-Photo courtesy of ISU Extension
A pasture under water due to recent flooding is shown. Iowa State University Extension and Outreach Forage Specialist Shelby Gruss said the first step farmers must take after a field is flooded is to evaluate the damage.

Record-breaking rainfall led to flooding of hay fields and pasture ground in areas of Iowa, particularly northwestern Iowa this summer. In fact, up to 1 million acres of farmland was affected in a four-state area.

So how do hay fields and pasture ground look now in Iowa? What can farmers do with flood-damaged fields direly needed as a feed source for livestock?

Iowa State University Extension and Outreach Forage Specialist Shelby Gruss said the first step farmers must take after a field is flooded is to evaluate the damage.

“Damage may vary depending on how long the forage was submerged, the species and the amount of sediment deposits,” she said. “It is essential to document and report damages.”

Next, walk through pastures and remove any debris that could be dangerous to livestock. Then, inspect and repair fencing and water systems. Make sure the livestock have access to clean water before they’re allowed back on the land, which should be postponed for a couple of weeks following flooding to prevent microbial contamination.

Also, be sure to remove sand and silt from fields, because any extra ash content can impact livestock performance.

“Many perennial forages can withstand flooding for up to a few days to weeks and can recover after the water recedes, so assess stands and check for root damage. Dark colored, musty and water-soaked roots are unlikely to recover,” she said. “Sediment deposited on the stands not only affects animals but also stand survival. Sediment deposits of more than 2 inches can smother plants.”

Alfalfa fields should be checked a month after flooding. They don’t tolerate flooding for long and could sustain substantial damage, Gruss said.

“Check the alfalfa roots 6 inches deep and look for browning, soft roots, a water-soaked appearance and rotted-off roots,” she said. “These are symptoms of root rot, such as phytophthora root rot, which may necessitate replanting the stand.”

Silt deposits in alfalfa fields can cause some of the same problems as those found in pastures. Large amounts of silt deposits (2 to 3 inches) can weaken the stand, and these areas may need to be reestablished.

However, be aware of reestablishing stands that are older than a year due to autotoxicity, Gruss said.

Despite pockets of the state receiving excessive flooding, many farmers are focused on squeezing in a fourth cutting.

“We’ve seen a lot of back and forth, rain and sun. The grounds that didn’t get excessive rain and standing water look great. The alfalfa fields woke up from a three-year drought. It’s a super tolerant crop and can handle a lot of heat. Some farmers may not squeeze in that cutting because rains pushed back the timing of their third cutting,” Gruss said.

“But overall, we’ve seen some really good yields. In fact, we’re seeing some of the best yields we’ve had for years.”

Hay fields flourish

Angie Rieck-Hinz, an ISU Extension field agronomist based in Wright County, said producers in her area are reaping considerably more tonnage off their hay ground this summer.

“We had ample moisture, but I’d say the quality of the second cutting was low because it was cut a little later due to constant rainfall,” Rieck-Hinz said. “It got rained on a lot. Producers will start cutting that third round in a couple weeks. There’s a possibility of a fourth cutting for some who didn’t even get a third round last year.”

Lance Lillibridge, a farmer from Benton County who raises livestock and corn, said pastures in his area were fairly dry but after recent heavy rains, the pastures are “looking really good.” He feeds his bales to his cattle herd, but can’t engage in rotational grazing as his cattle roam a timber-pasture.

“We’ve been super satisfied. Our hay ground has been amazing with the rain, possibly some of the best we’ve ever baled,” Lillibridge said. “We’ve got a third cut coming and, depending on the rest of the growing season, there might be a fourth. The quality has been fabulous.”

Recovering from drought

Meaghan Anderson, an Iowa State field agronomist based out of Story County, said excess rains in her areas helped pastures and hay fields recover from the ongoing drought.

“But it did make it a challenge to get a timely first hay cutting in central Iowa,” Anderson said.

“Everyone’s gotten two cuttings in so far and I imagine farmers will be looking for a third cutting with all the rainfall we’ve received.”

Anderson emphasized that late summer and fall are when farmers should implement management strategies to improve hay fields and pastures for the following year.

“In some cases, we can consider late summer seedings to fill in thin areas, especially with all the moisture we’ve had this year. Fall is a great time to soil sample, manage weed issues and fertilize hay and pastures,” Anderson said.

Leah Ten Napel, an Iowa State field agronomist based in Le Mars in northwest Iowa where flooding occurred, said the rains were welcomed since many pastures had been over-grazed or burned up after a significant lack of rain the last few years.

“The hay crops are growing well, but growers are finding it a challenge to work around rainfall to get the hay cut and dried before bailing,” Ten Napel said. “Most growers in northwest Iowa have gotten in a second crop and some even a third.”

Hay quality has been reported as good with some insect pressure in the hay crop this year, but not an extreme amount of damage, she said. Growers should continue scouting fields to watch for insect feeding and disease presence, while also keeping an eye out for any nutrient deficiencies in plants.

“Keeping a good stand and adequate fertility levels will help keep the hay crop healthy. If fields start to look over-grazed, herds should be pulled,” she said.

After the floods

Gentry Sorenson, an Iowa State field agronomist based in Algona, said that farmers did see flooded pastures due to river flooding and ponding.

“This did affect cutting in flooded areas. Some were a case-by-case basis. If waters receded quickly, we saw light damage. In other areas, water stood or continued to stand. In those cases, it may need to be reseeded,” he said. “In areas where it was not flooded, the rainfall helped spur good growth of pasture and hay. But it did make cutting and baling very difficult. Some did not cut the hay until the rainfall let up and this led to taller or more mature hay in some areas.”

Producers hope to get a third cutting of hay in Sorenson’s area and quality has been average, he said.

“Scout fields for weeds and stands for damage, and do stand counts in alfalfa. It’s not recommended to reseed alfalfa into an existing alfalfa stand that’s one year old or older due to autotoxicity. Grasses or clover can be used for reseeding troubled areas,” Sorenson said. “New alfalfa seeding should be completed by Aug. 10 in northern Iowa and cool season forages grass have a few weeks after Aug. 10. There’s a risk of high stand failure in new plantings if planted into dry soil and rainfall is low or erratic.”

Rieck-Hinz reminded growers that it’s important to replace the nutrients being removed from the fields, particularly with the higher tonnage this season.

“Alfalfa uses a lot of potassium and when you cut the bales and remove them from the field, you take off a lot of potassium. If you’re making a fourth cutting, consider replacing nutrients between the third and fourth cutting especially for the fall,” she said. “Also make sure there’s five to six weeks of uninterrupted growth between when the plant goes dormant and frost to give it enough recovery time before winter. It needs enough growth to support the roots and grow in order to have a viable stand for next year.”