Use of phosphorus fertiliser for increased productivity of legume-based sown pastures in the Brigalow Belt region – a review

The Brigalow Belt bioregion of southern and central Queensland supports a large percentage of northern Australia's sown pastures and beef herd. The Brigalow soils were widely thought to have adequate phosphorus (P) for cropping, sown pastures and grazing animals, which has led to almost no use of P fertiliser on sown pastures. The majority of pastures established in the region were sown with tropical grasses only (i.e. no legumes were sown). Under grass-only pastures, nitrogen (N) mineralisation rates decline with time since establishment as N is 'tied-up' in soil organic matter. This process leads to a significant decline in pasture and animal productivity and is commonly called 'pasture rundown'. Incorporating pasture legumes has been identified as the best long-term solution to improve the productivity of rundown sown grass pastures. Pasture legumes require adequate P to grow well and fix large amounts of N to increase the productivity of rundown sown grass pastures. Producers and farm advisors have traditionally thought that P fertiliser is not cost-effective for legume-based improved pastures growing on inland areas of Queensland despite there being little, if any, data on production responses or their economic outcomes. Recent studies show large and increasing areas of low plant available soil P and large responses by pasture legumes to P fertiliser on Brigalow soils. The economic analysis in this scoping study indicates potential returns of 9–15% on extra funds invested from the application of P fertiliser, when establishing legumes into grass pastures on low P soils (i.e. lower than the critical P requirement of the legume grown). Higher returns of 12–24% may be possible when adding P fertiliser to already established grass/legume pastures on such soils. As these results suggest potential for significant returns from applying P fertiliser on legume pastures, it is recommended that research be conducted to better quantify the impacts of P fertiliser on productivity and profit. Research priorities include: quantifying the animal production and economic impact of fertilising legume-based pastures in the sub-tropics for currently used legumes; quantifying the comparative P requirements and responses of available legume varieties; understanding clay soil responses to applied P fertiliser; testing the P status of herds grazing in the Brigalow Belt; and quantifying the extent of other nutrient deficiencies (e.g. sulphur and potassium) for legume based pastures. Development and extension activities are required to demonstrate the commercial impacts of applying P fertiliser to legume based pastures.

Developing Jungle Perch Fingerling Production to Improve Fishing Opportunities

This project has for the first time demonstrated the feasibility of hatchery production of jungle perch fingerlings. The research on jungle perch production has enabled a hatchery production manual with accompanying videos to be produced. This has given private commercial hatcheries the information needed to produce jungle perch fingerlings. Several hatcheries have already indicated an interest in producing jungle perch and will be assisted to do so in 2016. Currently jungle perch are not a permitted stocking species, so cannot be sold to fish stocking groups. However, hatcheries will be able to sell fingerlings to the aquarium trade or supply grow out facilities that could produce jungle perch for human consumption. Should jungle perch become a permitted species for stocking, this will provide hatcheries with a major new product option to sell to fish stocking groups. It would also benefit anglers by providing another iconic species for impoundment stocking programs. This could have flow-on benefits to regional economies through angler tourism. Should the pilot reintroductions of jungle perch into streams result in self-sustaining jungle perch populations, then there will be three restored jungle perch populations close to major population centres. This will create a new opportunity for anglers not normally able to target jungle perch. Since the majority of anglers who target jungle perch are catch and release fishers, angling is expected to have minimal impact on recovery of the populations. This project led to the development of a hatchery manual for jungle perch production and to a summary brochure. In late 2014 and in 2015 researchers were able to make the first ever releases of jungle perch fingerlings back into rivers and streams within their historical range.

The multidimensional causal factors of ‘wet litter’ in chicken-meat production

The problem of ‘wet litter’, which occurs primarily in grow-out sheds for meat chickens (broilers), has been recognised for nearly a century. Nevertheless, it is an increasingly important problem in contemporary chicken-meat production as wet litter and associated conditions, especially footpad dermatitis, have developed into tangible welfare issues. This is only compounded by the market demand for chicken paws and compromised bird performance. This review considers the multidimensional causal factors of wet litter. While many causal factors can be listed it is evident that the critical ones could be described as micro-environmental factors and chief amongst them is proper management of drinking systems and adequate shed ventilation. Thus, this review focuses on these environmental factors and pays less attention to issues stemming from health and nutrition. Clearly, there are times when related avian health issues of coccidiosis and necrotic enteritis cannot be overlooked and the development of efficacious vaccines for the latter disease would be advantageous. Presently, the inclusion of phytate-degrading enzymes in meat chicken diets is routine and, therefore, the implication that exogenous phytases may contribute to wet litter is given consideration. Opinion is somewhat divided as how best to counter the problem of wet litter as some see education and extension as being more beneficial than furthering research efforts. However, it may prove instructive to assess the practice of whole grain feeding in relation to litter quality and the incidence of footpad dermatitis. Additional research could investigate the relationships between dietary concentrations of key minerals and the application of exogenous enzymes with litter quality.