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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

Sustainable Agriculture

Publication Year

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Organic No-Till And Strip-Till Systems For Broccoli And Pepper Production, Dana Lipinski Jokela Jan 2016

Organic No-Till And Strip-Till Systems For Broccoli And Pepper Production, Dana Lipinski Jokela

Graduate Theses and Dissertations

Organic farmers rely extensively on tillage to incorporate plant residues, prepare seedbeds, and control weeds. However, tillage may have adverse effects on soil health, and conventional no-till production methods, which rely on herbicide for weed control, are not compatible with organic farming, so research was conducted on organic no-tillage (NT) and strip-tillage (ST), which rely on terminating a cover crop with a roller-crimper. Field research was carried out over two years (2013–14 and 2014–15) to compare two organic, cover crop-based reduced tillage systems (NT and ST) with conventional tillage (CT) in the production of organic bell pepper and ...


Climate-Smart Agriculture In Midwest Cropping Systems: Evaluating The Benefits And Tradeoffs Of Cover Crops, Andrea Diane Basche Jan 2015

Climate-Smart Agriculture In Midwest Cropping Systems: Evaluating The Benefits And Tradeoffs Of Cover Crops, Andrea Diane Basche

Graduate Theses and Dissertations

Climate-smart agriculture is a framework to develop and implement agricultural systems that facilitate reduced greenhouse gas emissions and increase resilience and productivity in the context of a changing climate. Winter cover crops are known to decrease soil erosion, increase soil carbon, improve water retention and have been hypothesized to reduce nitrous oxide emissions. Therefore they offer the potential to buffer projected climate change impacts for Midwestern agriculture, including increased rainfall variability. The overall objective of this dissertation research was to evaluate the mitigation and adaptation potential of cover crops in determining their efficacy as a climate-smart agricultural practice. In a ...


Strip Tillage And Rowcovers As A Potential Alternative To Black Plastic Mulch In Cucurbit Production, Jennifer Louise Tillman Jan 2015

Strip Tillage And Rowcovers As A Potential Alternative To Black Plastic Mulch In Cucurbit Production, Jennifer Louise Tillman

Graduate Theses and Dissertations

The use of tillage and plastic mulch are common practices among cucurbit growers to provide warm, moist, weed-free soil around plants. However, there are environmental drawbacks to the use of plastic mulches, such as the material waste given that these products are used for a single season, and the reduced soil health and stability that can come from frequent and intensive tillage. As an alternative strategy, a biological mulch can be formed by rolling and killing a cover crop stand by using a roller crimper. Narrow, tilled strips can be formed within this mulch for the crop to grow in ...


Motivation And Retention Of Iowa’S Master Gardener Volunteers, Bryn Takle Jan 2015

Motivation And Retention Of Iowa’S Master Gardener Volunteers, Bryn Takle

Graduate Theses and Dissertations

Retention of participants in volunteer organizations has been shown to be not only a challenge, but also a great benefit to the organization. Rising costs of training and continuing education make each interaction valuable from both perspectives. Volunteer opportunities are abundant but must be meaningful and engaging for the participants in order to keep them involved. Using electronic survey software, Iowa Master Gardeners were asked to respond to a series of questions investigating 1) the current demographics of the population, 2) reasons volunteers associate with the Master Gardener program, and 3) the continuing education topics and delivery methods most preferred ...


Suitability Of Winter Canola (Brassica Napus) For Enhancing Summer Annual Crop Rotations In Iowa, Rafael A. Martinez-Feria Jan 2015

Suitability Of Winter Canola (Brassica Napus) For Enhancing Summer Annual Crop Rotations In Iowa, Rafael A. Martinez-Feria

Graduate Theses and Dissertations

Winter canola (Brassica napus) could be a good candidate for enhancing cropping systems in Iowa because of its potential to provide environmental benefits and produce a marketable crop compatible with existing grain production and distribution schemes. However, it is still uncertain whether this crop would be suitable for helping balance environmental and financial goals of conventional cropping systems under the environmental and market conditions unique to Iowa. The work presented in this thesis is an effort to assess the suitability of winter canola for providing environmental benefits while fitting within the logistic and economic constrains of current cropping systems. Based ...


Cover Crop Impacts On Soil Quality During Miscanthus X Giganteus Establishment In Central Iowa, Joyce Y.J. Lok Jan 2015

Cover Crop Impacts On Soil Quality During Miscanthus X Giganteus Establishment In Central Iowa, Joyce Y.J. Lok

Graduate Theses and Dissertations

The primary goal of this thesis was to create a baseline for soil conserving Miscanthus establishment in the U.S. Since Miscanthus production is expected to occur on marginal lands with significant erosion potential, we focused our attention on soil quality indicators. The hypotheses of this study were to examine Miscanthus establishment with companion crops by studying: 1) morphological and hydrological soil parameters (soil bulk density, soil aggregate stability, and steady-state infiltration) and 2) percent soil surface cover via photogrammetry (live plant, mulch, and bare soil).

Treatments were Miscanthus (Miscanthus x giganteus), rye (Secale cereale), oat (Avena sativa), crimson clover ...


Values-Based Supply Chains: Local And Regional Food Systems In The Upper Midwest United States, Kevin Richard Duerfeldt Jan 2014

Values-Based Supply Chains: Local And Regional Food Systems In The Upper Midwest United States, Kevin Richard Duerfeldt

Graduate Theses and Dissertations

In recent years there has been growing public interest in sustainable food systems. One effect of growing interest is the proliferation of values-based supply chains or local food systems. The main limiting factor of local food systems is infrastructure for aggregation and access to supply chains. Food hubs have been identified as one solution. My purpose is to capture valuable data about the state of local foods industries in 2012 and inform organizations developing food hubs. To do this I surveyed characteristics of established food hubs and analyzed local Iowa vineyards and wineries, as a case study of an established ...