Farmers are always looking for ways to increase yields and profits and no-tillage may be a way to achieve this goal. However, a comprehensive study of the performance of no-tillage yields relative to conventional tillage yields and their net returns is lacking. This study evaluated the potential factors that influence differences in conventional tillage and no-tillage yields and net returns as explained by such factors as time, crop, precipitation, soil texture and geographic region. Data were collected from 442 paired tillage experiments growing corn, soybeans, cotton, oats, wheat and sorghum published in three refereed journals. Data were evaluated using a mixed model and logit model respectively, to evaluate differences in mean yields and downside risk with no-tillage compared to tillage. Sorghum and wheat were found to have higher no-tillage yields relative to tillage. No-tillage was also found to outperform conventional tillage in the southern United States with just the opposite occurring in the northern U.S. A silty soil was also found to reduce no-tillage yields. Several factors were found to decrease the chance of downside risk with no-tillage, they were sorghum, sandy soil, Northern Crescent, Northern Great Plains, Prairie Gateway and Southern Seaboard regions. Two factors that increased the chance of lowered no-tillage yields were increased rainfall and length of use of no-tillage. Differences in mean net returns and downside risk were evaluated using a mixed model and logit model. Results showed that no-tillage was more profitable than conventional tillage in the Mississippi Portal region, but less profitable in the Prairie Gateway. Net returns were lower for no-tillage wheat and soybeans when produced in a clay soil. Cotton grown in sand had higher no-till net returns, but increased rainfall decreased cotton net returns. A logit model showed certain factors decreased the probability of lower no-tillage net returns. There was less downside risk with wheat grown under no-tillage as well as less downside risk in the Southern Seaboard region and when no-tillage was used on a clay soil. There were factors that increased the probability of lower no-tillage net returns; increased precipitation, Northern Great Plains, Prairie Gateway and Basin & Range regions.

Cover crop use provides a myriad of benefits to soil health. Despite strong agronomic evidence of the benefits of using cover crops, farmers have been slow to adopt cover crop systems. Surveys show that this is due to a lack of understanding on how cover crop use will impact the farm, and limited economic analysis on the effects of cover crop use on the farm. <div> In this thesis, a variable-rate nitrogen study was analyzed to determine the relationship between applied nitrogen fertilizer and corn yields, and how a cover crop treatment impacts that relationship. Data were obtained from a case farm in Central Indiana. Production information was then translated into a partial budget to see how the use of the different cover crop treatments impacted net return per acre for corn production on the farm. Net returns were analyzed using both historical corn and nitrogen prices and stochastic modelling.</div><div> Results showed that the final impact on farm net return per acre associated with adoption of a cover crop system varies among cover crop species. Implementing annual rye resulted in a negative change to net return; while cereal rye and an oats and radish blend resulted in a positive change to net return. When additional benefits of cover crop use; such as drought tolerance, carbon content, and erosion reduction; are included, all three cover crop species resulted in a substantial increase in net return. This information will be of interest to farmers as a source to draw upon when making decisions regarding their own farms. Further research is needed to fully understand the relationship between cover crop use and farm profitability, particularly for farms at the early stages of adoption.</div>

There is sparse research literature in agricultural economics regarding early weaning as a potential alternative production/marketing strategy. The objective of this research is to estimate and analyze the impacts on net returns of alternative weaning dates for Tennessee cow-calf operations including alternative post-weaning treatments for calves. The Decision Evaluator for the Cattle Industry (DECI) simulation program was used for this study to produce outputs such as calf numbers, gender, and weights, other output including cow weights and body condition score, both at calving and at weaning, and pregnancy percentages. Forty-two simulations were run for average and summer drought weather, weaning at an average age of 135, 165, 195, 225, 255, and 285 days and selling at weaning or after a 60 or 90-day drylot backgrounding period. Prices for steers, heifers, and culled cows from 1995-2008 were taken from market reports. Costs were derived from University of Tennessee Extension Beef and Forage Budgets and USDA-NASS. The outputs from DECI were combined with prices to result in total revenues. Subtracting the costs of feed, interest, veterinary and medical, and marketing resulted in return to land, labor, management, and risk to the enterprise. The results of this study revealed that under average weather conditions in East Tennessee, marketing at weaning in November yielded the highest net return. Weaning in August and backgrounding for 60 days yielded the lowest net return with the base 90-cow herd. Under summer drought conditions, marketing at weaning in August resulted in the highest net return. Weaning in November and marketing after a 90-day backgrounding period yielded the lowest net return. Under the conditions used in this study, the only time early weaning makes economic sense is when herd size is increased for June or July weaning or under drought conditions when August (195 days) weaning and sale is optimal. Several limitations of this study imply that additional research is required on this topic before definite conclusions can be drawn.

There is sparse research literature in agricultural economics regarding early weaning as a potential alternative production/marketing strategy. The objective of this research is to estimate and analyze the impacts on net returns of alternative weaning dates for Tennessee cow-calf operations including alternative post-weaning treatments for calves.The Decision Evaluator for the Cattle Industry (DECI) simulation program was used for this study to produce outputs such as calf numbers, gender, and weights, other output including cow weights and body condition score, both at calving and at weaning, and pregnancy percentages. Forty-two simulations were run for average and summer drought weather, weaning at an average age of 135, 165, 195, 225, 255, and 285 days and selling at weaning or after a 60 or 90-day drylot backgrounding period. Prices for steers, heifers, and culled cows from 1995-2008 were taken from market reports. Costs were derived from University of Tennessee Extension Beef and Forage Budgets and USDA-NASS. The outputs from DECI were combined with prices to result in total revenues. Subtracting the costs of feed, interest, veterinary and medical, and marketing resulted in return to land, labor, management, and risk to the enterprise. The results of this study revealed that under average weather conditions in East Tennessee, marketing at weaning in November yielded the highest net return. Weaning in August and backgrounding for 60 days yielded the lowest net return with the base 90-cow herd.Under summer drought conditions, marketing at weaning in August resulted in the highest net return. Weaning in November and marketing after a 90-day backgrounding period yielded the lowest net return.Under the conditions used in this study, the only time early weaning makes economic sense is when herd size is increased for June or July weaning or under drought conditions when August (195 days) weaning and sale is optimal. Several limitations of this study imply that additional research is required on this topic before definite conclusions can be drawn.

<p>  </p> <p>Tar spot is a new foliar disease of corn in the United States. Tar spot was first detected in 2015 and is now among the most important corn diseases in the Midwest. Tar spot is caused by the obligate biotrophic fungus, <em>Phyllachora maydis</em> Maubl, from the genus, <em>Phyllachora </em>which consist of over 1,200 species of host-specific fungi. Due to the recent emergence, studies relating to <em>P. maydis</em> population dynamics in the U.S. are limited. How much genetic diversity, variation, and level of gene flow are occurring within and among these populations? Knowledge of the population dynamics is imperative for understanding the pathogen’s biology, ecology, epidemiology, and management. Currently, no corn hybrid is fully resistant to tar spot. Foliar fungicides are currently the most effective option for disease management, but best practices for fungicide management remain unknown. Better information is needed on fungicide efficacy and fungicide application timing to reduce tar spot severity, protect yield, and increase profitability for Indiana corn growers. </p> <p>This research dissertation presents four chapters to answers those questions and bridge the gaps between the knowns and unknows of this novel corn-<em>Phyllachora maydis</em> pathosystem. <strong>Chapter 1</strong> presents a literature review on tar spot of corn, its economic impact, the causal pathogen, its host, lifecycle, distribution, and known management strategies as a resource for understanding the pathosystem in the U.S. <strong>Chapter 2</strong> examines the genetic population structure, diversity, geneflow and mode of reproduction in Midwest U.S. by employing microsatellite (SSR) markers. <strong>Chapter 3</strong> presents results from multi-year, multi-location, small-plot field trials on the net return of foliar fungicides and fungicide timing on tar spot management in Indiana. Lastly, <strong>Chapter 4</strong> concludes by evaluating of an integrated management strategy for tar spot by examining the integration of tillage, corn hybrids and fungicide application in reducing tar spot severity while protecting yields.</p> <p>Results provided in this research dissertation will be used to guide future studies and provide stakeholders such as researchers, corn growers, extension personnel in academia and industry with valuable information needed to guide effective disease management decisions. </p>

Maintaining dissolved oxygen concentrations under different operating schemes (constant, manual or automated aeration control) was evaluated in 20 earthen catfish ponds ranging from 0.04 to 0.07 hectares in size. Ponds were assigned to treatments based on achieving equal distribution of biomass among treatments. Catfish weighing approximately 0.11 kg each were stocked at a rate of 14,820 catfish/hectare and were fed, to satiation, a 36% crude protein floating feed for the first week and switched to a 32% crude protein floating feed for the remainder of the study. Percentage weight gain, FCR and survival were calculated but did not differ among treatments. A partial enterprise budget analysis was generated to determine comparative value of different aeration techniques relative to production costs. Mean partial net returns did not differ among treatments. Complete comparison was not possible due to failure of automated monitors to record DO and to operate aerators under designed protocols.