Final report for LNC19-426
Project Information
Cover cropping is a practice that has been adopted to improve soil health and has been used as a forage resource for livestock. Despite the ecological benefits of cover cropping, the economic benefits might not be realized if the cover crop is not also used as a forage resource for livestock. Integrated crop and livestock systems (ICLS) have the potential to impact the agronomic quality of cropland. Yet, there is limited information to support ICLS grazing management decisions in the northern Great Plains and other semi-arid regions. A 3-year ICLS project was initiated during the spring of 2020. North Dakota State University Extension partnered with farming/ranching producers to establish five research sites located in central North Dakota, along with a demonstration site near the main campus of North Dakota State University. A full season annual forage cover crop was subjected to two forage utilization treatments: 1) 50% and 2) 75% degree of use. Comparisons were made to a non-grazed, annual forage cover crop. Treatments were imposed for 2 years, followed by a cash crop of corn (Zea mays L.). Differences in growing season conditions occurred, but livestock maintained their body condition while grazing during the late fall and early winter months. Despite a lack of changes in soil physical properties or primary soil nutrients, grazed cover crop treatments yielded more corn (P ≤ 0.05) than the non-grazed cover crop treatment. The net effect on profit was negative when cover crops were grown for the sole purpose of soil health, mainly due to the loss of cash crop revenue and no fertilizer savings being generated. However, net returns were less affected when the cover crop was sold as hay. The costs associated with a cover crop and ICLS were variable due to fence and water infrastructure, and environmental conditions. The costs per head per day ranged from $1.50 to $2.73, and savings was greater for the higher forage utilization treatment for both years. Cover crop budgets were also created for producers to use as a guide or tool for decision making.
The objective of this project is to identify the impacts of livestock grazing management on the environmental and economic sustainability of an ICLS. Specifically, the influence of forage utilization of grazing livestock on 1) soil physical and chemical properties, 2 ) crop production, 3) livestock production and 4) economics. This project will provide valuable information on the effects of different grazing management strategies in ICLSs, assisting producers in making management decisions. Project results will be disseminated through cafe talks, workshops, tours, bulletins, news articles, videos, and social media.
Cover crops have gained popularity as a practice implemented by producers across the United States. According to Wallander et al. (2021), cover crop acreage increased 50% between 2012 and 2017, with 15.4 million acres in 2017. North Dakota is no exception to this trend; acreage reports for North Dakota show an increase in annual crops planted for forage or grazing of 26,241 acres between 2019 and 2021 (USDA-FSA, 2021). Producers are incorporating cover crops to improve soil health and increase crop production (USDA, 2019; CTIC, 2017). Despite the ecological benefits of incorporating cover crops into a system, the economic benefits may not be realized if livestock are not incorporated into the system (Costa et al., 2014; Franzluebber and Stuedemann, 2015).
The benefits of integrated crop and livestock systems (ICLSs) include enhanced nutrient cycling as well as reduced inputs and livestock feeding costs. Research on the ecological impacts of ICLSs in semi-arid ecosystems, such as the Northern Great Plains, is limited (Faust et al., 2018). Livestock management decisions regarding stocking rate, stock density, and forage utilization have the potential to impact both environmental and economic sustainability of ICLSs.
Livestock management decisions, such as stocking rates, stock density and utilization have the potential to impact the environmental and economic sustainability of ICLSs. Limited information is available to producers in the Northern Great Plains to help make these management decisions. This producer-led demonstration project will aid in the development of best management practices for managing grazing livestock in ICLSs to enhance soil health, livestock production, crop production and economic sustainability.
Cooperators
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Research
Forage utilization of grazing livestock will increase the environmental and economic sustainability of annual crop systems as a result of 1) enhanced soil physical, chemical and biological properties, 2) increased crop production, 3) increased livestock production and 4) reduced financial inputs.
A three-year ICLS project was initiated in the spring of 2020. NDSU Extension partnered with producers to establish five research sites located in central North Dakota, along with a demonstration site near the main campus of NDSU. Each location was developed to test forage utilization rates in a split-plot design. An annual forage crop representing a cover crop was subjected to two forage utilization treatments: 1) 50% and 2) 75%. A non-grazed treatment served as the control and comparisons were also made to a traditional cropping system. Treatments were imposed for two years, followed by a cash crop of corn.
Forage Establishment
The annual forage crop planted by mid-June of 2020 and 2021 included and will include oats, sorghum sudangrass, foxtail millet, sunflower, radish, kale, turnip, flax and forage pea seed seeded at a rate of 18, 3, 2, 1.5, 1, 0.75, 0.75, 2 and 10 lbs/ac, respectively. After two years of an annual forage crop, corn was planted during the spring of 2022. Producers and site managers had the option to plant corn for use as silage or grain production.
Livestock and Grazing Management
Beef cattle were randomly assigned to forage utilization treatments, and carrying capacities were determined based on available forage production. Stocking rates were determined by dividing the available forage by anticipated dry matter intake per day per animal unit month, then divided by 30 to calculate animal units per day. Animal units per day was divided by the available animal units to predict the grazing period for each location and plot. The available forage for 50% and 75% utilization treatments was calculated using a 35% and 50% harvest efficiency of the total forage produced, respectively (Meehan et al., 2018). The estimated dry matter intake was based on recommendations in the Beef Cattle Handbook (National Research Council, 2016), but was increased by 20% according to trials previously conducted at NDSU Central Grasslands Research Extension Center (Fraase, 2012).
A visual scoring system was used to describe the relative fatness or body condition of cattle pre- and post-treatment (Wagner et al., 1988). Type and class of cattle varied from site to site and grazing turnout ranged from the late July to early October. Electric poly-wire and temporary posts were utilized as portable cross-fence to limit-graze livestock and maintain grazing efficiency. Each treatment was divided into four sections. Windbreak shelters were available for use and continued access to water was provided.
Soil Sampling
Soil samples were collected to characterize physical, chemical, and biological properties. Soil physical properties included bulk density, infiltration, and aggregate stability collected pre- and post-treatment. Six sub-samples were collected from a similar soil series within each treatment prior to seeding of annual forage crop. Soil chemical properties included soil nutrients, pH, and organic matter collected annually with assessment of nutrient distribution only occurring pre- and post-treatment. Samples for nutrient distribution were collected from each 1-acre sub-plot, whereas once yearly levels were extracted from a similar soil series within each treatment. Above ground residue was gently removed at each sampling site prior to conducting the sampling technique.
A soil core sampler with hammer attachment was used to measure bulk density at a depth of 0-6 inches. In calculating bulk density, the weight of the oven-dried soil was divided by the volume of the ring to determine lb/ft3. Soil infiltration was determined by utilizing the Cornell Sprinkle Infiltrometer system (van Es and Shindelbeck, 2003). It consists of a portable rainfall simulator that is placed onto a single 9.5-inch inner diameter infiltration ring and allows for application of a simulated rainfall event. Field-saturated infiltrability reflects the steady-state infiltration capacity of the soil after wet-up. It is based on the data collected at the end of the measurement period, or whenever steady-state conditions occur. Since the apparatus has a single ring, conversion factors from Reynolds and Elrick (1990) are needed to account for the three-dimensional flow at the bottom of the ring. Soil aggregate stability samples were collected with a tiling spade at a depth of 0-6 inches. A manual wet sieving method by Six et al. (1998) was used to develop an automated method for assessing aggregate stability. Due to variation in soil across locations, the sand correction procedure by Mikha and Rice (2004) was applied to each sample to remove the sand fraction from the water stable aggregates total. Soil nitrate-nitrogen (NO3-N), phosphorus (P), potassium (K), pH, organic matter (OM), sulfate-sulfur (SO4-S), zinc (Zn), and copper (Cu) were determined from samples collected at 0-6 and 6-12 inches with a 0.7-inch diameter soil probe. Soil nitrates (Vendrell and Zupancic, 2008) were measured using the Brinkmann PC910 Colorimeter. This colorimeter was also used to determine levels of P after applying the Olsen Test (Nathan and Gelderman, 2015). Potassium was measured using an atomic absorption spectrophotometer. Zinc and copper were extracted with diethylenetriaminepentaacetic acid and also measured with an atomic absorption spectrophotometer (Nathan and Gelderman, 2015). Recommended chemical soil test procedures for the North Central Region (Nathan and Gelderman, 2015) were used to analyze pH, OM, and SO4-S.
Forage Production and Utilization
Forage production and utilization of the annual crop was estimated by clipping six frames per experimental treatment within a similar soil series. Samples were oven-dried at 50°C for 48 hours, weighed, and multiplied by the appropriate conversion factor. Clipping for peak biomass production occurred during the week prior to grazing. Clipping to determine forage utilization occurred upon removal of cattle from the grazing treatments.
Livestock Performance
Beef cattle were stratified by a 2-day body weight and body condition score at the site in Fargo pre- and post-treatment, whereas cattle at the demonstration sites were scored for their body condition only. A visual scoring system developed by Wagner et al. (1988) was used to assess body condition.
Crop Production
Forage biomass of corn was estimated at physiological maturity by clipping six plots per experimental treatment within a similar soil series (Meehan and Sedivec, 2017). The size and shape of the plots depended on the type of row spacing established at each site. Clipping length was determined by the following formula: 10.8 ÷ (row spacing in inches ÷ 12) = length in feet. For example, 30-inch row spacing requires a clipping length of 4 feet 3 inches. Samples were oven-dried, weighed, and multiplied by the appropriate conversion factor.
The kernel count method was used to estimate corn grain yield by collecting fifteen cobs per experimental treatment within a similar soil series (Carlson and Reicks, 2019). This method is based on the premise that yield can be estimated from the components that constitute grain yield, including ear number, number of kernel rows, and kernels per row.
Economic Analysis
An economic analysis was conducted to evaluate the net effect on profit when a management change occurred. The management change included the adoption of a multi-species cover crop for soil health benefits such as potential fertilizer savings and/or saleable forage as opposed to cash crop production of grain corn during 2020 and 2021. An additional analysis was conducted to evaluate the costs associated with a cover crop system and an ICLS during 2020 and 2021.
Forage Production
Forage production was variable across sites. However, it is important to recognize that climate conditions, equipment calibration, and cropping history were also variable and differences were likely reflected in results. For example, the recommended seeding depth of the annual forage crop was approximately 2-cm. However, Fargo was seeded to a depth greater than 2-cm in 2020 resulting in poor germination of brassicas, which likely influenced both forage production and nutritive value. Fargo produced approximately 65% less forage when compared with other locations in 2020, despite greater growing season precipitation. The other sites averaged 7,145 to 16,182 kg ha-1. Strategies for successful field preparation and drill calibration were discussed with site managers and the problem did not persist in 2021.
The drought of 2020, followed by dry spring conditions during 2021, resulted in limited forage production across all sites except Fargo. While late season rain boosted growth or re-growth of forages in Fargo, Jamestown, Lehr, and Tappen, the lack of subsoil moisture reduced forage production for the majority of the sites. Average forage production ranged from 2,681 to 9,247 kg ha-1, with Fargo yielding the highest total.
Carrying capacities for the 50% forage utilization treatment ranged from 4.2 to 9.1 AUMs ha-1 and 1.2 to 4.7 AUMs ha-1 in 2020 and 2021, respectively. Carrying capacities for the 75% forage utilization treatment ranged from 2.5 to 11.1 AUMs ha-1 and 1.5 to 7.4 AUMS ha-1 in 2020 and 2021, respectively.
Grazing Management and Livestock Performance
Type and class of cattle varied from site to site, and grazing turnout ranged from late August to early October of 2020, and late July to early November of 2021. Grazing days (d) ranged from 13 d in McKenzie to 64 d in Lehr. Some locations with adequate forage production experienced less days due to inclement weather, increased intake, or inadequate water. Drought conditions during the fall of 2020, combined with an early frost on 7 September, reduced or halted plant growth and likely impacted forage nutritive value and intake.
The degree of use for the 50% forage utilization treatment was 46.5 ± 13.5% and 53.5 ± 4.5% in 2020 and 2021, respectively. The degree of use for the 75% forage utilization treatment was 58 ± 14% and 62 ± 13% in 2020 and 2021, respectively.
There were minimal changes in BCS over the grazing season in either year (Table 2.5). Despite differences in growing season conditions, there was no treatment or year effect, or treatment by year interactions.
Soils
Soil NO3-N, P, K, pH, OM, SO4-S, Zn, and Cu levels were summarized by year, treatment, depth, and location. No significant differences were observed between treatments for any of the soil chemical properties evaluated at either depth. Analysis of soil physical characteristics suggest that grazing cattle on cropland in the late summer or fall does not cause soil particle separation, soil compaction, or impede water infiltration. Bulk density was similar between the cover crop only and grazing treatments. Water infiltration varied between sites due to differences in soils, however, rates seemed similar across treatments at each location. Similarly, total soil aggregate stability did not differ between treatments. However, an increase in macroaggregates was observed over the study period, indicating increased soil stability.
Crop Production
There was no difference in corn biomass between treatments. However, treatments with livestock grazing had higher grain corn yields (P ≤ 0.05) than the non-grazed cover crop treatment (Table 2.6). The 50% forage utilization treatment yielded 14% more (P = 0.0468) and the 75% forage utilization treatment yielded 23% more (P = 0.0011) grain corn than the non-grazed, cover crop only treatment.
Economics
The change in cropping rotation for the purpose of potential fertilizer savings reduced income by $562.00 ha-1 and $989.66 ha-1 during 2020 and 2021, respectively. The change in cropping rotation for the purpose of potential fertilizer savings while capitalizing on forage production by selling large round hay bales reduced income by $56.18 ha-1 and $440.03 ha-1 during 2020 and 2021, respectively.
The costs associated with the cover crop and ICLS were variable across treatments mainly due to requirements of fence and water infrastructure for grazing treatments, and across years due to differences in forage production. The cost to graze a cow (animal unit) at the 50% forage utilization treatment was $1.50 and $2.73 per head per day in 2020 and 2021, respectively. These costs were reduced on the 75% forage utilization treatment to $1.29 and $2.10 in 2020 and 2021, respectively.
Differences in growing season conditions occurred, which is common in regions like the NGP, but livestock were able to maintain their body condition while grazing during the late fall and early winter months. Despite a lack of change in the primary soil nutrients or soil physical properties grazed cover crop treatments yielded more corn than the non-grazed cover crop treatment. Although the difference was not significant, grazed cover crop treatments also produced more corn biomass than non-grazed cover crop treatments. The gradual increases in soil OM suggest that crop diversification and livestock integration may have led to improvements in plant growth. Monitoring levels of soil C and microbial activity would help to better understand the implications of an ICLS.
We found that a change in cropping rotation for the purpose of soil nutrient contributions is not financially lucrative. Yet, there are opportunities to generate revenue through the value of the forage crop. The potential to generate revenue is dependent on variable input costs and market fluctuations. A sellable product such as hay or the opportunity to graze the annual forage and reduce winter feeding costs is likely to be of more interest to producers.
Education
A variety of educational approached were used to disseminate project curriculum and results including meetings, field days, articles, interviews, reports and social media. The project team developed curriculum and tools including cover crop kits, cover crop cost calculator, Extension publication and presentations to utilized in outreach. Hosted in-service trainings for Extension personnel and technical service providers to give them the skills and confidence to share curriculum and results, increasing the impact of outreach efforts. ,
Project Activities
Educational & Outreach Activities
Participation Summary:
Research results were shared at several state and regional events including the Central Grassland Research Extension Center Field, NDSU Beef Field Day, DIRT Workshop, Northern Plains Sustainable Agriculture Society Conference, as well as numerous county Extension Meetings. Project curriculum and/or results were presented at 11 café talks, 88 educational meetings, 9 webinars and 4 field days to 4,565 participants. Filmed 6 videos focused on integrated crop livestock systems and grazing cover crops. Hosted two in-service trainings for Extension personnel and technical service providers giving them the technical skills to engage with producers on annual forage options for livestock and livestock integration into crop systems. Created kits for Extension agents, NRCS and SCD personnel to grow cover crops to use in their programing efforts, distributed kits to 15 participants. Information was also shared via 21 articles, 29 media interviews and numerous social media posts, reaching an estimated 1,270,000 individuals.
Learning Outcomes
- Calculating forage production and stock rates for grazing cover crops.
- Selecting cover crop species for grazing.
- Soil health and economic benefits of grazing cover crops.
- Potential toxicity issues when grazing cover crops.
- Grazing management considerations for integrated crop livestock systems.
Project Outcomes
Integrated cover crop into their crop system for grazing.
Selected cover crops based on forage quality and/or biomass production.
Adjusted utilization rate when grazing cover crop based on project findings.
Three of the participating farmers had not previously utilized cover crop for grazing; two have continued to integrate cover crops for grazing as a source of high quality forage in the fall.
In 2021, North Dakota experienced a statewide drought impacting forage production. The participating producers were able to move animals off of pastures and onto the annual forage. This reduced stress to perennial pastures without having to reduce herd size to the extent of other ranchers impacted by the drought. All participants were thankful to have the alternate forage source available.