Archives

New model paves way for prediction of phosphorus mobility and runoff

Recent research into phosphorus (P) mobility and movement has resulted in a runoff prediction model for Alberta's livestock industry. The model will further assure the general public that the province's livestock industry is responsible and sustainable, particularly when it comes to protecting water quality.

"Our research has led to the development of a model that can predict P runoff from agricultural operations throughout the province, which will give producers greater ability to manage their own operations sustainably," says Dr. Dan Heaney, former head of the Agronomy Unit of the Plant Industry Division, Alberta Agriculture, Food and Rural Development (AAFRD). "As well, it has resulted in solid conclusions about the suitability of current agronomic soil tests for measuring P."

The research was funded in part by the Canada Alberta Beef Industry Development Fund (CABIDF).

Research conducted in Alberta in the late 1990s showed that P levels in surface water were too high in many areas, especially in areas with moderate or high agricultural operation intensity. However, that research did not evaluate the specific agricultural activities that might have contributed to the high levels. As such, producers were left without any concrete information as to how to manage their operations in a way that might reduce phosphorus loading following manure application.

"If the livestock industry in this province wants to be sustainable while undergoing expansion, it needs site specific management tools for P, and P mobility and movement," says Heaney. "We're confident our research will put the industry well on its way to being able to assess the risk of P movement and mobility, and what it means for siting operations and managing existing ones."

In step one of the research, more than 50 representative soils were collected from farmers and research plots throughout Alberta. Researchers compared soil tests and then performed a number of tests to characterize soils that had received manure, to determine the P sorption capacity (PSC) of the different soils - a higher PSC is considered better - and to quantify how P levels change in soil tests following manure application.

"Our research demonstrated that different soil types vary widely in their ability to absorb P and that their ability to absorb P is site-specific and could be mapped for most of Alberta. For producers, this can help in siting decisions," says Heaney. "We also found that the use of agronomic soil tests in P mobility assessment works well. While tests extract P in different ways, we found that producers can use one of several commonly available tests and get useful information."

Once researchers were confident they had a solid understanding of Alberta soils, PSC rates and soil tests for P, they initiated studies on runoff, looking at the interaction between soil and rainfall/snowmelt. Researchers then used all of the information gathered to develop an Edge of Field Phosphorus Export Model (EFPEM).

"The EFPEM is a system for mechanistic modeling, not statistical, of P mobility and P movement," says Heaney. "The EFPEM takes into account environmental variables of a specific site - including landscape, soil test results, soil type information and weather data - in order to predict how much P will be exported from the land following manure application. We input the variables, run the model and it comes up with an outcome."

Eventually, as it evolves, the modeling system will be able simulate different management practices and how that might influence runoff, for example, incorporation vs. injection manure application," says Heaney.

Producers are not currently using the EFPEM, but that doesn't mean there aren't immediate benefits, he adds. "Overall, the research has given us a greatly expanded knowledge base about P, its movement and mobility. We also gained a greater understanding of the different soil types in Alberta, which led to conclusions about where manure should and should not be applied.

"That's good news for Alberta's livestock industry if it wants to remain responsible, sustainable and accepted by the general public."

CABIDF is a joint $16.4 million fund of Alberta Agriculture, Food and Rural Development and Agriculture and Agri-Food Canada. The Fund is administered by Alberta Beef Producers and has supported more than 50 projects in six major categories identified to benefit the Alberta beef industry.

© 2004 Meristem Information Resources Ltd.
Meristem® is a registered trademark of Meristem Information Resources Ltd. All rights reserved.
Legal Disclaimer