Progress report for GNE22-300
In the Northeast, low availability of perennial cool-season forages during June through August stresses farm budgets and can lead to overgrazing which harms the long-term productivity and health of agricultural lands. Summer forage shortfalls will likely worsen as the climate changes and becomes hotter and dryer. Crabgrass (Digitaria ciliaris) is a warm-season annual forage that is productive in the southern United States but unknown in the Northeast. However, the ecology of its weedy relatives and recent studies from the Midwest suggest that it would be a highly useful alternative summer forage in northeastern dairy and livestock agriculture.
To fully investigate the innovative use of crabgrass in the Northeast, three experiments will be performed at the University of Massachusetts:
1) Crabgrass will be planted at four times (mid-May, early June, mid-June, and late June) and three seeding rates (3, 6, and 9 pounds per acre). Weekly sampling will explore the relationship between growth stages and forage yield and quality.
2) Improved crabgrass varieties will be evaluated for yield and quality with three nitrogen fertilizer treatments (50, 100-single application, and 100-split application pounds/acre). This will show the best crabgrass varieties suited to the Northeast and nitrogen management for single and multi-cut forage systems.
3) Crabgrass, pearl millet, and sudangrass will be grown and evaluated for their forage quality as hay and haylage.
Economic analysis will be performed to assess the costs and benefits of crabgrass forage. The results of this project will be used to make recommendations for regional crabgrass production.
1) Explore basic information on optimal sowing date, seeding rate, and time of harvest of Quick-N-Big crabgrass. Measure weekly growth, yield, and forage quality of crabgrass between 4 and 10 weeks after planting for crabgrass sown at four planting dates (mid-May to late June) and three seeding rates (3, 6, and 9 pounds/acre). Investigate the relationship between crabgrass growth stage, seasonal progression, and forage quality and yield. (Experiment 1)
2) Evaluate yield and quality performance of several crabgrass varieties grown under different nitrogen management treatments and quantify their regrowth after first-cut harvest. (Experiment 2)
3) Determine the quality of crabgrass haylage and fermentation profile compared to the quality of haylage made from pearl millet and sudangrass, using mini-silos. (Experiment 3)
4) Perform an economic analysis of crabgrass forage production. For this purpose, crabgrass forage will be compared to purchased hay and other common summer annual forages, including pearl millet and sudangrass. An enterprise budget for these three crops as well as locally purchased hay and haylage will be conducted. Data from all three experiments will be used in this analysis.
5) Establish research-based recommendations for the holistic production of southern crabgrass in the Northeast.
The purpose of this project is to evaluate an alternative forage to meet summer shortfalls in the northeastern dairy and livestock industry. The experiment fully investigates the growth, yield, and quality of southern crabgrass as dry hay and haylage for use in Northeast dairy and livestock operations. Specifically, it aims to quantify the effects of planting date, seeding rate, harvest timing, growth stages, and nitrogen management on forage quality and yield. Additionally, this project will compare the performance of crabgrass with pearl millet and sudangrass summer annual forages. Adoption of new crops always carries risk for farmers and this project aims to produce research-based recommendations for growing crabgrass in the Northeast.
Perennial cool-season grasses are the backbone of regional forage production, however these grasses are relatively unproductive during the summer slump in late June through late August. The use of warm-season annual crops can reduce or entirely eliminate the need for stored/purchased feed but current options are limited. Sorghum and sudangrass must be grown to 24” or more to avoid prussic acid toxicity and are typically one-cut forages. Pearl millet is somewhat suitable for multiple cuttings but the second harvest usually has low yields and must be cut at higher height than crabgrass to encourage regrowth. While these summer annuals grasses will continue to have their place on northeastern farms, alternative grasses will enable farmers choose options that fit their farm conditions. Crabgrass has been successful in southern forage rotations and could be effectively adopted in the Northeast with appropriate management.
There is almost no documented information on the use of crabgrass as a summer forage in the Northeast. The variety selection and planting date range are perhaps the most important primary information. Planting too early or too late can result in slow growth, poor yields, increased weed competition, or interference with following crop plans. Crabgrass is sensitive to soil temperature and performs poorly if planted too early. Late planting carries its own risks. It may give summer weeds a head start on the crabgrass, leave less time in the crop rotation with succeeding fall crops, and may lower crabgrass yields if the forage must be terminated prematurely to prepare the field. Crabgrass development is also sensitive to daylength thus planting at the wrong time could result in early flowering and lower yield and forage quality.
Additionally, nitrogen management, seeding rate, and harvest timing must be explored for successful adoption of this exciting crop. While these characteristics are likely to be more stable across different regions, they may interact in important ways with the variety and planting date and need to be explored so that the production of crabgrass in the Northeast is well documented.
The forage quality and yield of crabgrass as a summer annual forage clearly show that it could be an important part of livestock and dairy production in the Northeast. New summer forages are needed since climate change trends show that summers in the Northeast are likely to become hotter and dryer in the coming decades.
Field Site (Objectives 1, 2, and 3)
In the summers of 2022 and 2023, fields will be selected at the UMass Crop Research Farm in South Deerfield MA to implement three experiments. The soil will be tested at the UMass Soil Testing Lab and any deficiencies in mineral nutrients will be corrected.
Experiment 1: agronomic management, treatment implementation, and seasonal progression. (Objective 1)
Aged Quick-N-Big crabgrass will be planted as a four-replication, split-plot RCBD with planting date as the main plots and seeding rate as the sub-plot (Figure 1) following field preparation using mechanical tillage at the end of April and the beginning of May. Quick-N-Big crabgrass was chosen for this experiment because it performed the best in northern trials done by Wisconsin Extension (Newman, 2019). There will be four planting date treatments (mid-May, early June, mid-June, and late June) and three seeding rate treatments (3, 6, and 9 pounds/acre live seed) (Table 1). Later planting dates will be cultivated prior to planting to produce a clean seedbed for each planting date. The crabgrass will be planted using a custom-made Brillion cone seeder in sub-plots measuring 6 feet by 40 feet. Soil temperature will be measured at each planting date. Nitrogen fertilizer will be applied at planting to add 50 pounds/acre of nitrogen in the form of calcium ammonium nitrate.
Experiment 1: evaluation of growth, yield, and forage quality over time. (Objective 1)
Experimental plots will be observed and sampled for a duration of 10 weeks after planting. Since planting date is a treatment, evaluation of early-planted plots will begin before the final planting while late plantings will be measured and harvested through late August. Each week following planting, several measurements will be collected from a 1/4 m2 quadrat in each plot: 1) growth stage during the entire experiment, 2) ground cover at the beginning of crabgrass growth, and 3) forage yield and quality once crabgrass reaches about 6 inches in height.
Growth stage will be assessed following Moore et al. (1991). Ground cover will be measured using the Canopeo app (Patrignani and Ochsner, 2015) and will be measured until either canopy closure or stem elongation. Forage yield and quality will be assessed by collecting a biomass sample from a 1/4 m2 area. Forage will be manually harvested 3 inches above ground level to mimic grazing or harvest height. The collected forage will be dried in a forced-air oven at 130 degrees Fahrenheit, weighed to calculate yield, ground to 1 mm using a Foss mill, and analyzed for forage quality in terms of NDF (Neutral Detergent Fiber), ADF (Acid Detergent Fiber), crude protein, TDN (Total Digestible Nutrients), energy content, and RFV (Relative Feed Value) using an NIR machine (Unity Scientific, Milford, MA, USA). Growth stage measurement and sampling will continue until inflorescence emergence and pollination. While the specific timing of these measurements will depend on crabgrass growth, ground cover will likely be measured for the four weeks after planting while forage samples will likely be collected between four and ten weeks after planting. Thus, sampling will begin in late May, one week after the first planting, and continue until late August, approximately ten weeks after the final planting.
The results will be statistically analyzed as a repeated-measures, mixed-effect model with main effect explanatory variables of planting date, seeding rate, and measurement date as continuous, fixed effects. Year and plot nested within block will be used as random effects. Response variables will be ground cover, growth stage, yield, and various forage quality parameters. Separate analysis will be conducted with growth stage as an explanatory discrete fixed effect and yield and forage quality parameters as the response variables with the same random effects as described above. The analysis of Experiment 1 will show how the yield and quality of the crabgrass forage changes based on the growth stage and harvest timing and what the best planting date and seeding rate are for crabgrass grown in Massachusetts.
Experiment 2: agronomic management, treatment implementation, and seasonal progression. (Objective 2)
The field will be prepared using mechanical tillage at the end of May. Improved crabgrass varieties will be grown in a factorial split plot RCBD experiment with variety as the main plot and nitrogen fertility as the sub plot (Figure 1). There will be between four and six varieties of improved crabgrass depending on seed availability (potential varieties include Quick-N-Big, Quick-N-Big Spreader, Dal's Big River, Red River, Impact, and Mojo). Aged seed will be used to improve germination rate. There will be three nitrogen treatments: 1) low - 50 pounds/acre at planting, 2) high - 100 pounds/acre at planting, and 3) split - 50 pounds/acre at planting and 50 pounds/acre after the first harvest (Table 1).
The crabgrass will be planted at 6 pounds/acre live seed at the beginning of June using a custom-made Brillion cone seeder in sub-plots measuring 6 by 20 feet. The nitrogen fertilizer will be applied in the form of calcium ammonium nitrate (27% N). The two harvests will be done when the forage is in the boot stage, likely in mid-July and late August. If new varieties are released after the first year of the experiment, some varieties may be adjusted between the 2022 and 2023 seasons.
Experiment 2: evaluation of growth, yield, and forage quality over time. (Objective 2)
Plots will be evaluated weekly for 10 to 12 weeks after planting. For about the first four weeks, ground cover will be measured to assess grass growth using the Canopeo app (Patrignani and Ochsner, 2015) until canopy closure or stem elongation. Growth stage will be noted throughout the experiment following Moore et al. (1991). Additional notes will be recorded describing emergence, stolon and tiller development, lodging, and any potential diseases and insect damage.
When the forages are in the boot stage (stage R0) (Moore et al., 1991), about six weeks after planting, the crabgrass will be harvested 3 inches above the ground. The date of harvest and height at harvest for each plot at the first cutting will be recorded and a sample from a 1/4 m2 area will be dried in a forced-air oven at 130 degrees Fahrenheit. This sample will be weighed to calculate yield, ground to 1 mm using a Foss mill, and analyzed for forage quality in terms of NDF, ADF, crude protein, TDN, energy content, and RFV using an NIR machine (Unity Scientific, Milford, MA, USA). The rest of the plots will be clipped and removed around the sample area. Additional nitrogen fertilizer will be applied after harvest based on the nitrogen treatments. The crabgrass will then be allowed to regrow. Growth stage will again be assessed during regrowth until crabgrass regrowth reaches the boot stage, about six weeks after the first harvest. Second-cut crabgrass forage will be measured, sampled, and analyzed in the same manner as the first-cut harvest.
The results will be statistically analyzed as a mixed effect model with main effect explanatory variables of nitrogen rate as a continuous fixed effect and variety as a discrete fixed effect. Year and plot within block will be used as random effects. Response variables will be ground cover, various growth parameters, days to harvests, harvest yields, and various forage quality parameters. The results of the analysis of Experiment 2 will show how nitrogen application timing affects the development, yield, and forage quality or crabgrass and which crabgrass varieties are best suited for use in the Northeast in single-cut or two-cut forage production.
Experiment 3: Crabgrass Haylage. (Objective 3)
The field will be prepared using mechanical tillage at the end of May. Plot size are 6 x 20-feet. Quick-N-Big crabgrass, Exceed BMR pearl millet, and AS9301 sudangrass will be arranged in a four-replicate RCBD (Figure 1). The grasses will be planted at a rate of 6 pounds/acre live seed for crabgrass, 20 pounds/acre live seed for pearl millet and 30 pounds/acre live seed for sudangrass (Table 1). All three crops will be planted in early June using a custom-made Brillion cone seeder. Forages will receive 50 pounds/acre nitrogen as calcium ammonium nitrate (27% N) at planting. In the middle of July, the forages will be harvested three inches above the ground when crabgrass is in the boot stage and pearl millet and sudangrass are around 36 inches tall. Harvest date and growth stage based on Moore et al. (1991) will be assessed at harvest. Samples from a 1/4 m2 area will be dried in a forced-air oven at 130 degrees Fahrenheit. These samples will be weighed to calculate yield, ground to 1 mm using a Foss mill and analyzed for forage quality in terms of NDF, ADF, crude protein, TDN, energy content, and RFV using an NIR machine (Unity Scientific, Milford, MA, USA).
Samples will also be collected to make haylage. All of the forages will be separately chopped using an Ohio forage chopper to 1/2-inch lengths. Four replications of each species will then be packed into mini-silos (1-quart HDPE plastic jars). The material for each mini-silo will be packed by hand into each plastic jar. A 1-inch-wide iron bar will be used to pack (compress) the forage and each jar will be filled with a minimum of 28 ounces of forage to minimize the amount of air in each mini-silo.
The mini-silos will be sealed and stored at approximately 60 degrees Fahrenheit for five months. Extra mini-silos will be made so that fermentation can be monitored without opening the treatment silos. The silage samples will be sent to Dairy One Forage Lab to test for forage quality and fermentation profile. The samples will be frozen before shipping so that they do not mold in transport. Forage quality will be measured in terms of crude protein, ADF, aNDF, non-fiber carbohydrates, total digestible nutrients, net energy, and relative forage value. Silage fermentation profile will be evaluated in terms of acid content (lactic, acetic, lactic/acetic ratio, propionic, butyric, iso-butyric), VFA score, total acids, pH, crude protein, crude protein equivalent from ammonia, and ammonia N as a percentage of total N.
The results will be analyzed as a four-replicate, completely randomized design with the plant species treatment as a fixed discrete explanatory variable and the various aspects of forage quality and silage quality as response variables. The results of Experiment 3 will show how crabgrass hay and haylage compare with other summer annual grass hay and haylages and demonstrate its potential use as a high-quality stored forage.
Economic analysis (Objective 4)
The yield, forage quality, and time to harvests data from the crabgrass management treatments collected in experiments 1 and 2 will be compared to discuss how the best crabgrass production compares to other summer annual grasses in terms of growing season period, yield, and forage quality. The hay and haylage quality of the three summer annual grasses in experiment 3 will be compared to each other and to typical forage made from perennial grasses.
The marginal input and labor costs of all three summer annual forages will be used to calculate an enterprise budget for summer annual forage grasses in grazing and hay production systems. This budget will include field preparation, planting, and harvest labor costs (for hay) as well as fertilizer and seed input costs. The local price and forage quality of purchased locally grown hay and haylage will be used to determine the value of summer annual forages and calculate overall per acre profitability. Combined with agronomic management data from experiments 1 and 2 and haylage quality data from experiment 3, solid information will be provided to regional dairy and livestock farmers to decide whether crabgrass forage would be right for their operations.
Management Recommendations (Objective 5)
The results of all three experiments and economic analysis will be integrated with knowledge of regional cropping systems to develop research-based recommendations for southern crabgrass production in the Northeast. While each experiment will focus solely on crabgrass production, these recommendations will take into account on-farm limitations and practices to explore how crabgrass forage production would fit into existing crop rotation and seasonal forage needs.
Materials and Methods updates from 2022 field season
A few changes were made to the materials and methods during the 2022 field season.
In 2022, data collection for all experiments went well. We were unable to source seeds for Red River and Impact crabgrass varieties, so the crabgrass variety experiment (#2) only used Quick N Big, Quick N Big Spreader, Dal's Big River, and Mojo varieties.
In experiment 1 (planting date), forage quality analysis was only performed on the samples from 6 pounds/A seeding rate plots since we did not expect to see differences in forage quality as a result of seeding rate. Because the crabgrass is almost on the soil surface, we decided not to measure soil temperature at planting and instead will use weather data to compare years since the soil surface temperatures are highly variable with environmental weather conditions.
We decided to replace ground cover measurement with weed biomass measurement at 4 weeks after planting in experiment 1. We also decided to harvest experiment 1 at ground level rather than at a production height of 3 inches. The higher height was used for experiments 2 and 3.
In experiment 2, there was considerable difference in time to boot stage between varieties and the harvest dates were recorded.
Materials and Methods 2023 update
All research projects were repeated in the same manner as 2022. The season was much wetter than 2022.
Data analysis is ongoing but initial analysis suggests that between 5 and 7 weeks after planting is likely the main harvest window depending on whether quality or yield are most important in a particular production context. Further sample analysis and data interpretation is still under way.
Partial results are attached here:
This file shows the final layout of all three experiments in 2022: crabgrass layout 2022
This file includes the yield and field measurements from the planting date experiment (#1) in 2022: 2022 crabgrass planting date
This file includes the forage quality measurements from the planting date experiment (#1) in 2022: forage quality 2022 crabgrass planting date
This file includes the yield and field measurements from the variety experiment (#2) in 2022: crabgrass variety 2022
This file includes the yield and field measurements from the crabgrass/sudangrass/millet comparison experiment (#3) in 2022: CSM
2023 results update
This file shows the crabgrass layout in 2023
Forage quality and statistical analysis will be completed in the winter and spring of 2024.
Education & Outreach Activities and Participation Summary
Project outreach will occur during the course of and upon completion of this research project. On-farm field days, conference presentations, hands-on workshops, and publications will be used to facilitate discussion between farmers, researchers, and agricultural service providers and communicate the experimental results.
During the 2022 and 2023 growing seasons, outreach will focus on building interest in crabgrass as a summer annual forage. We will also begin communicating preliminary results after the 2022 season. These activities will be performed in two ways.
1) Conversation with farmers and extension agents at the research farm during annual field days - The experimental rationale and potential outcomes will be presented and qualitative differences between treatments will be discussed. In 2023, we will also present preliminary data from the 2022 season during the field day.
2) Video and photo documentation of experimental activities and plant growth - This will be used for the production of extension videos and for use in workshops presentations. Visual documentation is the ideal partner for accumulated data and these videos will allow for effective communication of our results, especially as permanent online resources.
After the completion of field work in August 2023, outreach activities will shift from building interest and discussion to the communication of results. This will be done in three ways.
1) Conference presentations - Research results will be presented in at least one international academic conference (2023 ASA-CSSA-SSSA Annual Conference) and at least one regional farmer-focused conference (NOFA Conferences), following the second year of the experiment.
2) Extension publications and videos - In order to educate farmers and agricultural service providers broadly and over a longer time frame, it is necessary to produce instructive materials which can be accessed online. To this end, we will produce a comprehensive extension monograph describing the agronomic management and economic analysis of crabgrass forage as well as an accompanying online video.
3) Peer-reviewed articles - To contribute to the scientific literature, the results of this research will be published in two or more articles in high-quality, peer-reviewed scientific journals describing and contextualizing the results.
Overall, these outreach activities will build interest at a regional level and allow us to share the results of these experiments, as well as economic analysis and management recommendations, with the large and diverse agricultural community of farmers, researchers, and agricultural service providers.
2022 education and outreach activities
In the spring of 2022, we published an extension article describing the goals of this research which was distributed to our newsletter list serve.
In September, a poster describing the yield differences seen in experiment 1 (planting date) was presented at the CAFE Summer Scholars undergraduate research forum.
On August 2nd, a research farm field day was held and the crabgrass research plots were shown to farmer and ag service provider attendees.
On August 17th, a demonstration at the Hadley Horse farm of the University of Massachusetts was shown to a working group meeting of regional extension educators focused on horse pasture.
2023 education and outreach activities
In the winter of 2023, the first year of results were presented at the Certified Crop Advisers annual meeting in Portsmouth NH (January 25th) and at a full day Managing forage Crops Workshop at UMass Amherst (February 21st).
On August 16th, a research farm Field Day was held and the crabgrass research plots were shown to farmer and ag service provider attendees.
Research results were also presented at an undergraduate research symposium on September 11th and at the Agronomy, Crop Science, and Soil Science Societies annual meeting on November 1st.