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Iowa State University

Plant Sciences

Graduate Theses and Dissertations

APSIM

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Cover Crop Effects On Maize Productivity: Insights From Statistical And Process-Based Models, Guillermo Marcillo Jan 2018

Cover Crop Effects On Maize Productivity: Insights From Statistical And Process-Based Models, Guillermo Marcillo

Graduate Theses and Dissertations

Winter cover crops can be an effective strategy to buffer soil and water impairing effects from intensively managed agriculture. While cover crops have shown potential to sequester off-season nitrate, control weeds, or promote nutrient cycling, knowledge gaps persist in regard to maize impacts driven by cover crop decision making. In this context, statistical and process-based models can be valuable tools for predicting changes in maize systems that include a winter cover crop. In a meta-analysis combining peer-reviewed research from several regions in the US, grain yields were found to change between 0 and 21% when maize (Zea mays L.) followed ...


Drivers Of Yield And Nitrogen-Loss Tradeoffs: Cropping System Evaluations With Process-Based Modeling, Rafael Alejandro Martinez-Feria Jan 2018

Drivers Of Yield And Nitrogen-Loss Tradeoffs: Cropping System Evaluations With Process-Based Modeling, Rafael Alejandro Martinez-Feria

Graduate Theses and Dissertations

The Midwest is one of the most productive agricultural regions, but mitigating loss of nitrogen (N) from cropland is needed to improve environmental quality. Tradeoffs between crop yield and N loss have been linked largely to the inefficient use of N fertilizers, but the contributions of more systemic factors such as soil characteristics, crop sequences, and genotypes have not been thoroughly studied. This dissertation examines and quantifies the impact of various genetic, environmental and management drivers of crop yield and N-loss tradeoffs in the maize and soybean cropping systems of the US Midwest, and identifies potential management strategies to lessen ...


How Does Inclusion Of Weather Forecasting Impact In-Season Crop Model Predictions?, Kaitlin Togliatti Jan 2017

How Does Inclusion Of Weather Forecasting Impact In-Season Crop Model Predictions?, Kaitlin Togliatti

Graduate Theses and Dissertations

Accurately forecasting crop yield in advance of harvest could greatly benefit decision makers. However, few evaluations have been conducted to determine the effectiveness of including weather forecasts, as opposed to using historical/climatology data, into crop models. We tested a combination of short-term weather forecasts from the Weather Research and Forecasting Model (WRF) to predict in season weather variables, such as, maximum and minimum temperature, precipitation, and radiation at four different forecast lengths (14 days, 7 days, 3 days, and 0 days). This forecasted weather data along with the current and historic (previous 35 years) data were combined to drive ...


A Comparison Of Carbon Storage Potential In Corn- And Prairie-Based Agroecosystems, Ranae Dietzel Jan 2014

A Comparison Of Carbon Storage Potential In Corn- And Prairie-Based Agroecosystems, Ranae Dietzel

Graduate Theses and Dissertations

Increasing carbon (C) in the soil is important both for removing harmful C from the atmosphere and improving the health of the soil. In this dissertation, I set out to examine how planting and harvesting prairies on soils suitable for corn affected soil C storage potential when compared to corn-based systems. I addressed three questions designed to a) improve our understanding of the fundamental differences between how prairies and corn grow throughout the year, b) test how prairies and corn add C to the soil after establishment, and c) use our current understanding of prairie and corn growth and C ...