Estimating Nutrient Transport Associated with Water and Wind Erosion Across New South Wales, Australia
38 Pages Posted: 13 Sep 2022
Nutrient transported from soils to water bodies not only threatens agricultural productivity and food security but also causes degradation of water quality and the environment in many parts of the world. However, nutrient transport through soil erosion is often ignored in the nutrient cycle studies; there is little understanding of how much nutrients are lost through water and wind erosion. In this study, we attempted to assess soil nutrient transport due to both water and wind erosion and its spatial and temporal variability across New South Wales (NSW), Australia. We estimated the mass fraction (%) of total nitrogen (N), total phosphorus (P) and soil organic carbon (SOC) in the eroded soil, and the total nutrient stock of the soil layer down to 200 cm. The estimated average N, P and SOC stocks in NSW topsoils (5 cm) are 160, 43, 2970 kg ha -1 respectively. There are great variations in the transport of nutrients by erosion in space and time, ranging from near zero in the Western region to 395 kg ha -1 yr -1 in the North Coast region. The average total nutrient transport rate is about 2.4% of the surface soil (0-5 cm) total stock in NSW due to both water and wind erosion. The total cost of nutrient transport is estimated at 4.2 billion Australian dollars for the entire state of NSW and 0.2 billion dollars from cropping areas per year. The areas with highest nutrient transport rates are the North Coast and Hunter regions due to the relatively high hillslope erosion and nutrient content of the soils. Nutrient transport from water erosion is about 90 times higher, on average, than that from wind erosion. We further analysed nutrient transport by soil erosion on cropping lands and identified the areas with high-risk and high capacity for land management improvements. The findings and methodology contribute to knowledge of nutrient transport due to erosion in broad nutrient circle studies.
Keywords: nutrient loss, organic carbon, water erosion, Wind erosion, water quality, land management
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