| authors: | Paramasivam, S. ; Alva, A. ; Fares, A. ; Sajwan, K.S. |
| title: | Vadose Zone Processes and Chemical Transport |
| year: | 2002 |
| source: | Proc. J Environ. Qual. 31:671-681 |
| URL: | Please log in to access the document. |
| abstract: | Understanding water and nutrient transport through the soil profile is important for efficient irrigation and nutrient management to minimize excess nutrient leaching below the rootzone. We applied four rates of N (28, 56, 84, and 112 kg N ha ?1; equivalent to one-fourth of annual N rates being evaluated in this study for bearing citrus trees), and 80 kg Br? ha?1 to a sandy Entisol with > 25- yr-old citrus trees to (i) determine the temporal changes in NO3-N and Br? distribution down the soil profile (2.4 m), and (ii) evaluate the measured concentrations of NO3-N and Br? at various depths with those predicted by the leaching Estimation and Chemistry Model (LEACHM). Nitrate N and Br? concentrations approached the background levels by 42 and 214 d, respectively. Model-predicted volumetric water content and concentrations of NO3-N and Br? at various depths within the entire soil profile were very close to measuring values. The LEACHM data showed that 21 to 36% of applied fertilizer N leached below the root zone, while tree uptake accounted for 40 to 53%. Results of this study enhance our efficiency, reduce N losses, and minimize the risk of ground water nitrate contamination from soils highly vulnerable to nutrient leaching. |
| keywords: | Nitrogen, nitrate, broadcasting, fertilizer, soil, irrigation |
