Biomedical subjects

Valtcho D Zheljazkov

Publications and source records attributed to Valtcho D Zheljazkov.

6 recordsLinked to original sources

PubMed2006

Compost, manure, and gypsum application to timothy/red clover forage.

Some of the most fertile agricultural land in Atlantic Canada includes dykelands, which were developed from rich salt marshes along the Bay of Fundy through the construction of dykes. A 2-yr field experiment was conducted on dykeland soil to evaluate the effect of fertility treatments: source-separated municipal solid waste (SS-MSW) compost, solid manure, commercial fertilizer, and gypsum on (1) timothy/red clover forage productivity, (2) N, S, and other nutrients uptake, and (3) residual NO(3)-N and NH(4)-N in the soil profile. All fertility treatments increased dry matter yields from the two cuts each year relative to the control. Residual soil NO(3)-N and NH(4)-N concentrations in the fall of the second year decreased with depth, and beyond 20-cm depth were lower than 1 mg kg(-1). Gypsum application equivalent to 40 kg S ha(-1) increased dry matter yields and N uptake by forage, and increased soil Mehlich 3-extractable S, tissue S, and uptake of S, Ca, P, Cu, Fe, and Mn relative to the control. High rates of compost can provide sufficient N, S, and perhaps other nutrients to a perennial forage system under the cool wet climate of Atlantic Canada with no heavy metal enrichment of forage. However, the chemical N provided greater total N uptake than organic sources, except the high rate of compost, suggesting that the N availability from organic sources was not well synchronized with forage N demand. Municipal solid waste compost may also increase soil and forage tissue Na, which might be of concern.

Agriculture↗

PubMed2005

Assessment of wool waste and hair waste as soil amendment and nutrient source.

A field and two container experiments were conducted to assess uncomposted wool and hair wastes as a nutrient source for crops and to evaluate their potential to improve soil biological and chemical properties. Overall, addition of wool or hair waste to soil increased yields of basil (Ocimum basilicum L. 'Trakia'), thorn apple (Datura innoxia Mill. 'Inka'), peppermint (Mentha x piperita L. 'Black Mitchum'), and garden sage (Salvia officinalis L. 'Desislava'), increased NH(4)-N and NO(3)-N in soil, increased total N (and protein) content in plant tissue, stimulated soil microbial biomass, and decreased mycorrhizae colonization of plant roots of thorn apple but not in basil. Wool and hair waste additions to soil altered slightly the content and composition of plant secondary metabolites (essential oils or alkaloids); however, overall the constituents remained within the "typical" range for the respective crops. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis demonstrated that wool and hair wastes decompose slowly under field or greenhouse conditions, and act as a slow release S, N, P, and K fertilizer. These results, along with the measured concentrations of NO(3)-N in soil at harvest, suggest that the addition of wool or hair waste of only 3.3 g kg(-1) of soil may support two to five harvests or crops under greenhouse conditions and two to four field seasons in field production systems, and would improve soil biological and chemical characteristics. Further research is needed to optimize the rate of application of these waste materials to the nutrient requirements of specific crops to avoid nitrate leaching into the ground water. In addition, the effect of wool and hair waste on other environmental end points should also be further investigated before specific recommendations for growers are provided.

Absorptiometry, Photon↗

PubMed2004

Application of high-Cu compost to dill and peppermint.

A controlled environment experiment was conducted to determine the effect of amending soil with various rates of high-Cu compost (0, 20, 40, and 60% compost/soil by volume) on dill (Anethum graveolens L.) and peppermint (Mentha X piperita L.) yields, on fractionation of Cu and Zn in soils, on elemental composition of soil and tissue, and on the essential oils. The compost contained about 2000 mg kg(-)(1) of Cu. Dill yields were greatest in the 20 or 40% treatments, but peppermint yields were greatest in the 20% treatment. Compost additions increased soil pH and electrical conductivity (EC), HNO(3) extractable soil B, Ca, K, Mg, Mn, P, S, Na, and Pb. Additions of high-Cu compost to soil increased tissue P, S, and Na in both crops and Mn, Mo, and Zn in dill but decreased tissue Ca, Cd, and Fe in both crops and Mn, Mo, and Zn in peppermint, increased Cu in all soil fractions including exchangeable, and increased tissue Cu of dill and peppermint as compared to unamended soil. Addition of 60% of high-Cu compost to soil resulted in 760-780 mg kg(-)(1) Cu in the growth medium. Nevertheless, Cu content in both crops reached only 12 mg kg(-)(1) DW in the 60% compost treatment, which is below the toxicity levels for plants and below the upper chronic dietary exposure for animals. The application of high-Cu compost altered chemical composition of dill and peppermint essential oils, but oils were free of Cu, Zn, Cd, Ni, Cr, and Pb. Results from this study suggest that mature composts with concentrations of Cu and Zn of 2008 and 321 mg/kg, respectively, can be used as a soil conditioner without risk for phytotoxicity or risk of increasing the normal range of Cu and Zn in crop tissue. However, the long-term effect of the accumulation of heavy metals in soils following repeated compost applications needs to be carefully considered.

Anethum graveolens↗

PubMed2004

Phytoavailability and fractionation of copper, manganese, and zinc in soil following application of two composts to four crops.

Two experiments were conducted to evaluate the effect of compost addition to soil on fractionation and bioavailability of Cu, Mn, and Zn to four crops. Soils growing Swiss chard (Beta vulgaris var. cicla L.) and basil (Ocimum basilicum L.) were amended (by volume) with 0, 20, 40, and 60% Source-Separated Municipal Solid Waste (SS-MSW) compost, and dill (Anethum graveolens L.) and peppermint (Mentha X piperita L.) were amended with 0, 20, 40, and 60% of high-Cu manure compost (by volume). The SS-MSW compost applications increased the concentration of Cu and Zn in all fractions, increased Mn in acid extractable (ACID), iron and manganese oxides (FeMnOX), and organic matter (OM) fractions, but decreased slightly exchangeable-Mn. Addition of 60% high-Cu manure compost to the soil increased Cu EXCH, ACID, FeMnOX, and OM fractions, but decreased EXCH-Mn, and did not change EXCH-Zn. Addition of both composts to soil reduced bioavailability and transfer factors for Cu and Zn. Our results suggest that mature SS-MSW and manure composts with excess Cu and Zn could be safely used as soil conditioners for agricultural crops.

Anethum graveolens↗

PubMed2003

Application of high Cu compost to Swiss chard and basil.

A greenhouse container experiment was conducted to evaluate the effect of high Cu compost on basil and Swiss chard productivity, and the accumulation of As, Ca, Fe, Hg, K, Mg, Na, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, S and Se in growth medium and plant tissue. The Cu content of the compost was over 1200 mg/kg, much higher than Canadian standards for type B compost quality. The treatments consisted of control soil (0% compost), and 20, 40 and 60% (by volume) of high Cu compost added to soil. All compost application treatments (20, 40 and 60%) resulted in increased dry matter yields in Swiss chard and basil. Addition of high Cu compost influenced basil plant development. Plants from the 20 and 40% treatments had higher numbers of buds and flowers. There were no differences between the control and 60% compost treatments with respect to flower initiation. Addition of 20, 40 and 60% compost to the soil resulted in increased EXCH fractions of Cu, but not of Mn and Zn. Compost additions resulted in increase in the HNO(3) extractable, CARB, FeMnOX, and in OM fractions of Cu, Mn and Zn in soils. Compost application increased soil pH and EC, soil HNO(3) extractable Ca, K, Mg, P, Na, B and Pb, but did not alter soil HNO(3) extractable Cd, Co, Cr, Mo, Ni, Se. Increased rates of compost application decreased tissue Ca in basil, tissue Na in both plants, increased tissue K, Mg in both plants, but, did not alter tissue P, Co, Cr, Mo, Ni of either plants, and B in basil. Tissue As, Hg, Pb, and Se from all treatments were under the detection limits of VGA-AAS (for As, Hg, Se) and ICP (for Pb). Compost additions altered basil oil chemical composition. Copper in the essential oil of basil was below 0.25 mg/l. In conclusion, the addition of high rates of relatively immature high Cu compost may not always increase Cu concentration in plants and in plant oils.

Beta vulgaris↗

PubMedDate not supplied

Source-separated municipal solid waste compost application to Swiss chard and basil.

A growth room experiment was conducted to evaluate the bioavailability of Cu, Mn, Zn, Ca, Fe, K, Mg, P, S, As, B, Cd, Co, Cr, Hg, Mo, Na, Ni, Pb, and Se from a sandy loam soil amended with source-separated municipal solid waste (SSMSW) compost. Basil (Ocimum basilicum L.) and Swiss chard (Beta vulgaris L.) were amended with 0, 20, 40, and 60% SSMSW compost to soil (by volume) mixture. Soils and compost were sequentially extracted to fractionate Cu, Pb, and Zn into exchangeable (EXCH), iron- and manganese-oxide-bound (FeMnOX), organic-matter (OM), and structurally bound (SB) forms. Overall, in both species, the proportion of Cu, Pb, and Zn levels in different fractions followed the sequence: SB > OM >> FeMnOX > EXCH for Cu; FeMnOX = SB > OM > EXCH for Pb; and FeMnOX > SB = EXCH >> OM for Zn. Application of SSMSW compost increased soil pH and electrical conductivity (EC), and increased the concentration of Cu, Pb, and Zn in all fractions, but not EXCH Pb. Basil yields were greatest in the 20% treatment, but Swiss chard yields were greater in all compost-amended soils relative to the unamended soil. Basil plants in 20 or 40% compost treatments reached flowering earlier than plants from other treatments. Additions of SSMSW compost to soil altered basil essential oil, but basil oil was free of metals. The results from this study suggest that mature SSMSW compost with concentrations of Cu, Pb, Mo, and Zn of 311, 223, 17, and 767 mg/kg, respectively, could be used as a soil conditioner without phytotoxic effects on agricultural crops and without increasing the normal range of Cu, Pb, and Zn in crop tissue. However, the long-term effect of the accumulation of heavy metals in soils needs to be carefully considered.

Beta vulgaris↗