By Matt Reese
When looking at the last year in the debate over nutrient management and water quality, the number 7.3 stands out.
This number is the severity of the Microcystis cyanobacteria bloom in Lake Erie in 2019, indicating a relatively severe bloom. It was very close to the National Oceanic and Atmospheric Administration prediction of 7.5 made earlier in the summer. The incredible amount of rainfall in the spring of 2019 would suggest a much more severe algal bloom number, but the drastic reduction in planted acres and nutrient application on farms helped reign in the severity.
The 7.3 of 2019 is an indication that — due to necessity or proactive stewardship — spring farm nutrient application can directly impact the severity of the algal bloom in Lake Erie. The 7.3 also indicates though, to get to an average annual severity closer to a desired level of 3, there are many other factors (both farm and non-farm) at play that researchers have yet to quantify or understand.
So, what can be learned by agriculture from 2019’s 7.3? Ohio State University Extension took a look at the situation to determine how much nutrient application for the 2019 crop was actually reduced.
“Quantifying the 2019 agricultural experience will be critical to understand the impacts from both an agricultural and environmental perspective,” said Greg LaBarge, CCA, with OSU Extension. “We surveyed retailers to get a handle on how much fertilizer was actually applied in the Western Lake Erie Basin. A Web survey of agricultural retail entities was developed that focused on phosphorus delivered from November 2018 to May of 2019 and corn planting progress from April 1 to June 25, 2019.”
Results were tabulated from seven agribusinesses representing 3.6 million acres in the Western Lake Erie Basin. In addition, phone interviews of 10 commercial manure applicators in the area were conducted. The survey found the tons of phosphorus sold was down 54% and manure application in the watershed was down 85% in spring of 2019.
“Basically, what we found was that nutrient applications were reduced by 54%. The retailers that responded represented a large percentage of the acres in the watershed,” LaBarge said. “That is certainly one data point we need to look at for understanding the 2019 agricultural season but also the season in relationship to the Western Lake Erie Basin and the harmful algal bloom.”
The numbers from 2019 hopefully offer some useful insights on their own, but have more value when compared to other years.
“We don’t want to take 2019 in isolation. We do have other years where we have seen fertilizer reductions due to weather or price and we have different harmful algal bloom results in those years,” LaBarge said. “This year’s algal bloom ended up being 7.3, which is certainly significant. Some of our best years for a small algal bloom are some of our worst years for agriculture because of droughts. We need to take an overall look at these different years to try and better understand what we need to be doing from a management standpoint.
“Why did we still see a 7.3 if agriculture is supposed to be the primary issue? There may be other things we need to think about. There may be soil test levels and legacy phosphorus issues that exist in fields and streams in the watershed. Water management is another area of management we need to focus on.”
Weeks after the announcement of the 7.3 algal bloom severity came the official announcement of Gov. Mike DeWine’s H2Ohio program that put forth a list of on-farm management practices to improve water quality, a means of providing economic incentives for those practices when implemented on farms and a proposed certification program to acknowledge the efforts of farms in taking steps to address the problem. H2Ohio also includes an effort to quantify current implementation of these practices on Ohio farms through the Ohio Agriculture Conservation Initiative. These on-farm practices are: 1. Soil testing, 2. Variable-rate fertilization, 3. Subsurface nutrient application, 4. Manure incorporation, 5. Conservation crop rotation, 6. Cover crops, 7. Drainage water management. 8. Edge-of-field buffers, 10. Wetlands.
There is no question that the 10 practices from H2Ohio have positive impacts for farms, nutrient management and water quality.
“Those 10 practices are important. We have done our own work on this, even before this administration. I was really pleased to see that the practices we believe we ought to be focusing on really lined up with what the State of Ohio did,” said Tadd Nicholson, executive director of Ohio Corn & Wheat. “These are practices are all rooted in science and we have a lot of belief that these will help us move forward in a positive direction. This is the first time the State of Ohio has allocated real dollars toward this. In agriculture we do have things we can do and we are willing to do those, but hardly any of them are free. We need to have some assistance and I think it is worth it to the State and so does the governor and the administration.”
The 7.3 does, however, bring up questions regarding the ability of those farm practices to successfully create a path to a future of consistent algal bloom severity levels near 3. The challenge continues to be that the conclusions from the available science are often muddled and unclear due to the incredible number of factors at play in the connection between farms and the 7.3.
In addition to measures in H2Ohio, 2019 saw continued efforts of the Blanchard River Demonstration Farms Network that facilitates extensive edge-of-field research to learn more about farm practices and the 7.3.
“Kevin King with USDA-ARS and his team are doing the monitoring on this. We just promote the results they share with us,” said Aaron Heilers, project manager for the Network. “We need to start by making sure everybody is doing the basics — the 4Rs, soil testing, watching how they apply their nutrients. Those are things every farmer should be doing. We need a critical mass of farmers doing these basic practices to move the needle. Then we can start looking at the individual on-farm practices for soil health and water management.”
The next tier of practices get more costly and cumbersome to implement with benefits that are often less clear. One example of this next tier is incorporation of nutrients with minimal soil disturbance using banded application through row starter or banding tool bars. This practice, though, requires increased application time, more down time for tender trucks at field edge and higher application equipment cost compared to surface broadcast applications.
“The edge-of-field data suggests that there can be a 46% reduction in phosphorus going down the stream if we incorporate or inject. The caveat there is ‘up to,’ but that is still a great practice. But how do we accomplish that as we look out across the landscape? Farmers pay the retailer to broadcast the fertilizer on. And I no-till, and that is a hard pill to swallow to maybe go back to incorporation,” Heilers said. “We are looking at different implements that can get that nutrient below the soil surface, but that comes with an expense. Farmers need to look at how that management change could impact their bottom line.”
The costs and benefits of other on-farm practices can become even more muddled when it comes to the 7.3 in 2019. As the focus moves to the Lake Erie algal bloom severity number of 2020 and beyond, many questions remain about what practices (on and off farms) will be required to bring that 7.3 down to a more acceptable level through measures within human control. For now, it seems, those remaining questions around 7.3 loom large.