Fractionation of soil phosphorus in a long-term phosphate fertilization

The changes in inorganic and organic phosphorus (P) fractions of soil resulting from long-term fertilization (40 years) were investigated. In order to improve understanding of the sink and sources of phosphorus, P-fractions were extracted from soil samples of 0-30 and 30-60 cm depth with different amounts of monoammonium-phosphate (MAP) and then determined. Stagnosol was the type of the studied soil. Phosphate fertilizer was applied in 26, 39 and 52 kgP/ha amounts during the period of 40 years. Samples were subjected to sequential extraction according to the modified Chang and Jackson method and BCR (Community Bureau of Reference) sequential extraction procedure in order to extract different forms of phosphorus. The Certified Reference material CRM 684 (River Sediment Extractable Phosphorus) was used to provide accuracy of the instrument and both used methods. Furthermore, the association of phosphorus with substrates was provided by comparison of the results of sequential methods of phosphorus species with the sequential extraction of metals (Fe, Al, Mn and Ca). Results of continuous fertilization during 40 years indicated the increase of all the phosphorus forms in the soil except of phosphorus bound to calcium and organic phosphorus. Application of higher amounts of P-fertilizer resulted in dominance of Al-P fraction in studied soil which indicated that this fraction was the most responsible for the migration of phosphorus along the soil profile

Frakcionisanje fosfora u zemljištu nakon dugotrajne primene fosfornog đubriva

The changes in inorganic and organic phosphorus (P) fractions of soil resulting from long-term fertilization (40 years) were investigated. In order to improve understanding of the sink and sources of phosphorus, P-fractions were extracted from soil samples from depths of 0-30 and 30-60 cm with different amounts of monoammonium-phosphate (MAP) and then determined. The studied soil was of the Stagnosol type. Phosphate fertilizer was applied in 26, 39 and 52 kg P ha(-1) amounts during a period of 40 years. Samples were subjected to sequential extraction according to a modified Chang and Jackson method and the Community Bureau of Reference (BCR) sequential extraction procedure in order to extract different forms of phosphorus. The certified reference material CRM 684 (river sediment extractable phosphorus) was used to confirm the accuracy of the instrument and of both employed methods. Furthermore, the association of phosphorus with substrates was provided by comparison of the results of sequential methods of phosphorus species with the sequential extraction of metals (Fe, Al, Mn and Ca). The results of continuous fertilization during 40 years indicated increases of all forms phosphorus in the soil except of phosphorus bound to calcium and organic phosphorus. Application of higher amounts of P-fertilizer resulted in the dominance of the Al P fraction in the studied soil, which indicated that this fraction was the most responsible for the migration of phosphorus along the soil profile.U ovom radu ispitivane su promene u frakcijama neorganskog i organskog fosfora (P) u zemljištu koje su izazvane 40 godišnjim đubrenjem amonijum-fosfatom (MAR). Đubrivo je dodavano u količinama od 26, 39 i 52 kg P po hektaru zemljišta. U cilju praćenja mobilnosti fosfora, ekstrahovane su fosforne frakcije sa dve različite dubine zemljišta: površinski sloj od 0-30 cm i dubina od 30-60 cm. Tip ispitivanog zemljišta je Stagnosol. Uzorci su u cilju ekstrahovanja različitih oblika fosfora podvrgnuti sekvencijalnoj ekstrakciji i to na dva načina: prema modifikovanoj Chang i Jackson metodi i BCR metodi. Sertifikovani referentni materijal CRM 684 (rečni sediment) je korišćen za praćenje tačnosti obe korišćene metode. Osim toga je proučeno vezivanje fosfora sa supstratima (Fe, Al, Mn i Ca) koji su ekstrahovani sekvencijalnom ekstrakcijom metala. Rezultati ukazuju da kontinualno 40 godišnje đubrenje dovodi do povećanja sadržaja svih oblika fosfora u zemljištu osim fosfora koji je vezan za kalcijum i organskog fosfora. Primenom veće količine fosfornog đubriva dolazi do dominacije frakcije fosfora vezanog za aluminijum u ispitivanom zemljištu što ukazuje da je ta frakcija najodgovornija za migraciju fosfora kroz zemljište

Methods for the assessment of background limits of Cd and Cr in the soil of Moravicki district

У раду су приказане различите методе одређивања границе природ ног садржаја Cr и Cd у земљишту Моравичког округа. Дистрибуција садр жаја испитиваних елемената је десно асиметрична, са високом дисперзијом, посебно садржаја Cr. Применом графичких метода (кумулативна крива–CDF и boxplot) добијене су границе природног садржаја за Cd 1,40 mg kg-1, и за Cr око 230 mg kg-1. За емпиријске методе коришћени су природни подаци и ло гаритамски трансформисани, при чему су добијене знатно веће вредности него у природној симулацији. Граничне вредности добијене различитим ме тодама се разликују. Карте показују да највећи део територије има релативно ниске концентрације испитиваних елемената чије границе природног садр жаја највише одговарају вредностима израчунатим методом [Median±2MAD] и ниже. На деловима територије са повећаним садржајима погодније су ра чунске методе [Mean±2Sd] и boxplot–обрачун горњег прага. Дате су границе природног садржаја за поједине хомогене геохемијске целине