Liberação de nitrogênio de ureia de disponibilidade gradual em função da temperatura e do tempo de incubação
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| Publikationsdatum: | 2015 |
| Format: | Master thesis |
| Sprache: | por |
| Quelle: | Repositório Institucional da UPF |
| Download full: | https://repositorio.upf.br/handle/123456789/9216 |
Zusammenfassung: | The environmental conditions affect the release of nitrogen (N) from slow release fertilizers. The objective of this work was to evaluate the effect of temperature and incubation time on N release of three slow release ureas. The percentageof total N of the tested ureas was 39 (Experiment 1; U39), 38 (Experiment 2; U38), and 37% (Experiment 3; U37). The experiments were carried out in laboratory at the University of Passo Fundo, Brazil, in 2014. The experimental units were tetra pak boxes containing 200 g of an Oxisol and the tested ureas (except the Control). These materials were incubated in chambers with temperature control. Thetested ureas were coated with elemental sulfur (S 0 ) and biodegradable polymers. The concentration of these substances were 11 and 1.5% (U39), 14 and 2.5% (U38), 16 and 3.0% (U37), respectively. Temperature and time of incubation were the evaluated factors. The experiment was a randomized block design (three replications). The tested temperatures were 5, 15, 25, 35 and 45 °C. The N release was evaluated for up to 90 (Experiment 1), 150 (Experiment 2), and 210 days(Experiment 3) of incubation. The effect of incubation time and the temperature on the percentage of N released from the granule and on the content of mineral and total soil N and pH were evaluated. TheN source (Slow release x conventional urea) effect on these variables was also evaluated. In all experiments, the lowest release of N was found at 5 (19 to 40%) and 15 °C (36 to 44%), depending on thetested urea. The 15 lowest temperatures also decreased total and mineral N increments on soil N and the pH value. At the end of the experiments, N released from the fertilizers was higher at 35 °C (71 and 90%, U37 and U38, respectively) or at 45 °C (96%, U39). Nitrogen release increases with time and temperature of incubation. This effect was higher at 90 (U39), 150 (U38) and 210 (U37) days and at25 to 45 °C. |