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Nutrient removal by a 4.6-ha urban stormwater treatment wetland system in a 20-ha water/nature park in southwest Florida has been investigated for several years, suggesting that the wetlands are significant sinks of both phosphorus and nitrogen although with a slightly decreased total phosphorus retention in recent years. This study investigates the role of sedimentation on changes in nutrient concentrations and fluxes through these wetlands. Sedimentation bottles along with sediment nutrient analyses every six months allowed us to estimate gross sedimentation rates of 9.9±0.1 cm yr−1 and nutrient sedimentation rates of approximately 7.8 g-P m−2 yr−1 and 81.7 g-Nm−2 yr−1. Using a horizon marker method to account for lack of resuspension in the sedimentation bottles suggested that net nutrient retention by sedimentation may be closer to 1.5 g-Pm−2 yr−1 and 33.2 g-N m−2 yr−1. Annual nutrient retention of the wetland system determined from water quality measurements at the inflow and outflow averaged 4.23 g-P m−2 yr−1 and 11.91 g-N m–2 yr−1, suggesting that sedimentationis a significant pathway for nutrient retention in these urban wetlands and that resuspension is playing a significant role in reintroducing nutrients, especially phosphorus, to the water column. These results also suggest that additional sources of nitrogen not in our current nutrient budgets may be affecting overall nutrient retention.
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A global FAOSTAT reference database of cropland nutrient budgets and nutrient use efficiency (1961–2020): nitrogen, phosphorus and potassium
Abstract. Nutrient budgets help to identify the excess or insufficient use of fertilizers and other nutrient sources in agriculture. They allow for the calculation of indicators, such as the nutrient balance (surplus if positive or deficit if negative) and nutrient use efficiency, that help to monitor agricultural productivity and sustainability across the world. We present a global database of country-level budget estimates for nitrogen (N), phosphorus (P) and potassium (K) on cropland. The database, disseminated in FAOSTAT, is meant to provide a global reference, synthesizing and continuously updating the state of the art on this topic. The database covers 205 countries and territories, as well as regional and global aggregates, for the period from 1961 to 2020. Results highlight the wide range in nutrient use and nutrient use efficiencies across geographic regions, nutrients, and time. The average N balance on global cropland has remained fairly steady at about 50–55 kg ha−1 yr−1 during the past 15 years, despite increasing N inputs. Regional trends, however, show recent average N surpluses that range from a low of about 10 kg N ha−1 yr−1 in Africa to more than 90 kg N ha−1 yr−1 in Asia. Encouragingly, average global cropland N use efficiency decreased from about 59 % in 1961 to a low of 43 % in 1988, but it has risen since then to a level of 55 %. Phosphorus deficits are mainly found in Africa, whereas potassium deficits occur in Africa and the Americas. This study introduces improvements over previous work in relation to the key nutrient coefficients affecting nutrient budgets and nutrient use efficiency estimates, especially with respect to nutrient removal in crop products, manure nutrient content, atmospheric deposition and crop biological N fixation rates. We conclude by discussing future research directions and highlighting the need to align statistical definitions across research groups as well as to further refine plant and livestock coefficients and expand estimates to all agricultural land, including nutrient flows in meadows and pastures. Further information is available from https://doi.org/10.5061/dryad.hx3ffbgkh (Ludemann et al., 2023b) as well as the FAOSTAT database (https://www.fao.org/faostat/en/#data/ESB; FAO, 2022a) and is updated annually.
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- PAR ID:
- 10488445
- Publisher / Repository:
- Earth System Science Data
- Date Published:
- Journal Name:
- Earth System Science Data
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 1866-3516
- Page Range / eLocation ID:
- 525 to 541
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/essd-16-525-2024
