Understanding how the environment and production and cultivation practices influence the composition and quality of food crops is fundamental to the production of high-quality nutritious foods. In this 3-year study, total phenolics, percent soluble solids, ascorbic acid, and the flavonoid aglycones quercetin, kaempferol, and luteolin were measured in two varieties of tomato (Lycopersicon esculentum L. cv. Ropreco and Burbank) and two varieties of bell peppers (Capsicum annuum L. cv. California Wonder and Excalibur) grown by certified organic and conventional practices in a model system. Significantly higher levels of percent soluble solids (17%), quercetin (30%), kaempferol (17%), and ascorbic acid (26%) were found in Burbank tomatoes (fresh weight basis; FWB), whereas only levels of percent soluble solids (10%) and kaempferol (20%) were significantly higher in organic Ropreco tomatoes (FWB). Year-to-year variability was significant, and high values from 2003 influenced the 3-year average value of quercetin reported for organic Burbank tomatoes. Burbank tomatoes generally had higher levels of quercetin, kaempferol, total phenolics, and ascorbic acid as compared to Ropreco tomatoes. Bell peppers were influenced less by environment and did not display cropping system differences.

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In the mid-1970s, University of California, Davis, students concerned about the environmental and social consequences of modern agriculture were interested in exploring the practice and theory of “alternative” agriculture. These students organized to create new educational opportunities to address needs that were not being met by the existing curricula. These student-initiated opportunities emphasized interdisciplinary analyses of agriculture and field-based experiential learning; they included student-organized courses and the development of the Student Experimental Farm (SEF) as a site for student education, research, demonstration, and extension projects. Over the next three decades, the SEF developed diverse experiential educational projects, classroom and field-based courses focusing on sustainable and organic agriculture, and several departments and programs offered additional, related courses and curricula. In 2004, an interdisciplinary curriculum committee within the College of Agricultural and Environmental Sciences began to develop an undergraduate major in sustainable agriculture. A team of faculty and students within the committee conducted a broad stakeholder survey of agricultural practitioners, academics, students, and alumni to help inform decisions regarding what content, skills, and experiences to include in the curriculum. The survey findings reinforced the original curricular and pedagogical themes articulated and acted upon by students 30 years prior. The proposed curriculum is aimed at integrating disciplinary and interdisciplinary coursework in natural and social sciences, significant on- and off-campus experiential learning, and an emphasis on professional and interpersonal problem-solving and communication skills. Educational theory supports these diverse educational approaches and is useful in helping design courses and curricula in organic and sustainable agriculture.

quality and pest management. Choosing the right cover crop is critical to successful cover cropping. Cover crops were frequently used on California farms in the first half of this century, but were rarely grown after the 1950s, when pesticides and fertilizers came into widespread use. In the last decade, however, farmers and researchers have taken a renewed interest in cover crops because of their potential role in reducing chemical inputs and improving soil quality. Cover crops are now recognized as an important component of "sustainable" production in most areas of California. Cover cropping can have both advantages and disadvantages (see sidebar, page 46). Proper choice and management of cover crops are important in maximizing the benefits and reducing potential problems. To select a species or mix, the grower should first determine the primary benefits he or she desires. Then consider the specific

Field experiments were conducted in 2000 and 2001 in Meridian, Calif. to evaluate the effects of cover crop mixtures and reduced tillage on yield, soil nitrogen (N), weed growth, and soil moisture content in organic processing tomato (Lycopersicum esculentum) production. The trial was set up as a randomized complete-block design with eight treatments consisting of a 2 × 3 (cover crop × tillage) factorial design, a fallow control (F) and a single strip-till (ST) treatment. Cover crop mixtures were either legumes (L), common vetch (Vicia sativa), field pea (Pisum sativum) and bell bean (Vicia faba), or those legumes with grasses (GL), annual ryegrass/triticale (Lolium multiflorum/xTriticosecale) in 2000; cereal rye (Secale cereale)/triticale in 2001. Tillage treatments included an incorporation of the cover crop at planting (IP), a delayed incorporation (DI) (17 to 19 days after planting), and no-till (NT). Due to regrowth of the annual ryegrass in 2000, tomato fruit yields in 2000 were reduced by 50% to 97% within all GL treatments. However, regrowth of the cover crop was not a problem in 2001 and yields were not different among treatments. Total percent weed cover was 1.6 to 12.5 times higher in NT than IP treatments in 2000 and 2.4 to 7.4 times higher in 2001 as weed pressure was mainly affected by tillage practices and less by cover crop type. In 2000, available soil N was 1.7 to 9.4 times higher in L than GL treatments and was significantly influenced by tillage, but there were no treatment effects in 2001 due to a 60% reduction in weed pressure and minimal or no cover crop regrowth. Soil moisture content did not differ between treatments in either year. These results demonstrate the importance of appropriate selection and termination of cover crops for their successful adoption in organic conservation tillage systems.