Small low-head diversion dams are capable of removing much of the flow of a river, often resulting in increased water temperatures and habitat loss. Warmer temperatures have been shown to accelerate aquatic invertebrate growth and development, and discharge reductions can reduce instream habitat, suggesting that water withdrawals may alter both...
This study focuses on one widespread characteristic of poor soil quality: hydrophobic soil. Previous research has produced conclusive evidence to show that soil hydrophobicity is affected by soil organic matter (SOM) and soil water content (WC). Hydrophobicity that responds to changes in WC is a unique form of surface hydrophobicity...
Ammonia (NH₃) volatilization and loss from nitrogen (N) fertilizer in agriculture negatively impacts crops, farm profitability, human health and surrounding ecosystems where it is deposited. A significant source of NH₃ volatilization occurs from surface application of urea on sandy soils with low pH buffering capacity such as those in the...
Ammonia (NH₃) volatilization can result in a substantial amount of surface applied nitrogen (N) being lost into the atmosphere, making it an environmental pollutant as well as reducing plant-available N. However, N can also be easily lost from the soil through leaching,
and nitrous oxide (NO₂). Enhanced efficiency N fertilizers...
Grass seed production in Oregon's Willamette Valley traditionally relied on open field burning for straw residue disposal and nutrient recycling. Changes in residue management from open field burning to methods that remove straw coincided with rapidly declining K soil test values. A survey of grass seed fields showed that many...
Christmas tree needle sampling to evaluate nutrient need is an established practice. Data to support the recommended fall sampling time in Oregon and Washington was not found. In addition, the recommendation for needle sampling of Fraser fir in North Carolina was made without data from winter months. The goal for...
The comfortable, sunny climate and numerous
recreational activities east of the Cascade Mountain
Range in Oregon and Washington attract many
new residents each year. Unfortunately, these new residents
often fi nd that their previous gardening experience doesn’t
translate into success in their new environment. Long-time
residents also are frustrated by...
The use of management units for soil testing and nutrient application is an
effective strategy to increase accuracy in monitoring and managing nitrogen (N), phosphorus (P), and other nutrients. A management unit can be a group of fields, a single field, or an area within a field. To measure changes...
In 2 consecutive years, ground beetles (Coleoptera: Carabidae) were sampled in commercial organic and conventional potato fields, using pit fall traps. Four conventional and 3 organic potato fields were surveyed to determine ground beetle taxa composition. In a related study, potato fields were assigned to 1 of 4 transitional systems...
Nitrogen can be lost when the quantity of available nitrogen exceeds crop demand or nitrogen availability is not in synchrony with crop demand. Either situation results in accumulation of available nitrogen, primarily in the nitrate form, at the end of the growing season. Over-winter nitrogen loss occurs primarily as nitrate-...