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Master of Science / Department of Agricultural Economics / Jeffery R. Williams / This study examines the economic profitability of reduced-tillage and no-tillage systems for corn, soybeans, and grain sorghum production in annual rotation with winter wheat, and monoculture wheat and grain sorghum in south-central Kansas. Net returns to land and management per acre for each of 13 production systems are calculated several different ways. Net returns are calculated using the 10-year average yield for each crop, the average crop price from 2009, and 2009 input prices. A distribution of net returns is also calculated using the actual historical yields and crop prices from 1997 to 2006 and 2009 input prices. This process is repeated, except average crop prices from 2006, 2007, 2008 and 2009 are now used. Finally, net returns are calculated using simulated yield and price distributions based on actual historical yields, four historical monthly price series, and 2009 input costs. Overall, the reduced-tillage wheat-soybean systems (RTWS) have the greatest net returns for each of the net return distributions. No-tillage wheat-soybean (NTWS) generally has the second highest net returns. Stochastic Efficiency with Respect to a Function (SERF) is used to determine the preferred management strategies under various risk preferences. SERF analysis indicates that RTWS is the system most preferred by all producers, regardless of their level of risk aversion. NTWS is typically the second most preferred system to RTWS. Using historical annual prices for 1997 to 2006 and the simulated monthly prices series for 2006 to 2009 and 2007 to 2009 to calculate the net return distributions, managers with higher levels of risk aversion prefer reduced-tillage wheat-grain sorghum (RTWG) over no-tillage wheat-soybean (NTWS). Sensitivity analysis shows that as the price of glyphosate falls, no-till systems become relatively more profitable. SERF analysis using the historic yields, 2006 to 2009 simulated monthly prices, and 2009 input costs with reduced glyphosate prices indicate that NTWS would be the system most preferred by producers at all levels of risk aversion. RTWS closely follows NTWS as the next preferred system with those conditions also for all levels of risk aversion.

Master of Science / Department of Agronomy / DeAnn Presley / In the Midwest there has been an increase in the number of vertical tillage (VT) implements sold and a large push in marketing these newer implements to producers. Vertical tillage is defined as shallow tillage, usually in the top 5 to 7.5 cm of the soil and results in no horizontal disturbance of the soil. The objective was to determine the short-term (one growing season) effects of a vertical-tillage operation on seedling emergence, crop growth and development, yield, residue decomposition, disease incidence and severity, quantification of pathogen propagules in soil and crop residue, and effects on the near-surface soil physical properties. The study was conducted during the 2010 and 2011 growing seasons at nine locations total for the two years throughout Kansas. The study compared vertical tillage against the producer’s current practice of no-till (NT), strip tillage (ST), or conventional disk (CD). Few significant differences were observed when studying soil properties, however not one treatment continuously had significant results and no trend was observed. Residue cover at all sites and across both years was significantly greater in the NT treatments. The residue cover also impacted the disease incidence and severity of Cercospora zea-maydis also known as gray leaf spot (GLS). Other diseases such as Marcophomina phaseolina and Fusarium spp. were not significantly impacted by one treatment or another. Overall, any differences in the soil, plant, and pathogen indicators have not resulted in significant yield improvements at any of the nine site locations of the two years of this study, but more site years will be needed to assess any potential benefits of VT. Information gained from this project will be disseminated to extension clientele including extension educators, producers, commodity groups, and agricultural professionals.

Published Article / To assess and predict runoff and soil loss on different tillage methods coupled with alternative cropping systems in the central highland vertisols of Ethiopia, a study was carried out at Ginchi, Agricultural Research Sub-Center during 1996. The experiment was conducted on runoff plots of 4 meter wide by 22 meter long, on surface slopes that range between 0.1% and 2.3%. The data collected was analyzed using regression models and an empirical formula developed by the Soil Conservation Service of America (SCS, 1964; 1972), known as curve number (CN). Both the regression model and the SCS simulated the mean daily runoff reasonably well with R2 93% and 83%, respectively. The overall results obtained explain that the improved tillage practice, BBF could drain the excess surface water safely.

Soil erosion research in the fields of agronomy, soils science and mechanics, agricultural engineering, hydrology, climatology, and other scientific disciplines has economic dimensions. In general, measurable and, at times, significant economic effects are associated with the effects of erosion in the other disciplines. Interactions between climate, soils, hydrology, and tillage practices are incorporated into a stochastic simulation model that considers twenty six combinations of five tillage systems, three initial soil depths, two soil associations, two slope classes, and two annual precipitation levels over one hundred years. The model endogeneously determines stochastic annual soil loss. Yield is a function of varying soil depth and technological advance. The model maximizes the wheat producer's objective, 100-year discounted quasi-rents from wheat production. Cumulative or total rent distributions that derive from alternative tillage systems in the different ecological circumstances are compared under stochastic dominance. In low rainfall, shallow soil areas, annual tillage systems were preferred to fallow ones, while conservation tillage dominated plow tillage. In high rainfall areas, for either shallow or deep soil, conservation tillage dominated plow tillage, while plow tillage dominated no-till. Manipulation of the tillage-associated rent distributions permitted the estimation of value-of-marginal product or willingness to pay curves (ordinary, profit-maximizing, input demand curves) that express the depth of soil as a function of its economic worth. Properties of these curves are discussed. Comparison of expected total returns and marginal returns to topsoil increments under alternative tillage systems in defined ecological circumstances paralleled the stochastic dominance results. Rankings of tillage systems by expected total returns differed between ecological areas and differed from rankings by marginal returns. Regardless of tillage system or ecological circumstances, the economic worth of each added soil increment diminished. The experiment showed that differential rates of soil loss associated with different tillage systems influence the decision to continue using or to initially invest in alternative tillages, and also influence the economically rational wheat producer's willingness to incur costs associated with soil conservation. Total and marginal rents associated with single tillages were found to vary greatly across ecological circumstances. The ability and the willingness to invest in soil conservation were somewhat divorced. This result has significance for soil conservation targeting. / Graduation date: 1986