Residual Soil Nitrate Content and Profitability of Five Cropping Systems in Northwest Iowa

Many communities in the Midwestern United States obtain their drinking water from shallow alluvial wells that are vulnerable to contamination by NO3-N from the surrounding agricultural landscape. The objective of this research was to assess cropping systems with the potential to produce a reasonable return for farmers while simultaneously reducing the risk of NO3-N movement into these shallow aquifers. From 2009 to 2013 we conducted a field-based experiment in Northwest Iowa in which we evaluated five cropping systems for residual (late fall) soil NO3-N content and for profitability. Soil samples were taken annually from the top 30 cm of the soil profile in June and August, and from the top 180 cm in November (late fall). The November samples were divided into 30 cm increments for analysis. Average residual NO3-N content in the top 180 cm of the soil profile following the 2010 to 2013 cropping years was 154 kg ha-1 for continuous maize (Zea mays L.) with a cereal rye (Secale cereale L.) cover crop, 31 kg ha-1 for perennial grass, 74 kg ha-1 for a three year oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-maize rotation. However, residual nitrate in the 90 to 180 cm increment of the soil profile was as low in the oat-alfalfa-maize cropping system as it was in the perennial grass system. For 2010 to 2013, average profit ($ ha-1 yr1 ) was 531 for continuous corn, 347 for soybean-winter wheat-maize, 264 for oat-alfalfa-maize, 140 for oat/red clover-maize, and -384 (loss) for perennial grass. Rotations utilizing tap-rooted perennial species, such as maize-maize-alfalfa-alfalfa or maize-soybean-winter wheat-alfalfa-alfalfa, appear promising from both economic and environmental perspectives

COMBINING FARMER EXPERIENCE AND ACADEMIC KNOWLEDGE: SUMMER AGROECOSYSTEMS ANALYSIS COURSE

To understand multiple dimensions and connections in today’s complex farming systems, it is essential to move beyond the narrow disciplinary focus found in most university agriculture courses and learn from farmers who are intimately integrated with farm decisions. In many ways, the classical agriculture department is a human construct developed for our convenience, and as such it scarcely represents an ecological structure operating on farms. To adequately delve into the mechanisms of crop/weed, crop/animal, product/market, and myriad other interactions involved in agriculture, it is essential that we draw on methods from the biophysical and social sciences to help us understand the human activity system that is farming. For more than a decade, we have led a week-long summer course that applies experiential and discovery learning to help students make sense of farm complexity. Students take responsibility for designing the inquiry, process information, and evaluate what they learn in the context of each farm. Team projects provide a measure of learning about farming systems, while individual reflection documents provide a place for self-evaluation and personal reflection. This course provides a bridge between farmer-based and academic knowledge, an integration of disciplines and methods, and a discovery process that builds student capacity to understand complexity and the dynamic nature of Midwest U.S. farms

Innovative Education in Agroecology: Experiential Learning for a Sustainable Agriculture

The transdisciplinary field of agroecology provides a platform for experiential learning based on an expanded vision of research on sustainable farming and food systems and the application of results in creating effective learning landscapes for students. With increased recognition of limitations of fossil fuels, fresh water, and available farmland, educators are changing focus from strategies to reach maximum yields to those that feature resource use efficiency and resilience of production systems in a less benign climate. To help students deal with complexity and uncertainty and a wide range of biological and social dimensions of the food challenge, a whole-systems approach that involves life-cycle analysis and consideration of long-term impacts of systems is essential. Seven educational case studies in the Nordic Region and the U.S. Midwest demonstrate how educators can incorporate theory of the ecology of food systems with the action learning component needed to develop student potentials to create responsible change in society. New roles of agroecology instructors and students are described as they pursue a co-learning strategy to develop and apply technology to assure the productivity and security of future food system