The influence that the application to a soil of different doses of poultry manure may have on nitrate concentrations of the leaching waters and some soil chemical characteristics was studied. The doses of poultry manure that could prevent nitrate pollution under the assay conditions were also determined. The assay was carried out in a greenhouse using 36 lysimeters of 300-l capacity, which were filled with 200 l of an Alfisol Udalf soil each. Treatments consisted of single applications of fresh poultry manure at doses of 45 (T1), 22.5 (T2), 11.25 (T3), 5.63 (T4), 2.82 (T5), 1.41 (T6), and 0.70 (T7) kg m −2 , 0.02 g of N per square meter as ammonium nitrosulfate (T8), and a control (T0; not fertilized). Lixiviates were gathered every 15 days from each replication and evaluated for NO 3 -N, P, Ca, Mg, K, electrical conductivity (EC) and sodium absorption rate. Soil samples were taken at the beginning and at the end of the assay and their physico-chemical characteristics (e.g., water saturation percentage, pH, OM, EC, and available P, K, Ca, and Mg) were analyzed. The amounts of NO 3 -N leached from the higher doses of poultry manure could represent very important economic losses of N and pose an environmental threat in field conditions. Results suggest that 2.82 kg m −2 of poultry manure or less could be used without negative effects to groundwaters higher than the control. No statistical differences of NO 3 -N lixiviation between the control and the application of ammonium nitrosulfate were observed. Treatments T1 and T2 produced the highest quantities of Ca, Mg, and K lixiviations. Harmful levels of EC were detected in T1 and T2 lixiviates. Available soil P increased in treatments T1 to T6, while available K and Mg and EC rose with the higher doses of poultry manure.
