Field and greenhouse experiments were conducted from 2013 to 2015 at the University of Wyoming to evaluate the response of Beta vulgaris (L.) to reflected-light quality. Large-pail field studies included a factorial arrangement of three varieties of B. vulgaris (sugar beet, table beet, and Swiss chard) and reflected-light treatments (using either colored plastic mulch, grass, or bare-soil controls). Greenhouse studies included sugar beet as influenced by either grass or soil surroundings. In all studies, grass was grown in separate containers from B. vulgaris, so there was no root interaction. Grass was clipped regularly to prevent shading and competition for sunlight. Reflected light from different-colored plastic mulches (red, blue, green, black, clear) did not affect B. vulgaris growth. However, reflected light from the grass reduced the number of leaves in all B. vulgaris varieties such that there were 10 to 14 fewer leaves in B. vulgaris surrounded by grass compared with the soil treatment at 90 d after planting in the field study. Shade avoidance cues from surrounding grass reduced B. vulgaris total leaf area by 49% to 66%, leaf biomass by 21% to 30%, and root biomass by 70% to 72%. Similar results were observed in greenhouse experiments, where the grass treatment reduced sugar beet leaf biomass by 48% to 57% and root biomass by 35% to 64%. Shade avoidance cues have the potential to significantly reduce B. vulgaris yield, even in the absence of direct resource competition from weeds.

Grass‐legume mixtures are considered viable alternatives to nitrogen (N)‐fertilized grass pastures, but there is a dearth of information on effects of seed mass ratios on productivity and economic returns. We evaluated the effects of grass‐legume seed mass ratios and N fertilizer rates on forage accumulation, nutritive value, and profitability. There were 15 treatments arranged in randomized complete blocks with four replicates. The treatments included four species (meadow bromegrass [Bromus biebersteinii Roem. & Schult] and three legumes—alfalfa [Medicago sativa L.], sainfoin [Onobrychis viciifolia Scop.], and birdsfoot trefoil [Lotus corniculatus L.]), various seed mass ratios (100:0, 50:50, 70:30, 50:25:25, and 50:16.7:16.7:16.7), and three rates of N (0, 56, and 112 kg N ha−1) applied only to meadow bromegrass monocultures. The 2‐yr average annual forage accumulation of meadow bromegrass receiving 112 kg N ha−1 was 6.89 Mg ha−1 yr−1, which was similar to the 30% alfalfa + 70% meadow bromegrass, 30% birdsfoot trefoil + 70% meadow bromegrass, 25% alfalfa + 25% birdsfoot trefoil + 50% meadow bromegrass, and 50:16.7:16.7:16.7 mixture treatments. Mixtures had greater nutritive value than N‐fertilized meadow bromegrass. All treatments except 100% sainfoin and 50% sainfoin + 50% meadow bromegrass treatments were profitable. On the basis of forage accumulation, nutritive value, and profitability, the 30% alfalfa + 70% meadow bromegrass and 30% birdsfoot trefoil + 70% meadow bromegrass seed mass ratios are simple mixtures that may be viable alternatives to 100% alfalfa and N‐fertilized meadow bromegrass monocultures.

Nitrogen (N) fertilizers are critical in today's agriculture especially in the United States. Leaching, methane and nitrous oxide emissions from N fertilizer use and the implications for global climate and water pollution raised serious concerns among environmentalists and agronomists. Prices of N fertilizers increased geometrically over the past few years. The projected increase in maize (Zea mays L.) ethanol production is expected to increase N fertilizer demand and prices. Hay prices are, however, staggering and producers are looking for alternatives to N fertilizers. This review paper assessed trends in fertilizer use and prices as well as factors affecting fixation and transfer of dinitrogen (N2) in forage production systems. Additionally, economic implications of using N fertilizers and grass‐legume mixtures are discussed. From the review, it was apparent that legumes have the potential to replace N fertilizers or at least complement the use of N fertilizers in forage production systems. However, N transfer in forage production systems is low. A lot more research is needed to answer the question “Why legumes fix so much N2 and transfer just a small proportion to other crops.” Similarly, identifying compatible grass‐legume species that enhance N2 fixation will be a giant step towards reduced N fertilizer use and ensuring environmental sustainability. With the sharp increase in N fertilizer prices, the use of legumes in forage production systems seems promising.

Field studies were conducted from 2009 through 2011 at the Sustainable Agriculture Research and Extension Center near Lingle, Wyoming, to evaluate great northern bean response to PRE flumioxazin mixed with either trifluralin, pendimethalin, or ethalfluralin. Seven treatments were arranged in a randomized complete block with three or four replicates y−1. The soil texture of the study site was loam in 2009 and 2011, and sandy loam in 2010. Soil organic matter ranged from 1.4% to 1.8%. Treatments included flumioxazin plus trifluralin, flumioxazin plus pendimethalin, flumioxazin plus ethalfluralin, ethalfluralin plus EPTC, imazamox plus bentazon (POST), hand-weeded control, and nontreated control. Dry bean density 4 wk after planting differed among herbicide treatments (P < 0.001). Treatments that included flumioxazin reduced dry bean density 54% compared with treatments without flumioxazin. Dry bean yield was influenced by dry bean density; on average, yield in flumioxazin-containing herbicide treatments was 30% less than treatments not containing flumioxazin, even though weed control was generally greater in flumioxazin treatments.

Leguminous crops such as sainfoin (Onobrychis viciifolia Scop.) have low N 2 fi xation; hence, supplementary N is usually provided to realize maximum yield. Nonetheless, N application should be justifi ed by economic benefi t to the cropping system. Th is study evaluated the productivity, nutritive value, and cost implications of N application in sainfoin under rainfed conditions at high elevations in Wyoming. Th e study was a 2-factorial experiment set in a randomized complete block design with four replications, where four cultivars (Delaney, Remont, Rocky Mountain, and Shoshone) and four N rates (0, 40, 80, and 120 kg ha -1 ) were the treatments. Sainfoin was established in 2012, and N was broadcast-applied in May 2013 and 2014 using urea as the N source. Th e profi tability of the N application was assessed using a benefi t-cost ratio analysis. Sainfoin yield and nutritive value was aff ected by cultivar and N application. Remont (1.08 Mg ha -1 ), Rocky Mountain (1.17 Mg ha -1 ), and Shoshone (1.16 Mg ha -1 ) produced higher forage dry matter (DM) than Delaney (0.84 Mg ha -1 ). Th e eff ect of N application on the forage DM was linear, but applying >80 kg N ha -1 did not result in signifi cant increase in the forage DM. Th e benefi tcost ratios for the three N rates were less than one in both years, which indicated a net loss in revenue. In general, sainfoin DM and crude protein (CP) increased with N; however, the increase in forage DM with N application was not economical due to higher production costs.

Kochia is one of the most problematic weeds in the United States. Field studies were conducted in five states (Wyoming, Colorado, Kansas, Nebraska, and South Dakota) over 2 yr (2010 and 2011) to evaluate kochia control with selected herbicides registered in five common crop scenarios: winter wheat, fallow, corn, soybean, and sugar beet to provide insight for diversifying kochia management in crop rotations. Kochia control varied by experimental site such that more variation in kochia control and biomass production was explained by experimental site than herbicide choice within a crop. Kochia control with herbicides currently labeled for use in sugar beet averaged 32% across locations. Kochia control was greatest and most consistent from corn herbicide programs (99%), followed by soybean (96%) and fallow (97%) herbicide programs. Kochia control from wheat herbicide programs was 93%. With respect to the availability of effective herbicide options, glyphosate-resistant kochia control was easiest in corn, soybean, and fallow, followed by wheat; and difficult to manage with herbicides in sugar beet.

There is a consensus within the scientific community that nitrogenous fertilizers are almost indispensable in today's agriculture. However, the geometric increase in nitrogenous fertilizer applications and the associated environmental concerns call for focus on more sustainable alternatives. Biological dinitrogen (N 2 ) fixation (BNF) is one of the most sustainable approaches to meeting crop nitrogen (N) demands. The BNF is, especially, important in low value crops (e.g., forages) and in developing economies. However, just like synthetic N fertilizers, BNF has issues of its own. Among the issues of great importance is the low and highly variable proportion of fixed N 2 transferred to non-N 2 -fixing plants. The proportion of transfer ranges from as low as 0% to as high as 70%, depending on a myriad of factors. Most of the factors (e.g., N fertilizer application, species, and cultivar selection) are management related and can, therefore, be controlled for improved N 2 fixation and transfer. In this chapter, we discuss current trends in BNF in selected legume crops, the global economics of BNF, and recent reports on N 2 transfer in agricultural production systems. Additionally, factors affecting N 2 transfer and management considerations for improving N 2 fixation and transfer are discussed.

Early-emerging weeds are known to negatively affect crop growth but the mechanisms by which weeds reduce crop yield are not fully understood. In a 4-year study, we evaluated the effect of duration of weed-reflected light on sugar beet (Beta vulgaris L.) growth and development. The study included an early-season weed removal series and a late-season weed addition series of treatments arranged in a randomized complete block, and the study design minimized direct resource competition. If weeds were present from emergence until the two true-leaf sugar beet stage, sugar beet leaf area was reduced 22%, leaf biomass reduced 25%, and root biomass reduced 32% compared to sugar beet grown season-long without surrounding weeds. Leaf area, leaf biomass, and root biomass was similar whether weeds were removed at the two true-leaf stage (approximately 330 GDD after planting) or allowed to remain until sugar beet harvest (approximately 1,240 GDD after planting).Adding weeds at the two true-leaf stage and leaving them until harvest (~1,240 GDD) reduced sugar beet leaf and root biomass by 18% and 23%, respectively. This work suggests sugar beet responds early and near-irreversibly to weed presence and has implications for crop management genetic improvement.