Dave L. Bjorneberg

Evaluation of In-Row Plant Spacing and Planting Configuration for Three Irrigated Potato Cultivars

Research studies have shown that planting potatoes (Solanum tuberosum L.) in a bed configuration can improve water movement into the potato root zone. However, plant spacing recommendations are needed for potatoes planted in a bed configuration. This study was conducted to evaluate the effect of in-row plant spacing and planting configuration on yield of Russet Burbank, Russet Norkotah, and Ranger Russet potatoes under sprinkler irrigation. For the three cultivars, the effect of in-row plant spacing (three spacing treatments) for each planting configuration (4 row conventional ridged-row [4RC], 5 row bed [5RB], and 7 row bed [7RB]), and the effect of planting configuration at a uniform population on total tuber yield, U.S. No. 1 tuber yield, tubers per ha, average size (by weight), and large tuber yield were investigated at the USDA-ARS Northwest Irrigation & Soils Research Lab in Kimberly, ID on a Portneuf silt loam (coarse-silty mixed mesic Durixerollic Calciorthid) in 2008 and 2009. The greatest influence of in-row plant spacing was on average size and tubers per ha. In general, as in-row plant spacing increased (plant population decreased) the average tuber size increased and tubers per ha decreased. There was little influence of in-row spacing on measured production variables under the bed planting configurations except for tubers per ha which generally increased with narrower plant spacing. For Russet Norkotah and Ranger Russet there were few differences in measured production variables between planting configuration treatments. For Russet Burbank, the 4RC planting configuration had 14.6% significantly greater total tuber yield than the 7RB planting configuration, 20.2% greater U.S. No. 1 tuber yield than both bed planting configurations, and 25.2 and 29.9% greater large tuber yield than the 5RB and 7RB planting configurations, in 2009. Optimum production of Russet Norkotah and Ranger Russet potatoes is possible under all the planting configurations and plant spacing range evaluated in this study, granting growers flexibility in their systems, however, evidence from this study suggests that production of Russet Burbank may be less suited to bed planting configurations.ResumenInvestigaciones han demostrado que plantar papa (Solanum tuberosum L.) en una configuración de cama puede mejorar el movimiento del agua hacia la zona de la raíz de la papa. No obstante, se necesitan las recomendaciones de espaciamiento de plantas de papa sembradas en la configuración de cama. Este estudio se condujo para evaluar el efecto del espaciamiento entre plantas en el surco y de configuración de plantación en el rendimiento de papa Russet Burbank, Russet Norkotah, y Ranger Russet bajo riego por aspersión. En 2008 y 2009, se les investigó a estas tres variedades el efecto en espaciamiento entre plantas en el surco (tres tratamientos de distancias) para cada configuración de plantación (4 surcos convencionales [4RC], cama de 5 hileras [5RB], y cama de 7 hileras [7RB]), y el efecto de la configuración de la plantación a una población uniforme, sobre rendimiento total de tubérculo, rendimiento de U.S. No. 1, tubérculos por ha, tamaño promedio (por peso), y rendimiento de tubérculo grande, en el Laboratorio de Investigación sobre Riego y Suelos del Noroeste del USDA-ARS en Kimberly, ID, en un suelo limoso Portneuf (mezcla de limo-grueso con medio Durixerollico Calciortido). La mayor influencia del espaciamiento de las plantas dentro del surco fue en el promedio de tamaño y tubérculos por ha. En general, a medida que aumentó el espaciamiento entre plantas en el surco (disminución en la población de plantas) el tamaño promedio del tubérculo aumentó y los tubérculos por ha disminuyeron. Hubo poca influencia en los espaciamientos dentro del surco en las variables de producción medidas bajo las configuraciones de plantación en camas, excepto para tubérculos por ha, que generalmente se aumentaron con espaciamientos más cortos entre plantas. Para Russet Norkotah y Ranger Russet hubo pocas diferencias en las variables medidas de producción entre los tratamientos de configuración de plantación. Para Russet Burbank, la configuración 4RC tuvo 14.6% significativamente más rendimiento de tubérculo total que la de 7RB, 20.2% más rendimiento de tubérculo U.S. No. 1 que las dos configuraciones de cama, y 25.2 y29.9% más de rendimiento de tubérculo grande que las configuraciones 5RB y 7RB en el 2009. Es posible la producción óptima de papa de Russet Norkotah y Ranger Russet bajo todas las configuraciones y de los rangos de espaciamiento entre plantas evaluados en este estudio, garantizándole a los productores flexibilidad en sus sistemas. No obstante, la evidencia de este estudio sugiere que la producción de Russet Burbank pudiera ser menos deseable para las configuraciones de plantación en camas.

Irrigated small-grain residue management effects on soil chemical and physical properties and nutrient cycling.

The effects of straw removal from irrigated fields cropped to wheat and barley on soil properties and nutrient cycling are a concern because of its potential impact on the sustainability of agricultural fields. The increasing demand of straw for animal bedding and the potential development of cellulosic ethanol production will likely increase the demand in the future. Previous reviews addressing changes in soil properties when crop residues are removed focused primarily on rain-fed systems. This article reviews published research assessing the effects of wheat and barley straw removal on soil organic carbon (SOC) and analyzes changes in nutrient cycling within irrigated wheat and barley production systems. The effects of straw removal on bulk density, saturated hydraulic conductivity, and other properties are reported from selected studies. Six studies compared SOC changes with time in irrigated systems in which wheat straw was removed or retained. These studies indicated that SOC either increased with time or remained constant when residues were removed. It is possible that belowground biomass was supplying C to soils at a rate sufficient to maintain or, in some cases, slowly increase SOC with time. A separate research review calculated the minimum aboveground annual carbon inputs needed to maintain SOC levels from nine wheat system studies. Calculations of the minimum aboveground annual C source inputs needed to maintain SOC levels were from rain-fed systems and are some of the best information presently available for use in evaluating residue removal effects in irrigated systems. However, long-term studies are needed to obtain reliable data for diverse irrigated systems. Significant amounts of nutrients are removed from the soil/plant system when straw is removed. Producers will need to determine the cost of the nutrient removal from their systems to determine the value of the straw.

Evaluation of Nitrogen and Phosphorus Fertilizer Placement With Strip Tillage for Irrigated Pacific Northwest Corn Production

Nutrient placement options with strip tillage (ST) can potentially improve plant nutrient utilization and increase crop yield compared to conventional fertilizer placement practices under conventional tillage (CT). The effects of tillage practice and N and P placement on grain yield, biomass yield (whole plant, grain + cobs + stover), and N and P uptake of field corn (Zea mays L.) were assessed on four sites during 2007 and 2009 at the USDA-ARS Northwest Irrigation & Soils Research Laboratory at Kimberly, ID. During each year, two locations (eroded and not eroded from furrow irrigation) were utilized as study locations. Band placement (15 to 20 cm below the soil surface) of fertilizer with ST increased corn grain yield by 12.5 (689 kg/ha) and 25.9% (1,626 kg/ha) on the eroded locations compared to broadcast N and P and 5 × 5-cm N under CT in 2007 and 2009, respectively. These increased yields also resulted in greater removal of N and P. Reduced tillage costs of ST with associated band placement of N and P could increase the economic productivity of many acres of land in the Pacific Northwest.