The organic P composition of semi-arid arable soils is largely unknown, but such information is fundamental to understanding P dynamics in irrigated agriculture. We used solution "P nuclear magnetic resonance (NMR) spectroscopy and phosphatase hydrolysis to characterize organic P in semi-arid arable soils from the western USA (organic C 2.0-30.7 g C kg' soil, clay 2-48%, pH 5.2-8.2, CaCO 3 <1-480 g kg -' soil). Total P concentrations ranged from 220 to 1210 mg P kg-' soil, of which between 12 and 45% was extracted with NaOH-EDTA. Inorganic orthophosphate was the dominant P compound, but concentrations determined by solution "P NMR spectroscopy were consistently greater than those determined by molybdate colorimetry. Concentrations of organic P were relatively small, and were dominated by orthophosphate monoesters (11-130 mg P kg-' soil), with smaller concentrations of orthophosphate diesters (0-7 mg P kg-1 soil). Pyrophosphate was present in almost all soils at concentrations up to 14 mg P kg -' soil. Bicarbonate-extractable organic P ranged from 1.7 to 22.8 mg P kg -' soil, of which between 37 and 87% was hydrolyzed by phosphatase enzymes, suggesting its bioavailability. Soil organic P concentrations were positively correlated with mean annual precipitation, organic C, clay, and oxalate-extractable metals (Al, Fe, Mn), and negatively correlated with mean annual temperature and soil pH. However, CaCO3 concentrations were not significantly correlated with any soil property. These results indicate that equilibrium levels of organic P in semi-arid arable soils are controlled by a balance between the physical protection offered by the soil matrix and the suitability of the environment for biological productivity.

Plant nutrition is the practice of providing to the plant the right nutrient, in the right amount, in the right place, at the right time. This paper gives an overview of the roles that each of the 16 essential nutrients have in plant nutrition, their relative mobility as related to deficiency symptom expression, and what is generally known about nutrient responses to field applications on potatoes (Solanum tuberosum L.) in the USA and Canada. Maintaining high crop yields with minimum nutrient losses to the environment is and will continue to be a significant challenge to the potato producer. Additional nutritional research efforts in geneticallymodified plants, precision agriculture, food quality and safety, fertilizer impurities, and other management concerns should significantly help the producer in this effort. RESUMENLa nutriciOn vegetal consiste en proporcionar a la Manta el nutriente corrects, la cantidad correeta, el lugar correct° y el momenta correcto. Este artIculo da una vision general de los roles que tiene cada lino de los 16 nutrientes esenciales en la plants, su movilidad en relaciOn con la expresiOn de los sintomas de deficiencia y lo que generalinente se conoce sobre las respuestas de la aplicaciim en papa (Solarium. tuberosum L.) en el campo, en ELIA y Canada. El hecho de mantener rendimientos altos con perdida minima de nutrientes en el suet() es y eontinuara siendo un desafio signiflcativo para el productor de papa. Cualquier esfuerzo de invesAccepted for publication 12 January 2005. ADDITIONAL KEY WORDS: Sofano on htherosum, essential elements, fertilization, tissue tests, research opportunities tigaciOn que se haga sobre nutriciOn adicional en plantas geneticamente modificadas, agricultura de precision, calidad alimentaria y seguridad, impurezas de los fertilizantes y otros aspectos de manejo deben ayudar significativarnente al productor.

No abstract

Drought is a worldwide constraint to dry bean (Phaseolus vulgaris L.) production. The objective of this research was to determine the response of three dry bean landraces and 13 cultivars evaluated under non-stressed (NS) and intermittent drought-stressed (DS) environments at Kimberly, Idaho in 2003 and 2004. The NS received seven irrigations in 2003 and five in 2004, and DS only four in 2003 and two in 2004. Most water use occurred within the top 0.5 m soil in both the NS and DS. Drought reduced biomass and seed yield, harvest index, and seed weight. Maturity was delayed in severe drought, but was similar or shortened by 1 to 6 d under moderate drought. Mean seed yield was reduced by 62% in 2003 and by 27% in 2004. Common Red Mexican and CO 46348 had high seed yield in both NS and DS environments, whereas 'Matterhorn' and 'Othello' yielded comparatively high under DS but moderately in NS environment. Drought resistance was inadvertently reduced from Common Red Mexican landrace to intermediate levels in 'NW-63' and 'UI 239' released in 1979 and 1993, respectively, and more recently released 'LeBaron ' (1999) and 'UI 259' (1996) were susceptible. Conversely, drought resistance was increased in newer pinto (Othello 1986; CO 46348) and great northern (Matterhorn 1998) releases compared to the landraces and older cultivars tested for those market classes. Seed yield in NS and DS was positively correlated. Seed yield was also correlated with harvest index in DS and NS. All early maturing cultivars except Othello (e.g., UI 59, US 1140, Common Pinto, Topaz, UI 320, and LeBaron) were susceptible. Common Red Mexican did not have any reduction in seed weight due to drought stress. Drought resistant genotypes should be used for determining irrigation frequency, amount of water to be applied, and mechanisms of resistance and for identifying, mapping, and pyramiding favorable genes for dryland and irrigation-assisted sustainable production systems.

The number of dairy cows in Idaho has increased by approximately 80% in the last decade, with the majority of these facilities located in southern Idaho, causing air quality concerns in this region. To determine the potential air quality impacts of these facilities, we measured ammonia (NH 3), methane (CH 4), and nitrous oxide (N 2 O) concentrations over the pens, wastewater storage pond, and composting area on a 700-cow open-lot dairy using open-path Fourier transform infrared spectrometry (OP/FTIR). Concentrations were measured for one or two days at each location during January, March, June, and September. Median NH 3 concentrations over the pens, storage pond, and composting area ranged from 0.14 to 0.39 ppmv, 0.04 to 0.17 ppmv, and 0.06 to 0.22 ppmv, respectively, with concentrations tending to be lower in January. Average CH 4 concentrations over the pens, storage pond, and composting area ranged from 2.07 to 2.80 ppmv, 1.87 to 2.15 ppmv, and 1.71 to 1.76 ppmv, respectively. Average N 2 O concentrations ranged from 0.31 to 0.33 ppmv for all areas, which was similar to global background N 2 O concentrations. Combined ammonia emissions for the pen and storage pond areas, calculated with a backward Lagrangian stochastic inverse-dispersion technique, were 0.

Potassium and N fertilization is often required for maximum potato (Solanum tuberosum L.) production. Nitrogen, K, and K-sources (KC1, K2SO4) are known to affect yield and quality of potatoes but N and K interactions as affected by K-source have not been defined. This study evaluated the N*K and K-source interactions on Russet Burbank tuber yields and specific gravity (SG) in two irrigated field experiments. Nitrogen rates of 0, 112, 224 or 336 kg ha' were combined with selected K rates of 0, 112, 224 or 448 kg ha as either KC1 or K2SO4 in an incomplete factorial. A multiple linear regression model was fit to the data and used to predict yield and SG for a complete factorial for each K-source. Both N and K applications increased yields independent of K-source. Nitrogen decreased yields at the 336 kg ha' rate. Potassium increased yields up to 448 kg K ha'. Both K-sources decreased SG a similar amount with N application; without N, KC1 decreased SG but K2SO4 did not. Nitrogen also decreased SG. Petiole NO 3-N and K concentrations were positively related to yields and negatively to specific gravities. The petiole K concentration 100 days after planting should be above 4.5 for highest tuber yields. The N*K*K-source interaction was important for yields at low available N and for SG at adequate N availabilities. This study showed that N or K fertilizers can be applied according to their respective soil test concentration and the crop's requirement, generally without consideration of K-source. CompendioPara una producciOn maxima de papa (Solanum tuberosum L.) se requiere frecuentemente de la fertilizaciOn nitrogenada y potasica. Se sabe que el nitrogeno (N), el potasio (K) y las fuentes de potasio (KCL, K2SO 4) afectan el rendimiento y la calidad de la papa, pero las interacciones del N y el K en relaciOn a la fuente de K no han sido definidas. Este estudio evaluO en dos experimentos de campo bajo irrigaciOn las interacciones de N*K con la fuente de K sobre los rendimientos en tuberculos y la gravedad especifica (GE) de Russet Burbank. Dosis de nitrogeno de 0, 112, 224 o 336 kg ha-1 se combinaron con dosis seleccionadas de K de 0, 112, 224 o 448 kg ha-1 como 'Contribution from USDA-ARS and the Utah Agric. Expt.

Considerable evidence exists that both N and K influence potato (Solanum tuberosum L.) yields and quality. The impact of nutrients on tuber quality parameters under field conditions should be identified so optimum management practices can be utilized. We evaluated the N and K fertilization by Ksources effects on concentrations of nutrients, reducing sugars, sucrose and starch in the stem and apical tuber ends from two irrigated field experiments with the Russet Burbank cultivar. Nitrogen rates of 0, 112, 224 or 336 kg ha-' were combined with selected K rates of 0, 112, 224 or 448 kg ha-' as either KCI or K2SQ4 arranged as an incomplete factorial. A multiple linear regression model was fit to the data and used to predict the response surface for a complete factorial for each K-source. Nitrogen applications increased or decreased reducing sugars in the apical and stem ends, respectively. Potassium decreased reducing sugars in both tuber ends. Sucrose was higher in the apical end than in the stem end but was not appreciably affected by fertilizer treatment. Nitrogen and potassium applications reduced dry matter and starch concentrations in both tuber ends. Potassium had a smaller effect on the apical end when starch was expressed on a dry weight basis, indicating that increased water content was a factor in the K effect. Both N and K concentrations in the tuber ends were negatively related to starch concentrations, but the relationship was different for the apical and stem ends. Tuber Cl concentration indirectly affected starch concentrations in the stem end when KCL was applied. The K fertilization effect on specific gravity depended upon the K concentration in the harvested tuber and was independent of K fertilizer source. These data illustrate the effects of preplant N and K fertilization rates on final tuber quality parameters. Additional studies are needed to further define the effects of nutrient concentrations at different plant growth stages. CompendioExiste considerable evidencia que tanto el N coma el K influencian los rendimientos y calidad de la papa (Solanum tuberosum L. campo, debe ser identificado de modo que pueden utilizarse practicas Optimas de manejo. Se evaluO la fertilizaciOn con N y K por los efectos de las fuentes de K sobre la concentraciem de nutrientes, los aplcares reductores, sucrosa y almidem en los extremos apical y terminal de tuberculos de dos experimentos de campo bajo irrigaciem, con el cultivar Russet Burbank. Se combinaron dosis de 0, 112, 224, o 336 kg ha' de N, con dosis seleccionadas de K de 0,112, 224 o 448 kg ha'', sea comb KC1 o como K2SO4, dispuestas como un factorial incompleto. Se dispuso la information convenientemente en un modelo de regresiOn linear multiple y se le utilizO para pronosticar la superficie de respuesta para un factorial completo para cada fuente de K. Las aplicaciones de N incrementaron o disminuyeron los azikares reductores en los extremos apical y terminal, respectivamente. El K redujo los azficares reductores en ambos extremos del tuberculo....

The amount and rate of soil N mineralization are important components that can be used to predin ct ecpregant N fertilizer application and to evaluate the d N fertilization during crop epowth. This study's was to evaluate the burl d polyethylene bag as a method, for characterizing the N mineralized field conditions during the cropping season. Soil (Xerollit Calciorthids) was placed in polyethylene bags and buried in the 0 to 45 an root zone of followed roils and where corn (Tea mays L) and potato (Solanunt taberonan L.) were being grown. The NO,-N content of the soil in the bags was compared with that in the root zone at selected time intervals (10 to 14 days) from April to October.The soil NOrN concentrations in the buried polynhylate bags were similar to those in irrigated fallow soils from April to October after correction for different soil water contents. The N-mineralization rate between sampling . intervals had an average ten tune coeffi.