The headwaters of Mattawoman Creek flow through Mattawoman Natural Environmental Area in Charles County, Md. The estuarine parts of the creek are considered a model for a fully restored Chesapeake Bay. (Photo by Will Parson/Chesapeake Bay Program)
When we talk about high phosphorus levels, we are talking in terms of soil phosphorus. High soil phosphorus has two main contributors:
1. Cumulative years of high phosphorus fertilization. For example, tobacco -- which has a long history of cultivation in areas of the watershed -- needs a lot of phosphorus to thrive. Farmers may have over-fertilized to ensure a vigorous crop.
2. Manure acts as a multivitamin for the land. It is a terrific source of nutrients and of great importance to the health and development of fields. Manure has long been known to help crops thrive, but there is a lack of understanding of the nutrient content of that manure and the eventual fate of those nutrients.
When the scientific community first began to look at the decline in water quality, it took a bit longer to recognize the implications of phosphorus on Bay and stream health because phosphorus behaves differently than nitrogen. Nitrogen is loosely held in soil, traveling either through soil or along with surface runoff after a big storm. Phosphorus molecules, in contrast, adhere tightly to particles of soil and organic matter. It was thought that phosphorus would not have as much of an impact because it was not leaving the field.
Fast forward, and the scientific community began to realize that soil has a capacity limit for holding phosphorus. This capacity limit changes based on the soil type. Over decades, many areas have reached their phosphorus capacity. Phosphorus that is not taken up by vegetation has nowhere to go but to leave the field. Phosphorus that cannot soak in is also leaving the field along with -- and inside of -- the sediment pollution. Hence, the phosphorus gap.
Many best management practices (BMPs) have been identified to help reduce the loss of phosphorus from fields. Nutrient management is a major one. Each state in the watershed takes a different approach regarding planning and requirements, but some sort of Nutrient Management Plan is critical. The popular shorthand for nutrient management is the 4 Rs: right source, right rate, right time, right place. This helps the farmer to save funds and supplies by using nutrients in an intentional way to have a robust crop, and at the same time helps reduce the impact to water quality and ecosystem health. The second crucial piece is to work towards curtailing erosion - here too farmers and environmental concerns are on the same page, as farmers do not want to see their topsoil washing away with the storms. Erosion can be managed with practices like riparian buffers, no till practices and contour farming. Cover crops span the situation and help with both issues.
For more information, look into the suite of BMPs and the efforts to assist farmers in switching to these practices:
http://www.nutrientstewardship.com/4rs
https://www.chesapeakebay.net/who/group/bmp_expert_panels
http://www.chesbay.us/Publications/CBC TA Report Boots on the Ground.pdf
The focus for the Bay Program's Agricultural Workgroup over the next two years is BMP implementation and verification.
Please send the latest updates on the FERC approval of the agreement between the 6 states (and DC) and Excelon. And if FERC hasn't yet approved the agreement put maximum pressure on them. Thanks.
It seems like many of the Chesapeake’s targets are being met or approached, but it is evident that phosphorous loading has one of the widest gaps in attaining the watershed’s goals. Do you believe the collaborative efforts across the watershed have been effective in reducing crop farmers’ phosphorous practices, as well as other nonpoint sources?
Thank you!
Your comment has been received. Before it can be published, the comment will be reviewed by our team to ensure it adheres with our rules of engagement.
Comments
Hello Mark,
When we talk about high phosphorus levels, we are talking in terms of soil phosphorus. High soil phosphorus has two main contributors:
1. Cumulative years of high phosphorus fertilization. For example, tobacco -- which has a long history of cultivation in areas of the watershed -- needs a lot of phosphorus to thrive. Farmers may have over-fertilized to ensure a vigorous crop.
2. Manure acts as a multivitamin for the land. It is a terrific source of nutrients and of great importance to the health and development of fields. Manure has long been known to help crops thrive, but there is a lack of understanding of the nutrient content of that manure and the eventual fate of those nutrients.
When the scientific community first began to look at the decline in water quality, it took a bit longer to recognize the implications of phosphorus on Bay and stream health because phosphorus behaves differently than nitrogen. Nitrogen is loosely held in soil, traveling either through soil or along with surface runoff after a big storm. Phosphorus molecules, in contrast, adhere tightly to particles of soil and organic matter. It was thought that phosphorus would not have as much of an impact because it was not leaving the field.
Fast forward, and the scientific community began to realize that soil has a capacity limit for holding phosphorus. This capacity limit changes based on the soil type. Over decades, many areas have reached their phosphorus capacity. Phosphorus that is not taken up by vegetation has nowhere to go but to leave the field. Phosphorus that cannot soak in is also leaving the field along with -- and inside of -- the sediment pollution. Hence, the phosphorus gap.
Many best management practices (BMPs) have been identified to help reduce the loss of phosphorus from fields. Nutrient management is a major one. Each state in the watershed takes a different approach regarding planning and requirements, but some sort of Nutrient Management Plan is critical. The popular shorthand for nutrient management is the 4 Rs: right source, right rate, right time, right place. This helps the farmer to save funds and supplies by using nutrients in an intentional way to have a robust crop, and at the same time helps reduce the impact to water quality and ecosystem health. The second crucial piece is to work towards curtailing erosion - here too farmers and environmental concerns are on the same page, as farmers do not want to see their topsoil washing away with the storms. Erosion can be managed with practices like riparian buffers, no till practices and contour farming. Cover crops span the situation and help with both issues.
For more information, look into the suite of BMPs and the efforts to assist farmers in switching to these practices:
http://www.nutrientstewardship.com/4rs
https://www.chesapeakebay.net/who/group/bmp_expert_panels
http://www.chesbay.us/Publications/CBC TA Report Boots on the Ground.pdf
The focus for the Bay Program's Agricultural Workgroup over the next two years is BMP implementation and verification.
Please send the latest updates on the FERC approval of the agreement between the 6 states (and DC) and Excelon. And if FERC hasn't yet approved the agreement put maximum pressure on them. Thanks.
It seems like many of the Chesapeake’s targets are being met or approached, but it is evident that phosphorous loading has one of the widest gaps in attaining the watershed’s goals. Do you believe the collaborative efforts across the watershed have been effective in reducing crop farmers’ phosphorous practices, as well as other nonpoint sources?
Thank you!
Your comment has been received. Before it can be published, the comment will be reviewed by our team to ensure it adheres with our rules of engagement.
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