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Towards an integrated phosphorus, carbon and nitrogen cycling model for topographically diverse grasslands


Bilotto, F and Vibart, R and Mackay, A and Costall, D and Harrison, MT, Towards an integrated phosphorus, carbon and nitrogen cycling model for topographically diverse grasslands, Nutrient Cycling in Agroecosystems pp. 1-67. ISSN 1573-0867 (In Press) [Refereed Article]


Contemporary understanding of how livestock influence nutrient cycling and flows in grazing systems is limited, particularly in topographically complex landscapes. Prominent slope and aspect variation affects primary production, animal behaviour and nutrient return. Here, we embed recent scientific advances in nutrient dynamics across complex landscapes to i) integrate a soil organic carbon (SOC) saturation function within a SOC and total soil phosphorus (TSP) model (Bilotto et al. 2019), ii) account for total soil nitrogen (TSN) dynamics, and iii) assess whether the improved model can sufficiently simulate spatial and temporal changes in TSP, SOC and TSN of hill country. A long-term P fertilizer experiment with contrasting P fertilization levels and sheep stocking regimes (herein, ‘farmlets’) was used for model testing. The new spatiotemporal model (herein, the Grass-NEXT model) predicted farmlet TSP and SOC stocks with high accuracy and TSN stocks with moderate performance [Concordance Correlation Coefficient (CCC), 0.75, 0.72 and 0.49, respectively]. The model simulated TSP, SOC and TSN distribution with moderate/strong performance across varying slopes (CCC, 0.94, 0.80 and 0.70) and aspects (CCC, 0.83, 0.67 and 0.51). Consistent with observed data, modelled changes in TSP and TSN were greater on low slopes and eastern aspects, but no pattern was observed for SOC stocks. The improved spatiotemporal model is an intuitive research tool for exploring management options for increasing SOC and TSN, and could be used as an instrument for monitoring nutrient dynamics in complex landscapes.

Item Details

Item Type:Refereed Article
Keywords:model, carbon, soil carbon, greenhouse gas emissions, nitrogen, phosphorus, nutrient flows, biodiversity, environment, terrestrial, grasslands, grazing, livestock, methane, stocking rates, topography, verification, eutrophication, nitrate, P, K, S
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Agriculture, land and farm management
Research Field:Agricultural management of nutrients
Objective Division:Environmental Management
Objective Group:Terrestrial systems and management
Objective Field:Soils
UTAS Author:Bilotto, F (Mr Franco Bilotto)
UTAS Author:Harrison, MT (Associate Professor Matthew Harrison)
ID Code:153117
Year Published:In Press
Deposited By:TIA - Research Institute
Deposited On:2022-09-07
Last Modified:2022-11-10

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