Integrating livestock and cover crops into irrigated crop rotations

Final report for SW18-021

Project Type: Research and Education
Funds awarded in 2018: $249,954.00
Projected End Date: 03/31/2022
Grant Recipient: University of Wyoming
Region: Western
State: Wyoming
Principal Investigator:
Dr. Jay Norton
University of Wyoming
Co-Investigators:
John Ritten
University of Wyoming
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Project Information

Abstract:

Changing markets, technology, and attitudes are creating opportunities for new paradigms
supporting wider adoption of soil-building practices, but there is little science-based information
about integrating livestock and cover crops into irrigated crop rotations. While a few producers
in the sugarbeet/malting barley production area of northwestern Wyoming and south central
Montana experiment with cover crops following barley harvest for soil cover and livestock
forage, uncertainties about costs and benefits, and how to navigate options, mean that intensive
tillage and expansive bare soil are still the norm in this region. To address questions about effects
of different cover crop options on subsequent cash crops, soil quality, forage yield and quality,
and farm economics we will establish an on-station trial in a producer-driven long-term rotation
experiment at the University of Wyoming Powell Research and Extension Center, an on-farm
experiment with at least five producers, and innovative education programs and products. We
will evaluate four types of cover crops following barley in systems where sugarbeet is the
subsequent crop. Cover crop types include volunteer barley regrowth, replanted barley, soil
building mix, and livestock production mix. The on-station experiment will be embedded in the
long-term rotation experiment where half of each cover crop plot will remain unharvested and
half will be harvested for hay. The on-farm experiments will be established after harvest of
irrigated barley where producers winter graze replanted barley. On-farm plots will be split, with
half ungrazed in 0.1-acre exclosures and half winter grazed with the rest of the field. The
participatory research will creating settings for farmer inquiry, peer-to-peer learning, and lasting
relationships. We will optimize those opportunities by 1) expanding our technological exchange
created for the long-term rotation experiment; 2) field-based hands-on workshops; 3) Extension
and research publications; and 4) impact evaluation with on-going responsive adjustments to
research and extension activities.

Project Objectives:

This project will provide producers with knowledge to implement soil-building practices for
more sustainable irrigated cropping systems. Specific objectives include quantifying and
comparing effects of four types of cover crops (volunteer barley, replanted barley, and two cover
crop mixes) and three residue treatments (hay, grazed, and no harvest) on:
1. Yield and quality of subsequent crops;
2. Soil quality and organic matter cycling;
3. Forage quality and quantity of the four cover crop types;
4. Water use efficiency in subsequent sugarbeets;
5. Costs and benefits of different cover crop/forage options;

Cooperators

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Research

Hypothesis:

A cover crop mix planted after barley harvest in sugarbeet-barley rotations will improve soil quality compared with no cover crop and with replanted or volunteer barley regrowth. Further, soil quality improvements will vary with management of cover crops for green manure, hay, or grazing.

Materials and methods:

During the 2020 growing season we tracked the plots established in 2018 through sugarbeet planting and harvest on the University of Wyoming Powell Research and Extension Center (PREC) at Powell, WY. We established new cover crop plots in the barley phase of the on-station long-term rotation experiment at PREC and sampled soils, biomass, and yields through the 2020 season. 

M.S student Taylor Bush completed and defended his thesis in April, 2020. Ph.D. student Dixie Crowe is building upon Taylor's work with two more field seasons (2020 and 2021) at the PREC field as well as expanding on the paired site study. She is communicating with cooperating farmers, NRCS, the PREC farm crew and others to locate fields with long-term soil-health practices and paired conventional fields to assess impacts of cover crops and minimum tillage on soil health indicators in the study area.

Precautions associated with COVID-19 limited our ability to carryout outreach and extension activities during 2020, but we received a one-year no-cost extension and intend to focus on outreach activities during the summer and fall of 2021. An advantage to this is that we will have a more complete dataset and results to share.

During the 2021 season we intend to continue the on-station experiment by tracking the sugarbeets that follow the 2020 cover crops and by establishing a new set of cover crop plots in the 2021 barley phase of the crop rotation experiment. We also plan to expand upon the paired site study and have identified additional study sites on farms in the study area. We postponed this paired-site sampling from 2020 to 2021 when we received the no-cost extension. 

Research results and discussion:

While research and extension activities were limited by COVID-19, we did accomplish all the seasonal soil and crop sampling for the ongoing on-station experiment during 2020. All samples were processed and time-sensitive lab work was completed, but laboratory restrictions and lack of student lab assistants have delayed final laboratory analyses and data interpretation. We are completing that work this winter and will present interim results at the 2021 Western Nutrient Management Conference, to be held online in March. 

Taylor Bush completed his MS thesis in April, 2021, reporting on 1) his paired-site study of two farms with long-term minimum-till and cover crop practices with adjacent conventionally tilled fields and 2) the first two years of the on-station study and the two-year on-farm study. We are preparing a "how-to successfully grow annual forage cover crops following irrigated small grains" extension bulletin based on Taylor's results and the experience we gained.

Results of the paired site study show that, while variable, soil-health practices are increasing soil organic carbon within 5 to 7 years of implementation. Surface soils (0-15 cm) at the farm near Ralston, Wyoming, indicated that 5 years of strip-till plus cover crops following barley in the sugarbeet-corn-barley-sunflower rotation increased SOC to 16.6 Mg SOC ha-1 compared with 11.6 Mg SOC ha-1 in the adjacent conventionally tilled field under a similar crop rotation, a significant increase of 43%. Surface soils at the no-till sugarbeet-barley-corn farm near Fromberg, Montana, did not contain more SOC than those of the adjacent conventionally managed field, possibly due to recent sediment deposits after a very intense rain event earlier in the year. Soil-health practices at both locations led to higher whole-soil-profile carbon stocks, with 17 and 7 Mg SOC ha-1 at the Ralston soil health and conventional fields, respectively, and 50 vs. 40 Mg SOC ha-1 at the Fromberg soil health and conventional fields, respectively.

The short-term study on six cooperating farms and the PREC station did not lead to significant differences in soil properties or subsequent sugarbeet yields, which is not surprising because, with the crop rotations being practiced, the study actually consisted of a one-year experiment on each of the study plots. Also, the plots with and without grazing and cover crops were imposed on fields already under minimum tillage and annual forage/cover crops following barley. Forage quality analysis indicated that the five-species cover crop mix was more productive and had much higher crude protein, relative feed value, and other quality indicators than barley alone. 

Jacob Asay completed his MS thesis in Agricultural Economics under direction of Co-PI Dr. John Ritten in Spring 2021. Jacob and John created partial budgets to estimate the relative profitability of the various cover crop options (volunteer barley, replanted barley, cover crop mix) in combination with different management options (green manure, haying, and grazing) over distribution of historical prices and production costs.  Ignoring any impact to subsequent sugar beet yields, results show that haying provides the most revenue and provides the most incentive to adopt cover cropping in the short term.  Haying, regardless of cover crop type, is the most likely management alternative to be economically viable.  Grazing the cover crop is next best alternative, either providing enough value in terms of forage to break even, or requiring around a half ton increased sugar beet yield in order to cover the costs of cover crop establishment.  Volunteer Barley is the cheapest cover crop in terms of establishment, and has the highest expected payout regardless o management option (expected net revel ranges from -$17.23/ac for green manure to $228.23/ac for haying).  Replant barley outperforms the cover crop mix for green manure and grazing options, while the cover crop mix performs better than the replant barley for the haying option. 

 

Table 1. Expected increase (or decrease) in net income per acre for each management option and cover crop type as compared to no cover crop, assuming no impact to subsequent sugar beet yields.

  Green Manure Hay Graze
Cover Crop -64.75 166.11 -21.65
Volunteer Barley -17.23 228.23 23.47
Replant Barley -31.83 145.54 -1.58

 

When including the impacts to subsequent yields of sugar beet observed in this study, from a maximum profit perspective, producers should choose to hay replanted barley (RBHAY) as that combination for cover crop type and management is expected to provide the highest gain to net revenue. RBHAY on average increased expected net revenue by over $485 per acre. This is not $485 per acre in profit, but rather a $485 per acre increase in profit compared to a no cover crop control. RBHAY has an expected average net revenue nearly $200 per acre higher than the second-best option of haying the cover crop mix (CCHAY) which has an average gain to net revenue of nearly $300 per acre, and RBHAY’s net revenue is almost $850 per acre higher than that of the green manuring the replanted barley (RBGM), which had the greatest average loss to net revenue of over -$360 per acre.

 

Table 2. Results of Partial Budget Analysis including impact to subsequent sugarbeet yields (change in profitability as compared to no cover crop) reported in $/acre

 

Green Manure

Hay

Graze

Cover Crop Mix

-196.87

299.84

-292.85

Volunteer Barley

-253.13

89.83

-424.26

Replant Barley

-360.80

485.21

-352.48

 

The preferred cover crop/management option may change however, if the producer’s goal is simply improving soil health. A goal of improving soil health would focus less on the immediate economic impacts of cover crops and more on the agronomic benefits of management. Scenarios including green manure or grazing would likely be more suitable for these conditions. This is due to the fact that both management options offer returns to the soil as opposed to haying that simply removes biomass. Green manure returns all the grown biomass back into the soil and increases soil organic matter levels . Grazing does remove biomass, however, unlike haying, livestock also add organic matter back through manure. The recycled nutrients in the form of manure, can have a positive effect on soil fertility. Recycled nutrients could help to return about 75-85% of the nutrients back to the soil. The cover crop mix yielded the most forage at 1.75 ton/ac, while volunteer barley and replanted barley yielded 1.68 ton/ac and 1.39 ton/ac respectively. This data would then suggest that the cover crop mix would be most beneficial to soil if the entirety of forage biomass was used for green manure or grazed with nutrient cycling effects of livestock. Under this assumption, either CCGM or CCGRZ the most likely scenarios to improve soil health. With the data available we are able to conclude which cover crop option is best for each management option, as well as what management option is best for each cover crop option. If the management option of green manure is incorporated into production cycles, then the cover crop mix would offer the best results in regard to net revenue. If haying is the management option of choice, then replanted barley should be the cover crop option used. When grazing the cover crop, the cover crop mix again offers the best result in net revenue. When choosing the management option best for each cover crop option, haying has the best net revenue for all cover crop options compared to the other management options.

Research conclusions:

Cover crops are becoming more widely accepted as a viable management practice because of their ability to provide important environmental and soil health benefits. However, adoption of cover crops remains low in certain areas, such as the Bighorn Basin in northwestern Wyoming, because these benefits have not yet been fully realized, and the high cost of cover crop integration into irrigated crop rotations appears prohibitive. This study aimed to determine if different cover crop management scenarios can provide additional income to producers. Cover crop types included in our study are cover crop mix, volunteer barley, and replant barley. The management options included in our study are, green manure, haying, and grazing. The combination of the cover crop types and management options lead to nine different scenarios included in this study. Our results indicate that haying has the highest net revenue across all cover crop management options. Volunteer barley is the cheapest cover crop option to establish and provides the second highest forage yield. Regardless of cover crop scenario, timeliness of management must be a forefront priority to allow success of a short season cover crop.

Participation Summary

Education

Educational approach:

We have an active "network for technological exchange" with frequent communication among researchers and cooperators. COVID-19 prevented the extension events we had planned for 2020, but our one-year no-cost extension will allow us to hold better events with more complete results near the end of the 2021 field season. Rather than hold virtual events, we focused on the research during 2020 and will hold on-farm mini-field days on cooperating farms that utilize the soil health practices, as well as on our PREC plots, and during research station field days in Wyoming and Montana. Norton recorded a "how-to" presentation in December, 2020, for our University of Wyoming Extension conference held in early January, 2021.

Educational & Outreach Activities

30 Consultations
3 Curricula, factsheets or educational tools
6 On-farm demonstrations
1 Online trainings
2 Tours
2 Webinars / talks / presentations
2 Workshop field days

Participation Summary:

6 Farmers
7 Ag professionals participated
Education/outreach description:

Our education and outreach activities were minimal this year because COVID-19 precautions. Taylor Bush completed his thesis, available on ProQuest, and we are preparing an extension bulletin based on his work. Jacob Asay completed his thesis, available on ProQuest, and we have prepared one bulletin and  are preparing another extension bulletin based on his work.

Learning Outcomes

6 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation
Key areas taught:
  • We did not record learning outcomes in 2020.
  • Distributed economic information in 2021, mainly highlighting the need or timely establishment
Key changes:
  • Cover crop selection, establishment, and management.

Project Outcomes

1 Grant received that built upon this project
Project outcomes:

Two MS Theses have been posted to ProQuest.  One bulletin is published and two more are in progress.

Information Products

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.