Object of research was hybrid ZP 434. Four variants of nitrogen nutrition were applied: 50 kg/ha, 100 kg/ha, 150 kg/ha 200 kg/ha and control. Second factor was two source of nitrogen ammonium-nitrate (KAN) and carbamide (Urea). Results showed that application of high amounts of nitrogen on soil with 0.17% of this nutrient had significant effect on maize plants, morphological characteristics productivity and nutritive value of grain. Effect of two different sources of nitrogen was influenced by water regime during growing period. Under conditions of better water regime Urea was more suitable for plant nutrition while effect of KAH was better under unfavorable water regime. Dvogodišnja istraživanja uticaja povećanih količina i oblika azota na organsku produkciju kukuruza izvedena su na Školskom dobru Poljoprivrednog fakulteta u Radmilovcu. Predmet proučavanja bio je hibrid kukuruza ZP 434. Obuhvaćene su četiri varijante ishrane kukuruza azotom 50 kg/ha, 100 kg/ha 150 kg/ha i 200 kg/ha aktivne materije i kontrola. Drugi faktor bila su dva oblik azotnih soli: krečni amonijumnitrat (KAN) i karbamid, odnosno diamid ugljene kiseline (Ureja). Rezultati ovih istraživanja pokazali su da na zemljištu srednje obezbeđenom azotom (0,17%) ovaj biogeni elemenat u povećanim količinama značajno utiče na morfološke i produktivne osobine biljaka, kao i na hranljivu vrednost zrna kukuruza. Oblik azotnih hraniva takođe, je uticao na ove vrednosti, ali je efekat Ureje, odnosno KAN-a bio različit pri različitom vodnom režimu. U uslovima povoljnijeg rasporeda padavina Ureja je bila pogodnija za ishranu biljaka, a KAN u godini sa nepovoljnijim vodnim režimom.

This paper deals with microbiological activity in natural pasture with ranker soil used in long-term experiment with no crop rotation. The purpose of this research was to observe the results of increased introduction of nitrogen fertilizer. Regarding microbiological characteristics, the number of certain systemic and physiological microorganism groups, dehydrogenase activity, and microbe biomass of S and N, were established. The number of bacteria was determined by the dilution method and by standard media. Dehydrogenase activity was determined by CASID et αl., (1964), microbial biomass S (VANCE et al, 1987), and ninhydrin-N (Amato and LADD, 1988) methods. It was found by chemical analysis that this soil falls into the very acit soil category (below 4 IM KC1), well provided with nitrogen, with the C/N ratio below 10 in all variants, with low presence of available phosphorus and potassium, and with highly mobile Al values. Microbiological analysis indicated that the introduction of nitrogen fertilizer influenced the presence of certain microorganism groups. A reduction in the number of amonificators, oligonitro-philes and Azotobacter was found. There were no major differences between experiment variants regarding the total number of bacteria and actinomycets. The largest number of fungi was found in the experiment variants in which larger quantities of N3P1K1 and 4Ρ1Κ1 were applied. The highest dehydrogenase activity value was found in the control experiment variant, and the lowest in variants with higher nitrogen fertilizer doses, i.e. N3P1K1 and N4P1K1. Biomass S ranged from 228 to 350 µgCg1 soil Biomass S presented 6.2-10.1% of total organic S in soils. The highest ninhydrine N value was found in the control variant. Our results show that abundant application of nitrogen fertilizer influences further pH level reduction in this, otherwise, acid soil, and that it also affects microbe diversity. U ovom radu praćena je prirodna mikrobiološka aktivnost prirodnog pašnjaka, na zemljištu tipa ranker, koji se koristi u okviru stacionarnog ogleda, bez plodoreda. Uzorci zemljišta su uzimani sa varijanti ogleda gde su primenjene rastuće doze azotnog đubriva. U okviru istraživanja utvrđen je broj određenih fizioloških i sistematskih grupa mikroorganizama, dehidrogenazna aktivnost i mikrobna biomasa C i N. Brojnost mikroorganizama je određena standardnim mikrobiološkim metodama na odgovarajućim hranljivim podlogama. Dehidrogenazna aktivnost je određena spektofotometrijski (CASIDA et al.,1964). Mikrobna biomasa je određena metodom po VANCE et al. (1987) and ninhidrinski -N (Amato and LADD, 1988) metodom. Mikrobiološke analize su pokazale da je primena đubriva uticala na brojnost pojedinih grupa mikroorganizama. Uočeno je smanjenje broja amonifikatora, oligonitrofila i azotobaktera dok ukupan broj bakterija i aktinomiceta se nije značajnije razlikovao po varijantama ogleda. Najveća dehidrogenazna aktivnost je bila u kontrolnoj varijanti a najmanja u varijantama sa višim dozama azotnog đubriva. Najveća vrednost N-ninhidrinskog utvrđena je u kontrolnoj varijanti ogleda. Unošenje visokih doza azotnog đubriva utiče na dalje smanjenje pH vrednosti, ovog inače veoma kiselog zemljišta, što se odražava na mikrobni diverzitet.

Our research has been made on brown forest soil that is used in long-term experiments. The soil we used had a certain crop rotation (wheat-corn) and had been fertilized according to a certain system for 30 years. In the experiment, quantities of nitrogen fertilizers were gradually increased after which samples were taken from O to 30 cm depths in order to establish plant and soil parameters for assessing the applied methods. Two experiments were made: one in the field and one in a controlled environment. On grounds of the established correlation interdependence between the methods applied (the total and easily hydrolyzed nitrogen) and the plant and soil parameters, in both field and pots, one can conclude that the methods of total and easily hydrolyzed nitrogen, from the standpoint of nitrogen availability in soil, are reliable. In the method of total nitrogen assessment, one should rely on the parameters regarding plants and soil in the field. In the method of easily hydrolyzed nitrogen, the parameters regarding plants and soil, in both the field and pots, are the same. Cilj ovog istraživanja je bio da se utvrdi da li se sadržaj ukupnog i lakohidrolizujućeg azota može koristiti kao merilo pristupačnosti azota zemljišta, kao i da se utvrdi koji se parametri biljaka i zemljišta (polje i kontrolisani uslovi) mogu smatrati pouzdanim za ocenu vrednosti korišćenih metoda. Istraživanja su obavljena na gajnjači koja se koristi u okviru stacionarnog ogleda već 30 godina. Za ova istraživanja su korišćeni uzorci zemljišta sa varijanti ogleda gde je primenjena rastuća doza azota đubiva. Uzorci zemljišta su uzimani sa dubine 0-30 cm, pri čemu su radi utvrđivanja što većeg broja parametara biljaka i zemljišta izvedena dva ogleda i to ogled u sudovima i u polju. Na osnovu utvrđenih korelativnih zavisnosti između korišćenih metoda i parametara biljaka i zemljišta u kontrolisanim uslovima i polju može se zaključiti da se metode ukupnog i lakohidrolizujućeg azota mogu smatrati pouzdanim za ocenu pristupačnosti azota zemljišta. Pri čemu kod vrednovanja metode ukupnog azota treba koristiti parametre biljaka i zemljišta u polju, a kod metode lakohidrolizujućeg azota ravnopravno i parametre biljaka i zemljišta u polju i kontrolisanim uslovima. Utvrđene vrednosti korelacionh koeficijenata su pokazale da se i organski ugljenik može koristiti kao veličina koja govori o pristupačnosti azota zemljišta, dok se odnos C/N smatra nepouzdanom veličinom.