Methane emissions of 60 steers (321 ± 14 kg) fed isocaloric forage diets differing in crude protein (CP) content were measured at ambient daily temperatures averaging -17.5°C to determine if increased nitrogen status, measured by blood urea nitrogen (BUN), decrease CH4 as a percent of gross energy intake (% GEI) from backgrounding cattle. Average BUN concentrations (mmol L-1) were 0.81, 1.82, 3.05 and 3.51 (SE ± 0.108) for diets with 6.9% (low), 10.3% (adequate for rumen microbes), 11.1% (adequate for muscle growth) and 13.6% (excessive) CP respectively. Methane (% GEI) emissions decreased with increasing CP over time (P=0.04). Increasing CP content increased BUN levels and decreased methane emissions (% GEI). Although models were developed to predict CH4 emissions (% GEI) from steers and cows using a backward-elimination process, BUN accounted for only 0.7 to 5.7% of the partial R2 and therefore has limited value when modelling methane emission predictions. / February 2016

Nine varieties of silage sorghum and one pearl millet variety were tested at the Maricopa Agricultural Center in Maricopa, AZ. Information on silage sorghum yield and quality can be of use to the dairy industry and help growers choose the best varieties based on their needs. We found no significant differences among the varieties for ash, ADF, and NDF. We did find significant differences in yield with Silo 700 BMR having the highest yield with 31.62 tons/acre and GS125 having the lowest with 20.53 tons/acre. We also saw significant differences in crude protein with ExpGD having the highest (3.47%) and Silo 700 BMR (1.93%) being the lowest.

Small grain varieties are evaluated each year by University of Arizona personnel. The purpose of these tests is to characterize varieties in terms of yield and other attributes. Variety performance varies greatly from year to year and several site-years are necessary to adequately characterize the yield potential of a variety. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1265.pdf.

The grain yield and nitrogen use efficiency of durum wheat vary in response to genotypic and nitrogen fertilization were studied in field during two growth seasons. The aim of this study was to evaluate the effects the N fertilizer rate on grain yield and quality under irrigated desert conditions in relation to N utilization. Six durum wheat cultivars (Duraking, Havasu, Kronos, Ocotillo, Orita, Topper) were grown in field trails under irrigated regimes at five N levels (0, 65, 110, 160, 240 lbs/acre) in 2010-2011 and six N levels (0, 65, 110, 160, 240, 360 kg ha-1) in 2011-2012 at Maricopa Ag Center. The results showed the varieties and N levels both significantly affected grain yield, grain protein concentration, and nitrogen use efficiency. A simple and rapid method to measure crop N status using SPAD meters was also developed. The results showed that using the differences in SPAD readings between the first and second fully expanded leaves is a useful way to improve effectiveness of SPAD meters in durum wheat N management.

Planting dates are known to affect wheat yields. Previous research has shown that the optimum planting date in Yuma is December 15 to January 15. Wheat is sometimes sown later than this in the Yuma area, and earlier planting dates have not been tested. To test a wide range of planting dates, six varieties(Duraking, Havasu, Joaquin, Kronos, WB-Mead, and Yecora Rojo) were planted at two seeding rates (160 and 240 lbs/A) and six planting dates at the beginning of each month from November through April at the Yuma Valley Agricultural Center. Grain yield averaged 6517 (Nov 4), 6339 (Dec 6), 6096(Jan 4), 5712 (Feb 1), 4962(Mar 1), and 3590(Apr 5). The late-flowering varieties performed relatively better at the earlier planting dates. Seeding rates of 160 and 240 lbs/A had no measureable effect on yield overall.

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Condensed tannins (CT) play an integral role in terrestrial nutrient cycling. Despite being the fourth most abundant terrestrial biochemical product, the regulatory processes of tannin production in plants and their subsequent ecological influences are not completely understood. The defining characteristic of CT’s is their affinity for proteins, though they willingly interact with minerals, carbohydrates, and other polyphenolic compounds. Previous tannin investigations in agriculture have centred on bioactivity related to ruminant digestive physiology and pathology. These studies have revealed that CT’s have the potential to increase liveweight gain, wool production, and sheep ovulation rates, prevent pasture bloat, reduce enteric and stockpiled manure greenhouse gas (GHG) emissions, and control gastrointestinal parasites. The present study has explored how tannin-containing resident plant material and applied manure derived from tannin-containing beef cattle diets influences tame forage biomass yield, proximate analysis, and tannin production, as well as residual fall soil nutrient status, in southern Manitoba. To test these hypotheses, we conducted an experiment over two growing seasons (2007-2008) where in the fall of 2007, both tannin-derived (sainfoin, Onobrychis viciifolia) and non-tannin (alfalfa, Medicago sativa) composted beef manures were applied at a rate of 44.8 t/ha in a randomized split plot fashion, including a manure-free control, on a four repetition randomized complete block design which included both tannin-containing and non-tannin containing forage monocultures and mixtures. Plant samples were harvested in two cuts, and soil measurements were taken in the fall of both years. It was found that across all sainfoin treatments, manure origin did not have a significant effect on plant CT concentration, which was extremely variable within treatments and cuts. Over four harvest dates, sainfoin CT concentrations ranged from 14.1 g/kg to 91.9 g/kg in monoculture plots, and 16.6 g/kg to 123 g/kg when grown in a mixture with meadow brome. In most cases, the presence of either manure type did not significantly affect soil nutrient status or forage yield, though results were similarly variable. Using a stepwise regression which included all soil and plant measurements across all cuts and treatments, it was found that NDF (R2 = 0.548) and plant phosphorus (R2 = 0.126) were the only significant model contributors to tannin concentration in sainfoin at P < 0.15. These findings suggest that nutrient effects of beef cattle manure are not realized in either plant or soil in the year following application, and consequently, that tannin agronomy requires longer-term analysis.