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California Agriculture, Vol. 51, No.5

Busting the dust: New PM-10 rules have uncertain ag impact
Cover:  Research has shown that respirable dust comes from soil. UC Davis scientists are measuring the amount of PM-10 generated by farming activities and analyzing its elemental content. Filtering devices sample air at different heights from the tower at center, and from the array of equipment at left, during wheat harvest near Kettleman City... Photo by Terry James .
September-October 1997
Volume 51, Number 5

Peer-reviewed research and review articles

Modified almond harvester reduces orchard dust
by Randal J. Southard, Robert J. Lawson, Henry E. Studer, Maria Brown
| Full text HTML  | PDF  
The conventional almond harvester pro duced about nine times as much total dust and six times as much respirable dust as the modified harvester.
Growing concern over the impacts of air quality on human health and the possible links between agricultural production and air quality has sparked interest in determining which agricultural practices produce significant amounts of dust and how dust generation can be reduced. A comparison of the dust generated by a conventional almond harvester with dust generated by a harvester modified to reduce dust was made by measuring particulate matter collected on air sampling filters in an orchard in the Sacramento Valley. Results show that the modified harvester produced significantly less respirable and total dust Equipment modification holds considerable potential to reduce occupational exposure to dust and to reduce impacts of agriculture on ambient air quality.
Computer model improves real-time management of water quality
by Nigel W.T. Quinn, Leslie F. Grober, Jo-Anne Kipps, Carl W. Chen, Earle Cummings
| Full text HTML  | PDF  
A forecasting model helps coordinate west-side agricultural and wetlands drainage with east-side reservoir releases to meet objectives for salt, boron and selenium levels in the San Joaquin River.
Members of the San Joaquin River Management Program's Water Quality Subcommittee have developed a water-quality forecasting model to help improve the timing, coordination and management of agricultural drainage and reservoir releases into the San Joaquin River. The goal of this effort is to improve water quality in the San Joaquin River and to meet federal and state water-quality objectives for salt, boron and selenium. A graphical user interface has been developed and features have been added to make this computer software useful and accessible to a wide range of decision makers.
Crust-breaking device improves water infiltration into furrows
by Shrini K. Upadhyaya, J. Jafari Far, Sayedahmad Shafii, H. Abdel Fattah
| Full text HTML  | PDF  
Breaking the crust near the furrow bot tom, along the sides of the bed, im- proved infiltration and reduced water losses to evaporation.
Surface irrigation may lead to thick depositional crusts at the soil surface, which can reduce infiltration rate. To break the crust on the sides of the bed near the bottom of a furrow, we developed a torpedo-shaped, winged cultivator. Field experiments were conducted on a tomato crop at UC Davis on Yolo loam soil during the summer of 1992. Breaking the crust with the device increased cumulative infiltration significantly, by almost 30%.
Community programs promote tree care
by Robert Sommer
| Full text HTML  | PDF  
Residents who participated in an organized tree planting program were more likely to have positive attitudes toward their trees.
Trees provide shade, reduce noise and make cities more attractive, among other benefits, but their survival depends on long-term care from humans. A survey of residents in three California cities found that people who planted trees themselves were more satisfied with the outcome than residents whose trees were planted by a city employee or a developer. Residents who participated in an organized planting program were also more likely to receive information on tree maintenance. Overall, 90% of the program participants received maintenance information, compared with only 16% of the nonparticipants.
Weed control improves survival of transplanted blue oak
by Theodore E. Adams, Peter B. Sands, William B. McHenry
| Full text HTML  | PDF  
Use of herbicides, porous plastic mulch mats and impervious plastic mats resulted in greater survival of blue oak seedlings than those grown with no weed control.
Weed competition is recognized as a factor affecting survival of California blue oak seedlings in artificial plantings. Three alternative weed-control strategies were examined in a series of annual plantings at two locations using 2- to 3-month-old nursery stock. The effects of herbicides, porous plastic mulch mats and impervious plastic mats were compared. No one strategy was superior, but all resulted in greater seedling survival than with no weed control, and generally also resulted in taller blue oaks. Use of herbicides was the least-expensive weed-control method. Much of the seedling mortality was attributed to depredation by rodents.
Dairy producers value DHIA milk testing, but some deterred by cost
by Gerald E. Higginbotham, Steven L. Berry, Kenneth E. Lanka, William R. VerBoort, Robin Seldin, Cathy Dei
| Full text HTML  | PDF  
A survey of the California Dairy Herd Improvement Association found that most members value production data provided by DHIA, but some quit because they think the program is too expensive.
A survey was conducted to assess the attitudes of past and current members of the California Dairy Herd Improvement Association (CDHIA) toward the DHIA program. Members placed importance on service and production data. Northern and southern DHIA members rated their local DHIA supervisor high with regard to knowledge and service. All regions rated their local DHIA management high with regard to knowledge and service. Over 50% of the northern and southern DHIA members rated laboratory service high. All regions were satisfied with the service of the dairy records processing centers. Cost and the dairies' adoption of on-farm milk-weight meters and/or computers were the most frequently cited reasons for discontinuing DHIA membership. Based on information collected in this survey, CDHIA members continue to look to DHIA records for production and management information.
Calcium chloride reduces rain cracking in sweet cherries
by Michael Rupert, Stephen Southwick, Kitren Weis, John Vikupitz, James Flore, Hong Zhou
| Full text HTML  | PDF  
Preliminary tests show that automated overtree application of calcium chloride reduces rain cracking in California sweet cherries and may also reduce postharvest decay.
Rain cracking of sweet cherry fruit is a worldwide problem and has resulted in substantial crop losses of California cherries in each of the past 4 years (1993–1996). Various strategies to reduce cracking have provided inconsistent results. During 1996, however, rain-timed applications of calcium chloride (CaCl2) via overtree sprinklers reduced the overall percentage of rain-cracked ‘Bing’ cherry fruit by nearly half at three locations in the Central Valley. Although these results were obtained in only one season, their consistency across sites is encouraging. In addition, a preliminary observation suggests this calcium treatment may also reduce postharvest disorders of rain-exposed fruit without affecting fruit firmness, size or weight. Some marginal leaf necrosis was noted at one site, suggesting that application rates may need to be adjusted. Overtree delivery of calcium chloride during rain provides the potential for cherry growers to reduce fruit cullage from rain. While the setup and operational costs are substantial, the increases in marketable fruit may make this system a profitable investment.
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California Agriculture, Vol. 51, No.5

Busting the dust: New PM-10 rules have uncertain ag impact
Cover:  Research has shown that respirable dust comes from soil. UC Davis scientists are measuring the amount of PM-10 generated by farming activities and analyzing its elemental content. Filtering devices sample air at different heights from the tower at center, and from the array of equipment at left, during wheat harvest near Kettleman City... Photo by Terry James .
September-October 1997
Volume 51, Number 5

Peer-reviewed research and review articles

Modified almond harvester reduces orchard dust
by Randal J. Southard, Robert J. Lawson, Henry E. Studer, Maria Brown
| Full text HTML  | PDF  
The conventional almond harvester pro duced about nine times as much total dust and six times as much respirable dust as the modified harvester.
Growing concern over the impacts of air quality on human health and the possible links between agricultural production and air quality has sparked interest in determining which agricultural practices produce significant amounts of dust and how dust generation can be reduced. A comparison of the dust generated by a conventional almond harvester with dust generated by a harvester modified to reduce dust was made by measuring particulate matter collected on air sampling filters in an orchard in the Sacramento Valley. Results show that the modified harvester produced significantly less respirable and total dust Equipment modification holds considerable potential to reduce occupational exposure to dust and to reduce impacts of agriculture on ambient air quality.
Computer model improves real-time management of water quality
by Nigel W.T. Quinn, Leslie F. Grober, Jo-Anne Kipps, Carl W. Chen, Earle Cummings
| Full text HTML  | PDF  
A forecasting model helps coordinate west-side agricultural and wetlands drainage with east-side reservoir releases to meet objectives for salt, boron and selenium levels in the San Joaquin River.
Members of the San Joaquin River Management Program's Water Quality Subcommittee have developed a water-quality forecasting model to help improve the timing, coordination and management of agricultural drainage and reservoir releases into the San Joaquin River. The goal of this effort is to improve water quality in the San Joaquin River and to meet federal and state water-quality objectives for salt, boron and selenium. A graphical user interface has been developed and features have been added to make this computer software useful and accessible to a wide range of decision makers.
Crust-breaking device improves water infiltration into furrows
by Shrini K. Upadhyaya, J. Jafari Far, Sayedahmad Shafii, H. Abdel Fattah
| Full text HTML  | PDF  
Breaking the crust near the furrow bot tom, along the sides of the bed, im- proved infiltration and reduced water losses to evaporation.
Surface irrigation may lead to thick depositional crusts at the soil surface, which can reduce infiltration rate. To break the crust on the sides of the bed near the bottom of a furrow, we developed a torpedo-shaped, winged cultivator. Field experiments were conducted on a tomato crop at UC Davis on Yolo loam soil during the summer of 1992. Breaking the crust with the device increased cumulative infiltration significantly, by almost 30%.
Community programs promote tree care
by Robert Sommer
| Full text HTML  | PDF  
Residents who participated in an organized tree planting program were more likely to have positive attitudes toward their trees.
Trees provide shade, reduce noise and make cities more attractive, among other benefits, but their survival depends on long-term care from humans. A survey of residents in three California cities found that people who planted trees themselves were more satisfied with the outcome than residents whose trees were planted by a city employee or a developer. Residents who participated in an organized planting program were also more likely to receive information on tree maintenance. Overall, 90% of the program participants received maintenance information, compared with only 16% of the nonparticipants.
Weed control improves survival of transplanted blue oak
by Theodore E. Adams, Peter B. Sands, William B. McHenry
| Full text HTML  | PDF  
Use of herbicides, porous plastic mulch mats and impervious plastic mats resulted in greater survival of blue oak seedlings than those grown with no weed control.
Weed competition is recognized as a factor affecting survival of California blue oak seedlings in artificial plantings. Three alternative weed-control strategies were examined in a series of annual plantings at two locations using 2- to 3-month-old nursery stock. The effects of herbicides, porous plastic mulch mats and impervious plastic mats were compared. No one strategy was superior, but all resulted in greater seedling survival than with no weed control, and generally also resulted in taller blue oaks. Use of herbicides was the least-expensive weed-control method. Much of the seedling mortality was attributed to depredation by rodents.
Dairy producers value DHIA milk testing, but some deterred by cost
by Gerald E. Higginbotham, Steven L. Berry, Kenneth E. Lanka, William R. VerBoort, Robin Seldin, Cathy Dei
| Full text HTML  | PDF  
A survey of the California Dairy Herd Improvement Association found that most members value production data provided by DHIA, but some quit because they think the program is too expensive.
A survey was conducted to assess the attitudes of past and current members of the California Dairy Herd Improvement Association (CDHIA) toward the DHIA program. Members placed importance on service and production data. Northern and southern DHIA members rated their local DHIA supervisor high with regard to knowledge and service. All regions rated their local DHIA management high with regard to knowledge and service. Over 50% of the northern and southern DHIA members rated laboratory service high. All regions were satisfied with the service of the dairy records processing centers. Cost and the dairies' adoption of on-farm milk-weight meters and/or computers were the most frequently cited reasons for discontinuing DHIA membership. Based on information collected in this survey, CDHIA members continue to look to DHIA records for production and management information.
Calcium chloride reduces rain cracking in sweet cherries
by Michael Rupert, Stephen Southwick, Kitren Weis, John Vikupitz, James Flore, Hong Zhou
| Full text HTML  | PDF  
Preliminary tests show that automated overtree application of calcium chloride reduces rain cracking in California sweet cherries and may also reduce postharvest decay.
Rain cracking of sweet cherry fruit is a worldwide problem and has resulted in substantial crop losses of California cherries in each of the past 4 years (1993–1996). Various strategies to reduce cracking have provided inconsistent results. During 1996, however, rain-timed applications of calcium chloride (CaCl2) via overtree sprinklers reduced the overall percentage of rain-cracked ‘Bing’ cherry fruit by nearly half at three locations in the Central Valley. Although these results were obtained in only one season, their consistency across sites is encouraging. In addition, a preliminary observation suggests this calcium treatment may also reduce postharvest disorders of rain-exposed fruit without affecting fruit firmness, size or weight. Some marginal leaf necrosis was noted at one site, suggesting that application rates may need to be adjusted. Overtree delivery of calcium chloride during rain provides the potential for cherry growers to reduce fruit cullage from rain. While the setup and operational costs are substantial, the increases in marketable fruit may make this system a profitable investment.

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