Richard N. Arnold

Potato nitrogen management by monitoring petiole nitrate level

Abstract Petiole nitrate nitrogen (NO3‐N) concentrations have been successfully used in Northwestern New Mexico to make timely nitrogen (N) recommendations for irrigated potatoes. However, a quick test and consistent sampling time is needed to precisely determine fertigation and to prevent over fertilization, especially in sandy soils. This study examined the petiole NO3‐N dynamics during the growing season for both chipping and table stock varieties. Readings from a quick in‐field sap NO3‐N meter were highly correlated with NO3‐N indications using the conventional laboratory method. The sap NO3‐N meter can significantly reduce testing turnaround time and has great potential for potato N management. Results showed that most consistent NO3‐N readings could be obtained by collecting tissue samples between 1100 and 1400 hours of the day.

Growth and Survival of Drip-Irrigated Hybrid Poplar in the Semi-Arid Four Corners Region

Abstract Rapid growth rates and versatility have made hybrid poplar (Populus L.) a common choice to fulfill timber and pulp needs in temperate regions with adequate precipitation. Hybrid poplar production in drier regions has recently received interest as an irrigated source of cut logs and shredded fiber. Ten hybrid poplar clones were selected from nurseries in Washington and Oregon to determine their growth potential and water-use requirements on a calcareous soil at the NMSU Agricultural Science Center in Farmington, NM. Planted in May 2002, the clones were evaluated for survival growth characteristics over two seasons. Clones 50-194 and 184-411 had poor survival and were not continued during the 2003 season. Clone OP-367 had low chlorosis ratings, the greatest height (4.16 m), basal diameter (9.16 cm), diameter at breast height (4.65 cm) and wood volume (2.87 m3 ha-1) during both seasons. A range of responses to environmental conditions of the Four Corners region was exhibited. Mid-season leaf greenness, as determined with a SPAD-502 chlorophyll meter, was a good predictor of growth characteristics. OP-367 appeared to be a potential candidate for inclusion in drip-irrigated wood production strategies for this and other arid/semi-arid regions of the world.

Broadleaf Weed Control in Field Corn with Postemergence Herbicides

A two-year study was conducted in 2002 and 2003 at the New Mexico State University Agricultural Science Center at Farmington, NM to evaluate postemergence herbicides for control of redroot and prostrate pigweed (Amaranthus retroflexus L. and Amaranthus blitoides S. Wats.), black nightshade (Solanum nigrum L.), common lambsquarters (Chenopodium album L.), and Russian thistle (Salsola iberica Sennen & Pau) and their effect on field corn (Zea mays) injury and yield. Herbicide treatments gave over 95% control of redroot and prostrate pigweed and common lambsquarters through August, in both years. Russian thistle control was 70% or less with DPX 79406, foramsulfuron, and nicosulfuron plus rimsulfuron when applied at 0.0115 plus 0.0115, 0.033, and 0.023 plus 0.012 lb a.i./acre, or in combination with mesotrione at 0.06 lb a.i./acre. Black nightshade control with foramsulfuron applied at 0.033 lb a.i./acre was 30 to 41% better than DPX 79406 or nicosulfuron plus rimsulfuron applied at 0.0115 plus 0.0115 and 0.023 plus 0.012 lb a.i./acre. This research indicates that when nicosulfuron plus rimsulfuron, DPX 79406, and foramsulfuron were applied in combination with diflufenzopyr plus dicamba, dicamba plus atrazine, mesotrione, or dicamba, broadleaf weed control increased significantly without field corn injury or yield reductions.

Climate-Based Coefficients for Scheduling Irrigations in Urban Xeriscapes

The decrease in water supply/demand ratios in the western U.S. is stimulating the regions municipalities to implement water conservation incentives. In response, many homeowners and businesses are replacing high water-using landscapes with drip-irrigated xeriscapes. Water-requirement information for the plant species that comprise these xeriscapes is lacking. Consequently, plants may still receive more water than necessary to sustain acceptable growth and appearance and water may not be conserved. The objectives of this project were to evaluate the growth and aesthetic quality of various drought-tolerant plants that have potential for use in urban landscapes of the western U.S. Intermountain zone under variable levels of microirrigation and then to formulate climate-based (Penman-Monteith reference ET), landscape coefficients (KL) or plant factors (PF) that may be used along with measurements of plant canopy area to develop effective irrigation scheduling recommendations for these plants. A xeriscape garden was split into four differentially irrigated sections (0, 20, 40, and 60% of reference ET) and at least one individual of more than 90 plant species were planted into each section. An average canopy area was used to adjust irrigation treatments and then actual plant canopy measurements were used to formulate PF for each species. While PF varied significantly between species, results indicate that an overall KL or PF of about 0.3 may be appropriate for water management planning on xeric landscapes.