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Stolons of `Raleigh', `Floratam', and FX-332 St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] were sampled from the field between October and March in two consecutive years to evaluate accuracy of an electrolyte leakage (EL) method for predicting freezing tolerance. Lethal temperatures of stolons estimated using EL were compared to those obtained by regrowth tests in the greenhouse. Mean lethal low temperatures for regrowth and EL methods over 12 sampling dates were `Floratam', –4.5C (regrowth) vs. –4.4C (EL); FX-332, –4.2C (regrowth) vs. –4.9C (EL); and `Raleigh', –6.0C (regrowth) vs. –5.4C (EL). A positive correlation (r = 0.81) was observed between EL-predicted and regrowth lethal temperatures for `Raleigh', which exhibited some acclimation during the first sampling year. The EL technique consistently predicted a lower lethal temperature for `Raleigh' than for `Floratam', which corroborates field observations concerning freezing tolerance of these two cultivars.
The Commonwealth of Virginia has mandated a recycling goal of 10% of municipal solid waste (MSW) by 1991, 15% by 1993, and 25% by 1995. Yardwaste (leaves, grass clippings, shrub and tree prunings) comprises 15% to 20% of MSW going to landfills daily. Yardwaste can be recycled by collecting material, piling it into large windrows, and allowing it to decompose by comporting. The finished product can be used as a soil amendment by nurseries, landscapers, farmers, local/state government projects, and homeowners.
The Virginia Co-op. Ext. Service at VPI&SU was authorized to perform a feasibility study on implementing a statewide yardwaste comporting program. The methods included a literature review, site visits in other states to assess technologies, and surveys to determine potential uses and users of composted yardwaste in Virginia.
The study was presented to the Virginia Dept. of Waste Mgmt. in November 1989, and as House Document No. 34 to the Virginia General Assembly. Three bills and one joint resolution are pending.
Abstract
A method of obtaining systematic records of the growth arising at each node on grape vines (Vitis vinifera L. or interspecific hybrids including this species and various American species of Vitis) is described and illustrated. Derived variables which can be calculated from these records are listed and a code is given which enables construction of tables of the derived variables by computer.
A participatory, on-farm research and extension program has been established around 16 demonstration comparisons of biologically integrated soil building–pest management systems and conventionally managed systems within the West Side row crop area of California's San Joaquin Valley. In each of the biologically integrated parcels, cover crops and composted organic materials are integrated into rotations wherever appropriate, whereas in the conventionally managed parcels, mineral fertilizer applications are made. Pest management practices are evaluated and biologically and informationally intensive alternatives are developed through a participatory process. Indices of soil quality including nutrient status, water stable aggregates, organic matter content, and phospholipid fatty acids are routinely monitored. Information related to the objectives, structure and monitoring activities of this project during the establishment phase will be discussed.
Overuse of chemical N fertilizers has been linked to nitrate contamination of both surface and ground water. Excessive use of fertilizer also is an economic loss to the farmer. Typical N application rates for processing tomato (Lycopersicon esculentum Mill.) production in California are 150 to 250 kg·ha-1. The contributions of residual soil NO3-N and in-season N mineralization to plant nutrient status are generally not included in fertilizer input calculations, often resulting in overuse of fertilizer. The primary goal of this research was to determine if the pre-sidedress soil nitrate test (PSNT) could identify fields not requiring sidedress N application to achieve maximum tomato yield; a secondary goal was to evaluate tissue N testing currently used for identifying post-sidedress plant N deficiencies. Field experiments were conducted during 1998 and 1999. Pre-sidedress soil nitrate concentrations were determined to a depth of 60 cm at 10 field sites. N mineralization rate was estimated by aerobic incubation test. Sidedress fertilizer was applied at six incremental rates from 0 to 280 kg·ha-1 N, with six replications per field. At harvest, only four fields showed a fruit yield response to fertilizer application. Within the responsive fields, fruit yields were not increased with sidedress N application above 112 kg·ha-1. Yield response to sidedress N did not occur in fields with pre-sidedress soil NO3-N levels >16 mg·kg-1. Soil sample NO3-N levels from 30 cm and 60 cm sampling depth were strongly correlated. Mineralization was estimated to contribute an average of 60 kg·ha-1 N between sidedressing and harvest. Plant tissue NO3-N concentration was found to be most strongly correlated to plant N deficiency at fruit set growth stage. Dry petiole NO3-N was determined to be a more accurate indicator of plant N status than petiole sap NO3-N measured by a nitrate-selective electrode. The results from this study suggested that N fertilizer inputs could be reduced substantially below current industry norms without reducing yields in fields identified by the PSNT as having residual pre-sidedress soil NO3-N levels >16 mg·kg-1 in the top 60 cm.
Overuse of chemical N fertilizers has been linked to nitrate contamination of both surface and ground water. Excessive fertilizer use is also an economic loss to the farmer. Typical N application rates for processing tomato production in California's Central Valley are 150-250 kg·ha-1, and growers generally fail to fully consider the field-specific effects of residual soil NO3-N concentration, or N mineralization potential of the soil. The purpose of this research was to determine the effects of sidedress N fertilizer application, residual soil NO3-N, and in-season N mineralization, on processing tomato yield. Research was conducted during the 1998 and 1999 growing seasons at 16 field sites. Pre-sidedress soil nitrate concentration was determined at each trial site to a depth of 1 m, and aerobic incubation tests were conducted on these soils (top 0.3 m depth) to estimate N mineralization rate. Sidedress fertilizer was applied at six incremental rates from 0 to 280 kg N/ha, with six replications of each treatment per field. Only five fields showed yield response to fertilizer application; yield response to fertilizer was associated with lower pre-sidedress soil nitrate levels. In most fields with fertilizer response, yield was not increased with sidedress N application above 56 kg·ha-1. Mineralization was estimated to contribute an average of ≈60 kg N/ha between sidedressing and harvest. These results suggest that N fertilizer inputs could be reduced substantially below current industry norms without lowering yields, especially in fields with higher residual soil nitrate levels.
In Fall 1995, 12 row crop farmers in conjunction with Univ. of California, NRCS and private agency advisors established the West Side On-Farm Demonstration Project to conduct demonstrations of soil and pest management options aimed at sustained profitability and environmental stewardship in the western San Joaquin Valley of California. Monitoring of soil physical, chemical, and biological properties is done in side-by-side on-farm comparisons of plots amended with organic inputs and unamended plots. Intensive monitoring of beneficial and pest insects is carried out within each comparison block, and the data generated is used to guide pest management decision-making at each site. Yields and soil characteristics of the amended plots did not differ from those of unamended plots after the first year. The on-farm context and the cooperative farmer–scientist interactions of this project facilitate the development of timely and relevant research directions to be pursued beyond the core set of monitoring activities.