Toxicity effect of application of non composted poultry manure on soil and Amaranthus caudatus

Abstract

The study was conducted at Adekunle Fajuyi Military Cantonment, Odogbo Barracks, Oojo, Ibadan in May 2010. Soil samples were collected from 6 farmers’ fields, growing with Amaranthus caudatus, sown at a rate of 10 kg/ha by broadcasting. The fields with an average size of 12m 2 were selected at random, based on units within the barracks at a distance of about 200m apart. The farmers applied, dry, uncomposted Poultry manure at 1 – 2 weeks before planting at an average rate of 200 t/ha by broadcasting and incorporated into the soil with hoe. Surface soil samples were collected at random from each field, air dried and sieved. They were chemically analysed for pH, particle size distribution, exchangeable bases, ECEC, N, Av. P, Organic Matter, micronutrients [Fe, Mn, Cu, and Zn] and heavy metals [Pb, Cd, Ni and Cr]. The levels of soil fertility indicators, such as Nitrogen, phosphorus, potassium, Effective cation exchange capacity, organic matter and the base saturation were above optimum while that of Mn and Cu were below toxicity level. Levels of Zn and Fe of 221-203.5 and 44.3 – 86.8 mg/kg respectively are far above toxicity values of 1.0 – 2.0 and 5-9mg/kg respectively thereby causing nutrient imbalance and toxicity, thus resulting in yellowing of Amaranthus crops.