Nitrogen and phosphorus budgets for the sub-tropical Richmond River catchment, Australia |
| |
Authors: | Lester J McKee Bradley D Eyre |
| |
Institution: | (1) San Francisco Estuary Institute, 180 Richmond FieldStation, 1325 South 46th Street, Richmond, CA, 94804, U.S.A.;(2) School of Resource Science and Management, Southern CrossUniversity, Lismore, NSW, 2480, Australia |
| |
Abstract: | Nitrogen and phosphorus budgets were developed forfour sub-catchments in the Richmond River catchmentfor two study years. The catchment is used for avariety of farming pursuits including dairying, beef,cropping, fruit, nuts, forestry, and sugar cane. Eachsub-catchment varies in hydrology, the proportion ofeach land use, and the population density whichenabled a unique opportunity to study fluxes andstorage associated with a variety of environmentalfactors. Total loadings entering each sub-catchmentvaried from 12 to 57 kg ha–1yr–1 fornitrogen and 0.25 to 6.6 kg ha–1yr–1 forphosphorus with little inter-annual variation.Averaged across the whole catchment, nitrogen fixation(47%) dominated the inputs; fertiliser (26%) andrainfall (21%) made up the next largest inputs.Fertiliser inputs dominated the phosphorus budget(65.5%); rainfall and manures making up 13% and 12%respectively. Produce dominated the outputs of bothnitrogen and phosphorus from the four sub-catchmentsbeing greater than the riverine export. The deliveryof nitrogen to catchment streams ranged from <1 to24% of the total inputs and the delivery of phosphorus to catchment streams ranged from <1 to 39%. Storage of phosphorus in catchment soils varied between –0.32 and 4.46 kg ha–1yr–1. Whendenitrification and volatilisation were estimated using data from other studies, storage of nitrogen ranged from 1 to 24 kg ha–1yr–1. Despite theepisodic nature of runoff in the sub-tropical RichmondRiver catchment, the magnitude of nutrient fluxes andstorage appear similar to other catchments of theworld which have mixed land use and relatively lowcatchment nutrient loadings. |
| |
Keywords: | denitrification export landuse N fixation nutrients volatilisation |
本文献已被 SpringerLink 等数据库收录! |
|