Field Work Frenzy!

For the last three weeks our team of interns and the Agricultural Water Management team have been busy collecting field research data from our Conservation Learning Lab sites. To gather baseline measurements of soil health, we collected bulk density samples last fall and are in the process of measuring water infiltration and soil aggregate stability.

Both the Story County and Floyd County locations have five fields participating in the project, representing 50-68% of the watershed.  We are collecting data from three samples points in each soil type within the field for a total of 36 samples sites per watershed. We will compare these measurements in three years to those taken after the addition of cover crops to all fields and a decrease in tillage (transition to strip-tillage) for half of the fields.

story panaramaMeasuring Infiltration

Healthy soil has adequate pore space to receive and retain rainwater.  By increasing the infiltration potential of soil, we can reduce runoff and soil erosion during rain events.  Healthy soil also has better water holding capacity during periods without rain.

Using the Cornell Sprinkle Infiltrometer, we are looking to find out how much water is able to permeate into the soil. The infiltrometer–essentially a portable rainfall simulator–connects to a 9.5 inch metal ring that has been installed in the ground.  We calibrate the infiltrometer to “rain” about 0.5cm/minute within the metal ring.

After recording the time of first runoff, we record the height of the water in the infiltrometer and the volume of runoff every three minutes.  We continue this process until a steady state is achieved in the volume of runoff (about an hour).

Each runoff sample is poured into a cylinder for measurement. Calculating the difference between how much water is gone from the infiltrometer and how much has runoff, we can compute how much of the water that has infiltrated into the soil.

Collecting Samples for Aggregate Stability

Soil SamplingAggregate stability is a soil health indicator that provides a measurement of the soils ability to resist erosion, especially from water. It is desirable to have stable aggregates to withstand rainfall and water movement compared to weak aggregates that can seal the surface of the field and decrease infiltration. The weak aggregates can also create a crust that can make it difficult for seedlings to emerge.

Check back for updates as the team begins to process the soil samples that were collected near the infitrometer sites.


Still smiling as the storm rolls in! Our interns are outstanding.

Liz Juchems


Cover Crops: One Piece of the Puzzle in CLL Project

Cover crops are an important tool for helping keep soil, nitrogen and phosphorus in the field – instead of our water bodies. Because they grow outside the typical corn/soybean growing season, cover crops help reduce soil erosion and take up nutrients that could otherwise leave the field. It is also the most popular practice among our Conservation Learning Lab (CLL) farmer partners.

The CLL project is studying the impact of conservation practices implementation at the watershed scale in Floyd and Story County.  The conservation planning process within the watersheds has yielded cover crop contract enrollment of 675 acres and 1,081 acres, respectively, starting this fall covering 50-68% of the crop acres within the watershed.

Cover_crop_April_Berger_FarmThe farmer partners chose to seed either winter cereal rye and oats.  These grass species are easy to establish, relatively inexpensive and are the leading biomass producers in our cover crop research projects – keeping that soil covered (reducing the loss of phosphorus) and taking up nitrogen.

The Iowa Nutrient Reduction Strategy team reviewed cover crop research results from across Iowa and the Midwest and found that cereal rye and oats reduced nitrogen loss by 31% and 29%, respectively.  Similarly, the reduction of phosphorus when adding cereal rye is about 29%, primarily as a result of reduced soil erosion. According to our RUSLE2 calculations, a cereal rye cover crop added to a no-till system can reduce soil erosion by 30-80% and can be even larger when transitioning from a conservation tillage system.

Be sure to keep checking back as we will be providing updates as the cover crops are seeded this fall!

The project is funded by the Iowa Department of Agriculture and Land Stewardship (IDALS) and the United States Department of Agriculture – Natural Resources Conservation Services (USDA-NRCS) of Iowa.

It’s a Wrap on Field Work 2016!

Friday, December 9th marked the end of the Iowa Learning Farms 2016 field work season. Throughout the year we have collected water samples, cover crop biomass samples, spring nitrate soil samples, and seeded our cover crop plots.  Following harvest, with help from Carl Pederson and a Giddings Rig, we collected bulk density soil samples for our Conservation Learning Labs project.

Bulk density is the weight of soil in a given volume and can be used to evaluate the level of soil compaction. Bulk density values increase with compaction and tend to increase with depth.  Soils with high bulk density restrict root growth and can results in lower crop yields. Our samples will also be analyzed for nutrient contents in our soil processing lab.

The samples were collected prior to adding a cover crop and reducing tillage to gather baseline measurements within our two watersheds.  The sample cores are three inches in diameter by twelve inches in length and due to their size, we enlisted the Giddings Rig probe.

Check out the photos series below for a glimpse into the sampling process! img_0172

For each field, we collected three samples per soil type that made up 10% or more of the field.  This ranged from 6-15 samples per field.  Before heading to the field, each sampling site was randomly selected within the soil type and GPS points assigned.  The points were uploaded to our handheld GPS unit for easy site locating in the field. img_0171With temperatures in the low 20’s and 30’s, we used the truck dashboard to keep the plastic caps flexible.  To help remember which way is up, the red caps (aka the sun) = top and black caps (aka the earth) = bottom.  A simple, but necessary step for processing back in the lab! img_20161202_115557111_hdr

When we reached the GPS point, we loaded up a plastic core and aligned the rig in place.  The hydraulic system slowly pushed into the soil to minimize collection compaction.  With the frost setting in, there were times the rig really had to work to get the full sample.

Once the sample is out of the ground, the plastic tube was removed and caps placed on the ends to keep the soil secured.  The samples were labeled and placed in a 5-gallon bucket for storage and transport.img_20161202_121316924The sampler is cleaned using a wire brush and putty knife to prepare it for the next location.  We then hopped back in the truck and travel to the next point in the GPS.

In three days, we collected 108 samples from 12 fields in Floyd and Story County.  Traveling across the tilled fields provided a bumpy ride for us and the rig.  We managed to shear a bolt at the end of day two, but Carl was able to get it fixed in record time and we were back at it again!


Despite the cold weather, I enjoyed collecting the samples. I have collected a lot of different samples during my time as an undergraduate intern and staff at the Iowa Learning Farms, but this was my first time collecting bulk density samples with the Giddings Rig. I look forward to keeping you updated on the processing and measurement process as I keep learning.


Liz Juchems

ILF Launches Conservation Learning Labs Project

cll_logoIowa Learning Farms has launched a project—The Conservation Learning Labs—that will study how implementation of conservation practices can reduce nitrogen and phosphorus loss at the watershed scale in Iowa. The project is funded by the Iowa Department of Agriculture and Land Stewardship (IDALS) and the United States Department of Agriculture – Natural Resources Conservation Services (USDA-NRCS) of Iowa.

The project is specifically focused on small watersheds — between 500 and 1,300 total acres in size—and the widespread adoption of cover crops on a large percentage of the watershed’s agricultural land. The two pilot watersheds were chosen because of their size and because the watersheds already have a Conservation Reserve Enhancement Program (CREP) wetland on-site that will provide baseline water quality monitoring data on nitrogen and phosphorus loads over several years. We will be able to see how nutrient loads might be affected in real time based on the implementation of cover crops on the land.

Our main focus: Can high levels of cover crop implementation be obtained on a small watershed scale, and water quality improvements documented accordingly?


Goldilocks and the Three Scales of Nutrient Load Research

The Iowa Nutrient Reduction Strategy (NRS) lays out in-field and edge-of-field conservation practices that, if implemented, can improve Iowa’s water quality and reduce N and P export. Much of the research highlighted in the NRS is from small, plot-scale research projects. While these controlled studies are essential to our understanding of nutrient loads, results at the plot scale can differ from actual nutrient loads that we see at a larger scale (HUC-12 and larger watersheds). In-stream processes such as bed and bank erosion can add variability and complicate the overall picture in larger watersheds of how we assess agricultural source loads.

It’s the Goldilocks principle: plot scale research is too small, and HUC-12 watersheds are too large. The sweet spot is somewhere in between. This is why the Conservation Learning Labs project will target the scale at which nutrient loads are actually delivered: small watersheds containing less than 2,000 acres.


High Levels of Implementation Required

The NRS gives us a road map that we can use to reduce nutrient loads; however, high levels of adoption of conservation practices are required. Iowa has made great progress in recent years as we see farmers across the state adopting minimum or no-tillage practices and seeding more cover crops. If ones looks closely, more wetlands, buffers and bioreactors have also begun to dot the landscape. But we have a long way to go.

Despite our continued improvement, we will still need more than ten million total cover crop and no-till acres throughout Iowa to reach the goals of the NRS. Edge-of-field practices like wetlands and bioreactors will also be required at a much higher rate than we currently see.


Just like the NRS, the Conservation Learning Labs project will rely on high adoption of cover crops in the agricultural acres of the pilot watersheds. Iowa Learning Farms has reached out to landowners and farm operators in each of these pilot watersheds to talk to them about the project and to ask for their participation. Cost share dollars are available if they agree to seed a cover crop in fall of 2017.

So far, both pilot watersheds have at least 50% of the agricultural acres in the watershed tentatively committed to seed a cover crop in fall of 2017. We will continue to work with farmers in the months ahead to maximize cover crop adoption in each pilot watershed. Stay tuned for updates!

Julie Whitson