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Soil biochar application effects in agricultural systems are not well understood. Corn (Zea mays L.), soybean (Glycine max L.), wheat (Triticum aestivum L.), cereal rye (Secale cereal L.), and alfalfa (Medicago sativa L.) were grown on two soils amended with four rates of biochar, a Marietta fine sandy loam (fine-loamy, siliceous, active, thermic Fluvaaquentic Eutrudept) and a Houston silty clay (very fine, smectitic, thermic Oxyaquic Haplaudert) and allowed to equilibrate for 56 days. To investigate a possible nitrogen effect, three nitrogen rates were added to non-legume species. Our results revealed reductions in nutrient uptake across all crops, but this followed the same trend as shoot dry weight production and plant tissue concentration for pots treated with biochar. The significant reduction in uptake and tissue concentration are believed to be linked to smaller plant sizes. Therefore, it is believed that biochar applications are not having an effect on plant growth.

Improved prediction of forage quality and cow performance may enhance the nutritional management of beef cows. In two 12 mo trials, mature beef cows (n=136) grazing tall fescue pastures were used to compare estimates of forage quality and animal performance. Forage quality was estimated by proximate analysis of forage samples (FOR) or by near infrared reflectance spectroscopy of fecal samples (FNIR). Nutritional Balance Analyzer (NutBal), NutBalPro and 1996 NRC Nutrient Requirements of Beef Cattle (NRC) programs were used to predict animal performance. The objectives were to compare FOR and FNIR estimates of CP and TDN and to evaluate the accuracy of cow performance predicted by FNIR-NutBal, FNIR-NutBalPro and FOR-NRC systems. Initial BW, body condition score (BCS), hip height and breed were used to establish cow biotypes for prediction programs. Every 28 d, cow BW and BCS were measured and forage and fecal samples collected. Weather data, cow status and FOR or FNIR results were entered into NutBal, NutBalPro and NRC programs. Forage CP estimated by FNIR (CPFNIR) or FOR (CPFOR) were similar. In trials 1 and 2, correlation coefficients between CPFNIR and CPFOR were r = .24 and r = .43, respectively. Forage TDN estimated by FNIR was greater (P <.05) and lowly or moderately correlated to FOR estimates. Actual BW change between weigh periods (BWCHG) and ADG were similar to NRC predictions, but less (P<.0001) than predicted by NutBal or NutBalPro. The NutBal or NutBalPro mean BCS change between weigh periods (BCSCHG) were greater (P<.001) than NRC or Actual BCSCHG. Actual and NRC BCSCHG were similar (P>.2, trial 1) or tended (P<.1, trial 2) to be similar. Cow performance estimated by NRC was highly correlated to Actual. Absolute differences in animal performance were also investigated for each prediction program. In trials 1 and 2, NutBal and NutBalPro over-predicted BWCHG, ADG and BCSCHG by 40 kg, 1.25 kg/d and .75 BCS, respectively, compared to actual cow performance. It appears that FNIR is a promising predictor of forage CP but not TDN. Also, the FOR-NRC is a satisfactory predictor of cow performance. / Master of Science

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Thesis (Ph. D. - Renewable Natural Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 118-125).

Forage sorghum (FS) [Sorghum bicolor (L.) Moench] is a warm-season biomass crop with the potential to become a bioenergy feedstock. The objective of this study was to screen potential FS genotypes for increased chilling tolerance and biomass productivity. The experiments were conducted in Fargo and Hickson, ND, in 2017 and 2018. Seventy-two genotypes of FS were tested at 24, 12, and 10℃. The genotypes were ranked from high to low vigor index and 12 genotypes were planted on two seeding dates: early (10 May) and late (27 May). Field emergence index values were greater for the late-seeding compared with the early-seeding date. Stand establishment and seed mortality were affected by the seeding date. Biomass yield correlated with emergence index and normalized vegetative index. Some of the genotypes tested had increased chilling tolerance and biomass yield when seeded earlier than normal, and may be used for breeding chilling tolerance into FS.