Potential for foliar phosphorus fertilisation of dryland cereal crops: a review

Corrected by Erratum: Potential for foliar phosphorus fertilisation of dryland cereal crops: a review, in Crop and Pasture Science 62(5) 444 - 444. The sentence on page 662 is incorrectly stated & a reference incorrectly cited.Although not commonly used in dryland cropping systems to date, foliar phosphorus (P) fertilisation may allow a tactical response to prevailing seasonal climatic conditions, with the added benefit of reduced input costs at sowing. However, variable outcomes have been reported from field trials predominantly conducted in the USA, and to a lesser degree in Australia. The effectiveness of foliar P is dependent on soil P status, soil water status, crop type, fertiliser formulation and prevailing climatic conditions. This review argues that the potential of foliar P fertilisation in Australian dryland cereal cropping could be enhanced by altering formulations for enhanced leaf penetration using adjuvants, and by accurately assessing the responsiveness of sites before application. This review demonstrates that it is important to use appropriate techniques such as isotopic labelling, to measure the efficacy and mode of action of foliar formulations.S.R. Noack, T. M. McBeath and M.J. McLaughli

Forage Yields from 2008-2009 Small Grains

Introduction Livestock and forage production are the largest contributors to agricultural income in the primary service region of the Noble Foundation. The small grains variety testing program which includes oats, rye, triticale and wheat is designed to provide up-to-date performance information to producers in Oklahoma and Texas about varieties that are commercially and commonly available. In addition, the program provides a tool to evaluate and compare experimental breeding lines emerging from the Noble Foundation breeding program as well as other public and private breeding programs. The program is intended to furnish producers with supplemental information and to aid decision-making and idea formation. The information coming from the variety testing program should be a valuable tool when used with similar information from other sources. The objective of this report is to summarize forage and grain yields from the 2008-2009 small grains variety trials. Materials and Methods The small grains variety trials were conducted at the Noble Foundation Dupy Farm (Dale silt loam) near Gene Autry and the Red River Demonstration and Research Farm near Burneyville, Okla. The experimental design was a randomized complete block with three replications. The experimental unit is a 5- by 10-foot plot of a single variety. The trial consisted of 30 entries of wheat, 10 entries of oats, 14 entries of rye and 12 entries of triticale that were evaluated during the 2008-2009 crop growing season. The entries were seeded in a clean-tilled seedbed on Oct. 1, 2008, at the Dupy Farm (Dupy) and on Sept. 29, 2008, at the Red River Demonstration and Research Farm (Red River). Depending on the crop and variety, approximately 90 to 120 lbs/ac (pure live seed basis) of seed was planted which amounts to 2,000,00 PLS/ac. Each entry was drilled in two adjacent 5- by 10-foot plots, in 7-inch rows, at 1-inch planting depth with a HEGE 500 drill. These adjacent plots were used to represent forage only and dual purpose (forage and grain). Fertilization consisted of preplant incorporation of 80 lbs N/ac on Oct. 3, 2008, at Dupy and on Oct. 6, 2008, at Red River. Soil tests showed all other nutrients to be adequate at both locations. Plots received a topdress application of 80 lbs N/acre on Feb. 5, 2009, at Dupy and on Feb. 6, 2009, at Red River. Annual ryegrass was controlled using Amber application at 0.56 ou/ac on Oct. 2, 2008, at both farms. Plots are harvested with a HEGE sickle bar forage plot harvester at a 3-inch height. Adjacent plots of each variety were harvested at the same time for forage during fall until first hollow stem stage of wheat was reached. At hollow stem stage, the dual purpose half is no longer harvested and was allowed to grow for grain production. At Dupy, forage-only plots were harvested on Jan. 23, March 2, April 22 and June 2, 2009. At Red River, they were harvested on Feb. 10, March 3, May 5 and June 6, 2009. At Dupy, dual purpose plots were harvested on Jan. 23, and at Red River, they were harvested on Feb. 10, 2009. Data was analyzed with the general linear models procedure in SAS (Statistical Analysis Software, Cary, N.C.), and means were separated by the least significant difference (LSD) method (P ≤ 0.05)

Biomass Yield and Nutrient Responses of Switchgrass to Phosphorus Application

Increasing desire for renewable energy sources has increased research on biomass energy crops in marginal areas with low potential for food and fiber crop production. In this study, experiments were established on low phosphorus (P) soils in southern Oklahoma, USA to determine switchgrass biomass yield, nutrient concentrations, and nutrient removal responses to P and nitrogen (N) fertilizer application. Four P rates (0, 15, 30, and 45 kg Pha−1) and two N fertilizer rates (0 and 135 kg Nha−1) were evaluated at two locations (Ardmore and Waurika) for 3 years.While P fertilization had no effect on yield at Ardmore, application of 45 kg Pha−1 increased yield at Waurika by 17%from 10.5 to 12.3Mg ha−1. Across P fertilizer rates, N fertilizer application increased yields every year at both locations. In Ardmore, non-N-fertilized switchgrass produced 3.9, 6.7, and 8.8Mg ha−1, and N-fertilized produced 6.6, 15.7, and 16.6 Mg ha−1 in 2008, 2009, and 2010, respectively. At Waurika, corresponding yields were 7.9, 8.4, and 12.2 Mg ha−1 and 10.0, 12.1, and 15.9 Mg ha−1. Applying 45 kg Pha−1 increased biomass N, and P concentration and N, P, potassium, and magnesium removal at both locations. Increased removal of nutrients with N fertilization was due to both increased biomass and biomass nutrient concentrations. In soils of generally low fertility and low plant available P, application of P fertilizer at 45 kg Pha−1 was beneficial for increasing biomass yields. Addition of N fertilizer improves stand establishment and biomass production on low P sites

Discrimination of Switchgrass Cultivars and Nitrogen Treatments Using Pigment Profiles and Hyperspectral Leaf Reflectance Data

The objective of this study was to compare the use of hyperspectral narrowbands, hyperspectral narrowband indices and pigment measurements collected from switchgrass leaf as potential tools for discriminating among twelve switchgrass cultivars and five N treatments in one cultivar (Alamo). Hyperspectral reflectance, UV-B absorbing compounds, photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) of the uppermost fully expanded leaves were determined at monthly intervals from May to September. Leaf hyperspectral data was collected using ASD FieldSpec FR spectroradiometer (350–2,500 nm). Discrimination of the cultivars and N treatments were determined based on Principal Component Analysis (PCA) and linear discriminant analysis (DA). The stepwise discriminant analysis was used to determine the best indices that differentiate switchgrass cultivars and nitrogen treatments. Results of PCA showed 62% of the variability could be explained in PC1 dominated by middle infrared wavebands, over 20% in PC2 dominated by near infrared wavebands and just over 10% in PC3 dominated by green wavebands for separating both cultivars and N treatments. Discriminating among the cultivars resulted in an overall accuracy of 81% with the first five PCs in the month of September, but was less accurate (27%) in classifying N treatments using the spectral data. Discrimination based on pigment data using the first two PCs resulted in an overall accuracy of less than 10% for separating switchgrass cultivars , but was more accurate (47%) in grouping N treatments. The plant senescence ratio index (PSRI) was found to be the best index for separating the cultivars late in the season, while the transform chlorophyll absorption ration index (TCARI) was best for separating the N treatments. Leaf spectra data was found to be more useful than pigment data for the discrimination of switchgrass cultivars, particularly late in the growing season

Impact of sp2 carbon edge effects on the electron-transfer kinetics of the ferrocene/ferricenium process at a boron-doped diamond electrode in an ionic liquid

The electrochemical properties of boron-doped diamond (BDD) electrodes are strongly influenced by the boron doping level and the presence of sp2 carbon impurities. In this study, the impact of highly localized sp2 carbon concentrated at the edge of a BDD electrode, arising from laser cutting during fabrication and exposed during electrode polishing, on the resulting overall electrode kinetics is identified. Fourier transformed large-amplitude alternating current (FTAC) voltammetric data for the usually ideal Fc0/+ (Fc = ferrocene) process in the highly viscous ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate show relatively poor agreement with simulations based on a uniformly active electrode surface using the Butler–Volmer formalism for the electrode kinetics. In this ionic liquid medium, the impact of heterogeneity on the macroscopic electrode activity is enhanced under the conditions of slow mass transport, where sites of disparate activities are spatially decoupled on the voltammetric time scale. Physically blocking this edge region leads to a response that is much more consistent with a uniform electrode and substantially improves the agreement between the FTAC voltammetric experiment and simulation (standard heterogeneous electron-transfer rate constant, k0 = 0.0015 cm s–1). To complement the macroscopic measurements, local voltammetric measurements with an electrochemical droplet cell show directly that the sp2 carbon found in the edge region is able to support much faster electron-transfer kinetics for the Fc0/+ process than the sp3 BDD surface. Overall, this study demonstrates that caution should be taken in reporting electrode kinetic data obtained at BDD or any other heterogeneous electrode materials. Macroscopic electrode kinetic characterization in traditional electrochemical media such as acetonitrile is blind to such heterogeneities in the activity. However, tuning the diffusional time scale through the use of FTAC voltammetry in viscous ionic liquids provides a powerful approach for detecting the spatially nonuniform electrode activity