The management of P in agriculture must maximize the benefit to producers and minimize any adverse environmental effects. The latter arise from the loss of P from soil to standing freshwater. Even very small amounts of P can raise the concentration above the critical value for eutrophication. Such small quantities can be lost in eroded soil, in surface runoff and in drainage water. The relative importance of these pathways depends on many factors, including topography, rainfall, farming system, soil characteristics, and the bioavailability of the P that is lost. The success of agriculture in increasing food production to meet the increasing needs of humankind, especially since the 1950s, owes much to the use of P in fertilizers and animal feeds. What is now required is to ensure that P, a finite earth resource, is not wasted and that soils do not become so enriched with P that there is an unnecessary risk of too much P being carried to water from agricultural soils. The concept of taking account of critical soil P values to optimize the use of P in both fertilizer and manures is discussed here.

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In this forum we highlight innovative thought, design, and research in the area of interaction design and sustainability, illustrating the diversity of approaches across HCI communities. --- Lisa Nathan and Samuel Mann, Editors

This article presents the development of a Geographical Information Systems (GIS) workflow that harvests high‐volume and high‐frequency near real‐time data from a public General Transit Feed Specification (GTFS) and calculates metrics for the assessment of on‐time and route speed performance for a public transit system. The approach is applied to near real‐time and static GTFS data collected over a 9‐month period for the City of Calgary, Alberta, Canada. The workflow uses two Azure Virtual Machines (VMs), one to harvest the data and the other to process observations in parallel using Python and the ArcGIS API libraries. A Web GIS application is described that queries data from MongoDB to visualize the performance results in spatiotemporal form. The purpose of the workflow and Web GIS application is to provide actionable information to transit planners to improve public transportation systems. The data management and analysis workflow is transferable to similar GTFS data from other cities.

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