E. van Santen

SOIL CARBON RELATIONSHIPS WITH TERRAIN ATTRIBUTES, ELECTRICAL CONDUCTIVITY, AND A SOIL SURVEY IN A COASTAL PLAIN LANDSCAPE

Soil organic carbon (SOC) estimation at the landscape level is critical for assessing impacts of management practices on C sequestration and soil quality. We determined relationships between SOC, terrain attributes, field scale soil electrical conductivity (EC), soil texture and soil survey map units in a 9 ha coastal plain field (Aquic and Typic Paleudults) historically managed by conventional means. The site was composite sampled for SOC (0-30 cm) within 18.3 × 8.5-m grids (n = 496), and two data sets were created from the original data. Ordinary kriging, co-kriging, regression kriging and multiple regression were used to develop SOC surfaces that were validated with an independent data set (n = 24) using the mean square error (MSE). The SOC was relatively low (26.13 Mg ha−1) and only moderately variable (CV = 21%), and showed high spatial dependence. Interpolation techniques produced similar SOC maps but the best predictor was ordinary kriging (MSE = 9.11 Mg2 ha−2) while regression was the worst (MSE = 20.65 Mg2 ha−2). Factor analysis indicated that the first three factors explained 57% of field variability; compound topographic index (CTI), slope, EC and soil textural fractions dominated these components. Elevation, slope, CTI, silt content and EC explained up to 50% of the SOC variability (P ≤ 0.01) suggesting that topography and historical erosion played a significant role in SOC distribution. Field subdivision into soil map units or k-mean clusters similarly decreased SOC variance (about 30%). The study suggests that terrain attributes and EC surveys can be used to differentiate zones of variable SOC content, which may be used as bench marks to evaluate field-level impact of management practices on C sequestration.

Chlorophyll meter predicts nitrogen status of tall fescue

Abstract The nitrogen (N) status of a crop can be used to predict yield and supplemental N fertilizer requirements, and rapid techniques for evaluating the N status of crops are needed. A study was conducted to determine the feasibility of using a hand held chlorophyll meter (SPAD 502, Minolta Co. Ltd., Japan) to monitor N status of tall fescue (Festuca arundinacea Schreb.). Four diverse tall fescue genotypes were grown at three locations in Alabama and fertilized at four N‐rates from 0 to 336 kg ha‐1. A similar experiment was conducted in the greenhouse using soil from the same field sites. Chlorophyll meter readings (SPAD) were taken, and extractable chlorophyll content, tissue N concentration and dry matter yield were determined at harvest. SPAD, extractable chlorophyll content, tissue N concentration, and dry matter yield increased quadratically (0.67 < R2 < 0.99) with increasing N fertilization in both experiments. All genotypes responded similarly to applied N, with some differences in magnitude. Re...

Frequency and diversity of fungi colonizing tissues of upland cotton.

A study of the mycoflora of upland cotton in Alabama was conducted throughout the 2000 and 2001 growing seasons. Plants were sampled at seedling, first bloom, full bloom, and maturity stages of development. Thirty-seven genera representing 58 species of fungi were isolated, including 9 species of Fusarium. Fusarium oxysporum, F. solani, and F. equiseti were the most common members of this genus occurring at all four sampling stages in both years. Eight species accounted for 67% of the total fungi isolated during the two-year study. Alternaria alternata was the most common fungus encountered, accounting for 19 and 10% of the total fungi isolated in 2000 and 2001, respectively. Twenty species of fungi are reported for the first time colonizing upland cotton tissues.

Experimental Transmission of Corynebacterium pseudotuberculosis Biovar equi in Horses by House Flies

Background The route of Corynebacterium pseudotuberculosis infection in horses remains undetermined, but transmission by insects is suspected. Objectives To investigate house flies (Musca domestica L.) as vectors of C. pseudotuberculosis transmission in horses. Animals Eight healthy, adult ponies. Methods Randomized, controlled, blinded prospective study. Ten wounds were created in the pectoral region where cages for flies were attached. Three ponies were directly inoculated with C. pseudotuberculosis. Four ponies were exposed for 24 hours to 20 hours C. pseudotuberculosis‐inoculated flies. One negative control pony was exposed to noninoculated flies. Ponies were examined daily for swelling, heat, pain, and drainage at the inoculation site. Blood was collected weekly for CBC and biochemical analysis, and twice weekly for synergistic hemolysis inhibition titers. Results Clinical signs of local infection and positive cultures were observed in 7/7 exposed ponies and were absent in the negative control. In exposed ponies, peak serologic titers (1 : 512 to 1 : 2,048) were obtained between days 17 and 21. Seroconversion was not observed in the negative control. Neutrophil counts were higher in the positive and fly‐exposed groups than in the negative control (P = .002 and P = .005) on day 3 postinoculation. Serum amyloid A concentrations were higher in the positive control than in the negative control and fly‐exposed ponies on days 3 (P < .0001) and 7 (P = .0004 and P = .0001). No differences were detected for other biochemical variables. Conclusions and Clinical Importance House flies can serve as mechanical vectors of C. pseudotuberculosis and can transmit the bacterium to ponies.

Distribution of Bovine Viral Diarrhoea Virus Antigen in Persistently Infected White-Tailed Deer (Odocoileus virginianus)

Infection with bovine viral diarrhoea virus (BVDV), analogous to that occurring in cattle, is reported rarely in white-tailed deer (Odocoileus virginianus). This study evaluated the distribution of BVDV antigen in persistently infected (PI) white-tailed deer and compared the findings with those from PI cattle. Six PI fawns (four live-born and two stillborn) from does exposed experimentally to either BVDV-1 or BVDV-2 were evaluated. Distribution and intensity of antigen expression in tissues was evaluated by immunohistochemistry. Data were analyzed in binary fashion with a proportional odds model. Viral antigen was distributed widely and was present in all 11 organ systems. Hepatobiliary, integumentary and reproductive systems were respectively 11.8, 15.4 and 21.6 times more likely to have higher antigen scores than the musculoskeletal system. Pronounced labelling occurred in epithelial tissues, which were 1.9-3.0 times likelier than other tissues to contain BVDV antigen. Antigen was present in >90% of samples of liver and skin, suggesting that skin biopsy samples are appropriate for BVDV diagnosis. Moderate to severe lymphoid depletion was detected and may hamper reliable detection of BVDV in lymphoid organs. Muscle tissue contained little antigen, except for in the cardiovascular system. Antigen was present infrequently in connective tissues. In nervous tissues, antigen expression frequency was 0.3-0.67. In the central nervous system (CNS), antigen was present in neurons and non-neuronal cells, including microglia, emphasizing that the CNS is a primary target for fetal BVDV infection. BVDV antigen distribution in PI white-tailed deer is similar to that in PI cattle.

Cover Crop Biomass Harvest Influences Cotton Nitrogen Utilization and Productivity

There is a potential in the southeastern US to harvest winter cover crops from cotton (Gossypium hirsutum L.) fields for biofuels or animal feed use, but this could impact yields and nitrogen (N) fertilizer response. An experiment was established to examine rye (Secale cereale L.) residue management (RM) and N rates on cotton productivity. Three RM treatments (no winter cover crop (NC), residue removed (REM) and residue retained (RET)) and four N rates for cotton were studied. Cotton population, leaf and plant N concentration, cotton biomass and N uptake at first square, and cotton biomass production between first square and cutout were higher for RET, followed by REM and NC. However, leaf N concentration at early bloom and N concentration in the cotton biomass between first square and cutout were higher for NC, followed by REM and RET. Seed cotton yield response to N interacted with year and RM, but yields were greater with RET followed by REM both years. These results indicate that a rye cover crop can be beneficial for cotton, especially during hot and dry years. Long-term studies would be required to completely understand the effect of rye residue harvest on cotton production under conservation tillage.

CRUDE PROTEIN, AMINO ACID AND ALKALOID CONTENTS OF ANNUAL SWEET LUPIN ( LUPINUS SPP. L.) FORAGES AND SEEDS GROWN IN ETHIOPIA

Though bitter white lupin (Lupinus albus L.) is a traditional crop in Ethiopia, sweet lupins are new to the country. As a result, the nutritional value of low-alkaloid lupins has not been evaluated under Ethiopian conditions. Crude protein, amino acid and alkaloid contents of 16 cultivars of three annual lupin species grown in four lupin growing locations (Merawi, Finoteselam, Kossober-1 and Kossober-2) of Ethiopia were evaluated. Location × cultivar interaction was a significant source of variation for all traits (p < 0.0001). In all locations, blue entries had either similar (p ≥ 0.0584) or higher (p ≤ 0.0235) forage crude protein content than the Local Landrace, white group and yellow entry. Compared with the Local Landrace, white and blue entries, the sole yellow entry had higher (p ≤ 0.0148) seed crude protein content at all locations except at Kossober-2, where it had similar (p = 0.8460) crude protein content as white entries. The Local Landrace had the highest forage and seed alkaloid contents. However, sweet blue Vitabor and Sanabor entries had the lowest forage and seed alkaloid contents, respectively. Low alkaloid and higher crude protein contents of sweet lupins grown in Ethiopia show the possibility to use sweet lupin forage and seeds as cheap home-grown protein source for livestock feed and human food in the country. However, for more reliable information, the laboratory results need to be verified by animal and human evaluations of the crop.

Evaluation of Methods to Improve the Diagnosis of Systemic Inflammation in Alpacas

BACKGROUND The stoic nature of alpacas and limitations of current diagnostic tests make early recognition of inflammatory diseases in this species challenging. OBJECTIVES In a model of mild systemic inflammation, this study evaluated the utility of different clinical and clinicopathologic variables as accurate predictors of inflammation in alpacas. ANIMALS Twelve clinically healthy alpacas were randomly assigned to equal-sized treatment (TG) and control (CG) groups. After collection of initial blood samples (0 hour), lipopolysaccharide (LPS; 20 μg/kg/24 h) or saline was administered by SC osmotic mini-pumps (OMP) for 96 hours. Additional blood samples were collected at 12, 18, 24, 36, 48, 72, 96, 120, 144, and 240 hours and differential leukocyte counts and concentrations of globulin, albumin, iron, haptoglobin, and serum amyloid A were measured. RESULTS Mild swelling was observed at OMP implantation sites in both groups. Other clinical signs of systemic inflammation were not observed. Total leukocytes, neutrophils, albumin, and globulin concentrations were not significantly different between groups. Compared with CG-alpacas, TG-alpacas had fewer lymphocytes (P = .0322), more band neutrophils (P = .0087), and higher neutrophil/lymphocyte ratios (P = .0295) during the first 96 hours of the study. During LPS administration, serum iron concentrations were significantly decreased in TG-alpacas (P < .0001). Haptoglobin concentrations of TG-animals exceeded those of CG-animals after removal of OMP (P = .0056). Serum amyloid A was not detectable in alpacas in this study. CONCLUSION AND CLINICAL IMPORTANCE These results indicated that neutrophil/lymphocyte ratios and serum iron concentrations are early indicators of inflammation in alpacas. Additional research is needed to evaluate the acute phase protein responses of alpacas.

Remnant oak savanna acts as refugium for meadow fescue introduced during nineteenth century human migrations in the USA

In 1990, an unknown forage grass was discovered growing in the shade of a remnant oak savanna in southwestern Wisconsin. Over 12 years, the practice of feeding mature hay on winter pastures spread this grass onto over 500 ha via seedling recruitment. Analysis of amplified fragment length polymorphic (AFLP) markers on 561 plants, compared to a diverse sample of wild European collections of perennial ryegrass (Lolium perenne L.), Italian ryegrass (L. multiflorum Lam.), meadow fescue (Festuca pratensis Huds. = L. pratense (Huds.) Darbysh.), and tall fescue (F. arundinacea Schreb.), identified a highly diverse population that was more closely allied with F. pratensis than the other species, based on genetic distances. Genomic in situ hybridization (GISH), using both Lolium- and Festuca-specific probes, led to effective hybridizations by only the Festuca-specific probes and gave indications of close homology to the F. pratensis genome. Similarly, genetic distance analysis using PCR-based Lolium expressed sequence tag (EST) markers on a subset of genotypes, compared to the four control species, clearly identified F. pratensis as the closest relative. Sequence analysis of the trnL intron of cpDNA distinguished the unknown plants from F. arundinacea, but not from Lolium. Additional survey work has identified this grass on 12 other farms within an area of about 20,000 ha. Soil samples accompanying plant samples indicated no seed banks and most farm records indicate no commercially introduced seeds during the twentieth century. We hypothesize that seeds of meadow fescue may have arrived with some of the earliest European immigrants to Wisconsin and spread along the historic Military Ridge Trail, a network of frontier U.S. Army forts connected by a major thoroughfare.

Organic weed control in white lupin ( Lupinus albus L.)

Legumes such as white lupin (Lupinus albus L.) provide a valuable nitrogen source in organic agriculture. With organic farming hectarage increasing and white lupin interest increasing in the southeastern USA due to newly released winter hardy cultivars, non-chemical weed control practices in lupin are needed. A two-year experiment was established at two locations in Alabama. Five weed control practices were evaluated: one pre-emergence (PRE)-applied herbicide (S-metolachlor), two mechanical (hand hoed) and two cultural (living mulch utilizing two black oat cultivars) weed control treatments. Fourteen weed species were encountered. S-metolachlor provided above 80% control of most weed species present in this experiment. The cultivation treatments and black oat companion crops also provided good weed control of many of the weeds encountered. Crop injury of all treatments was low on a 0 to 10 scale with 0 representing no injury: < 2.0, < 1.3 and < 1.2 by S-metolachlor, the cultivation treatments and the black oat companion crops, respectively. Grain yield of cultivars ABL 1082, AU Alpha and AU Homer were 1540, 1130, 850 kg ha - 1 , respectively, when treated with the conventional treatment, S-metolachlor. Grain yield in the organic treatments was equivalent. The cultivation treatments and black oat companions were successful alternative weed control practices in white lupin production.