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Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks into marginally productive cropland can engender ecosystem services and enhance climate resiliency while also diversifying farm incomes. We use one of the oldest bioenergy-specific field experiments in North America to evaluate economically and environmentally sustainable management practices for growing perennial grasses on marginal cropland. This long-term field trial called 9804 was established in 1998 in eastern Nebraska and compared the productivity and sustainability of corn (Zea mays L.) --both corn grain and corn stover--and switchgrass (Panicum virgatum L.) bioenergy systems under different harvest strategies and nitrogen (N) fertilizer rates. This experiment demonstrated that switchgrass, compared to corn, is a reliable and sustainable bioenergy feedstock. This experiment has been a catalyst for other bioenergy projects which have also expanded our understanding of growing and managing bioenergy feedstocks on marginal cropland. We (1) synthesize research from this long-term experiment and (2) provide perspective concerning both the knowledge gained from this experiment and knowledge gaps and how to fill them as well as the role switchgrass will play in the future of bioenergy. [ABSTRACT FROM AUTHOR]

Energy availability from forages is limited by fiber concentration because fiber is slowly and incompletely digested, whereas cell solubles are almost completely digested. Thus, the proportion of fiber to cell solubles is a major determinant of energy availability in forages. Grasses normally have more fiber than legumes, especially in leaves. Grass fiber is more digestible than that of legumes, but that of legumes digests at a faster rate. Ruminants digest 40-50% of legume fiber and 60-70% of grass fiber. Some fiber cannot be digested no matter how long it remains in the rumen. Lignin is thought to interfere with microbial degradation of fiber polysaccharides by acting as a physical barrier and by being cross-linked to polysaccharides by ferulate bridges. In addition to the effects of lignin, physical and structural barriers may limit fiber digestibility. Because the middle lamella and primary wall of thick-walled cells are so highly lignified, many cells can be digested only from the interior of the cell. For many cells, access to cell interiors is limited because of large particle sizes. Forage digestibility could be improved by reducing the amount of lignified cells or by developing improved cultivars so that lignified cells are more digestible. KEY WORDS: energy availability digestible fiber lignin cell wall structural barriers

Soybean harvest leaves little residue, potentially subjecting the soil to negative environmental impacts. Additionally, integrated livestock producers with crops and cattle identified a need to fill early spring forage deficiencies. Planting winter-hardy cereal cover crops after soybean harvest provides ground cover until the next cash crop is planted and has potential for early spring grazing before perennial pastures are ready. A 3-year study was conducted near Mead, Nebraska to evaluate the grazing potential of winter wheat, winter triticale, and cereal rye when planted after soybean harvest. A 7.3-ha field was split into nine 0.81-h paddocks and paddocks were then randomly assigned to a small cereal species (n = 3 paddocks per treatment), then divided further into 2, 0.4 ha paddocks to allow for rotational grazing within the assigned paddock. Growing steers were stratified by body weight (BW) and randomly assigned to paddock with 6 steers per paddock in years 1 and 2, and 5 steers per paddock in year 3. Steers were limit-fed at 2% of BW to equalize gut fill and weighed before and at the conclusion of grazing. Grazing was initiated when a paddock reached 13 cm. The initial BW did not differ among treatments (P > 0.05) with steers weighing 303, 335, and 372 kg in years 1 through 3, respectively. The final BW did not differ among treatments (P > 0.05). There was a treatment by year interaction (P = 0.01) for average daily gain (ADG). There were no differences (P > 0.05) in ADG among treatments in year 1 (1.9 kg/d) or year 3 (1.3 kg/d). However, in year 2, steers grazing rye gained more (P < 0.01) at 1.4 kg than wheat (0.83 kg) and triticale (0.67 kg), which did not differ (P > 0.05). There were no differences (P > 0.05) among treatments for animal unit months (AUM) per hectare. Year 1 provided the most (P < 0.01) grazing at 5.1 AUM/ha, year 2 provided the least (P < 0.01) at 2.4 AUM/ha, and year 3 was intermediate at 3.1 AUM/ha. For gain per hectare (GPH), there were no differences (P > 0.05) among treatments. Steers in year 1 had greater (P < 0.01) GPH (390 kg/ha) than subsequent years, with year 2 (93 kg/ha) being less (P < 0.01) than year 3 (151 kg/ha). For all 3 years, there were no differences among treatments in pre-graze (P > 0.05) or postgraze biomass (P > 0.05). These data suggest that during early spring there are no major differences in the grazing potential and growing cattle performance for wheat, rye, or triticale in eastern Nebraska. [ABSTRACT FROM AUTHOR]

Winter-hardy small grains offer an opportunity to improve soil health as a cover crop, and they can also be used as a forage source for cattle. Winterhardy small grains differ in the time needed to reach various maturity stages. Species selection may also impact yield and nutritive value. A two-year study was conducted in eastern Nebraska to determine the effect of species and maturity on yield and nutritive value of winter-hardy small grains used for silage. Three species were evaluated; cereal rye, winter wheat, and winter triticale at four stages of maturity: boot, anthesis, milk, and soft dough. The experimental design was a randomized complete block design with four blocks per year. Small grain species were considered whole plots with maturity at harvest considered sub-plot. Each year, the small grain species were randomly assigned within each block. Within each plot, maturity was randomly assigned to one quarter of each plot. Dry matter (DM) forage yield, crude protein (CP), digestible organic matter (DOM), and nutrient yield per hectare were measured and analyzed using the mixed procedure of SAS. Forage yield increased for all species (P < 0.01) with maturity, except for wheat, where there was a decrease at soft dough. Forage yield of cereal rye and triticale did not differ (P>0.05), except at soft dough where triticale was greater (P < 0.01) than cereal rye. Forage yield of triticale and cereal rye yield was greater (P£0.05) than wheat at anthesis and soft dough. Crude protein (% DM) decreased (P < 0.01) with maturity across all species. Among species, CP for cereal rye was greater (P£0.01) than triticale at boot, anthesis, and soft dough, but not different (P³0.10) from wheat at boot, milk, and soft dough. At boot, anthesis, and milk stages, CP of triticale was not different (P³0.07) than wheat, but triticale was lower than wheat (P < 0.01) at soft dough. The DOM (% DM) decreased (P < 0.01) with maturity, except at soft dough. The DOM of cereal rye and wheat did not differ (P > 0.05), but both were greater (P < 0.01) than triticale. Cereal rye and triticale had greater (P £ 0.05) nutrient yields than wheat in terms of energy (DOM) and CP. There was no difference for CP yield across stages (P = 0.10), but there was an effect of maturity on DOM yield. The DOM yield increased from boot to anthesis, (P = 0.05), anthesis and milk did not differ (P = 0.08) and increased (P < 0.01) again at soft dough. This suggests that planting either cereal rye or triticale resulted in the greatest nutrient yield per acre. Harvest at anthesis had increased yield compared to boot with minimal loss in nutritive value; for maximizing energy yield per acre, harvesting at soft dough was the best option. [ABSTRACT FROM AUTHOR]

Cereal rye, winter wheat, and winter triticale are commonly planted cover crops in corn and soybean systems and have the potential to provide early spring grazing. The three cover crops differ in growth pattern. Therefore, a study was conducted to investigate the grazing potential of the three species, including the timing of the start of grazing and nutritive value of forage as measured by growing calf gain. A 7.3 hectare field was divided into 9, 0.81-hectare paddocks. Three paddocks (n = 3 replicates per treatment) were randomly assigned to each treatment: variety not stated cereal rye, Pronghorn winter wheat, or NT11406 triticale. Pastures were seeded in Mid-September following early maturity soybean harvest and received no fertilizer. Fifty-four steers (305 kg SD ± 5 kg) were stratified by weight and assigned to one of nine groups which were then assigned to a paddock. The paddocks were split in half. Steers were turned out when forage reached a 12.7 cm height and rotated to the other half once the occupied half reached 5 cm. Grazing began April 3 for rye pastures and April 9 for triticale and wheat pastures. Two groups of cattle grazing rye were pulled April 29 due to limited forage. All remaining cattle were pulled May 8 to allow for soybean planting. Throughout the grazing period pre and post-graze biomass did not differ (P ≥ 0.36) among treatments. Average daily gain did not differ among treatments (P = 0.88) averaging 1.79, 1.86, 1.84 kg/day for rye, wheat and triticale, respectively. Likewise, gain per hectare did not differ (P = 0.80) among treatments with 378, 399, 394 kg/ha for rye, wheat, and triticale, respectively. Rye offered grazing a full week before triticale and wheat, but all three small grain cereal species resulted in desirable animal performance. [ABSTRACT FROM AUTHOR]