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1. Groundwater Protection in California: Nitrogen Planning and ReportingConcern over the environmental consequences of nitrogen released into the environment from agricultural operations goes back at least to the 1970s. Through the federal Clean Water Act (1972) and various state laws dating to that same time period, government has had the power to regulate nitrogen use for decades. However, only in recent years have serious attempts to restrict agricultural N usage become widespread. In California several Regional Water Quality Control Boards have recently introduced... D. Muck, T. Hartz |
2. Improving Nitrogen Use Efficiency of Cool Season Vegetable Production Systems with Broccoli RotationsNitrate leaching in leafy vegetable production in the Salinas Valley, CA is a continuing problem. Increased levels of nitrate in groundwater resources affects the ability of municipalities to access drinking water that meet federal water quality standards. Regulations by the Central Coast Regional Water Quality Control Board are now requiring growers to improve nitrogen use efficiency (NUE) in production fields. In prior studies we found that above ground biomass nitrogen (N) at crop maturity... R. Smith, M. Cahn, T. Hartz |
3. Cropmanage: an Online Decision Support Tool for Irrigation and Nutrient ManagementVegetable and berry growers on the central coast of California are under growing regulatory pressure to reduce nitrate loading to ground and surface water supplies. Two tools available to farmers to improve nitrogen use efficiency of these crops are the soil nitrate quick test (SNQT) for monitoring soil residual N concentrations and evapotranspiration (ET)-based irrigation scheduling for estimating crop water requirements. We developed a web-based software application, called CropManage (https://ucanr.edu/cropmanage),... M. Cahn, T. Hartz, R. Smith, B. Noel, L. Johnson, F. Melton |
4. Irrigation and Nitrogen Management Web-based Software for Lettuce ProductionLettuce growers on the central coast of California are under increased regulatory pressure to reduce nitrate loading to ground and surface water supplies. Two tools available to farmers to improve nitrogen use efficiency of lettuce are the quick nitrate soil test (QNST) for monitoring soil mineral nitrogen levels and weather-based irrigation scheduling for estimating water needs of the crop. We developed a web-based software application, called CropManage (https://ucanr.edu/cropmanage), to facilitate... M. Cahn, R. Smith, T. Hartz, B. Noel |
5. Efficient N Fertility and Irrigation Management in Vegetable and Berry ProductionNitrogen (N) fertility and irrigation management for vegetable and berry production has historically been done on an ‘agronomic’ basis, with the sole focus on producing the optimal crop. For these crops N fertilizer and water costs are a small portion of overall production costs, and an even smaller portion of crop value; consequently, these inputs have not been scrutinized as closely as they have been for lower value crops. However, throughout the West concern over environmental water... T. Hartz, R. Smith, M. Cahn |
6. Regional Water Board Impacts on Vegetable Production in CaliforniaMore than 300,000 ha of vegetable crops are produced annually in the coastal valleys of central California. In these valleys vegetable production dominates the landscape, and since most fields produce two or more crops per year the annual fertilizer input is very high. Not surprisingly, environmentally problematic levels of soluble phosphorus in surface waters, and nitrate-nitrogen (NO3-N) in both surface- and groundwater, are common. The Central Coast Regional Water Quality Control Board (WQCB)... T. Hartz |
7. Efficient N Management for High-yield Vegetable ProductionVegetable production is an N-intensive industry; rates of N fertilization can be very high, particularly where multiple crops per year are produced. In vegetable production areas across the country high nitrate-nitrogen (NO3-N) concentration in surface water and groundwater is focusing regulatory scrutiny on fertilization practices. Furthermore, escalating energy prices mean higher N fertilizer costs, making efficient N management an economic as well as an environmental necessity. The basic principle... T. Hartz |
8. Elemental Sulfur with Iron: Kentucky BluegrassIron (Fe) is known to improve greenness of Kentucky bluegrass (KBG; Poa pratensis L.), although applications are relatively costly and labor intensive. A new fertilizer material, elemental sulfur impregnated with Fe (ES-Fe), may provide an alternative source of Fe for KBG. The effects of ES-Fe on KBG was evaluated comparing 55 lb-Fe ac-1 ES-Fe to ferrous sulfate (FS) at the same rate and chelated Fe as a foliar (CF) or soil applied (CS) in a glasshouse study. A separate... B. Hopkins, B. Webb, K. Marcroft, R. Christenson, V. Jolley |