Agriculture is often associated with nitrate leaching into water bodies. Planting winter cover crops has been identified as one solution to reduce nitrate leaching and other agricultural related water issues. However, the adoption rate of cover crops in the Upper Midwest is low over many years due to a lack of economic incentives. One alternative solution is to double crop one economically viable winter annual crop and a spring crop in the same year. Here we introduce a double cropping system between a winter annual, winter barley, and a summer annual, short-season soybean to the Upper Midwest. Many end-users of barley, including malsters and brewers, have indicated strong desire in sourcing locally grown malting barley in the Upper Midwest. Sourcing locally grown barley reduces transportation costs and the shipping time for local malsters and brewers. Although the barley end-use market continues to expand, production of barley in Minnesota has declined from 900,000 acres per year in 1980 to just 90,000 acres today. Therefore, with a new barley production market fueled by the local brewing industry, researchers at the University of Minnesota (UMN) are working to develop an economically viable winter barley-soybean double cropping system. As a winter annual, winter barley provides numerous agroecosystem services, and diversified income to growers in addition to soybeans. Currently, the UMN winter barley-breeding program has developed several lines exhibiting improved winter hardiness for the growing conditions in the Upper Midwest. Winter barley matures around the end of June, and a short-season soybean variety will immediately be planted after the harvest of winter barley. In addition, a new project funded by Minnesota Department of Agriculture (MDA) is investigating the breeding of winter barley and soybean in a dual- cropping system optimized for productivity in Minnesota. “Assessing agroecosystem services and end-use malting quality of winter barley in a soybean-winter barley double cropping system in the Upper Midwest” would extend that work to characterize nitrate utilization, biomass accumulation, and end-use malting quality in a winter barley- soybean double cropping system.
This project will provide multiple learning and action outcomes. The major learning outcome of this project is to gain a better understanding of the agroecosystem and agronomic characteristics of winter barley and soybean utilized in a double cropping system with soybeans. Our goal is to make both growers and end-users aware of the issues surrounding mono-cropping production and its potential impact on nutrient leaching. Research findings will be packaged into education and outreach activities with express goals to raise awareness about plants on the landscape with impacts to water quality. The main action objective of this project is to add agroecosystem and end-use malting value to the winter barley-soybean double cropping system, and promote adoption of winter barley as a new winter annual in rotation with soybean in a double cropping scenario to growers and end-users.
The entire experiment is a Random Complete Block Design (RCBD), replicated three times in each location. Three locations, two sites in Minnesota (St. Paul and Rosemount), and one site in Wisconsin, (Alma) were include in the study. Three treatments were incorporated, in which the winter barley-soybean double cropping treatment initiated in the fall, and the full-season and short-season soybean treatments were imposed in May and July of the following spring to summer accordingly. A winter barley variety that exhibited superior winter-hardiness was selected for the experiment. Two commercial soybean varieties were chosen for the soybean treatments, a Maturity Group (MG) ‘II’ variety and a MG ‘0.5’ variety were used in the full and short season soybean treatments, respectively. Each field plot were 5 or 3.75 feet wide and 15 feet long, depending on the specific experimental site. Row spacing of 10 to 15 inches were chosen for all the treatments, and soybeans were drill-planted into the winter barley residues in the winter barley-soybean double cropping treatment. No till was practiced in the double cropping treatment to eliminate soil disturbance and foster sustainable cropping practices to protect soil health.
Each fall, immediately after planting or prior to planting the winter barley double cropping treatment, soil sampling took place at three plots randomly chosen for each treatment. Soil sampling at 12’ and 24’ depths took place within the sampling points at each plot. The same sampling procedures were followed in May and July for all the treatments. So a total of three sampling times were imposed in this study.
Once the snow completely melts and the weather becomes ideal for assessing winter survival in the spring, visual assessment of overwinter survival took place and it is evaluated in percentage from 0-100. Destructive biomass collection followed immediately, where a grid of half a square meter or similar dimensions were used as to establish a boundary. Scissors were used to cut all the above-ground plant materials and the biomass samples were sent to 95 degree Celsius dryers to be dried out first before weighing.
Soil moisture sensors were installed in the spring immediately after the full-season soybean were planted in all three treatments at each location. The sensors were in place to measure the soil temperature and soil moisture content and recorded information every two hours for the next four to five months, or until the soybeans are fully mature. We installed the sensors at two depths in two random areas of one plot also randomly selected for the trial. No large replications of the sensors were included due to the high cost of the sensors and the data-loggers that needed to accompany sensors.
Preliminary soil sampling results showed that the soil-nitrate contents generally reduced for the winter barley-soybean double cropping system from the initial fall assessments to the spring and the summer. Soil-nitrate levels were much lower at the 24 inches depth than at 12 inches for all the treatments. These findings are in agreement with the hypothesis that winter barley could serve to scavenge nitrate in the topsoil and reduce the likelihoods of nitrate from moving to deeper soils. We observed similar reduction of soil-nitrate levels for the full-season soybean treatment from the initial assessment to the second sampling date in July. In July, when we planted the last treatment of short-season soybean treatment, the soil-nitrate levels were found higher than at the other two treatments. This indicated that living plants and biomass production reduced the soil-nitrate concentrations, and planting the winter barley-soybean double cropping system provided a continuous living cover that lowered soil-nitrate throughout the year. The full-season and short-season soybean conditions served important control factors that allowed us to compare the different soil-nitrate levels across all treatments. An additional year of soil sampling results will be necessary to confirm and complete the data analysis. All the results will be subjected to statistical testing to determine if statistical differences are present for different treatments, and at different sampling time points.
Not all experiments are carried out in perfect conditions and designs. We also experienced several challenges during this project. Managing the experiment across three different sites, and working with different topographies created obstacles that prevented us to plant and establish the study, and conduct data sampling of the experiment at the most ideal timeframes. However, we prepared and pursued appropriate contingency plans when necessary. A major issue we faced was inconsistent winter weather conditions, include an adequate amount of snow, steadily lowering temperatures transitioning into the winter, and freeze-and-thaw cycles that instill winter injury on winter barley plants. In the spring, after careful evaluations of the survival rating of winter barley plants, we chose to use winter wheat as a surrogate due to poor survivability of winter barley in two of the experimental sites.
Destructive biomass sampling, and spring and summer soil samplings all took place at two trials in St. Paul and Rosemount where a winter wheat-soybean double cropping system was carried out. We did not find any distinctive correlation between weight of biomass samples and ultimate grain yield in the winter barley or winter wheat surrogate trials, and often times, winter barley can tiller and compensate for reduced survival at thinner establishment densities, so assessing biomass in early spring may not capture the true biomass characteristics for winter cereal crops. We are exploring new ideas to quantify and capture the biomass production of winter barley, and soil-nitrate samples explained some changes in nitrate levels tested, but we cannot attribute to the nitrate changes solely due to growing winter barley. Further testing of nitrate changes in winter barley plants, for example, in kernels, leaves, and roots/stem systems will be important to identify if the nitrate is taken up by the plants while comparing to a control treatment.
Understanding the weather conditions throughout the double cropping system will be crucial to not just the winter barley growing season from the fall to the summer, but for soybean production immediately after the harvest of the winter barley. More weather data synthesis, include air temperature, precipitations are collected, and we installed the soil moisture sensors in 2018 from May to October in all the treatments at all the locations to gain a more comprehensive understanding of soil temperature, moisture at two experimenting depths, 2.5 and 5 inches deep. The sensors were collecting data every two hours, and we will begin to analyze this data set very soon.
In 2018, the double cropping soybean yield was extremely low, ranged from no harvestable yield due to late maturity to only 5 BU/AC at the Alma, WI site. This is extremely low in contrast to the full season soybean treatment, where an average yield of 41 BU/AC was harvested, and it was only a 12% reduction compared to the Buffalo County yield average at 47 BU/AC. Winter wheat and soybean following winter wheat results were acquired at the other two locations due to poor winter barley survival results, but the maturity issue was even more serious for the winter wheat-soybean double cropping scenarios. In fact, both the winter barley and winter wheat began the growth and development in the spring much later than usual due to a very cold and delayed spring season. It was challenging to plant spring crops as much as for the winter crops to phase out of dormancy and enter the new growth and development phase in 2018. However, late maturity of winter cereals led to later planting of soybean across all the double cropping treatments. If earlier maturity of winter cereals could be established, then more positive maturity conditions that may lead to undamaged soybean grains from fall frosts, and increased yield may be observed in the next year of our experiment.
We delayed our experiment and extended the grant to 2020 due to a very challenging fall season in 2018 to continue our experiment. Excessive precipitations throughout late September through October and the extremely cold temperatures in October prevented us from establishing the study on-time. The extension was approved, and we are hopeful that the planning of the experiment, and the fall establishment and spring establishment will be conducted under better weather conditions in the fall of 2019.
Educational & Outreach Activities
Several outcomes and impacts have been accomplished through this grant. Becky Zhong, the lead investigator of the project was invited by our collaborator of the project, Mr. Carl Duley to present at a barley field-day workshop in Buffalo County, WI in July, 2018.
Becky shared the concept of double cropping winter barley and soybean, and brief results of this project, particularly the soil-nitrate assessment between different treatments to an audience of approximately 50 people in attendance. Growers from the regional area, as well as a few traveled from Iowa, along with other researchers, extension and county-level environmental agency staff and representatives joined for this field day.
Following the meeting, a farmer-advisory panel discussion took place. Carl Duley, Buffalo County Extension specialist and our farmer participant, Joe Bragger joined in and gave input during this discussion with Becky Zhong. A major discussion was about the soil structure at the Bragger farm, which is heavy-clay soil that have created issues for us to soil sample at 30-60 cm depth. Carl mentioned the challenge of planting soybean after winter barley harvest, due to slow growth of winter barley in the spring given the extremely cold weather conditions in mid-April. Becky talked about the soil moisture sensors that were installed at each of the three treatment plots, and she explained the purpose of having these sensors to Joe and Carl. The sensors were installed to monitor the soil temperature and soil moisture conditions in two depths (2.5 inches and 5 inches) at every two hours. Data acquired from these sensors can provide supplemental information to explain for the differential productivity (mainly yield that will be evaluated) for double cropping and monocropping treatment comparisons. These discussions clarified a lot of information between all the collaborators, and everyone agreed to organize a farmer-advisory panel discussion next summer.
In addition, Becky has spoken about the double cropping concept and information about the preliminary findings of this project at the 2017 and 2018 Prairie Grains Conference in December at Grand Forks, ND. The conference brought together approximately 100 barley growers in the Red River Valley region to engage in barley production-related discussions and talks. Becky also distributed handouts about the double cropping concept to growers at the meeting in 2018.
Becky also presented information about the importance of winter crops, particularly winter barley to improve the water quality conditions and possibly providing viable economic profit to about 100 attendees at the Social Science Night at the Minnesota Science Museum in the summer 2017.
During the “largest Minnesota Get together”, Minnesota State Fair each year, Becky conducted outreach at the Forever Green Initiative stand where she interacted with over 300 people in 2017 and 2018 about winter crops, and the research efforts and preliminary findings of this project about the nitrate retention and biomass that winter barley provided as a winter cash/cover crop.
Through our farmer-advisory panel discussions, we shared our common interests for winter barley and the winter barley-soybean double cropping systems, and we each discussed some issues that we believed were the most important to this project. These sharing and discussion meetings are very important for me and all the collaborators, especially our farmer collaborator, Mr. Joe Bragger. Participating in a research project, and finding out the results and discuss challenges and change-of-plans for our project are not just valuable for academic personnel involved in this project, but to the practitioner community as well. Many of our collective and individual comments and views about diversifying the current soybean production systems through planting winter barley are summarized, and I plan to share these at more growers-focused, and non-growers focused stakeholders meetings, possibly with end-users for the winter barley product, maltsters and brewers included. Because winter barley is a new crop to the Upper Midwest, the preliminary findings about the agroecosystems services and potential economic benefits of winter barley from this project will be introduced to growers, and a potential outcome will be farmer interviews and surveys that may take place for us to gain an exchange of information between us and the practitioners about growing winter barley.
We developed a lot of understandings from the first year of the project about growing winter barley, which is a relatively new crop in the Upper Midwest. I think our winter barley project team has become more adaptable and quicker to respond to changes for the research trial due to different weather conditions, soil conditions at the sites we chose for the study. These challenges actually made us more prepared and aware of how to sustainably view and carry our activities in our project. For example, we observed poor overwinter survival of winter barley at two sites, but these findings did not stop us from thinking that the winter barley did not scavenging the residual soil-nitrate, and instead, we pursued contingency plans and found similar results in winter wheat when it was planted and had higher survival ratings than the winter barley.
I think the challenges we faced and trial-and-errors lessons which all became very valuable for us provided a lot of experiences for us to continue to conduct research and understand that sustainable agriculture is not an easy topic of agriculture to attempt or pursue, but there are indeed environmental and economic benefits of sustainable agriculture practices. These sustainable agriculture changes may not at first appear as immediate economic and/or environmental benefits, but we did see the results of harvesting two crops, and found much lower soil-nitrate level for the winter barley-soybean double cropping system than the two soybean monocropping treatments. The positive awareness and impacts of sustainable agriculture I gained from this project are invaluable to us and will help us to continue to work on this trial and make a positive inspiration to me beyond this experiment to other research projects.