West-central Minnesota Research Articles

Food Security and Food Desertification: A West-Central Minnesota Case Study

Food Security and Food Desertification: A West-Central Minnesota Case Study

Flow Rate and Volume Estimates from Variable Frequency Drive Operated Drainage Sump Pumps

Highlights This article provides an overview of operations and benefits of using a variable frequency drive to operate agricultural subsurface drainage system sump pumps. A methodology is proposed to monitor flow rates leaving agricultural subsurface drainage pump stations via a MATLAB algorithm. The results of this research were mixed because the algorithm estimates did not always match with the corresponding flowmeter measurements. Abstract. Subsurface drainage plays a crucial role in excess water removal through perforated pipes buried in the soil. The Red River Valley of eastern North Dakota and west central Minnesota often requires pumped drainage outlets due to its flat topography, with many modern systems incorporating variable frequency drives (VFD) for improved efficiency. VFDs adjust pump speeds to match drainage needs, but this dynamic operation complicates accurate flow rate estimation for edge-of-field monitoring. This project aimed to devise an automated method for calculating flow rate estimates from VFD pumping systems involving tank geometry, operational water levels, and pump duty cycling. Linear regressions with calibration data from a transit-time ultrasonic flowmeter produced mixed outcomes. Some linear regressions revealed errors in calculated versus measured flow rate of =14%, while other regressions showed errors nearing 40%. To address this, future efforts should explore methods incorporating the pump’s electrical characteristics. This approach would provide a more accurate representation of the unstable and intricate pumping operations during transient conditions. Keywords: Edge-of-field monitoring, Flow rate, Pump, Red River Basin, Subsurface drainage, Variable frequency drive

Increased Light Exposure Decreases Lichen Abundance on Linden Trees in the Prairie Grassland Biome of West Central Minnesota

Increased Light Exposure Decreases Lichen Abundance on Linden Trees in the Prairie Grassland Biome of West Central Minnesota

Water-quality outcomes of wetland restoration depend on hydroperiod rather than restoration strategy

Land managers increasingly use wetland restoration to improve water quality, particularly in cultivated landscapes. In agricultural wetland restoration, managers regularly excavate accumulated sediments eroded from the surrounding landscape to increase water storage capacity, decrease invasive species cover, or improve water quality. However, it is unclear whether the effects of sediment excavation are influenced by wetland hydroperiod. Additionally, we lack data on how long excavation effects persist in restored wetlands. We examined dissolved nutrient concentrations (i.e., NH4+, NO3–, total dissolved N, soluble reactive P, total dissolved P, and dissolved organic C) as proxies for water quality in 54 restored agricultural wetlands ranging from 1 to 10 y post-restoration in the Prairie Pothole Region of west central Minnesota, USA. In 26 of these wetlands, restoration practitioners restored natural (i.e., either seasonal or semipermanent inundation) hydrological regimes by removing subsurface tile drainage and plugging surface drainage ditches (business-as-usual treatment). In 28 wetlands, practitioners removed accumulated sediment and redeposited it on the surrounding landscape (excavated treatment) prior to restoring hydrology. We found that wetlands in the excavated treatment group initially experienced reduced dissolved P concentrations, but over time P levels increased, particularly in wetlands with shorter hydroperiods. Excavated wetlands had lower NH4+ and dissolved organic C concentrations compared with business-as-usual wetlands, but the trend was driven by differences between restoration treatments in semipermanent wetlands. N and P dynamics were almost universally related to hydroperiod, both immediately following restoration and over the ensuing years. We postulate that the effects of hydroperiod are likely related to differences in redox conditions via direct mechanisms (water level fluctuations related to hydroperiod) and indirect mechanisms (development of dense emergent macrophyte communities in seasonal wetlands). In basins with seasonal hydroperiod, inorganic N concentrations decreased over time and inorganic P concentrations increased, suggesting net P mobilization concurrent with growing N limitation. Our results illustrate that hydroperiod regulates the expression of legacy P following wetland restoration, with little long-term effect of sediment removal on water quality outcomes.

Double-cropping oilseed sunflower after winter camelina

Double-cropping as a means of sustainably intensifying oilseed production could promote farmer adoption of new and alternative use oil crops like camelina [Camelina sativa (L.) Crantz]. Previous research indicated that double-cropping sunflower (Helianthus annuus L.) after winter camelina in the upper Midwest USA tended to reduce sunflower seed yield and oil content as compared with monocrop sunflower. However, new semidwarf hybrid sunflower genotypes with early maturity may be better suited for developing double-cropping systems for oil production in the upper Midwest and northern Great Plains. To evaluate seed and oil yields of winter camelina (cv. Joelle) and double-cropped sunflower compared with monocrop sunflower, a field study was conducted across two growing seasons (2017–2019) in west central Minnesota USA. One early maturing semidwarf oil sunflower hybrid, Honeycomb NS, and three common commercial full season oil hybrids were evaluated. Additionally, soil moisture to a 1-m depth was monitored during both growing seasons, which did not appear to limit production of the two crops in a single season at the study site. Although delayed sowing associated with double-cropping generally reduced sunflower seed yield, oil content, and the oleic/linoleic acid ratio compared with monocrop controls, these decreases were less for the early maturing hybrid Honeycomb NS. During one season of the study, total oil yield (winter camelina + sunflower) of double-cropped Honeycomb NS was 1.5 times greater than its monocrop counterpart. In addition to sustainably intensifying oil production, double-cropping sunflower with winter camelina might appeal to producers wanting to reduce the risk of one or the other crop failing in any given year. Nevertheless, double-cropping in the upper Midwest USA can be risky due to year-to-year variations in weather and length of growing season.

Assessment of organic substrates as sites for zebra mussel (Dreissena polymorpha) attachment in four West-Central Minnesota Lakes

Zebra mussels (Dreissena polymorpha) are an aquatic invasive species generalist with known ecological and economic impacts due to their settlement and attachment characteristics as well as their filtration abilities. Although zebra mussel attachment to abiotic substrates has been extensively studied, the importance of organic substrates for established zebra mussel populations in North American waters has not been evaluated. We assessed organic substrates in four west-central Minnesota lakes. Using qualitative analysis, we found most substrates were used proportionally to their availability. A quantitative assessment revealed significantly more zebra mussels attached to detritus than pondweeds (P < 0.05). Algae (filamentous and Chara spp.) were a significant suitable substrate for zebra mussel attachment (P < 0.05). Furthermore, more juvenile zebra mussels were found on organic substrates than were adults (P < 0.001). Although not always a consistent substrate, biological material as a vector for zebra mussel spread and settlement should be considered in further research to mitigate subsequent invasions and manage already naturalized populations.

Aquatic Vegetation and Invertebrate Communities of Big Stone National Wildlife Refuge

Abstract Observed degradation of aquatic systems at Big Stone National Wildlife Refuge, located in west-central Minnesota, have been associated with sediment-laden inflows from riverine systems. To support management, a study was conducted during 2013–2014 with overall goals of characterizing the aquatic invertebrate and vegetation communities of the Big Stone National Wildlife Refuge and exploring relations between these communities and various water-quality parameters. Sample sites were located along an observed vegetation gradient and assigned to three predetermined habitat zones for comparison purposes: upstream, transition, and downstream. Of the 12 species of aquatic vegetation that were identified, invasive narrowleaf cattail Typha angustifolia dominated the upstream zone (observed at &amp;gt;90% of sample locations), coontail Ceratophyllum demersum and narrowleaf cattail were most common in the transition zone (collected or observed at 100 and 83% of sample locations, respectively), and coontail and narrowleaf pondweed Potamogeton strictifolius were most common in the downstream zone (collected at 100 and 64% of sample locations, respectively). Measured values for the water-quality parameters varied among dates, reflecting the continually fluctuating nature of riverine systems. Based on general observations across sample dates, turbidity and dissolved oxygen concentrations were greatest in the upstream zone sample sites, while oxidation-reduction potential was greatest in the downstream zone sites. There were 115 unique aquatic invertebrate taxa identified to varying levels of taxonomic resolution. Results suggested that there were overall differences in invertebrate biomass among the sample dates, but that there were no strong trends among the sample zones. Aquatic invertebrates and vegetation communities, along with the water-quality parameters, varied temporally and showed irregular relations among the sample zones. These general observations emphasize the importance of temporally and spatially intensive sampling to account for natural variation. Moreover, short- and long-term streamflow and water-level information obtained for this study demonstrated substantial variability that must be considered when conducting biotic inventories and monitoring water quality, as well as when using such data to assess management options. Periodic monitoring of wetlands and associated streamflows, along with sediment loads and water quality of inflows, should allow Big Stone National Wildlife Refuge staff to identify habitat degradation and potential contributing factors, and to develop strategies to achieve specific management objectives and goals.

Distribution and Concentration of Neonicotinoid Insecticides on Waterfowl Production Areas in West Central Minnesota

Neonicotinoid insecticides have been reported to occur widely in surface waters, including those of wetlands within the Prairie Pothole Region (PPR). In the US portion of the PPR, the US Fish and Wildlife Service has established Waterfowl Production Areas (WPAs) in an effort to enhance waterfowl production. Most WPAs have an area of protected upland surrounding wetlands that can act as a buffer to reduce the transport of contaminants, including pesticides. We assessed the extent that neonicotinoid insecticides occurred in the ponded water of wetlands within WPAs located along a gradient of agricultural influence throughout west-central Minnesota. Of the five neonicotinoids we tested for, two were not detected. However, at least one of the other three, imidacloprid, clothianidin and thiamethoxam, were detected in 29% of our wetland water samples. Additionally, both the occurrence and total concentrations of neonicotinoids were higher in sites with higher surrounding crop use. Neonicotinoid insecticides, if persistent for long periods of time, have the potential to affect aquatic-invertebrate communities within PPR wetlands. Our research indicates that areas often perceived as protected may still be at risk to neonicotinoid contamination, emphasizing the importance of maintaining effective grassland buffers around wetlands.

Electrical and Thermal Energy Consumption in Midwest Commercial Swine Facilities

Abstract. Interest and concern is growing regarding sustainability of agricultural production systems including pork production. Information on the electrical and thermal energy consumption of pork production systems in the Midwestern United States is scarce. Understanding how swine production systems utilize electrical and thermal energy will help determine how this consumption can be reduced. This study evaluated the electrical and thermal energy (heating fuel) use of six commercial swine barns located in west central Minnesota. All barns were representative of typical Midwestern pork production systems. Energy monitoring was done on two barns from each stage of production: two breed-to-wean barns, two nursery barns, and two finishing barns. Breed-to-Wean Barn A used an average of 11.36 kWh and 1.29 L of propane per weaned pig produced. Breed-to-Wean Barn B used an average of 11.9 kWh and 1.17 L of propane per weaned pig produced. Heat lamps used at least 58% of the total electrical energy in both barns. Nursery Barn A and B used an average of 2.4 and 2.1 kWh and 1.63 and 1.55 L of propane per feeder pig produced, respectively. Ventilation fans used at least 50% of the total electricity in both barns. The tunnel-ventilated finishing barn used an average of 14.4 kWh and 1.29 L of propane per finished pig produced, and the curtain-sided finishing barn used an average of 4.1 kWh and 1.85 L of propane per finished pig produced. Ventilation accounted for 72% and 81% of the total electrical energy in the tunnel-ventilated and curtain-sided finishing barns, respectively. These data will be useful in targeting specific areas of pork production that have potential for improved energy efficiency. Keywords: Commercial pork production, Consumption, Electricity, Energy, Heat lamps, Propane, Swine, Ventilation.

Regression‐Kriged Soil Organic Carbon Stock Changes in Manured Corn Silage–Alfalfa Production Systems

Core IdeasRegression kriging with elevation, topographic wetness index, field (west vs. east), and irrigation (yes vs. no) accurately predicted soil organic C (SOC) in the 0 to 15‐ and 15 to 30‐cm layers.Lack of spatial structure and a lack of relationships between SOC and auxiliary variables precluded the use of regression kriging for the 30 to 60‐ and 60 to 90‐cm layers.From 0 to 15 cm, SOC in the west field increased by 7% because of gains in irrigated portions of the field, but no changes were found in the east field or from 15 to 30 cm in either field.Simple means indicated SOC gains of 13% in the 30 to 60‐cm layer and 24% in the 60 to 90‐cm layer across both fields.Typical field management practices associated with large, modern dairies can sequester SOC.Accurate measurement of soil organic C (SOC) stock changes over time is essential to verify management effects on C sequestration. This study quantified spatial and temporal changes in SOC stocks on adjacent 65‐ha corn (Zea maysL.) silage–alfalfa (Medicago sativaL.) fields receiving liquid dairy manure in west central Minnesota. We used regression kriging to interpolate SOC in four soil layers in 2006 and 2015, and calculated stock changes over time. Regression kriging with elevation, topographic wetness index, field (west vs. east), and irrigation (yes vs. no) accurately predicted SOC in the 0 to 15‐cm (R2= 0.89) and 15 to 30‐cm layers (R2= 0.51–0.95), where variogram analysis indicated moderate to strong spatial correlation. From 0 to 15 cm, SOC in the west field increased by 7% (+4.5 Mg C ha–1) over the study period caused by gains in irrigated portions of the field. No changes were found in the east field or from 15 to 30 cm in either field. Below 30 cm, a lack of spatial structure and a lack of relationships between SOC and auxiliary variables was found, but simple means indicated SOC gains of 13% (+4.7 Mg C ha–1) in the 30 to 60‐cm layer and 24% (+3.9 Mg C ha–1) in the 60 to 90‐cm layer across both fields. Regression kriging with easily acquired auxiliary variables offers a highly accurate method of monitoring SOC stock changes over time to 30 cm depth. Current management practices maintain or increase SOC in these fields.

Subirrigation System Performance and Evaluation in the Red River Valley of the North

Abstract. Using a subsurface drainage system, subirrigation (SI) applies water below the ground surface and raises the phreatic water to within or near the root zone. SI is relatively new to the Red River Valley (RRV) of the North in eastern North Dakota (ND) and west central Minnesota (MN). In 2011, two SI field sites in the RRV were installed and have shown promising results in optimal water management and increasing agricultural production. Unlike a surface irrigation system, SI supplies water below the ground surface over a long duration; water loss is generally through crop transpiration; and SI leads to negligible water loss via wind, surface runoff and evaporation. Therefore, a new method was developed to evaluate the SI system performance. Water application efficiency (Ea) was calculated through the soil moisture changes in the root zone before and after the SI application with known amounts of SI, precipitation, and evapotranspiration (ET). Uniformity coefficient (UC) and distribution efficiency of low quarter (DULQ) were estimated from the total depth of water stored in the root zone. The SI system performance in 2014 and 2015 showed that the Ea was over 100% in 2014 and 78% for the ND 2015 site-year. The Ea values were high, indicating that the SI system either performed better than typical surface irrigation systems with minimal water loss, or the SI system and/or the methods need improvement in accurate ET estimation to help close the water budget. The UCs were 67% to 86%, and the DULQs were 48% to 78%, much lower than typical sprinkler and surface irrigation systems, possibly due to the unique SI flow path. Overall, the evaluation indicated that a SI system is effective as a water supply, but the uniformity needs to be improved with a longer SI duration or smaller flow rate or an alternative SI system design. Keywords: Red River Valley of the North, Subirrigation, Uniformity, Water use efficiency.

Using the TRANSLATE Framework to Support Practice Transformation: Perspectives of a Practice Facilitator.

In 2008, the Minnesota Department of Health (MDH) awarded Statewide Health Improvement Partnership (SHIP) funding to community health boards (CHBs), directing them to partner with schools, worksites, communities, and health care to address obesity and tobacco use/exposure. Each CHB selected one of two health care strategies: implement obesity and healthy lifestyle guidelines or connect clinics to community resources. The CHB in rural west-central Minnesota chose to champion clinical guideline implementation, assigning one of its own county-level public health nurses the role of practice facilitator (PF). This decision set the stage for a novel community partnership between public health, clinical guideline developers, and local providers of relevant clinical services. This community perspective describes how the PF organized support for clinical guideline implementation using the TRANSLATE framework, and explores the capacity of the TRANSLATE framework to accommodate particularities of clinical partners that is necessary in working to transform evidence-based knowledge into real-world practice.

LiDAR-based volume assessment of the origin of the Wadena drumlin field, Minnesota, USA

The Wadena drumlin field (WDF; ~7500km2) in west-central Minnesota, USA, is bordered along its outer extremity by the till-cored Alexandria moraine marking the furthest extent of the southwesterly-flowing Wadena ice lobe at c. 15,000kyr BP. Newly available high-resolution Light Detection and Ranging (LiDAR) data reveal new information regarding the number, morphology and extent of streamlined bedforms in the WDF. In addition, a newly-developed quantitative methodology based on relief curvature analysis of LiDAR elevation-based raster data is used to evaluate sediment volumes represented by the WDF and its bounding end moraine. These data are used to evaluate models for the origin of drumlins. High-resolution LiDAR-based mapping doubles the streamlined footprint of the Wadena Lobe to ~16,500km2 increases the number of bedforms from ~2000 to ~6000, and most significantly, reclassifies large numbers of bedforms mapped previously as ‘drumlins’ as ‘mega-scale glacial lineations’ (MSGLs), indicating that the Wadena ice lobe experienced fast ice flow. The total volume of sediment in the Alexandria moraine is ~71–110km3, that in the drumlins and MSGLs is ~2.83km3, and the volume of swales between these bedforms is ~74.51km3. The moraine volume is equivalent to a till layer 6.8m thick across the entire bed of the Wadena lobe, suggesting drumlinization and moraine formation were accompanied by widespread lowering of the bed. This supports the hypothesis that drumlins and MSGLs are residual erosional features carved from a pre-existing till; swales represent ‘missing sediment’ that was eroded subglacially and advected downglacier to build the Alexandria Moraine during fast ice flow. Alternatively, the relatively small volume of sediment represented by subglacial bedforms indicates they could have formed rapidly by depositional processes.

Comparison of several Brassica species in the north central U.S. for potential jet fuel feedstock

Hydrotreated renewable jet fuel (HRJ) derived from crop oils has been commercially demonstrated, but full-scale production has been hindered by feedstock costs that make it more costly than petroleum-based fuels. Maintaining low feedstock costs while developing crops attractive to growers will be key to producing affordable HRJ and creating a dependable supply. Several Brassica oilseed species could potentially serve as feedstock, but genotypes agronomically and economically well suited for a given region will likely vary with environment and current cropping systems. The objectives of this study were to evaluate seed and seed oil yields of 12 summer annual Brassica genotypes representing six different species [Brassica napus L., Brassica rapa L., Brassica juncea L., Brassica carinata L., Sinapis alba L., and Camelina sativa (L.) Crantz.] and identify environmental factors that might limit their growth and oil production. The study was conducted during 2013 and 2014 in west central Minnesota, U.S. on a Barnes loam soil. This study is part of a larger project focused on evaluating the same set of oilseeds across the major wheat (Triticum aestivum L.) growing areas of the U.S. Seed yields for the 12 spring-sown crops in Minnesota ranged from 1058 to 3718kgha−1 in 2013 and 515 to 2020kgha−1 in 2014. The range in seed oil yield was 287–1588kgha−1 in 2013 and 210–885kgha−1 in 2014. Plant lodging was a serious issue in 2013, but it varied widely among genotypes. In 2014, which was characterized by an abnormally wet spring, disease infection {most likely white leaf spot [Pseudocercosporella capsellae (Ellis & Everh.) Deighton 1973]} and flea beetle [Phyllotreta cruciferae (Goeze)] feeding led to plant damage, but these were primarily confined to certain Brassica napus cultivars. In west central Minnesota, certain B. napus canola lines and B. carinata produced the greatest seed and oil yields. B. carinata was the latest maturing species in the study, produced the highest biomass, and tended to have low harvest indices, indicating ample room for yield improvement. For any given ecoregion, striking a balance among crop yield, agricultural input costs, and optimum species/cultivar choice for a particular cropping system will be important for providing a reliable and affordable feedstock for HRJ.

Water Use in Camelina–Soybean Dual Cropping Systems

Global population growth is increasing the demand for food, feed, fiber, and fuel. Recently, we reported that winter camelina (Camelina sativa L.) can be feasibly double‐ (DC) and relay‐cropped with soybean [Glycine max (L.) Merr.] in the northern Corn Belt region as an option for sustainably intensified crop production. However, water availability can be a limiting factor for dual crop systems. Therefore, the present study determined seasonal water use in various winter camelina–soybean dual crop systems that included two sequential DC and two relay‐crop treatments compared with a full‐season monocropped soybean (Mono‐Soy). The rooting characteristics of camelina were also evaluated. The study was conducted on a Barnes loam soil (fine‐loamy, mixed, superactive, frigid Calcic Hapludoll) in west central Minnesota over two growing seasons in 2010 and 2011. Camelina had a meager root system with 82% of its root density found in the top 0.3 m of soil. Although both DC and relay‐crop treatments used more seasonal water than a sole soybean crop, on average it was only 26 and 50 mm greater in 2010 and 2011, respectively. Camelina is a low water user compared with soybean. Total cropping system water use efficiency for relay‐cropping was comparable to the sole soybean crop, but for the DC treatments was less. This cropping strategy is a way to sustainably integrate food and fuel production to meet societal needs of a growing population. Moreover, our results indicate that it may be amenable to most rainfed‐farming areas in the upper Midwest where soybean is grown.

Application of single-grain OSL dating to ice-proximal deposits, glacial Lake Benson, west-central Minnesota, USA

Glacial Lake Benson formed in west-central Minnesota as the Des Moines lobe of the Laurentide ice sheet retreated north of a small moraine in the Minnesota River lowland. Although previous research has constrained the timing of glacial Lake Agassiz immediately to the north, little age control is available for the formation of glacial Lake Benson and ice-marginal positions to the south. In order to constrain the age of glacial Lake Benson and test the application of single-grain optically stimulated luminescence (OSL) dating to ice-marginal deposits, seven OSL samples were collected from a variety of depositional settings. These included deltaic deposits linked to specific lake levels, pro-glacial fluvial, ice-contact and supra-glacial deposits. Single-grain OSL results indicate evidence for incomplete resetting (partial bleaching) of the luminescence signal, as expected for glacial environments, and therefore ages were calculated using a minimum age model. OSL results constrain the timing of ice-margin retreat and lake formation to 14.4–14.8 ka. Analysis of single-grain equivalent dose distributions indicates that deposits created by glacial-dominated processes typically had higher over-dispersion (>50%) and greater positive skew (>0.9) than deposits originating from fluvial processes. These results suggest that water-lain deposits should be targeted for OSL sampling over those created by glacial processes when dating ice-proximal settings.

Potential for behavioral reproductive isolation between greater prairie-chickens and sharp-tailed grouse in west-central Minnesota

When ecological or behavioral species-isolating mechanisms are relaxed or incomplete, hybrid zones form. Greater prairie-chickens (Tympanuchus cupido) hybridize with sharp-tailed grouse (T. phasianellus) wherever their ranges overlap. The objective of this study was to document the potential for reproductive isolation between greater prairie-chickens and sharp-tailed grouse in west-central Minnesota, a newly established sympatric and hybridizing population which developed following the translocation of greater prairie-chickens to the area. We describe and evaluate several potential mechanisms of behavioral isolation (intensity of display and aggressive behaviors, and vocal and non-vocal sounds). In addition, we monitored copulation success to determine the patterns of interspecific mating. Individuals of putative mixed genetic makeup (based on morphology) comprised 8 % of the population, a rate higher than previously reported for most areas of the hybrid zone between these two species. Apparent hybrid individuals stomped their feet faster than parental species during courtship displays, and their vocalizations were intermediate between the parental species. Intensity of display and aggressive behaviors were similar for parental species and hybrids. All copulations observed involved conspecific pairs; hybrid males were not observed to mate. Taken together, this study documents behaviors that might reinforce reproductive isolation (foot stomping and vocalization) and other behaviors that are similar among the parental species and hybrids that would hinder reproductive isolation (display and aggressive behaviors). We suggest that the small population sizes of both greater prairie-chickens and sharp-tailed grouse in this newly established population contribute to the higher rate of hybridization than is observed elsewhere in this hybrid zone.

Dual Cropping Winter Camelina with Soybean in the Northern Corn Belt

Sustainably balancing biofuel crop production with food, feed, and fiber on agricultural lands will require developing new cropping strategies. Double‐ and/or relay‐cropping winter camelina (Camelina sativaL.) with soybean [Glycine max(L.) Merr.] may be a means to produce an energy and food crop on the same land in a single year. A study was conducted between 2009 and 2011 in west central Minnesota to evaluate yields, seed quality, economics, and within‐field energy balance of winter camelina–soybean double‐ and relay‐cropping systems compared with a conventional monocropped full‐season soybean. Systems included methods to hasten camelina harvest (e.g., swathing and desiccating) to promote early soybean growth. Camelina seed yields were unaffected by cropping system and ranged from 1.1 to 1.3 Mg ha−1. Relay‐cropped soybean yields were greater than double‐cropped soybean and were 58 to 83% of that for the monocropped control. Seed oil and protein content of double‐ and relay‐cropped soybean were comparable to their monocropped counterpart and combined seed oil yield for the dual crop systems was as much as 50% greater. Net economic returns for the relay‐crop treatments were competitive with that of the full‐season soybean. Moreover, net energy of the relay‐crop treatments was generally as high as the sole soybean crop, but energy efficiency (outputs/inputs) was less due to greater inputs. Results indicate that dual cropping of winter camelina with soybean is agronomically viable for the upper Midwest and might be an attractive system to growers seeking a “cash” cover crop.

Rolled–Crimped Winter Rye Cover Effects on Hand-Weeding Times and Fruit Yield and Quality of Cucurbits

Pesticide-free vegetables are in demand at farmers’ markets featuring locally grown products. Weeds often are deleterious in such crops, and managing them without herbicides is difficult. Stale seedbeds and rolled–crimped winter rye (Secale cereale L.) cover crops are nonchemical methods that may help manage weeds effectively. These methods were compared over two growing seasons as they affected fruit yield, fruit quality, and hand-weeding times in west-central Minnesota for transplanted cucumber (Cucumis sativus L.), pumpkin (Cucurbita pepo L.), and watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai). Cumulative hand-weeding times were 82–85 h·ha−1 in stale seedbed systems but 5–18 h·ha−1 in rolled–crimped rye mulch systems. Even without hand-weeding, cucumber yields and quality scores in rye mulch were similar to those in stale seedbeds augmented with preemergence herbicide and hand-weeded. Pumpkin yields were reduced by 25% in rye mulch systems, but quality was not affected. Watermelon had yield reductions up to 75% in rye mulch compared to stale seedbeds with weed control. Cucumber, pumpkin, and watermelon have high, moderate, and low potential, respectively, for herbicide-free production in rolled–crimped winter rye mulch in cold–temperate growing regions.

A multiscale assessment of tree avoidance by prairie birds

In North America, grassland bird abundances have declined, likely as a result of loss and degradation of prairie habitat. Given the expense and limited opportunity to procure new grasslands, managers are increasingly focusing on ways to improve existing habitat for grassland birds, using techniques such as tree removal. To examine the potential for tree removal to benefit grassland birds, we conducted 446 point counts on 35 grassland habitat patches in the highly fragmented landscape of west-central Minnesota during 2009–2011. We modeled density of four grassland bird species in relation to habitat composition at multiple scales, focusing on covariates that described grass, woody vegetation (trees and large shrubs), or combinations of grass and woody vegetation. The best-supported models for all four grassland bird species incorporated variables measured at multiple scales, including local features such as grass height, litter depth, and local tree abundance, as well as landscape-level measures of grass and tree cover. Savannah Sparrows (Passerculus sandwichensis), Sedge Wrens (Cistothorus platensis), and Bobolinks (Dolichonyx oryzivorus) responded consistently and negatively to woody vegetation, but response to litter depth, grass height, and grassland extent were mixed among species. Our results suggest that reducing shrub and tree cover is more likely to increase the density of grassland birds than are attempts to improve grass quality or quantity. In particular, tree removal is more likely to increase density of Savannah Sparrows and Sedge Wrens than any reasonable changes in grass quality or quantity. Yet tree removal may not result in increased abundance of grassland birds if habitat composition is not considered at multiple scales. Managers will need to either manage at large scales (80–300 ha) or focus their efforts on removing trees in landscapes that contain some grasslands but few nearby wooded areas.