Comparisons of organic and conventional maize and tomato cropping systems from a long-term experiment in California

Yield differences and trends, organic matter accumulation, and the loss of nutrients to deeper soil horizons are discussed using data from organic and conventional maize/tomato cropping systems from the Long Term Research on Agricultural Systems Project (LTRAS) at the University of California, Davis. Compared to the conventional system, higher and increasing yields of tomatoes were observed in organic systems, but lower yields of maize. Fruit quality, measured as soluble solids, was not significantly different. Soil organic matter increased in the organic system, but remained stable in the conventional one. More irrigation water was used in the organic system than in the conventional one due to higher rates of infiltration, but less winter runoff occurred during the rainy season for the same reason. There was no measurable loss of inorganic N (NO3, NH4) in soil to 3 m depth in either the conventional or organic system after ten years of farming

Economic sustainability modeling provides decision support for assessing hybrid poplar-based biofuel development in California

Biofuels are expected to play a major role in meeting California's long-term energy needs, but many factors influence the commercial viability of the various feedstock and production technology options. We developed a spatially explicit analytic framework that integrates models of plant growth, crop adoption, feedstock location, transportation logistics, economic impact, biorefinery costs and biorefinery energy use and emissions. We used this framework to assess the economic potential of hybrid poplar as a feedstock for jet fuel production in Northern California. Results suggest that the region has sufficient suitable croplands (2.3 million acres) and nonarable lands (1.5 million acres) for poplar cultivation to produce as much as 2.26 billion gallons of jet fuel annually. However, there are major obstacles to such large-scale production, including, on nonarable lands, low poplar yields and broad spatial distribution and, on croplands, competition with existing crops. We estimated the production cost of jet fuel to be $4.40 to$5.40 per gallon for poplar biomass grown on nonarable lands and $3.60 to$4.50 per gallon for biomass grown on irrigated cropland; the current market price is $2.12 per gallon. Improved poplar yields, use of supplementary feedstocks at the biorefinery and economic supports such as carbon credits could help to overcome these barriers

Review of research to inform California's climate scoping plan: Agriculture and working lands

Agriculture in California contributes 8% of the state's greenhouse gas (GHG) emissions. To inform the state's policy and program strategy to meet climate targets, we review recent research on practices that can reduce emissions, sequester carbon and provide other co-benefits to producers and the environment across agriculture and rangeland systems. Importantly, the research reviewed here was conducted in California and addresses practices in our specific agricultural, socioeconomic and biophysical environment. Farmland conversion and the dairy and intensive livestock sector are the largest contributors to GHG emissions and offer the greatest opportunities for avoided emissions. We also identify a range of other opportunities including soil and nutrient management, integrated and diversified farming systems, rangeland management, and biomass-based energy generation. Additional research to replicate and quantify the emissions reduction or carbon sequestration potential of these practices will strengthen the evidence base for California climate policy

Farming in transition: Analysis – Scientists and farmers try new approach to research

The Sustainable Agriculture Farming Systems Project is one of several newer, large-scale experiments that have contrasted idealized cropping practices with existing ones. The common objective of these experiments has been to develop and compare cropping systems substantially different from current practice, with each system following separate rules of management. Difficult conceptual and methodological issues arise when both development and research are objectives in a project, and when many factors change simultaneously

Can feedstock production for biofuels be sustainable in California?

The use of crops and crop residues as feedstocks for biofuels increases domestic and global supplies, creates new industries, and may result in reduced greenhouse-gas emissions. Uncertainty about the best crop and residue sources, technologies for manufacture, future public policy, and the global supply and price of oil make it difficult to predict the best approach. California growers can produce feedstocks from grain, oilseed and woody crops and, in the Imperial Valley, from sugar cane. If the technology for making ethanol or other liquid fuels from cellulose becomes cost-effective, then saline and other wastewaters may be used in biofuel feedstock production of salt-tolerant crops, particularly perennial grasses. However, recent global increases in biofuel production have raised questions about their impacts on food and feed prices, climate change and deforestation. New state laws affecting energy use and mandating greenhouse-gas reductions require that the sustainability of all biofuels be assessed. Sustainability should take into account factors at both the global and local scales, including resource-use efficiency, cropping-system adaptability and the potential of biofuels to remediate agriculture’s environmental effects

Stephen Kaffka: Pioneering UCSC Farm and Garden Manager, Agronomist

Stephen (Steve) Kaffka came to UC Santa Cruz as a philosophy student in 1967 and began volunteering in Alan Chadwick’s Student Garden Project in the same year. He worked side-by-side with Alan Chadwick and eventually became the student president of the Garden in 1968. In this oral history, conducted by Ellen Farmer at her house in Santa Cruz, California on August 31, 2007, Kaffka shares his recollections of Alan Chadwick and the Garden in the late 1960s and early 1970s, as well as the period after Chadwick left, when Kaffka managed the Farm and Garden and formalized the apprentice program through University of California Santa Cruz Extension.Although Alan Chadwick was deeply troubled by the specialization and fragmentation of scientific practice within the academy, paradoxically, Kaffka, perhaps Chadwick’s closest apprentice at UCSC, ended up with a distinguished career as a research agronomist. After he left UC Santa Cruz in 1977, Kaffka earned his Ph.D. in agronomy from Cornell University, and now directs UC Davis’s Center for Integrated Farming Systems. He is also director of the California Biomass Collaborative and extension specialist in the Department of Plant Sciences at the University of California, Davis. He chairs the BioEnergy Work Group for the University of California’s Division of Agriculture and Natural Resources, and participates on several advisory committees for the California Energy Commission and California Air Resources Board. Kaffka conducts research on water quality and agriculture in the Upper Klamath Basin, and the reuse of saline drainage water for crop, forage, energy biomass feedstocks and livestock production in salt-affected areas of the San Joaquin Valley. He has M.S. and Ph.D. degrees from Cornell University in agronomy and a B.S. from UC Santa Cruz in biology. In May, 2008, Kaffka was the subject of an NPR documentary, “Are Organic Tomatoes Better?” which featured his research comparing the nutritious value of organic versus conventionally grown tomatoes

Saline water can be reused to irrigate sugarbeets, but sugar may be low

Salt is currently being transported into the San Joaquin Valley via rivers and irrigation water at about three times the rate that it is being removed, endangering the productivity of agricultural land. As a possible salt-management solution, the San Joaquin Valley Drainage Implementation Program seeks to reuse saline water, such as tile drainage water or shallow well water, in crop production. Sugarbeet is a deep-rooted, salt-tolerant crop that can be used as part of a cyclic reuse program to reduce drainage-water volume and conserve high-quality water. Although sugarbeets grown with saline water produced adequate yields on test plots, sugar percentages declined because nitrogen also was present in the irrigation water source. For this reason, irrigating sugarbeets with alternative water sources is more complex, requiring accounting of nitrogen in reused water together with soil nitrogen to assure adequate crop quality