Assessing the Long Term Impact of Phosphorus Fertilization on Phosphorus Loadings Using AnnAGNPS

Abstract

High phosphorus (P) loss from agricultural fields has been an environmental concern because of potential water quality problems in streams and lakes. To better understand the process of P loss and evaluate the effects of different phosphorus fertilization rates on phosphorus losses, the USDA Annualized AGricultural Non-Point Source (AnnAGNPS) pollutant loading model was applied to the Ohio Upper Auglaize watershed, located in the southern portion of the Maumee River Basin. In this study, the AnnAGNPS model was calibrated using USGS monitored data; and then the effects of different phosphorus fertilization rates on phosphorus loadings were assessed. It was found that P loadings increase as fertilization rate increases, and long term higher P application would lead to much higher P loadings to the watershed outlet. The P loadings to the watershed outlet have a dramatic change after some time with higher P application rate. This dramatic change of P loading to the watershed outlet indicates that a “critical point” may exist in the soil at which soil P loss to water changes dramatically. Simulations with different initial soil P contents showed that the higher the initial soil P content is, the less time it takes to reach the “critical point” where P loadings to the watershed outlet increases dramatically. More research needs to be done to understand the processes involved in the transfer of P between the various stable, active and labile states in the soil to ensure that the model simulations are accurate. This finding may be useful in setting up future P application and management guidelines.

Understanding students’ learning experience on a cultural school trip: findings from Eastern Indonesia

“…Fägerstam (2014) emphasized that the 'educational aspect' of a trip contributed to students' experience through communication, shared experience, as well as expansion and confirmation of academic knowledge. Besides improving students understanding and fostering acquisition of practical skills, school trips are claimed to contribute to various learning outcomes, including stimulation of students' curiosity (Falk & Dierking, 1997), individual growth (Rickinson et al, 2004;Stone & Petrick, 2015) and social and interpersonal impacts (Dohn, 2013;O'Brien & Murray, 2007). Bloom et al (1956) highlighted the equal importance of the affective and psychomotor domains of learning, which can be enhanced through experiential learning.…”

Phosphorus dynamics in vegetated buffer strips in cold climates: a review

“…This watershedscale model requires three main data inputs: (i) topographic data, (ii) soil and land use data, and (iii) climate data. With specific regard to buffers, a GIS-based framework has been developed to integrate plot-scale VBS effectiveness modeling and modeling with AnnAGNPS at the watershed scale (Yuan et al 2011). This framework is currently focused on integrating VBS into the model with the intention of reducing sediment loading but could become useful with respect to P loading if P inputs can be accurately assessed.…”

Agricultural watershed modeling: a review for hydrology and soil erosion processes

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