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While it is recognized that farming alternatively is inherently knowledge intensive, in the United States, farmer knowledge has been widely overlooked and under-documented within the scientific literature. Farmer knowledge of soil in particular is understudied in the US, especially given that healthy soils have been identified as the basis for resilient agriculture. Applying an exploratory, case study approach, we interviewed 13 organic farmers based in Yolo County, California to understand how organic farmers in this region acquire knowledge about their soils, to document what organic farmers in this region know about their soils, and to share key management practices organic farmers use to build soil health in the region. We found the organic farmers in this study acquire knowledge about their farming systems primarily through direct observation, personal experience, experimentation, and inherited wisdom. To evaluate soil health, farmers in this study cited using a range of indicators, including soil structure, crop health, growth habits of weeds, and soil biology. We found that these organic farmers possess extensive place-based knowledge of their local farming systems, and that this knowledge base represents an important source for innovation and adaptive management in scientific and policy-making contexts. [ABSTRACT FROM AUTHOR]

Fresh-market tomatoes (Lycopersicon esculentum Mill.) are increasingly produced with subsurface drip irrigation in California, as growers adapt to decreased water availability. Drip irrigation improves water use efficiency, but may reduce the soil volume where conditions are optimal for microbial and root activity. This poses complications for organic growers, whose cropping systems are dependent on microorganisms to convert the nitrogen (N) from organic sources into plant-available N. To investigate grafting as a potential practice to increase access to N, grafted and non-grafted "Brandywine" heirloom tomatoes were grown with drip irrigation in a two-year field trial. The three rootstocks were "Maxifort," "Fortamino," and "DRO138TX." Prior to each growing season, a legume cover crop mix was grown and labeled with 15N ammonium sulfate to track tomato N uptake from cover crop residues. There were no significant differences in yield, N uptake and N partitioning in the plants due to rootstock treatments. Leaf analyses suggested that the tomato plants were not N deficient in either year. However, there was a significant difference in total N uptake from cover crop residues between years. This was caused by large differences in N concentration in the cover crop. Plants responded to a lower N availability by producing less vine biomass, while producing the same fruit yield. A budget revealed that the tomato plants accessed a considerable amount of N from the soil below 60 cm of the profile to cover their demand. [ABSTRACT FROM AUTHOR]

Composts can have beneficial effects on strawberry production and these benefits can be dependent on the type of compost used. Four commercial composts were evaluated: cow manure, spent mushroom, yard trimmings, and vermicompost. The nutrient composition, abundance of fungi and bacteria, and microbial activity were determined. Five field trials assessed effects on plant growth, root development, soil microbial activity, nutrient availability, and yield during one growing season. Manure and mushroom compost significantly increased soil electrical conductivity levels to 9.9 ± 1.7 dS/m and 7.3 ± 0.8 dS/m, respectively. Manure, yard trimmings, and mushroom composts shifted soil pH toward optimal levels for up to 7 months. Mushroom compost had the greatest effect on soil nitrate, which was up to 32 mg/kg of soil higher than non-amended soil. Significant effects on yield were more likely to occur where environmental conditions and management practices were less than optimal or compost was not routinely added. Several factors important to plant production were significantly affected by compost: soil salinity, plant establishment, soil nitrate, production curves, soil microbial activity, and soil pH. [ABSTRACT FROM PUBLISHER]

The article discusses the influence of several factors in strawberry production in California including land stewardship, soilborne pathogens and climate. It highlights the decline availability of suitable land to produce an acceptable yield of strawberries. It also cites the use of preplant soil fumigation for strawberry production.

Presents informations during the annual business meeting of American Psychological Association in San Francisco, California. Status of affiliate membership; Expenses for the Division's four annual teaching awards; Total budget for 1992.