April 1 Webinar: Stream Channel Incision & Groundwater Depth in Riparian Corridors

Iowa Learning Farms will host a webinar on Wednesday, April 1 at noon. This webinar will explore the relationship between stream channel incision and the depth to groundwater in riparian corridors.

Riparian vegetated buffers have the capacity to remove nitrogen from shallow groundwater in the riparian corridors, but this function depends on the denitrification potential of these areas. The highest potential for denitrification will occur in areas with available organic carbon and high levels of nitrate, where there is also saturation of the riparian zone near the ground surface. Interactions between the shallow groundwater table and riparian vegetation will also remove nitrogen from groundwater through plant uptake.

By determining the relationship of precipitation, evapotranspiration, stream stage and soil characteristics to the groundwater depth in the riparian corridor, it may be possible to better guide vegetated buffer planning. This could maximize buffer efficiency in areas where it is not possible to monitor groundwater depth. Streams with a higher degree of incision may be less likely to have elevated groundwater tables, reducing their potential for nitrate removal from shallow groundwater.

Hilary Pierce, an Extension Outreach Specialist with Iowa State University, will discuss this research project, which analyzed six sites in southwestern Minnesota.

A Certified Crop Adviser board-approved continuing education unit (1 CEU) is available for those who are able to participate in the live webinar. Information about how to apply to receive the credit will be provided at the end of the live webinar.

Don’t miss this webinar!

DATE: Wednesday, April 1, 2020

TIME: 12:00 pm

HOW TO PARTICIPATE: shortly before 12:00 pm on April 1st:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

Or, go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

Dial: +1 312 626 6799 or +1 646 876 9923

Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

–Hilary Pierce

Terminating Cover Crops This Spring

Content was originally published on March 25, 2020 on the Integrated Crop Management News blog hosted by Iowa State University Extension and Outreach and authored by Meaghan Anderson, Rebecca Vittetoe, and Bob Hartzler.

As temperatures warm this spring, cover crop termination is on the to-do list for some Iowa fields.  Killing cover crops with herbicides is the most common termination method. The effectiveness of herbicides at terminating a cover crop depends primarily on three things: 

  1. Cover crop species and growth stage
  2. Herbicide and rate used
  3. Environment

The cool and fluctuating temperatures encountered in spring often make terminating cover crops challenging. Farmers are limited to a few products like paraquat (Gramoxone; group 22), glufosinate (Liberty; group 10), or glyphosate (Roundup; group 9) for cover crop termination. Glyphosate is the most consistent option for termination, especially as cover crops increase in size. The group 1 herbicides (e.g. clethodim, fluazifop, etc.) do not provide effective control of cereal rye. If cereal rye or other grass species are seeded with a legume, inclusion of 2,4-D or dicamba with glyphosate will improve consistency of control. This addition can also be helpful if broadleaf winter annuals are present. 

In a study encompassing eight site-years across five states, treatments containing glyphosate provided the most consistent cereal rye control (Figure 1). Cereal rye ranged from 5-54 inches tall at termination in the experiments. While control of cereal rye did not differ statistically between most paraquat and glyphosate treatments, paraquat-based treatments were much less consistent than glyphosate-based treatments. Glufosinate treatments were less effective and less consistent than glyphosate treatments. While paraquat can provide acceptable control in some situations, neither glyphosate alternative (paraquat, glufosinate) provides as consistent control as glyphosate under the cool and variable spring conditions. Dicamba combinations with the three burndown herbicides provided similar results to 2,4-D combinations (data not presented).

Figure 1. Control of cereal rye cover crops with select herbicide treatments.
* represents treatment mean; box represents the mid 50% of the data set, providing information on consistency of treatments. Herbicide rates:  glyphosate: 1.0 lb/A; paraquat: 0.75 lb/A; glufosinate: 0.5 lb/A; 2,4-D: 0.5 lb/A; saflufenacil: 1 oz/A; metribuzin: 0.12 lb/A. Herbicides applied in 15 gal/A. Adapted from Whalen et al. 2020.

Vegetative growth in rye requires temperatures of at least 38 F. While air temperatures may be favorable some days, cool soil temperatures can slow growth. Herbicides are most effective on actively growing plants; thus, very early spring termination treatments may provide less than complete control. Leaving a small check strip is a simple and easy way to see if the cover crop is dying following termination.

Iowa State University researchers generally recommend terminating the cover crop with herbicide 10 -14 days prior to planting corn to protect yield; however, that time frame is less critical for soybeans. Waiting to terminate until after your crop is planted, especially in non-GMO corn, can be risky.

Termination options are more limited, and the cover crop can quickly become an uncontrollable weed in non-GMO crops. Additionally, it is important to check with your crop insurance agent for any specific cover crop requirements that they may have prior to planting corn or soybeans.

Always look at the herbicide labels for directions and any restrictions for the subsequent crop. A quick and easy place to look up herbicide labels is www.cdms.net or www.greenbook.net.

Reference:

Whalen DM, Bish MD, Young BG, Conley SP, Reynolds DB, Norsworthy JK, Bradley KW (2020) Herbicide programs for the termination of grass and broadleaf cover crop species. Weed Technol. 34: 1–10.

Additional information on cover crop termination:

Conservation Best Practices Manual Available for Free Download

The Conservation Learning Group has published the Whole Farm Conservation Best Practices Manual to aid farmers in selecting conservation measures appropriate for their farms.

Designed primarily for farmers just starting out through three years of adopting conservation practices, the manual provides a broad range of information that could be beneficial to any producer. The manual is available for free download or in hard copy from the ISU Extension Store.

Covering in-field topics including tillage management, cover crops and diverse rotations, and edge-of-field practices such as wetlands, bioreactors, saturated buffers, controlled drainage and prairie strips, the manual provides detailed information regarding implementation and expected outcomes.

In addition, it includes comprehensive graphical decision tools to aid farmers in determining the best approaches for each area on their farm.

“A primary goal in producing this manual is to help farmers succeed with conservation practices based on the vast array of ongoing research and field studies conducted at Iowa State and beyond. We’ve heard from farmers across the state that sometimes it’s difficult to navigate discrepancies between different research reports and recommendations regarding conservation and water quality practices. With this manual, we’ve pulled together the most important parts from the rich sets of research on cover crops and other conservation efforts in Iowa and presented them using consistent language in an easy-to-use graphical format.”

Mark Licht, assistant professor and extension cropping systems specialist at Iowa State and CLG member

The manual was developed based on numerous meetings and working groups among stakeholders, researchers, agency representatives and communications specialists, who worked together to provide a comprehensive resource for farmers. The content was also presented to farmers at multiple events, prior to public release, to gather feedback on usability and the graphical decision tools included.

“This manual will be an excellent tool for our conservation planners to utilize as they work with farmers to adopt these management practices. I was involved in the working groups which discussed the best strategies for farmers who are new to these practices. It’s our hope with this advice that they will be successful early in the adoption of these practices both agronomically and from a conservation standpoint.”

Kevin Kuhn, resource conservationist for the USDA Natural Resource Conservation Service

Conservation Learning Group will continue to evaluate responses to the manual and update it with emerging information and data from research projects.

“This is not meant to be a static guide. As our experiences and knowledge base grow, we will continue to communicate with producers and provide the best advice we can to maximize their successes with conservation practices.”

Mark Licht

The manual was developed in cooperation with the Iowa Soybean Association, Iowa Agriculture Water Alliance and Practical Farmers of Iowa, and with the support and input from multiple local, state and federal organizations.

This manual is a joint publication of Iowa State University and USDA-Natural Resources Conservation Service, supported by the Natural Resources Conservation Service, U.S. Department of Agriculture, under number 6000004181.

–Liz (Juchems) Ripley

Carbonate, the Other Soil Carbon

On Wednesday, Iowa Learning Farms hosted a webinar about research on calcium carbonate and the potential for carbon storage in Iowa’s soils.

Mark Rasmussen, Director of the Leopold Center for Sustainable Agriculture, described how calcium carbonate is formed and shared information about its distribution. Regarding the research into carbonate nodules in soil, Rasmussen explained, “We are interested in these nodules because carbonate minerals form one of the largest reservoirs of carbon on the planet and these minerals play a significant role in the long-term balance between atmospheric carbon and climate.”

A slide from the webinar, detailing estimates of carbon amounts from Monger et al., Geology, 2015

Some of the research questions being posed are:

  • How are carbonate nodules formed?
  • How much carbon in a given soil profile exists as carbonate nodules?
  • How old are these carbonate nodules?
Carbonate nodules

Rasmussen said that the group hopes to carry out research this summer at the Iowa State University Western Research Farm, where they will collect soil samples in different areas and at different depths, and then measure the carbonate. They plan to study the effect of intensive row cropping on carbonate reserves, hypothesizing that, because intense row cropping and fertilizer use slowly acidifies soil, there will be less carbonate reserve in these intensely row cropped areas compared to others.

Watch the full webinar here! We also have many other great archived webinars available here: https://www.iowalearningfarms.org/page/webinars.

Join us next week, at noon on April 1, when I will be presenting on my MS thesis research: “The Effect of Stream Channel Incision on Groundwater Depth in Riparian Corridors”.

–Hilary Pierce

Iowa Learning Farms Weekly Webinars

Iowa Learning Farms will be hosting weekly webinars every Wednesday at noon. For those who can’t join us live, the webinars will be recorded and archived on our website!

Join us today at noon to learn more about carbonate with Mark Rasmussen and check out the full schedule (through the end of April) below.

–Hilary Pierce

March 25 Webinar: Carbonate, the Other Soil Carbon

Iowa Learning Farms will host a webinar on Wednesday, March 25th at 12:00 pm, which will focus on carbonate research and the potential for carbon storage in Iowa soils.

Wind-blown loess soils of western Iowa contain a significant amount of calcium carbonate in the form of the mineral calcite. These soils are naturally calcareous due to the calcium carbonate that formed from minerals originally deposited in glacial parent material. Some carbonate is present in the form of carbonate nodules, which can readily be seen in the soil profile. How much carbon is stored as carbonate in Iowa’s soils? Are there land management practices that degrade or stimulate carbonate deposition? Mark Rasmussen, Director of the Leopold Center for Sustainable Agriculture, will discuss these questions, as well as other aspects of the research being done on carbonate, during this webinar.  

“We are interested in these nodules because carbonate minerals form one of the largest reservoirs of carbon on the planet and these minerals play a significant role in the long-term balance between atmospheric carbon and climate,” said Rasmussen. “A major focus of our study is to understand the biological and chemical processes that result in carbonate formation including the carbon source used in its formation.”

A Certified Crop Adviser board-approved continuing education unit (1 CEU) is available for those who are able to participate in the live webinar. Information about how to apply to receive the credit will be provided at the end of the live webinar.

Don’t miss this webinar!

DATE: Wednesday, March 25, 2020

TIME: 12:00 pm

HOW TO PARTICIPATE: shortly before 12:00 pm on March 25th:

Click this URL, or type this web address into your internet browser: https://iastate.zoom.us/j/364284172

Or, go to https://iastate.zoom.us/join and enter meeting ID: 364 284 172 

Or, join from a dial-in phone line:

Dial: +1 312 626 6799 or +1 646 876 9923

Meeting ID: 364 284 172

The webinar will also be recorded and archived on the ILF website, so that it can be watched at any time. Archived webinars are available at https://www.iowalearningfarms.org/page/webinars.

–Hilary Pierce

Valuing the Environmental Services on Iowa farms​​​​​​​ – Webinar Recap

This month’s webinar put a spotlight on the work Iowa Interfaith Power and Light (IPL) is doing to help bring farmers and their innovative skills to the table to help address climate change. Matt Russell, Executive Director for Iowa IPL, encourages farmers to embrace the call to abundance and value of environmental service on Iowa Farms.

Founded in 2006, Iowa IPL is a part of the national Interfaith Power & Light movement. They are a statewide organization mobilizing the religious community to become leaders in the movement for climate action, working with over 300 congregations.

Matt finds hope in helping harness the innovative potential of farmers to help address climate change. Agriculture plays a big role in reducing greenhouse gas emissions and the sequestering of carbon, namely through practices including conservation tillage, integrating livestock, extending crop rotations, permaculture (something growing all year long), and clean energy like ethanol.

“Regenerative agriculture, a key to adapting to and mitigating climate change, is not just implementing practices from a list. It is instead farmers innovatively implementing practices to maximize their ecological services.”

-Matt Russell

An example of this innovation would be the move from a two crop rotation like corn/soybean to a five year, four crop rotation. For example: corn, soybean, small grain, alfalfa with cover crops that can be grazed by livestock, a solar powered water system for the animals, and chemical use reduction.

“Are farmers victims of climate change? Sure but we all are.  Are farmers part of the cause of climate change? Sure but we all are. What’s unique about farmers is that by the nature of our work we can make a difference in climate change immediately.”

-Matt Russell

Be sure to check out the archive of this webinar to learn how working to address climate change can have a positive impact on water quality, hear how Russell and Iowa IPL are working with Iowa farmers to encourage this necessary innovation and get a glimpse of how Matt is working to do the same on his own farm.

You can catch up on all our previous webinars any time by visiting our website.

–Liz (Juchems) Ripley