Manure nutrient handling focus of 4R conference

August 26, 2021 | Kriss Nelson

Right source, right rate, right time and right place make up the 4Rs of nutrient stewardship. Presentations covering each one of those concepts and more were the focus of an Iowa Soybean Association sponsored event held on Aug. 16 at Dordt University in Sioux Center.

More than 50 farmers and agribusiness professionals attended the Fertilizer Institute’s annual 4R Conference.

This was the third year for the 4R Conference in Iowa. Iowa Soybean Association (ISA) Senior Field Services Program Manager Scott Nelson said the conference is rotated throughout the state with the emphasis of topics addressed to local conditions. This year’s focus was manure management which is an integral part of agricultural production in northwest Iowa.

“The group of farmers gathered with the idea to be proactive in their nutrient management and to learn and share best practices for managing nutrients,” Nelson said.

Four sessions complimented the 4Rs of Nutrient Stewardship.

About the 4R Nutrient Stewardship concept

The 4R concept refers to best practices when it comes to nutrient stewardship. They are:

-          Right Source: matches fertilizer type to the crop needs

-          Right Rate: matches amount of fertilizer type to crop needs

-          Right Time: makes nutrients available when crops need them

-          Right Place: keep nutrients where crops can use them

“It is so important,” said Nelson. “We live in a time of increasing fertilizer prices and some of the ways that farmers can manage around that dramatic increase of NPK (nitrogen, phosphorous and potassium) is to follow the 4R concepts as a guide to improve their nutrient management as well as protect natural resources.”

Right source, right rate

“Supplemental N in Manured Cropping Systems” covered the right source, right rate portion of the 4R concept and was presented by Steve Leusink, field agronomist for Corteva and Jeff Koops, nutrient management specialist/technical service provider at Farmers Cooperative Society.

While manure is a very important source of crop nutrients, it can be very heterogenous as a source of nitrogen, phosphorous and potassium.

“For this reason, the speakers greatly emphasized testing manure at its source to improve manure rate recommendations. Due to its heterogeneity, farmers often supplement their manure applications with additional synthetic fertilizer, especially nitrogen,” said Nelson.

Leusink and Koops further stressed the need to base these nitrogen rate recommendations on nitrogen credits from manure testing and crop removal.

“To their credit, the speakers did a very good job in making nitrogen recommendations that optimize corn yield, while protecting natural resources,” Nelson said.

Right time

The session “Time of Manure Application Effects on Yield” which was based on the right time component of the 4Rs of Nutrient Stewardship was presented by Karl Leikvold, plant nutrition and performance manager with Winfield..

Karl began his talk with a demonstration on how various forms of nitrogen move within the soil profile. He then showed worldwide satellite images of ammonia loss to the environment.

The talk was fitting for the geography of the conference’s location, Nelson said.

“Sioux County, Iowa, had some of the largest ammonia loss in the world. This release of ammonia from cropping systems not only reduces the amount of nutrients for crop production, it also contributes significantly to climate change,” said Nelson.

Leikvold concluded his talk with research data on timing of manure applications showing that early fall manure applications are generally lower yielding compared to late fall and spring applications. This is because early fall applications are generally made in warmer soil that converts ammonia in the manure into the nitrate form that is more easily lost to crop production via leaching and denitrification.

Right place

The 4R component, right place, was covered by Dan Andersen, assistant professor of ag and biosystems engineering at Iowa State University, during his presentation on “Cover Crops and Low Disturbance Knives in Manured Cropping Systems.”

Andersen reviewed his research on cover crops in manured cropping systems.

“In this data, they show both a yield and water quality benefit for cover crops in manured cropping systems,” he said. He then reviewed different strategies for cover cropping such as inter-seeding.

“As Dan is a world-renowned expert in manure management, much of his session time was spent on answering and discussing audience questions and ideas,” Nelson said.

The final session “New Technology for Managing Manure: Manure Sense” was given by Devin Hoekstra, Precision Ag consultant for C&B Operations.

Nelson said Manure Sense is potentially a step-in change of technology for manure management.

In this system, an NIR (Near Infrared Spectrometry) sensor measures the nutrient content in manure during application at a rate of 4,000 times per second. By changing application or pump speed, Manure Sense solves the problem of manure heterogeneity by applying nitrogen or phosphorous at a constant rate of nutrient rather than a constant manure volume.

“Devin showed their data where actual applied manure nitrogen varied in fields ranging from 100 to 240 pounds of nitrogen per acre without Manure Sense. With Manure Sense, farmers and applicators were enabled to apply a constant rate of manure nitrogen which theoretically would increase yield and provide better protection of natural resources,” said Nelson.

The conference also allowed for farmer testimonials, Nelson said, where they shared about their own cropping systems and ways farmers are improving nutrient management in their area.

Continuous improvement

The 4R Conference, Nelson said, is proof Iowa’s producers are diligent with their nutrient management and are caring for the environment.

“Farming gets a bad name as a big polluter, but here is an example how farmers are coming together from the local area to continuously improve their nutrient management, to improve their economics as well as protecting natural resources,” he said.

Chuck White, ISA District 1 Director and farmer from Spencer attended the 4R conference to learn more about utilizing manure in the most efficient ways. 

“There was a lot of basic good information,” he said. “Times are changing. We are going to higher and higher yields and our nutrient levels are changing so we have to stay up to date. It was just a fantastic way to educate farmers and bring them up to speed on what our latest technologies are and the best way to grow a great crop.”

White said he especially enjoyed Andersen’s presentation that focused on manure application into cover crops using low disturbance knives.

“Incorporating manure into cover crops has been a challenge for a lot of farmers to be able to apply the manure to the cover crop without disrupting them,” he said.

Utilizing a different application method of manure into cover crops was just some of the new technologies and research presented at the conference that impressed White.

“They have found in research it is best to apply the manure closer to when the plant needs it. Actually, in-season would be the best,” he said. “There are companies out there looking at doing that, trying to get robotic equipment to actually apply the manure to the corn crop during the growing season. That would be the ultimate in efficiency and for application timing. Those kinds of technologies are coming.”

White was also intrigued with learning of the introduction of John Deere’s Harvest Lab 3000.

“That gives you on-the-go readings of the manure you are applying,” he said. “You get the exact nutrients as you go through the field so you can go out there and do a prescription application.”

The event was sponsored by The Fertilizer Institute, The Mosaic Company, Corteva, Environmental Tillage Solutions, the Iowa Agriculture Water Alliance and the Iowa Pork Producers Association.

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