Nitrogen dynamics in flooded soil resulting from the application of urea and poultry litter in the presence and absence of rice plants

Abstract

The objective of this study was to monitor the formation of ammonium (NH4 + ) and nitrate (NO3 - ) in flooded soil and to measure N recovery by rice plants after the application of urea and poultry litter in pots in a greenhouse with the use of an Entisol Aeric. The treatments were: poultry litter incorporated into the soil 10 days before flooding, and urea in two forms of application: a) the whole dose in the formation of the mudding, before rice sowing; and b) the dose split in three times (30, 50 and 70 days after rice sowing) and a control (no N). The dose of N was equivalent to 200mg/kg of soil in all treatments. To each treatment four buckets were cultivated with rice and four remained without plants. After flooding, the N-NH4 + concentration in the soil increased in all treatments, including control (no N), being higher when the urea was incorporated into the soil followed by poultry litter. However, throughout the experimental period the highest N-NH4 + concentration occurred when urea was applied in split form. The N-NO3 - present in the soil was completely lost in less than a week after soil flooding. The highest rates of N recovery by plants occurred when the urea was applied in split form with 62% followed by poultry litter, and incorporated urea with 22% and 20% respectively. N-fertilizers applied before rice sowing are less efficient than split N to supply N demands by rice plants.