Indiana reported a record number of cover crops this year to help absorb nutrients and reduce runoff, but scientists and environmental activists say more should be done to help improve water quality locally and regionally.

Hoosier farmers planted cover crops and small grains on 1.5 million acres of farmland in late 2021, matching a record amount set in 2020, according to the results of a new survey by the Indiana State Department of Agriculture.

Cover crops and small grains, like winter wheat or cereal rye, are usually planted after the fall harvest to help reduce soil loss and improve overall ground health. By adding living roots to the soil throughout the winter, the practice also improves water infiltration into the soil, and some cover crops, like legumes, serve as natural fertilizers. 

State agriculture officials said the use of cover crops planted last year prevented an estimated 2.1 million tons of sediment from entering Indiana’s waterways. The state agency also boasted that the winter crops prevented 5.1 million pounds of nitrogen and over 2.5 million pounds of phosphorus from entering Indiana’s waterways. The two chemicals are commonly found in farmland fertilizers.

 Jerry Raynor (Courtesy USDA)


The conservation survey also showed that about 70% of Indiana’s farmed acres were not tilled, and 18% employed “reduced tillage” after the 2021 harvest.

“Indiana farmers continue to help lead the way through their dedication to conservation farming,” Jerry Raynor, Indiana conservationist for the U.S. Department of Agriculture, said in a statement. “The work being done by farmers throughout the state to promote soil health through no-till farming and the planting of cover crops will have positive impacts for generations to come.”

The latest state data does not reveal cover crop percentages for 2022. Andy Tauer, executive director of public policy for the Indiana Farm Bureau, said it’s likely that even more Indiana farmers will adopt cover crops this year, given the rising cost of fertilizer.

“Many farmers around the state are only applying the exact amount of fertilizer that the crop needs at that time,” he said. “Making sure we don’t over-apply then equally has some water quality, environmental benefits.”

More work needed to help improve water quality

Still, less than 10% of farmers statewide plant cover crops, and roughly 38% do not till their fields, according to state data. 

Numerous incentives are in place to encourage farmers to employ methods to reduce runoff, but low participation puts further strain on already dismal water quality in Indiana.

study published earlier this year found that the state has the dirtiest waterways in the country.

Nearly 25,000 miles of Indiana’s rivers and streams are too polluted for swimming and recreation, mostly due to bacteria and nutrients that leach from various agricultural operations. 

Livestock waste and excessive fertilizer applications are the main sources of non-point water pollution in Indiana rivers, according to the Hoosier Environmental Council

During periods of rain or melting snow, sediment and nutrients from manure or chemical fertilizer wash off crop fields and into the state’s waterways, leading to high concentrations of E. coli bacteria and the growth of harmful algae.

The report noted that a loophole in the Clean Water Act allows most agricultural runoff to go unregulated.

“Indiana’s waters have benefited from the Clean Water Act, but unfortunately, they also illustrate some of the gaps in the law,” said Indra Frank, Environmental Health & Water Policy Director for the Hoosier Environmental Council. 

“We have seen persistent, unresolved impairments, especially for E coli bacteria in our rivers and streams, in part from industrial agricultural runoff,” she continued. “And unfortunately, we have also seen examples of Clean Water Act permits used to send water contaminated with coal ash into our rivers. We need to halt pollution like this.”

Dead Zone

With 90% of Indiana’s waterways draining to the Mississippi River, the state’s farmland runoff also contributes to an annual “dead zone” in the Gulf of Mexico.

The dead zone, also known as a hypoxic zone, is primarily fueled by Mississippi River discharge and nitrogen and phosphorus runoff, mostly from the Corn Belt. The dead zone contains almost no oxygen, leading to the deaths of large quantities of marine life. 

In 2001, the U.S. Environmental Protection Agency and 12 Mississippi River basin states — including Indiana — agreed to take action to reduce the Gulf dead zone by two-thirds by 2015. Researchers estimated that this would require reducing nitrogen loads reaching the Gulf by about 45%

Because nitrogen and phosphorus loadings at the mouth of the Mississippi River haven’t seen much improvement, that deadline has since been extended to 2035.

Recent measurements revealed this year’s Gulf dead zone is more than 1,000 square miles smaller than the five-year average — which could be a hopeful sign. But Nancy Rabalais, a professor at Louisiana State University who measures the Gulf dead zone annually, cautioned that “this summer was an unusual year for Gulf hypoxia.” 

She said a combination of weather events led to the smaller size this year. Drought conditions in the Midwest additionally reduced the water flow from the Mississippi River into the Gulf of Mexico during June and July.

“Agricultural interests are trying to reduce their nutrient flux, but it’s going to take a bigger effort than what’s being done right now,” Rabalais said.

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