Traveler Gun Irrigation of Field Grown Nursery Stock

The objective of this study was to determine annual irrigation costs for field-grown plants in Ohio by species of plant and size of firm. This objective was accomplished by synthesizing two model field nurseries using an economic engineering approach. Once the nurseries were simulated, growing space was divided into five equal parts with each segment being assigned a plant group. In the 50-acre nursery each group was allocated 8 acres of field production plus corresponding space in the propagation house, overwintering facility, holding area, and field bed area. In the 200-acre nursery each plant group was allocated 35 acres, plus corresponding space in the central facility. In each plant group, one specific species was chosen as representative for the group. Total costs of installing irrigation systems were estimated at about $82,500 for a 50-acre field nursery and$167,800 for a 200-acre field nursery. Total annual costs for irrigating the 50-acre nursery were $15,095. Irrigation costs per salable plant (represents the total costs of irrigating the plant from the time it is placed in the field bed as a liner until sale) were$0.73 for slow growing evergreens (Taxus), $0.52 for fast growing evergreens (Juniperus),$0.49 for deciduous shrubs (Viburnum), $1.62 for shade trees (Acer rubrum),$1.11 for ornamental trees (Malus), and averaged $0.73 for all species, In the 50-acre nursery, costs of irrigation were approximately 3.3$35,355. Per salable plant costs were $0.39 for slow growing evergreens (Taxus),$0.28 for fast growing evergreens (Juniperus), $0.26 for deciduous shrubs (Viburnum),$0.86 for shade trees (Acer rubrum), $0.59 for ornamental trees (Malus), and averaged$0.39 for all species. Costs of irrigation were about 2.9% of total annual costs for the 200-acre nursery. Costs of irrigation averaged approximately 87% higher per salable plant in the 50-acre nursery than in the 200-acre. Large-size commercial field nurseries use equipment and labor more efficiently than small-sized nurseries. As a result, large nurseries have a lower cost of irrigation per salable plant

Atmospheric dry and wet deposition of sulphur and nitrogen species and assessment of critical loads of acidic deposition exceedance in South Africa

We tested the hypothesis that acidic atmospheric pollution deposition, originating from the South African central industrial area, poses an environmental threat across a larger region within the dispersal footprint. A network of 37 passive monitoring sites to measure SO2 and NO2 was operated from August 2005 to September 2007. The area extended over the entire northern and eastern interior of South Africa. Monitoring locations were chosen to avoid direct impacts from local sources such as towns, mines and highways. Dry deposition rates of SO2 and NO2 were calculated from the measured concentrations. Concentrations of sulphur and nitrogen species in wet deposition from a previous study were used in conjunction with measured rainfall for the years 2006 and 2007 to estimate the wet deposition over the region. The calculated total (non-organic) acidic deposition formed the basis for an assessment of exceedance of critical loads based on sensitivity of the regional soils. Regional soil sensitivity was determined by combining two major soil attributes available in the World Inventory of Soil Emission Potentials (International Soil Reference and Information Centre). Results indicate that certain parts of the central pollution source area on the South African Highveld have the potential for critical load exceedance, while limited areas downwind show lower levels of exceedance. Areas upwind and remote areas up and downwind, including forested areas of the Drakensberg escarpment, do not show any exceedance of the critical loads