Nitrogen flows and balances in four grassland‐based systems of dairy production on a clay‐loam soil in a moist temperate climate

This study examined productivity, nitrogen (N) flows and N balances in grassland‐based systems of dairy production in Ireland. There were four stocking densities of dairy cows on grass/white clover pastures and four inputs of N as fertilizers, concentrates and biological fixation over 2 years; 2001 and 2002. Annual stocking densities were 1·75, 2·10, 2·50 and 2·50 cows ha^?1. Associated N inputs were 205, 230, 300 and 400 kg ha^?1 respectively. There were eighteen cows per system. Cows calved within a 12‐week interval in spring with a mean calving date of 28 February and lactation extended until mid‐December in each year. There were no differences in annual milk yield (6337 kg cow^?1; s.e.m. 106·1), live weight or body condition score. Pre‐grazing N concentrations in herbage increased (P < 0·001) with increasing N input, whereas there were no differences in N concentrations in silage reflecting optimum N inputs for silage production. Grazed herbage accounted for 0·64, silage 0·26 and concentrates 0·10 of annual dry matter consumed by the cows. Annual intakes of N ranged from 144 to 158 kg cow^?1 and were mostly influenced by N concentration in grazed herbage. Annual output of N in milk and liveweight change was 38 kg cow^?1 and was not different between systems. Annual N surpluses increased with increasing N inputs from 137 to 307 kg ha^?1, whereas the proportion of N inputs recovered in products declined from 0·34 to 0·24. More efficient N use was associated with lower N inputs and in particular lower N concentrations in grazed herbage.     

Determining the consistency of thermal habitat segregation within and among Arctic charr morphotypes in Gander Lake,Newfoundland

Abstract – Otolith carbon and oxygen isotope data obtained from distinct genetic and ecological groups of lacustrine Arctic charr, Salvelinus alpinus L., from Gander Lake, Newfoundland, were used to examine hypotheses regarding the consistency of differential habitat use among the groups. Results indicated thermal habitat separation by group, with small ‘pale’ individuals consistently remaining in cooler profundal habitats and larger ‘dark’ individuals more frequently occupying warmer upper water column habitats. Theoretical measures of resource separation and competition indicated lower thermal habitat overlap among the forms and greater within‐form competition. Depth at capture data indicated more varied short‐term use of available lake habitats by ‘dark’ form Arctic charr, possibly as a result of cannibalistic foraging on profundal ‘pale’ form fish. Nominal capture depth data only partially explained observed variation in the mean temperature of occupied thermal habitat, suggesting that capture depth can only be used as a rough index of thermal habitat use. Provided that sufficient thermal gradients exist in the environments being studied, otolith oxygen isotopes provide a useful means of establishing the significance of niche differentiation among individuals.     

Diversity and distribution of Victoria Land biota

Understanding the relationship between soil biodiversity and ecosystem functioning is critical to predicting and monitoring the effects of ecosystem changes on important soil processes. However, most of Earth's soils are too biologically diverse to identify each species present and determine their functional role in food webs. The soil ecosystems of Victoria Land (VL) Antarctica are functionally and biotically simple, and serve as in situ models for determining the relationship between biodiversity and ecosystem processes. For a few VL taxa (microarthropods, nematodes, algae, mosses and lichens), species diversity has been intensively assessed in highly localized habitats, but little is known of how community assemblages vary across broader spatial scales, or across latitudinal and environmental gradients. The composition of tardigrade, rotifer, protist, fungal and prokaryote communities is emerging. The latter groups are the least studied, but potentially the most diverse. Endemism is highest for microarthropods and nematodes, less so for tardigrades and rotifers, and apparently low for mosses, lichens, protists, fungi and prokaryotes. Much of what is known about VL diversity and distribution occurs in an evolutionary and ecological vacuum; links between taxa and functional role in ecosystems are poorly known and future studies must utilize phylogenetic information to infer patterns of community assembly, speciation, extinction, population processes and biogeography. However, a comprehensive compilation of all the species that participate in soil ecosystem processes, and their distribution across regional and landscape scales is immediately achievable in VL with the resources, tools, and expertise currently available. We suggest that the soil ecosystems of VL should play a major role in exploring the relationship between biodiversity and ecosystem functioning, and in monitoring the effects of environmental change on soil processes in real time and space.     

Worms in smallholder livestock systems: technologies and practices that make a difference

Australian scientists, in partnership with Asian, African and Pacific nations have longstanding interests in applied research on helminth parasite control. Many technologies and practices have been successfully developed to control the parasite problems of smallholder and emerging farmers. This wide range extends from simple herbal remedies to complex, integrated use of chemicals, feeding and breeding. In many cases widespread adoption has been limited by lack of technical support, poor access to input markets and lack of incentives for poorer farmers to seek out and pay for innovations. A further new approach may be required that encompasses the wider production and market environment. The biological, social and economic context of each 'emerging farming system' is different and the matching of technologies to each system requires sound understanding of farmer needs and requirements. Thus, it is essential that farmers, extension workers, and scientists jointly decide what technologies to try, what results mean and, if successful, how to sustain their use. In one Asian example a range of technologies were considered for pig, large ruminant and goat production and parasite control through a participatory process which was also used to agree on what determines sustainability beyond testing. The criteria use to screen technologies and practices were (a) continued availability of inputs including dewormers, (b) dependence on related innovations (e.g. weaning or fencing) and (c) degree of community organisation required (e.g. control of breeding or communal grazing). On this basis deworming with chemicals, especially for Toxacara infection in cattle and buffalo calves following on from supplementary feeding with forages were the most feasible entry points. Further interventions were dependent on changes to the production system, including the introduction of weaning and controlled breeding. Further, the incentives for these production changes could not exist without improved market access and market signals for improved weight and condition. Examples such as this point to the need for stronger multidisciplinary and participatory approaches to parasite control.     

An evaluation of pre-emergent herbicides for container-grown ornamental plants

Two applications of 5 herbicides were evaluated during spring and summer for weed control and phytotoxicity on 25 species of trees, shrubs and herbaceous perennials. Weed control was considered to be effective if herbicide-treated pots contained at most 20% of the weeds in untreated pots. Oxyfluorfen applied at 1.25, 2.5 and 5.0 kg ha^?1 provided effective control of grass and broad-leaved weeds for 8 weeks after the first application, and the 2 higher rates effectively controlled all weeds for 12 weeks after the second application. Oxadiazon at 2.0, 4.0 and 8.0 kg ha^?1 effectively controlled all weeds for 8 weeks after the first application, but only the highest rate was effective 12 weeks after the second application. Napropamide at 5.0, 10.0 and 20.0 kg ha^?1 effectively controlled grasses for up to 12 weeks, but only effectively controlled broad-leaved weeds at the 2 higher rates for 8 weeks after the first application and failed to control them after the second application. Alachlor at 4.0, 8.0 and 16.0 kg ha^?1 and oryzalin + trifluralin at 0.5, 1.0 and 2.0 kg ha^?1 provided effective control of grasses for 8 weeks after the first application. These herbicides at the highest rate also controlled broad-leaved weeds for 8 weeks after the first application. However alachlor and oryzalin + trifluralin failed to provide effective control of any weeds after the second application.Competition from weeds reduced the shoot dry weight (SDW) of unweeded control pots by 20% compared with hand-weeded control pots. None of the herbicides produced visible clamage in any plants. The SDW of 8 species treated with some of the herbicides was significantly lower than the corresponding hand-weeded control plants, and for 6 of these species some herbicide treatments were identified as being possibly phytotoxic. Oxyfluorfen appeared to inhibit the growth of Photinia and Coleonema, and alachlor inhibited the growth of Photinia, Eriostemon, Azalea ‘Splendens’, Lavendula and Coleonema. Oryzalin + trifluralin appeared to inhibit the growth of Bauhinia, and napropamide and oxadiazon inhibited the growth of Coleonema.     

Immunization and Parenteral Chemotherapy for the Control of Cattle Grubs Hypoderma Lineatum

Immunization with two types of warble larvae antigens A and B, the latter treated with tannic acid, and injections of dimethoate, an organic phosphate, were tried for the control of prehypodermic larvae of Hypoderma lineatum De Vill., and H. bovis L., in range calves.

In test groups of 20 calves, given intramuscularly, antigen A had no effect, but combined treatment with antigens A and B reduced the number of H. bovis L., larvae by 81 per cent (P<.001), and proved as effective as dimethoate subcutaneously or intramuscularly. H. lineatum De Vill., did not respond to any treatment.

Antigen B and dimethoate were free from harmful effects on the host, but antigen A caused anaphylaxis and irritation at the site of injection.

     

Fenitrothion plus (1R)-phenothrin,and pirimiphos-methyl plus carbaryl,as grain protectant combinations for wheat

Duplicate field trials were carried out on bulk wheat in commercial silos in Queensland and New South Wales. Laboratory bioassays on samples of treated grain at intervals over 9 months, using malathion-resistant strains of insects, established that treatments were generally effective. Fenitrothion (12 mg kg^?1)+ (1R)-phenothrin (2 mg kg^?1) was more effective than pirimiphos-methyl (6 mg kg^?1) + carbaryl (10 mg kg^?1) against Sitophilus oryzae (L.) and Ephestia cautella (Walker); the order of effectiveness was reversed for S. granarius (L.). Against Rhyzopertha dominica (F.), Tribolium castaneum (Herbst), T. confusum Jackquelin du Val and Oryzaephilus surinamensis (L.), both treatments effectively prevented the production of progeny. The order of persistence was pirimiphos-methyl> (1R)-phenothrin>carbaryl or fenitrothion. During processing from wheat to white bread, residues were reduced by 98% for carbaryl, >44% for (1R)-phenothrin, 98% for fenitrothion and 85% for pirimiphosmethyl.