『Abstract
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 NO3-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
NO3-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 NO3-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.
Keywords: Poultry manure; Lysimeter; Lixiviation; Nitrate nitrogen;
Phosphorus; Cations; Electrical conductivity; Soil』
1. Introduction
2. Materials and methods
2.1. Description of the assay
2.2. Treatments
2.3. Irrigation
2.4. Samplings
2.5. Analytical techniques
2.6. Statistical analysis
3. Results and discussion
3.1. Evaluation of leachates over time
3.1.1. Nitrate nitrogen
3.1.2. Calcium
3.1.3. Magnesium
3.1.4. Sodium
3.2. Potassium
3.2.1. Electrical conductivity and sodium absorption rate
3.3. Influence of the treatments on the chemical composition
of the soil
4. Conclusions
References