Sugarcane Response to Nitrogen Fertilization on a Histosol with Shallow Water Table and Periodic Flooding

Sugarcane (Saccharum spp.) is increasingly exposed to periodic floods and shallow water tables on Histosols in Florida’s Everglades Agricultural Area (EAA). In the past, when these soils were usually well drained, they provided excess N for sugarcane through microbial oxidation. It is not known if supplemental N would now improve yields because microbial oxidation is reduced by shallow water tables and periodic floods. The purpose of this study was to evaluate the effects of N fertilizer rates on two sugarcane cultivars exposed to a 25-cm water-table depth with and without repeated 2-day floods. Two studies were planted in containers in 2001 and 2002 with two sugarcane cultivars and five equally spaced rates of N fertilizer from 0 to 200 kg ha⁻¹. Leaf, stalk and root weights were reduced by periodic flooding and the magnitude of the reduction sometimes differed between cultivars. Plant weights, leaf chlorophyll content (SPAD) and leaf N content were often highest near an N rate of 100 kg ha⁻¹. Usually, N fertilizer rate did not interact with water treatment. Nitrogen fertilization may be useful for sugarcane exposed to water-table depths of 25 cm with and without 2-day repeated floods on EAA Histosols.     

Integrating local and scientific knowledge for adaptation to land degradation: Kalahari rangeland management options

Despite numerous assessments of the sensitivity and resilience of drylands to degradation, there has been little research into the way affected communities innovate and adapt in response to land degradation. This paper shows how local and scientific knowledge can be combined to identify rangeland management strategies to reduce or adapt to land degradation. To achieve this, we have developed and applied a four‐stage social learning approach based on stakeholder participation in three degradation ‘hotspots’ in communal rangelands of the Kalahari, Botswana. This approach aims to collate, evaluate and apply both scientific and local knowledge on rangeland degradation and management options. First, current practice and possible management options were identified from the literature. Second, a series of semi‐structured interviews with rangeland users identified local knowledge of strategies to reduce and adapt to land degradation. Third, these options were discussed and evaluated with rangeland stakeholders in focus groups held across each study region. Finally, the outputs from these focus groups were used to produce rangeland assessment guides for each region that provided management options agreed to be locally relevant by both researchers and local stakeholders. The study found that the majority of strategies reported in the literature were not suitable for use by pastoralists in the Kalahari. However, many of the strategies suggested by stakeholders could only be applied effectively under common property regimes, giving impetus to the growing literature encouraging institutional reform to strengthen common property management regimes. The research stimulated a social learning process that combined knowledge from local stakeholders (both pastoralists and extension workers) with the scientific knowledge of researchers to provide a range of management options that could help land managers reduce or adapt to land degradation. By combining participatory research with insights from scientific literature in this way, more relevant results were provided than either approach could have achieved alone. Copyright © 2007 John Wiley & Sons, Ltd.     

Mastocytoma in the common carpal sheath of the digital flexor tendons of a horse

A 13-year-old Morgan gelding was examined for right forelimb lameness and tenosynovitis of the right common carpal sheath of the digital flexor tendons. The horse had moderate right forelimb lameness at the trot and marked effusion of the right common carpal sheath of the digital flexor tendons. Ultrasonographic examination revealed a soft tissue mass within the proximal pouch of the affected tendon sheath, located adjacent to the distal physis of the radius. Cytology and culture of the fluid revealed a sterile, eosinophilic tenosynovitis. Tenoscopic exploration confirmed the presence of a capsulated soft tissue mass. Thecotomy was required to fully debride the mass, which histology revealed to be a mast cell tumour. At 22 months postoperatively, the horse developed mild right forelimb lameness and eosinophilic tenosynovitis because of recurrence of the mastocytoma. Mastocytosis is a possible differential diagnosis in any horse exhibiting lameness associated with tenosynovitis. Surgical excision combined with rest and postoperative intrasynovial and systemic corticosteroids may be palliative.     

Solar wind outflow and the chromospheric magnetic network

Observations of outflow velocities in coronal holes (regions of open coronal magnetic field) have recently been obtained with the Solar and Heliospheric Observatory (SOHO) spacecraft. Velocity maps of Ne7+ from its bright resonance line at 770 angstroms, formed at the base of the corona, show a relationship between outflow velocity and chromospheric magnetic network structure, suggesting that the solar wind is rooted at its base to this structure, emanating from localized regions along boundaries and boundary intersections of magnetic network cells. This apparent relation to the chromospheric magnetic network and the relatively large outflow velocity signatures will improve understanding of the complex structure and dynamics at the base of the corona and the source region of the solar wind.     

United States Department of Agriculture-Agricultural Research Service stored-grain areawide integrated pest management program

The USDA Agricultural Research Service (ARS) funded a demonstration project (1998-2002) for areawide IPM for stored wheat in Kansas and Oklahoma. This project was a collaboration of researchers at the ARS Grain Marketing and Production Research Center in Manhattan, Kansas, Kansas State University, and Oklahoma State University. The project utilized two elevator networks, one in each state, for a total of 28 grain elevators. These elevators stored approximately 31 million bushels of wheat, which is approximately 1.2% of the annual national production. Stored wheat was followed as it moved from farm to the country elevator and finally to the terminal elevator. During this study, thousands of grain samples were taken in concrete elevator silos. Wheat stored at elevators was frequently infested by several insect species, which sometimes reached high numbers and damaged the grain. Fumigation using aluminum phosphide pellets was the main method for managing these insect pests in elevators in the USA. Fumigation decisions tended to be based on past experience with controlling stored-grain insects, or were calendar based. Integrated pest management (IPM) requires sampling and risk benefit analysis. We found that the best sampling method for estimating insect density, without turning the grain from one bin to another, was the vacuum probe sampler. Decision support software, Stored Grain Advisor Pro (SGA Pro) was developed that interprets insect sampling data, and provides grain managers with a risk analysis report detailing which bins are at low, moderate or high risk for insect-caused economic losses. Insect density was predicted up to three months in the future based on current insect density, grain temperature and moisture. Because sampling costs money, there is a trade-off between frequency of sampling and the cost of fumigation. The insect growth model in SGA Pro reduces the need to sample as often, thereby making the program more cost-effective. SGA Pro was validated during the final year of the areawide program. Based on data from 533 bins, SGA Pro accurately predicted which bins were at low, moderate or high risk. Only in two out of 533 bins did SGA Pro incorrectly predict bins as being low risk and, in both cases, insect density was only high (> two insects kg(-1)) at the surface, which suggested recent immigration. SGA Pro is superior to calendar-based management because it ensures that grain is only treated when insect densities exceed economic thresholds (two insects kg(-1)). This approach will reduce the frequency of fumigation while maintaining high grain quality. Minimizing the use of fumigant improves worker safety and reduces both control costs and harm to the environment.     

A sandwich enzyme immunoassay for bovine interferon-γ and its use for the detection of tuberculosis in cattle

An in vitro cellular assay for bovine tuberculosis has recently been developed. This assay detects gamma-interferon released in response to specific antigen in a whole blood culture system. The bio-assay previously described for the detection of bovine gamma-interferon (IFN-gamma) has now been replaced with a sandwich enzyme immunoassay (EIA) which utilises two monoclonal antibodies to bovine IFN-gamma. The EIA detects less than 25pg/ml of recombinant bovine IFN-gamma and is specific for biologically active bovine IFN-gamma; and does not detect bovine alpha or beta interferon. IFN-gamma from sheep, goat and buffalo, but not from pig, deer or man, are also recognised by the EIA. The bovine IFN-gamma EIA when used in conjunction with the whole blood culture system has resulted in a simple, rapid and sensitive in vitro assay for specific cell mediated immune responsiveness to M. bovis infection in cattle.     

Cyclic nucleotide phosphodiesterase: high activity in a mammalian photoreceptor

Purified outer segments of bovine rods exhibit phosphodiesterase activity against adenosine and guanosine cyclic 3',5'-monophosphates (cyclic AMP and cyclic GMP). The enzyme hydrolyzed cyclic GMP more rapidly than cyclic AMP at low substrate concentrations. The presence of high phosphodiesterase activity in this highly specialized organelle suggests that this enzyme may function in control of cyclic nucleotide concentration during visual excitation or adaptation.