Evaluating Nitrates and Forage Quality in Fall Regrowth of Annual Cereal Forages

Final report for OW17-021

Project Type: Professional + Producer
Funds awarded in 2017: $19,972.00
Projected End Date: 10/31/2020
Grant Recipient: Montana State University Extension
Region: Western
State: Montana
Principal Investigator:
Dr. Tracy Mosley
Montana State University Extension
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Project Information

Abstract:

Annual cereal forages serve an integral role in integrated crop/livestock production systems across the West. Recently, producers have realized the values of annual cereal forages in rotational systems when renovating alfalfa, integrating them into systems to supplement perennial forages, and in cover crop mixes. Cool-season annual cereal forages most widely used in Montana and across the West include barley, wheat, oats, and triticale.

There are many advantages of growing annual cereal forages including adaptation to cool climates and higher elevations, they are easy to grow with no special equipment required beyond a grain drill, they are productive in dryland and irrigated systems, they provide good nutritional quality to livestock, and they are effective at disrupting weed and disease pest cycles and rodent problems. With the myriad benefits of using cool-season annual cereal forages, there are also disadvantages. Primary disadvantages include being annual crops that require yearly planting and the potential for nitrate accumulation.

Nitrates in cereal forages have the potential to cause nitrite poisoning in livestock, which, depending on the severity, can lead to economic losses due to weight loss, abortion, reduced breeding rates, weak calves, reduced milk production, and animal death. Nitrate content of cereal forages can be assessed both qualitatively and quantitatively. Montana State University Extension developed the Nitrate “QuickTest” protocol for qualitatively evaluating nitrate presence with a diphenylamine/sulfuric acid solution. Additionally, growers send samples to a laboratory to obtain quantitative analyses of nitrate content of cereal forage hay. More recently, the nitrate strip test has been developed at the University of Georgia to obtain qualitative nitrate results that can be used by professionals without a laboratory test. 

Livestock producers have inquired frequently in the fall with Montana State University Extension offices regarding the nitrate content of cereal grain regrowth, often referred to as volunteer growth. These producers, wishing to capitalize on the new growth, want to better understand the potential for nitrates, but many have little experience grazing it and approach the situation with caution.

Research regarding the potential for nitrate accumulation in fall regrowth of cereal forages is unavailable and nutrient quality of the feed is limited. Producers have largely relied on Nitrate QuikTests to evaluate the safety of using this feed resource due to its convenience. Additionally, comparisons of the Nitrate QuikTest and quantitative laboratory analyses do not exist for fall cereal growth. Therefore, the purpose of this study was to evaluate the nitrate content of cereal growth in the fall, 2) evaluate the forage quality of the available growth, and 3) evaluate how environmental conditions and crop management strategies impact nitrates and forage quality, and 4) evaluate the accuracy of the Nitrate QuikTest and Quantofix Nitrate Strip Test on fall cereal growth.

This participatory research project allowed participating producers to run their operations as they normally would, while allowing access to fields for data collection. Production practice information was shared, data was synthesized to obtain results, and solutions and actions were formulated for management.

Project Objectives:
  1. Evaluate nitrate content and forage quality of fall growth of annual cereal forages on five to ten fields per year. 
  2. Compare results of Nitrate QuikTest and Quantofix Nitrate Strip Test to laboratory analyses.
  3. Evaluate effect of soil moisture and environmental conditions on nitrate content of forage.
  4. Educate producers, Extension faculty, and others regarding the potential for nitrates and forage quality of cereal forage fall growth, accuracy of the Nitrate QuikTest and Quantofix Nitrate Strip test, environmental conditions and management actions impacting nitrate levels, and strategies for minimizing risk of economic loss by grazing forages with high nitrates.
  5. Evaluate change in knowledge, behaviors, and attitudes; producer adoptions of recommended strategies; and changes in management by producers as a result of this information.

Cooperators

Click linked name(s) to expand
  • Alan Redfield
  • Matt Pierson
  • Roger Nelson
  • Dave Haug
  • Ned Zimmerman
  • Phil Johnstone
  • Cleve Swandal

Research

Materials and methods:

Fields with annual cereal forage fall growth were sampled in September and October 2017 and 2018. Fourteen irrigated fields were sampled in early September through early October in 2017 and 2018. Each fall, when forage growth had reached a level that prompted the producer to turn livestock into the field to graze it, the producer informed me that it was time to sample their field.

Forage composition varied across the 14 fields, with annual cereal forages either planted alone or in mixtures. Three fields were planted to hay barley alone; three fields included hay barley + alfalfa; two fields were hay barley + alfalfa + oats; three fields were hay barley + alfalfa + orchardgrass; one field was hay barley + oats + orchardgrass; one field was hay barley + oats + peas; and one field was hay barley + oats + peas + turnips.

At the time of sampling, forage was clipped in 10 random locations across each of the 14 fields. One or two forage samples were collected at each location. One sample was collected from each of the 10 locations within the three fields that included hay barley alone. Two samples were collected from each of the 10 locations in the remaining 11 fields planted to mixtures. The first was a sample of only annual cereal forage(s), and the second sample included the entire mixture, with species clipped and collected in proportion to their availability in the field.

At the time of sampling, I also recorded soil moisture using a FieldScout TDR100 Soil Moisture Meter, soil temperature within the top six inches of soil, cloudiness, and time of day at each location. Samples were later analyzed in the laboratory for nitrate concentrations and forage quality (crude protein, total digestible nutrients). Additionally, comparisons between nitrate levels of forages using the Nitrate QuikTest, the Quantofix Nitrate Strip Test, and laboratory analyses were made qualitatively.

Regression analysis was used to evaluate relationships among variables.

Research results and discussion:

Results:

Fall regrowth of the annual cereal forages generally had low nitrate concentrations (Table 1). Among the 14 fields sampled, nitrate content averaged 0.14% for the annual cereal forage(s) planted either alone or in mixtures, while nitrate content averaged 0.10% in the total forage from the 14 fields. Nitrate content was toxic (i.e., > 0.44%) in only one sample, where the nitrate content of hay barley from a field in hay barley + alfalfa measured 0.67%.

Nitrate content of annual cereal fall regrowth was poorly correlated with environmental conditions at the time of sampling, including soil moisture content (R2 =0.24), soil temperature (R2 = 0.03), percent cloudiness (R2 = 0.04), and time of day (R2 = 0.02).

Fall regrowth of the annual cereal forages alone or the annual cereal forage mixtures had excellent forage quality (Table 1). Crude protein content ranged from 13.3% to 26.1% and averaged 20.1% across all pastures. Total digestible nutrients ranged from 68.2% to 72% and averaged 70.7% across all pastures. Forage mixes that included alfalfa had the highest crude protein and total digestible nutrients.

Additionally, laboratory analysis of the nitrate content of both mixed forage and annual cereals alone indicated that, in general, fall growth of annual cereal forages contains low levels of nitrates (Table 1). Only one field of the fourteen had annual cereals that tested above the 0.44% threshold of safety, which was the hay barley in one alfalfa/hay barley mix pasture (NO3=0.67%).

 

Table 1. Crude protein, total digestible nutrients, and nitrate content of mixed forages and nitrate content of annual cereals.

Crop

Mixed Forage 

% Crude Protein

Mixed Forage   

% Total Digestible Nutrients

 Mixed Forage  

 % Nitrate (NO3)

Annual Cereals 

 % Nitrate (NO3)

alfalfa, hay barley

26.1

72.0

0.23

0.35

alfalfa, hay barley, oats

22.1

72.9

0.05

0.15

alfalfa, hay barley, orchardgrass

20.5

71.6

0.05

0.04

hay barley, oats, orchardgrass

17.2

69.2

0.06

0.13

hay barley, peas, oats

17.1

67.4

0.17

0.12

hay barley

14.9

69.0

0.11

0.12

hay barley, peas, oats, turnips

13.3

68.2

0.03

0.06

 

In comparisons between the qualitative Nitrate QuikTest, Quantofix Nitrate Strip Test, and laboratory analyses, nitrate levels were detected at safe levels in most cases. Across all fields, the percentage of nodes in which nitrates were detected with the Nitrate QuikTest, averaged 9.8% (range=0-40%); averaged 593 ppm (range=0-2500 ppm) of nitrates detected with the Quantofix Nitrate Strip Test averaged; and averaged 0.14% (range=0.02-0.67%) percent NO3 in the laboratory analysis, which all fall into the category which is safe to feed all animals. One field containing alfalfa and hay barley reported 40% of nodes with nitrates, 2500 ppm nitrates, and 0.67% NO3 across the three tests, respectively, which deems it safe to feed only to non-pregnant livestock as per the Nitrate QuikTest recommendations, but safe to feed with adequate feed and water as per the Quantofix Nitrate Strip Test recommendations. All of the remaining fields fell within safe levels across tests.

 

Impacts:

In Park County, six producers, representing nearly 2,000 acres of cereal grain hay production, requested 10 qualitative tests on oats, hay barley, triticale, sudangrass, and barley regrowth in September 2016 alone. Half of these tests, representing approximately 1,200 acres of production (0.5 tons/acre regrowth), had nitrates present. The 1,200,000 pounds of forage that could not be grazed by livestock, coupled with an average lease rate of $30 per cow-calf pair in Park County, had the potential to create an economic loss of $34,890 in grazing loss potential if it had forced the producers to lease pasture elsewhere.

In the fourteen pastures sampled in this project, there was an average of 0.64 tons of production per acre, which equates to 1,280 pounds of available forage per acre that is high in nutritional value and poses little risk of nitrate poisoning to livestock. The availability of this forage has the potential to save producers with integrated crop and livestock systems money annually on feed costs, can be a resource used to take pressure off of native, perennial pastures in the fall, and can have many nutritional benefits for cattle as they move into late gestation.

Participation Summary
7 Farmers participating in research

Educational & Outreach Activities

28 Consultations
4 Webinars / talks / presentations
7 I had one-on-one interactions with each project participant. In these interactions, we were able to discuss the potential variable that impact nitrate content of annual cereal forages, their experiences with it, results for their fields, and overall project results.

Participation Summary

7 Farmers
1400 Ag professionals participated
Education/outreach description:

Education and outreach activities included one-on-one consultations with ranchers that initially agreed to participate in the project, and additional discussions with those who had fields that met the project criteria, and those that spent time in the fields sampling with me. I presented a poster  at the National Association of County Agriculture Agents (NACAA)in Chattanooga, TN in July 2018 and submitted an abstract for consideration for a Search for Excellence in Sustainable Agriculture award to the National Association of County Agriculture Agents in 2020. This resulted in a Regional Winner award and views on the NACAA website due to the conference being transitioned to a virtual offering due to COVID-19.

Consultations with ranchers provided an opportunity to engage and discuss their operations, how annual cereal forages fit into their grazing regimes, and how various factors have the potential to affect nitrate quantity in that forage. There is a high level of interest from them regarding the potential for nitrates, the nutrient quality of the forages available in the fall, differences in nitrate and forage quality between species, and additional ways to incorporate annual cereals to reduce production and feed costs.

I received many follow-up consultations from Extension agents and producers regarding the results of this project. Nitrate toxicity has become a highly recognized concern across Montana and the results from this project have provided a platform for additional education.

 

Learning Outcomes

30 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

22 Farmers changed or adopted a practice
40 Farmers intend/plan to change their practice(s)
2 New working collaborations
Project outcomes:

The results of this project, which was not a formal, replicated research project, provide a platform and a sound basis for a researcher to develop a research project that quantitatively compares the efficacy of the three methods used to evaluate nitrate presence and the risk to animal health of feeding fall growth of annual cereal forages. 

This project has provided significant information regarding the value of integrated cropping and livestock systems as a means to reduce fall feeding costs, preserve native grasslands when livestock can be moved off of areas that may initiate fall regrowth and native vegetation could potentially be harmed by fall grazing, and minimize the risk associated with nitrate poisoning of livestock by annual cereal forages in the fall. Collectively, this contributes to the sustainability of integrated production systems by increasing production efficiency and reducing production costs with a safe, nutritious forage source. 

Success stories:

One ranch that participated in the project experienced great gains on calves weaned off of 2-year old cows that were struggling to maintain weight. They weaned the calves to take pressure off the cows and turned the weaned calves into the pasture in late October 2017. These participants originally did not intend to use the pasture, which had a hay barley, peas, oats cover crop planted in the spring, but with the flash drought that hit during late summer of 2017, range resources were limited and of poor quality and they needed a boost for both the cows and the calves.

The rancher reported, “So, the field you sampled, we turned weaned calves out on and they gained, on average, 2.2lbs /day on just the regrowth. (Some did way better than that) There was 34 head there for 24 days and there is still some feed there, but we got busy doing other things and didn’t turn anything else out there. We were very happy with the results, especially since it turned dry and we were able help the young cows out and use the feed when it was ready..”

Recommendations:

My assessment is that this project was highly valuable in a geographic area where fall grazing of cereal forages is ample. Producers in the area benefitted from knowing that these fields provided a safe, nutritious forage base in the fall. 

The primary key to the success of this project was the cooperative and interested producers that participated and/or sought information when results were generated. They were responsive when I asked for their participation and for them to contact me when fields were ‘grazing ready’, and they trusted me to enter their property to conduct sampling. In several cases, the producers helped me sample their fields. 

One challenge of the project was that I transitioned from and Extension agent position to a Regional Department Head position during the middle of the project, which limited my ability to continue to be engaged with the local producers. Another challenge was that when I was ready to start distributing the final results of the project at workshops, seminars, and conferences, I was limited by COVID-19 restrictions.

The topic of nitrate toxicity in annual forages is one that is popular in Montana, as producers are realizing the potential for this grazing resource to become an integrated part of their management programs. However, they need to understand the pros and cons and potential risks present with integrating this practice into production systems. Therefore, I believe there should be future research in a replicated trial to solidify the results that I obtained through this project.

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.