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Many farmers are continuously looking for new ways to protect soil and increase yields and returns on investment. No-tillage and reduced-tillage farming may provide ways to achieve these goals. Such practices have been found as the alternative to overcoming the environmental challenge posed by conventional tillage practice and providing significant economic returns. However, a comprehensive study of the factors affecting the adoption and adoption intensity of these practices is lacking. This paper intends to fill this gap by utilizing a double hurdle model to analyze farmer survey data. The data used in this study were obtained from a survey of 350 commodity crop producers about their land management practices and attitudes in the eastern part of South Dakota. Our findings indicated that determinants affecting the adoption decision and intensity of adoption are mostly different. In addition to this, factors affecting no-tillage and reduced tillage adoption are also mostly different. Our findings indicated that farmers were more likely to practice no-till to control soil erosion, improve soil quality, increase yield, and earn profit from farming. Similarly, farmers involved in decision-making years for a longer period had positive influence on the adoption of reduced tillage. We found that: 1) farm size as a common factor affecting no-tillage and reduced tillage adoption and 2) that distance from home to field and rainfall had a positive and a negative impact on reduced tillage and notill adoption respectively. Similarly, our results suggest that farmers who have high erodible land are more likely to expand no-till acres. As a result, outreach efforts aimed towards these populations may be more successful in increasing the percentage of no-till acres adoption.

In the face of climate change and more frequent extreme weather, increasing crop resilience to weather anomaly has become a critical issue. This study explores the relationship between conservation practices (cover crop, no-tillage) and the resilience of corn and soybean to extreme precipitation, based on county-level data from the U.S. Corn Belt from 2005 to 2018. Crop insurance indemnities reflect crop losses and therefore reflect crop resilience. The research constructs three county- and year-fixed-effect regression models. Regression results show that as the degrees of weather extremes increases, the crop indemnities increase in general. When the interaction of extreme weather and conservation practices is taken into consideration, the relationships between conservation practices and indemnity level are not consistent, and they are based on the degree of weather anomaly. Corn cover crop acres are negatively correlated with the corn indemnity regardless of the precipitation level, and the soybean no-tillage acres are positively correlated with the soybean indemnity regardless of the precipitation level. However, for the corn no-tillage practices and the soybean cover crop practices, only when the precipitation is close to an average level do they negatively correlate with their corresponding crop indemnity levels. The capacity and resilience cultivation effect of conservation practices may vary across different crops and practices.

Soil physical and hydraulic properties control the major soil functions related to the imbibition, transmission and retention of water, air, heat and nutrients. Adoption of no-tillage in Tennessee through the last decades has considerably decreased the fluvial soil losses. However, the long-term effect of no-tillage on soil hydro-physical properties and its interaction with companion practices such as cover crops and crop sequence has not been fully discovered.In this project, three long-term experiments located in West Tennessee Research and Education Center in Milan and Jackson, TN were studied in 2015 and 2016 for soil hydro-physical properties. The effect of 34 years of tillage, fertilization and cover crop, 15 years of crop rotation on no-tillage with winter fallow and 37 years of a range of tillage intensities and no-tillage with and without cover crop on soil physical properties were assessed. Relationship between soil physical properties were determined and by relating the soil physical properties to corn, cotton and soybean yield and long-term yield stability, the most effective cropping and tillage managements were identified.Long-term no-tillage substantially improved soil aggregation, water infiltration and transmission and cotton yield than conventional tillage. Effect of cover crops on measured soil physical properties were less evident than the effect of no-tillage. However, planting hairy vetch and wheat cover crops improved the soil aggregation and increased the water infiltration and transmission significantly compared with no cover crop. No-tillage planted with hairy vetch cover crop experienced significantly higher quasi-steady and cumulative infiltration compared with the other treatment combinations in both years. Cropping corn, cotton and soybean in double cropping sequences did not favor soil in improved physical quality than monoculture while existence of corn in cropping system either as continuous cropping or in sequence improved soil physical quality. Corn rotated with soybean and cotton increased yield and decreased the long-term variance in soybean yield. Under sub-humid climate of Tennessee with relatively high decomposition rate of organic matter, the magnitude of residue turnover and below-ground root activity was found to be key factors increasing the no-tillage potential for additional improvement in soil quality and yield.

Agronomic practices, including tillage, crop rotation and N fertilization, have been developed to efficiently manage soil N dynamics and crop N nutrition. These practices can affect soil organic carbon (SOC) and soil total nitrogen (STN) sequestration, and consequently influence soil nitrogen mineralization (SNM) and crop N nutrition. However, little research has been systematically and simultaneously conducted to examine the effect of agronomic management on (1) SOC and STN stocks; (2) SNM; and (3) crop N nutrition. Burley tobacco (Nicotiana tobacum L.) is a N demanding crop and subject to inefficiency in N fertilization. Moreover, conservation tillage and rotation have been integrated into traditionally tillage intensive tobacco cropping systems. Thus, a tobacco tillage and rotation study was used to test how agronomic practices can affect N dynamics and crop N status in a series of sequential experiments. Firstly, different tobacco production systems were utilized to investigate the effects of tillage and rotation on soil aggregate stabilization and associated SOM sequestration. No-tillage and rotation management enhanced SOC and STN stocks, mainly by increasing the proportion of macroaggregates and SOC and STN concentrations. Secondly, a series of studies were conducted on SNM, including: (1) comparison of laboratory and in situ resin-core methods in estimating SNM; (2) evaluation of the influence of N fertilizer application on SNM; and (3) comparison of chemical indices for predicting SNM across management treatments over time. Laboratory method had different results relative to in situ method due to sample pretreatments. Fertilizer N application had a priming effect on SNM, but priming depended on both the N fertilizer rate and the background SOM level. The effect of rotation/tillage treatments on SNM was stable across years and SOC appeared to be the best indicator of SNM among other soil carbon and N estimates. Thirdly, a N fertilizer study for different tillage systems was conducted in 2012 and 2013. Crop parameters and plant available N (PAN) were collected to investigate the impact of tillage on tobacco production. Crop parameters showed that no-tillage can result in N deficiency in dry years. Similar PAN for both tillage methods suggested N deficiency in no-till tobacco was due to the crop’s lower N uptake capacity. In 2014, tobacco root analysis confirmed that no-tillage can result in less root exploration of the soil volume than conventional tillage.

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.

Winter annual cover crops, winter rye (Secale cereale) and hairy vetch (Vicia villosa roth.), can reduce weed density and build soil health in organic production systems. There is considerable interest in integrating cover crops and reduced tillage with organic vegetable production; but few studies have been conducted in regions with short growing seasons and cool soils such as the upper Midwest. We evaluated no-tillage production of tomato, zucchini, cauliflower, and bell pepper planted into winter rye, hairy vetch, and a winter rye-hairy vetch mixture that were mechanically suppressed with a roller-crimper at two locations in Minnesota. Average marketable yields of tomato, zucchini, and bell pepper in the cover crops were reduced 58-87%, 27-75% and 62-92%, respectively, compared to a no-cover control. Winter rye and the mixture reduced average annual weed density at St. Paul by 96% for 8-10 weeks after rolling (WAR) and hairy vetch mulch had 80% control for 2-8 WAR; while at Lamberton, there was no consistent effect of cover treatments on weed populations. Winter rye and the mixture had higher average residue biomass (5.3 and 5.7 Mgha-1) than hairy vetch (3.0 Mgha-1) throughout the season in addition to higher biomass N content in most cases. Cover crop mulches reduced soil temperature by 2.9° to 5.7° C compared to a no-cover control for 4-5 weeks after planting which delayed vegetable growth and could have contributed to reduced yields in the cover crop mulches. In addition, low levels of soil N (

Rising demand for organic soybeans (Glycine max L.), coupled with high price premiums for organic products, has producers interested in making the transition to organic soybean production. However, organic soybean producers and those making the transition cite weed management as their biggest limitation. Current organic weed management relies heavily on cultivation. Cultivation has negative consequences on soil health and producers are interested in organic reduced and no-till production. Rye (Secale cereal L. cv. Rymin) cover crop was evaluated for weed suppression abilities and effects on soybean yield. Experiments were planted in 2008 and 2009 at three site locations. Rye was planted in the fall of each year and killed at soybean planting with a roller-crimper or flail-mower, creating thick weed-suppressing mulch with potential allelopathic properties. The mulch was augmented with one of three additional weed control tactics: pre-emergence corn gluten meal (CGM), post-emergence clove oil, or post-emergence high-residue cultivation. Rolled-crimped and flail-mowed treatments had similar weed suppression abilities. There were no differences between CGM, clove oil, or cultivation at most sites. Rye biomass level was the only independent variable that affected weed control. Rye biomass levels higher than 9,000 kg ha-1 were sufficient in controlling weeds. Organic soybean yields were similar to weed-free soybean yields at rye biomass levels higher than 9,000 kg ha-1. Goldsboro 2008, where rye biomass was 10,854 kg ha-1, the organic rye-only treatment yielded at 2,190 kg ha-1 and the weed-free treatment yielded at 2,143 kg ha-1. Plymouth 2008, where rye biomass was 9,526 kg ha-1, the organic rye-only treatment yielded 2,694 kg ha-1 and the weed-free treatment yielded at 2,809 kg ha-1. On the contrary, at low rye biomass levels (4,450- 6,606 kg ha-1), the organic rye-only treatment yielded 628- 822 kg ha-1 less than the weed-free treatment. High rye biomass levels are critical to the success of this production system. However, at rye biomass levels greater than 10,000 kg ha-1, severe soybean lodging was induced and potentially limited yield potential.

High-biomass cover cropping enhances marketable yields in organic production of vegetables, linked to the improvement of soil quality and weed control. Although, during transition from chemical to organic cover-cropping production, especially with no-till systems, reduction of nitrogen availability to the main crop and increase in weed and pest pressure may occur. In 2004-2005, summer and fall broccoli (Brassica oleraceae L. Botrytis Group) crops were grown in twin rows on permanent (controlled traffic) raised beds (185-cm wide). Before broccoli transplanting, high-biomass cover crops were grown in specific bed areas. Legumes (Vicia villosa, Glycine max L., and Crotolaria juncea L.) on bed tops (grow zones) and grass species (Secale Cereale L., Setaria italica L., and Sorghum bicolor X S. bicolor var. Sudanese) in the alleyways (bed shoulders and bottoms). Experimental treatments were tillage (conventional, CT; and no-tillage, NT), farmscaping (with and without), and nitrogen sidedressing (with and without, applied 3 weeks after transplanting as a mixture of sodium nitrate - 22 kg N ha-1 - and feathermeal - 44 kg N ha-1). Weeds were managed by mechanical cultivation in CT and a spot weeding by hand in NT treatments. High numbers of beneficial insects (Cotesia glomerata, Cotesia orobenae and Diadegma insulare) kept the primary insect pest population (Pieris rapae, Evergestis rimosalis (Guenee), and Plutella xylostella) at a pest to predator ratio below 4:1. Although the excellent insect pest control was attributed to the farmscape plantings, pest level and crop yields were not significantly affected by farmscaping (likely due to the close proximity of the farmscaped plots (10-50m from non-farmscaped)). Broccoli yield averaged 62% higher in fall than summer (12.1 vs. 7.5 t ha-1) likely due to cool weather conditions during broccoli head development (October), increasing head size, uniformity, and marketability. In 2004, broccoli yield in CT plots was either equal or slightly higher than NT (9.5 vs. 9.0 t ha-1). However, in 2005, broccoli yield in CT plots was significantly higher in both spring (8.8 vs. 6.8 t ha-1; p = 0.0258) and fall crops (13.5 vs. 12.3 t ha-1 with p = 0.0484). Nitrogen sidedressing improved yield in all plots (9.8. vs. 12.7 t ha-1) and particularly in NT (8.6 vs. 12.1 t ha-1), indicating that availability and/or synchrony of nitrogen was a limiting factor. Incorporating high-N legume residues in the grow zones resulted in a lesser N response in CT.

The approach taken for this dissertation has involved: (a) A literature review on the theory and practice of adoption and diffusion of innovations.The review concentrates on adoption and diffusion of agricultural innovations. The review has covered those papers the author considered were most important. The author's opinion has been 'employed' throughout the review, particularly in the conclusions to each section. (b) Discussion on the use of film in New Zealand agriculture. This chapter includes a literature review, interviews and reference to the film produced; Direct Drilling in New Zealand. (c) Two questionnaires used to determine, in a practical sense, the potential for a film on direct drilling. (d) A summary and conclusion complete the dissertation.

TD-44 A Thesis presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Forestry, Fisheries and Wildlife, Under the Supervision of Professor Ron J. Johnson. Lincoln, Nebraska: December, 1984. Copyright (c) 1984 Kent E. Holm