No abstract

Outdoor lighting incapacitates and destroys some moths. It disturbs flight, navigation, vision, migration, dispersal, oviposition, mating, feeding, and crypsis. It may also snift circadian rhythms. Lamps may incinerate or desiccate moths, or lead to moth’s destruction by birds, bats, spider, and vehicular traffic. Conservation efforts need to consider disruptive ecological effects of outdoor lighting. Low pressure sodium lamps may reduce these effects.

The cumulative effects of management practices on nitrate‐nitrogen (NO3‐N) leaching and groundwater quality are frequently difficult to document because of the time required for expression and the diversity of interacting processes involved. This work reports results of a N and water management program initiated by the Central Platte Natural Resource District (CPNRD) in Nebraska. Cultural practices recommended by the CPNRD and reported by producers for the 1988 growing season, representing approximately 3900 fields covering 84 210 ha of irrigated corn (Zea mays L.) indicated NO3‐N contamination of groundwater was influenced by yield goals and fertilizer N application rates. Groundwater NO3‐N concentrations were positively correlated with residual N in the surface 0.9 m of soil prior to the growing season, reflecting the effects of past N and water management practices. Yield goals in 1988 averaged 9% higher than the average 10.0 Mg ha−1 corn yield attained, which accounts for an average of about 20 kg N ha−1 in excess of the average N recommendation. By comparison, in a 1980 to 1984 study from an area within the CPNRD, yield goals averaged 28% greater than actual yields. Overly optimistic yield goals in 1988 accounted for 42% of the average excess N application rate of 48 kg ha−1 (based on University of Nebraska recommendations). A large portion of average excess N application is attributed to producers in 14% of the area who applied >100 kg N ha−1 more than the recommended rates. Fertilizer N applied showed little relationship to fertilizer N recommended. Better education and more stringent measures may be required to address the select group of producers who fail to follow CPNRD recommendations.

Philosophical differences exist in the interpretation and recommendations made from soil test values acquired by different organizations that provide advice to farmers on fertilizer use. It was the objective of this study to evaluate the economic and agronomic impacts of these varied philosophies with particular reference to concepts of cation ratio, nutrient maintenance, and nutrient sufficiency level. Field experiments were conducted during 1973–1980 on four major soils of Nebraska comparing yields of corn (Zea mays L.) grown with fertilizer treatments as recommended by five soil testing laboratories operating in the state. The 29 field comparisons revealed no real yield differences despite wide variation in number, rate, and cost of nutrients applied. Since soil test levels are increasing or at least holding steady with the “nutrient sufficiency” approach to soil testing, we find no economic or agronomic basis for the “balance” or “maintenance” concepts on these representative soils of the western Corn Belt. Not to be overlooked are environmental implications nor the waste of energy and resources from any approach responsible for excessive fertilizer use. It is recognized that reserves of available nutrients in the deep subsoils and underlying soil‐forming materials in this region have a substantial bearing on soil test calibration and that different calibrations may exist with less favorable subsoil rooting conditions.

Action spectra were determined for lightinduced phase shifts of the circadian rhythm of adult emergence in Drosophila pseudoobscura. The action spectra for advance and delay phase shifts are similar; the most effective wavelengths are in the blue region, with a sharp cutoff above 500 nanometers. This similarity suggests that the same photoreceptive pigment mediates both advance and delay phase shifts.