Bradley A. King

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.

Estimation of Furrow Irrigation Sediment Loss Using an Artificial Neural Network

AbstractThe area irrigated by furrow irrigation in the United States has been steadily decreasing but still represents about 20% of the total irrigated area in the United States. Furrow irrigation sediment loss is a major water quality issue, and a method for estimating sediment loss is needed to quantify the environmental effects and estimate effectiveness and economic value of conservation practices. Artificial neural network (NN) modeling was applied to furrow irrigation to predict sediment loss as a function of hydraulic and soil conditions. A data set consisting of 1,926 furrow evaluations, spanning three continents and a wide range of hydraulic and soil conditions, was used to train and test a multilayer perceptron feed forward NN model. The final NN model consisted of 16 inputs, 19 hidden nodes in a single hidden layer, and 1 output node. Model efficiency (ME) of the NN model was ME=0.66 for the training data set and ME=0.80 for the test data set. The prediction performance for the complete data se...

Site-Specific Sprinkler Irrigation in a Water Limited Future

Available water supplies for irrigation are becoming more and more limited in the western USA and other locations around the world, and this trend is accelerating. This will entail major changes to the physical and managerial aspects as well as the designs of the water delivery and on-farm irrigation systems. Resource conservation as well as achieving environmental benefits under these conditions will likely require the adoption of non-uniform water applications, also known as site-specific irrigation. A water and energy limited future will be the catalyst that finally brings many of the existing precision agricultural technologies together for irrigated agriculture. Highly managed deficit irrigation strategies will be fundamental to managing limited water supplies, which will be enhanced by spatially managing soil water through improved irrigation timing to minimize negative effects of intentional drought stresses on yields and quality in each area of a field. Integrated management approaches involving many aspects of precision agriculture technologies will assist producers in optimally meeting particular site-specific requirements of soil water, plant growth, reduced leaching or other criteria such as agrichemical applications in different areas of a single field. The combined use of distributed wireless sensor networks, various sensors mounted on the irrigation machine structure (with continuous geo-referencing) and remotely sensed information will be indispensable in providing real time feedback for necessary integrated decision support programs. This will require integration of system hardware, sensor systems and decision support software into comprehensive management systems, which will be challenging as significant knowledge gaps exist.

New Proportional Chemical Injection System for Improved Chemigation Uniformity with Center Pivots

Constant rate chemical injection into center pivots equipped with an end gun and/or corner watering system results in chemical application errors of 12 to 42% due to system flow rate variations caused by the variable wetted radius of the system. Proportional chemical injection systems for center pivots currently on the market utilize a flow meter to adjust chemical injection rate. The typical installed piping arrangement for a center pivot system is not conducive to accurate and reliable flow rate measurement with flow meters. We have developed a proportional chemical injection system which uses direct measurement of end gun operating pressure and/or status of control valves along a corner watering system to calculate system flow rate for controlling chemical injection flow rate. This approach overcomes reliability problems associated with flow meters. Operation of the proportional chemical injection system was tested with N fertilizer application on a commercial center pivot equipped with an end gun and corner watering system. The proportional chemical injection system reduced the coefficient of variation in N concentration of the applied water by 61% compared to conventional constant rate chemical injection. The components of the proportional chemical injection system are described.

DROUGHT TOLERANCE SELECTION IN SUGAR BEET

Increased water demands and drought have resulted in a need to determine if drought tolerance exists in sugar beet lines. This study was conducted to determine if drought tolerance existed among a group of genetically diverse sugarbeet hybrids by evaluating sucrose yields over a range of water inputs levels. The study was conducted over three consecutive growing seasons (2008-2010) at the NWISRL in Kimberly, ID on a Portneuf silt loam (coarse-silty mixed mesic Durinodic Xeric Haplocalcid) to assess the production of six KWS breeding hybrids and one commercial hybrid under a range of water inputs [125% (W1), 100% (W2), 75% (W3), 50% (W4), and 25% of estimated crop evapotranspiration (ETc) and rain-fed (W6)] with water applied 3 times a week. Some of the hybrids have been previously tested under drought conditions in proprietary trials. All six were selected for this study based on their known genetic background, preliminary information about variation under drought stress conditions, and a close relationship to actual market hybrids. The experimental design was established based on the use of a line source irrigation system. Impact nozzles (Weather Tec G50V 23 degree; nozzle size and type = 6.5 MPS; flow rate = 12.4 Lpm) were spaced at 6.1 m intervals down the line to provide uniform irrigation distribution for a given perpendicular distance from the line. Water amount treatments were based on applying irrigation to supplement precipitation to match 100% crop water requirement (W2), based on the 1982 Kimberly-Penman Reference Evapotranspiration Model (Wright, 1982) using data from an Agrimet weather station (U.S. Bureau of Reclamation, Boise, ID); the remaining treatments receiving amounts of water based on the distance from the line source. Irrigation depth decreased as perpendicular distance from the line increased. Drought susceptibility index (DSI) is defined as a criterion to evaluate hybrids with more stable performance under water stress (Siahpoosh et al., 2011). The DSI compares yield differences under water stressed and optimum water levels and is calculated as: 1