Trace Elements Characterization in Fresh and Composted Livestock Manures

Research Article

Austin J Hydrol. 2014;1(2): 6.

Trace Elements Characterization in Fresh and Composted Livestock Manures

Faridullah1*, Aneesah Pervaiz1, Muhammad Irshad1, Arif Alam2, Qaisar Mahmood1*and Muhammad Ashraf3

1Department of Environmental Sciences, COMSATS Institute of Information Technology, Pakistan

2Department of Development Studies, COMSATS Institute of Information Technology, Pakistan

3Department of Civil Engineering COMSATS Institute of Information Technology, Pakistan

*Corresponding author: Faridullah, Qaisar Mahmood, Department of Environmental Sciences, COMSATS Institute of Information Technology, Pakistan

Received: October 02, 2014; Accepted: November 28, 2014; Published: December 04, 2014


Animal manure is identified as the alternative of fertilizers to enhance the soil fertility and crop production. But the application of animal manure may contaminate the environment with heavy metals; thus it is imperative to determine the heavy metal contents of manures. The present study was aimed to compare the trace elements in fresh and composted animal manures using the sequential fractionation method. Composted and fresh animal manures from four different animals, [buffalo (BF), cow fresh (CW), goat (GT) and poultry (PL)], were selected to determine various fractions of iron (Fe), zinc (Zn), nickel (Ni), manganese (Mn) and mercury (Hg). Metals were stepwise fractionated into exchangeable, adsorbed, organically bound, carbonate precipitated and residual forms. The extractability of elements considerably varied depending on the type of livestock and extraction method. The composted and fresh manure exhibited the lower concentrations of water soluble extractable metals as compared to other fractions. A great proportion of metal was detected in carbonate and residual forms. Irrespective of the form of element, the reagents were varied in order of HNO3> EDTA >NaOH> KNO3> H2O, while metal species were found in the order of Fe> Hg >Mn> Zn > Ni. Iron, Mn and Hg were found in higher concentration in composted manures whereas Ni and Zn concentrations were sparingly higher in fresh manures. Analytical results indicated that composting of animal manures might have encouraged soil microbial activity, which promoted trace mineral supply thus improving the plant nutrition. The variations in the heavy metals could be related to the chemical properties of the individual metals and the characteristics of manure.

Keywords: Composting; Livestock manures; Heavy metals; Fractionation


Livestock manure has been used for centuries as a fertilizer for farming, as it improves the soil structure that holds more nutrients and water for better crop production. It also encourages soil microbial activity which promotes the trace element supply thus improving plant nutrition. Animal manure either fresh or composted has been traditionally applied to the agricultural fields for decades as an organic fertilizer [1]. The use of composted manure will contribute more to the organic matter content of the soil. Fresh manure may contain higher amounts of viable weed seeds, which can lead to the weed problems. In addition, various pathogens may be present in fresh manure which can cause various illnesses to individuals eating fresh produce. The residual effects of the manure and compost are important. When manure and compost are used to fertilize crops, soil organic matter will increase with the passage of time and subsequent rates of fertilizer application can generally be reduced because of increased nutrient cycling. Composts are considered as valuable product used for soil amendment of agricultural lands. The application of composted animal manure has increased over the years. This practice not only improves the quality of the crops but also preserves the environment [2,3]. However, non-composted manure or immature compost may impart adverse effects on plant growth and/or seed germination [4,5].

Heavy metal contamination of soil is a major concern because of their toxicity and threat to human life and other biota. Toxic heavy metals entering the ecosystem may lead to geo-accumulation, bio-accumulation and bio-magnifications. Excessive accumulation of heavy metals in soil and other media may eventually enter food chain [6,7]. Consequently, many countries in the world have established specific guidelines and standards for the application of composts in agricultural lands.

Trace metal composition of composts widely varied depending on the sources, composting process [6] and geographical location [8]. Like soils sediments and sludge, trace metals can exist in a variety of forms in composts. These forms include water soluble, exchangeable, bound to organic substances, occluded or co-precipitated with oxides, carbonates and phosphates, or other secondary minerals and ions in the crystalline lattices of the primary minerals [7,9,10,11]. Total trace metal composition of composts is of little importance in determining the total metal uptake by plants and consequently contamination of the food chain since different forms have variable mobility, bioavailability and potential environmental contamination. It is therefore, important to know the distribution of each trace metal form [10,11]. Conceptually, sequential fractionation categorizes metals associated with chemically homogeneous fractions that ultimately affect metal availability. Sequential extraction (or fractionation) procedures have been predominantly developed to determine the amounts and proportions of metals present as different forms in soil or sediment samples [12,13].

Metals fractionation in animal waste can provide useful information to predict their bio-availability and the potential for contamination of soils and waters. Most researches on metal contamination of soils have been conducted in relation to municipal sewage sludge application and to date; very little work has been done on metal input from animal manure byproducts as fresh and composted ones [14]. Research reports on the concentration of metals in composted and fresh manure samples are particularly lacking. Therefore, the present study was aimed to evaluate the metal constituents (Fe, Zn, Ni, Mn, Hg) in fresh and composted animal manures.

Materials and Methods

Animal composted waste and fresh manure samples were collected from the village Pohar, District Abbottabad. Fresh and composted manure samples of different animals were collected. These included: cow (CW), buffalo (BF), poultry (PL) and goat (GT). The manure samples were air dried, crushed, and sieved (< 0.5 mm) to ensure homogeneity and digested in a mixture of acids (HNO3 and HClO4). Total elements i.e. nickel (Ni), iron (Fe), zinc (Zn) and mercury (Hg) in the extract of digested manure samples were determined by atomic absorption spectrophotometer (IBSRAM.1994). The sample weighing 0.25 g was digested with 5 mL concentrated HClO4 over a hot plate for 1 h. After drying 20% HNO3 was added to the sample and it was heated again for 1h. The solution was diluted to 50 mL with deionized water and passed through a 0.22 μm filter. The P was determined by a spectrophotometer at 710 nm [15]. The manure samples were extracted for water soluble P, K, Ca, Mg and other metals using deionized distilled water.. Potassium, Ca, Mg, and other metals were determined by an atomic absorption spectrophotometer (Model Z-2300, Hitachi, Japan). Soil pH were measured in soil-water (1:5; w: v) suspensions (Table 1). Treatments were applied in triplicates and data was statistically analyzed using Stat view software (SAS, 1999).