Interseeded Cover Crops Results
Studies such as this will be shared by area farmers starting this week at On-Farm Research Updates (Feb. 15 at Holthus Conv. Center in York)! RSVP at: go.unl.edu/2023ofr. Since 2019, a group of area farmers have been interseeding cover crops into early season corn (V3-V4) and soybean (VE-V2). The goals for interseeding cover crops into cash crops include: providing nutrients for the cash crop, weed control, erosion control, diversity, reducing inputs such as fertilizer and chemicals, and providing forage for grazing after harvest. Interseeding of cover crops can also occur at other growth stages, such as at male row destruction in seed corn or at senescence in late-season corn and soybean. This article will focus on our results from early-season interseeding of cover crops into corn and soybean.
In 2019, two farmers interseeded cover crops (one drill interseeded and one broadcast) into corn in York and Seward counties. Both got establishment and showed no yield differences between interseeded and check. In 2020, a partnership formed between The Nature Conservancy, Upper Big Blue NRD, Extension, Kelloggs and area farmers. A four row interseeder was purchased. Six farmers chose to conduct studies via on-farm research where they maintained the same field-scale strips of interseeded cover crops and check treatments for 3 years. The different cover crop mixes and rates can be viewed at jenreesources.com.
From 2020-2022, fields were impacted by July 9, 2020 and 2021 wind events and June 14, 2022 hail. We had 12 site-years of corn studies and 2 site-years of soybean studies. Biomass samples of the cover crops and also weeds were taken each September. Cover crop biomass ranged from 200 lb/ac to 4 tons/ac depending on the location, hybrid, irrigation, and storm events. In 10 of 12 site-years, interseeded cover crop had more biomass than the check treatment (weeds).
Yield: No corn yield difference between check and interseeded in 6 of the 12 site-years. Yield losses ranged from 2-10 bu/ac in the remainder. No soy yield difference between the interseeded and check.
Net Return: In 10 of the 12 corn site-years, and 1 of the soybean site-years, the check treatment had a higher net return. (However, no benefit to grazing, reduced inputs, etc. was given to interseeding).
Soil Health Values (PLFA & Haney): Large numerical increases in soil health numbers when all 6 sites were combined (as well as some individual sites). Significant increase in the Check from 2020 to 2022. Significant increase in the Interseeded from 2020-2022. However, because this happened for both treatments, when comparing Check vs. Interseeded from 2020 vs. 2022, there is no difference. Why? All farmers were incorporating additional soil health practices across their entire fields (planting rye each fall, grazing, adding biological products, etc.) that would have impacted both cover crop and check treatments. Good news: all increased their overall soil health (soil microbial pops and scores) in 3 years.
Soil Nutrient Values: There were no differences between OM, pH, P, S, K, and base saturations between Check and Interseeded from 2020 to 2022 across sites. Numerical changes occurred at individual sites.
Our studies proved that drill interseeding of cover crops into early season corn and soybeans can be achieved for establishment that lasted after harvest with regrowth of perennial covers into the spring. We also showed this in spite of a number of PRE- herbicides used. We increased beneficial insects and saw pest insects feeding on cover crop instead of cash crop. We increased diversity in the fields and had additional cover aiding erosion control. We also showed reduced water use in the corn where the diverse cover crop was used compared to the check treatment. The disappointment to me was the low amount of forage for those desiring to graze after harvest and the spotty survival of perennials in the spring. However, those who grazed said there was value in the amount of green material present at harvest coupled with the corn residue. Additional challenges can include the fact that it does look ‘messy’, one needs to think through herbicide options ahead of time, and we need to put dollars to additional benefits that are harder to calculate (soil erosion, etc). Next week I’ll share our next steps in where we’re headed.
Grateful for a little moisture last week! Lots to share based on questions. For those with poultry, the highly pathogenic avian influenza (HPAI) has impacted a fourth Nebraska farm. Farms impacted thus far have been in Merrick, Butler, and Holt counties. All were under quarantine with birds being humanely depopulated and disposed of in an approved manner. HPAI is a highly contagious virus that spreads easily among birds through nasal and eye secretions, as well as manure. The virus can be spread in various ways from flock to flock, including by wild birds, through contact with infected poultry, by equipment, and on the clothing and shoes of caretakers. Wild birds can carry the virus without becoming sick, while domesticated birds can become very sick. Symptoms of HPAI in poultry include: a decrease in water consumption; lack of energy and appetite; decreased egg production or soft-shelled, misshapen eggs; nasal discharge, coughing, sneezing; incoordination; and diarrhea. HPAI can also cause sudden death in birds even if they aren’t showing any other symptoms. Poultry owners should restrict access to your property and poultry and report unusual poultry bird deaths or sick birds to NDA at 402-471-2351, or through USDA at 866-536-7593. More info: https://nda.nebraska.gov/animal/avian/index.html
Preliminary farm real estate numbers were released this week at: https://cap.unl.edu/realestate.
Weed Guides: We didn’t receive 2022 weed guides. I do have some flash drives with PDF copies for those interested. Otherwise, print copies can be purchased at: https://marketplace.unl.edu/default/ec130.html.
CropWatch at cropwatch.unl.edu covers a variety of topics including drought outlook and BT trait table.
On-Farm Research Results Book: PDF version can be viewed at: https://go.unl.edu/vfi4.
Nutrient Management: If you’re applying fertilizer this spring or in-season, it may be an opportunity to cut back on fertilizer rates in some strips. Protocols for consideration that can be adjusted at: https://jenreesources.com/2022/02/06/jenrees-2-6-22/.
Also received questions regarding starter fertilizer. Javed Iqbal and Laura Thompson shared the following in this week’s CropWatch, “From 1995 to 2019, farmers working with the Nebraska On-Farm Research Network conducted 35 studies looking at starter fertilizer on corn. The results of these studies can be found in the Results Finder database at http://resultsfinder.unl.edu/. Some were in the same field for a number of years, others moved around. Various starter materials were evaluated, and not all studies reported soil test Phosphorus (P) levels.” UNL’s critical soil test levels for P are when Bray-P is less than 20 ppm for corn after corn (C/C) or 15 ppm for corn after soybean (C/S). The information below is focused on studies comparing 10-34-0 to no starter.
“Eighteen of the studies compared a 10-34-0 starter fertilizer in the range of 4-6 gal/ac to a no starter check. Soil P levels were between 4 and 35 ppm. The crop yield response across range of soil P levels:
- For soils with P soil tests at or below 10 ppm, there was an average yield increase of 14.3 bu/ac due to the starter (four sites).
- For soils with P soil tests of 10-20 ppm, there was an average increase of 2.6 bu/ac (five sites).
- For soils with P soil tests of 20-35 ppm, there was an average increase of 0.3 bu/ac (nine sites).
- When all the data were combined, regardless of soil test values, there was an average increase of 4 bu/ac.
In spite of this analysis, of the 18 studies, only five had statistically significant differences. Of these five, the average yield increase was 12 bu/acre and the average soil test P level was 9 ppm.
To summarize, when fertilizer is used as a starter (as defined above with soil test levels above the critical value), the data shows that it is largely not effective in terms of yield or economical response (even though plants with starter applied will be greener early on); however, if the fertilizer is added to a soil that tests low for soil test P (less than the critical value), a yield response to that fertilizer is expected.
A similar analysis of the soybean on-farm research found six starter studies between 1992 and 2015, with only three sites reporting soil test P, all of which were greater than 17 ppm. Average yields for the no-starter studies were 61.2 bu/ac and for soybeans with starter, 61.3 bu/ac.” If you’re interested in trying this for yourself in corn or soy, consider this simple protocol.