Enrichment of Trace Metals in an Ultisol Impacted by Applied Broiler Litter Irenus A. Tazisong Zachary Senwo Robert Taylor

Introduction  In the United States, the broiler industry is a major source of agricultural income.  The livestock industry produces 50% of the profits of U.S. agriculture.  It is also presumably the most rapidly expanding livestock generating system in the world.  In the US, Alabama is ranked third in terms of broiler chicken (Gallus gallus) production.  In 1999, Alabama accounted for over 970 million birds.

Introduction cont.  Generated about 1.5 million Mg of broiler litter.  Broiler litter generated is composed of birds droppings, feathers, bedding materials etc.  Broiler litter is highly rich in macro and micro nutrients as well as pathogens.  A critical problem facing the burgeoning industry in the southeastern US is the vast amount of wastes generated yearly and problem of safe disposal.

Introduction cont.  Broiler waste are mainly applied to agricultural lands as organic fertilizer.  Inexpensive source of macro and micronutrients.  Enhance soil productivity and quality e.g. improve aggregate formation and stability.  Repeated land application results to detrimental buildup of elements.

Introduction cont.  Buildup of elements beyond required concentration for plant growth may result to:-  1) leaching into ground water  2) elements washed into surface water  3)elements being toxic to plants

OBJECTIVES a) evaluate enrichment trends of 5 plant nutrients(Cu, Fe, Mn, Ni, Zn) and two potential pollutants (Pb, Cd). b) To assess the degree of the enriched trace metals in this soils.

Materials and Method  Soil samples collected in triplicate from 0-20cm, 20-40cm, and 40-60cm depth.  Soil samples collected on a 3-8% slope in the Sand Mountain region of north Alabama.  Soils has been managed for pasture and received annual broiler litter applications for 0, 5, 10, 15, and 20 years.  Rate of application has 0, 2.27, 2.27, 3.63, and 1.36 Mg ha -1 yr -1.

Materials and Method cont.  Soil samples were air-dried, ground to pass a 2-mm sieve and stored at room temperature.  Soils samples were characterized for :- -pH -Electrical conductivity (EC) -Total C, N and S -NO 3 -N and NH 4 -N -Ca, K, Mg and Na (Mehlich 1984).

Materials and Method cont.  Trace metal and extractable Al were extracted with Diethylenetriamine pentaacetic acid (DTPA) (Lindsay and Norvell 1978).  Trend analysis was determined using polynomial contrast analysis.  Enrichment factor was calculated using the formula:- EF = (Z/Al) amended /(Z/Al) control Where: EF = enrichment factor Z = trace metal concentration (mg kg -1 ) Al = total Al concentration (g kg -1 )  Statistical analysis were performed using Statistical Analysis System (SAS) 2005 version 9.1.

Results and Discussion

Results and Discussion cont.

Conclusion  Results obtained from this study revealed that continuous applying broiler litter to land will lead to: a) metal build up in soil leading to plant toxicity b) alteration of soil physiochemical properties. c) leaching and washing of elements into ground and surface water.

Conclusion cont.  It can be deduced from trend analysis that metal accumulation in soils from long-term applied broiler litter did not follow a linear trend.  Applying broiler litter to agricultural land as a source of nutrients and waste disposal is not a risk-free management practice.

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