Theme 1: Grassland Ecology
Description
Topographical features such as slope and aspect influence primary production, animal behavior and nutrient return to grazed grasslands. A new model was developed based on data collected during 40+ years of research in hill country landscapes, a long-term experiment on varying phosphorus (P) fertilizer rates and associated sheep stocking regimes. The Grass-NEXT model was able to simultaneously simulate total soil P (TSP), soil organic carbon (SOC) and total soil nitrogen (TSN) stock change and distribution in a topographically complex (hill country) landscape from 2003 to 2020. This model provided a basis for exploring, accounting, and reporting on changes in TSP, SOC and TSN stocks in response to current management practices (e.g., varying amounts of P fertilizer rates applied) in complex grazed systems. The model provided insights on both the combination of topographical features that provided the largest spatial and temporal variability across the landscape, and where more intensive sampling is required to detect a significant minimum change of 3% in total SOC stocks. Further work could improve the quantification of grazing activities and excreta deposition that would help to detect specific clusters of variation on topographical complex landscapes to facilitate soil sampling design.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Grass-Next – A Process-Based Model to Explore Nutrient and Carbon Dynamics in Topographically Complex Grazed Grasslands
Topographical features such as slope and aspect influence primary production, animal behavior and nutrient return to grazed grasslands. A new model was developed based on data collected during 40+ years of research in hill country landscapes, a long-term experiment on varying phosphorus (P) fertilizer rates and associated sheep stocking regimes. The Grass-NEXT model was able to simultaneously simulate total soil P (TSP), soil organic carbon (SOC) and total soil nitrogen (TSN) stock change and distribution in a topographically complex (hill country) landscape from 2003 to 2020. This model provided a basis for exploring, accounting, and reporting on changes in TSP, SOC and TSN stocks in response to current management practices (e.g., varying amounts of P fertilizer rates applied) in complex grazed systems. The model provided insights on both the combination of topographical features that provided the largest spatial and temporal variability across the landscape, and where more intensive sampling is required to detect a significant minimum change of 3% in total SOC stocks. Further work could improve the quantification of grazing activities and excreta deposition that would help to detect specific clusters of variation on topographical complex landscapes to facilitate soil sampling design.
