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To understand how soil color is influenced by soil components at the farm scale, we evaluated spatial variation in soil color and related soil properties in Japanese paddy fields. After harvest of rice, 246 surface soil samples were collected in 10-m grids from five contiguous irrigated paddy fields, each with an area of about 0.5 ha. The samples were analyzed to determine color parameters (L*, a*, and b*), and contents of total C, total N, Fe oxides, sand, and loss-on-ignition. The results obtained were modeled and mapped geostatistically. All color parameters indicated strong spatial dependence with long ranges (>85 m). In contrast, total C and N showed short ranges (about 40 m). The contents of Fe oxides, sand, and loss-on-ignition showed intermediate ranges (50–85 m). The ranges of these properties and their distribution patterns suggested that the contents of total C and N were influenced by long-term application of manure and that sand content was influenced by topography and past land consolidation. Further soil color analysis after removal of organic matter or silt plus clay particles revealed that soil organic matter, texture, and Fe oxides affected soil color parameters in a complex manner. Prediction of total C from soil darkness was hindered by the presence of silt plus clay particles containing Fe oxides. On the other hand, citrate-dithionite extractable Fe was estimated accurately from the b* value (yellowness), which can be useful for predicting the occurrence of akiochi (autumn decline) disease of rice at the farm scale. [ABSTRACT FROM AUTHOR]

Organic farming practices are a possible way to reconcile agricultural production and water quality, but the comparative merits of conventional and organic farming practices regarding the nitrogen (N) issue are complex and still being debated. This study was designed to investigate the choices governing conversion to organic farming of an experimental mixed dairy farm in Lorraine (eastern France) and to highlight the associated changes in N fluxes. The study was conducted over a suitably long period of time at a farm scale integrating the diversity of practices in one conventional and then two autonomous organic systems (a grazing livestock system and a mixed dairy system). Two indicators were used to draw up the main features. First, the farm-gate N budgets show that the organic farm has a balance twice as low as the conventional system. Second, the soil surface balance exhibited substantial differences between functional zones. Finally, this study shows that an accurate estimation of soil surface balance requires taking into account the spatial distribution within the farm area based on practices and their rationale. [ABSTRACT FROM PUBLISHER]

In a time of shrinking public budgets, determining the most appropriate Land Grant University (LGU) response to expanding crises in the agri-food system has critical implications. Is the most effective role for public scientists to develop cutting-edge technologies that enable industrially organized farms to improve production efficiencies and compete more favorably in global markets? What is the distinctive function of public sector research and extension given increasingly sophisticated private information providers? Using data from a large scientific survey of Wisconsin farmers, this study explores views of representative farmers on the current directions of the LGU system and assesses who is benefiting from existing programs. While overall farmer support for a public system of research and extension is high, findings suggest that the goals of some programs may be at odds with many respondents' needs. The results also reveal an unmistakable bias in the types of farms that appear to be benefiting from LGU resources, with smaller and diversified farms being largely underserved. However, they also suggest broad based support for research and extension initiatives targeted at sustainable agriculture priorities. [ABSTRACT FROM AUTHOR]