Ten paired irrigated dairy farms under biodynamic (BD) and conventional (CV) management were compared over a 4-year period (1991–94). The paired farms were located in the irrigation districts of northern Victoria and southern New South Wales and were matched for soil type, climate, cattle breed and farm area. Farms had been practising BD principles for an average of 16 years before the commencement of the study and had not received phosphorus (P) fertiliser for an average of 17 years. The effects of farm management on soil chemical and biological properties and the nutritive properties and botanical composition of pasture were examined at varying sampling times during the study. Soil Olsen extractable P concentrations were consistently 2–3 times higher under CV management at various sampling depths (mean = 22 mg/kg, 0–10 cm), and were generally marginal under BD management in the surface 10 cm (mean = 8.5 mg/kg). Low soil extractable P concentrations were also reflected in consistently lower mean pasture P concentrations under BD management (0.25 compared with 0.35% on CV farms). Lower soil and pasture P concentrations under BD management were the result of a large negative P balance across BD farms (–17 kg P/ha.year). A mean negative P balance under BD management was a result of low P imports (2 kg P/ha.year) in comparison with large quantities of P (19 kg P/ha.year) effectively lost from the farming system through animal products, estimated losses in water runoff and slowly reversible soil P reactions. These results suggest that greater P imports are required to ensure the future sustainability of BD dairy pasture farming systems. There were few differences in soil biological properties, with earthworm weights significantly higher under CV management, but no difference in soil organic carbon, humus concentration, the weight of the organic mat or microbial biomass, between the two management systems.
Two monitoring projects were conducted to investigate weaner mortality in commercial Merino flocks in the Yass and the Central Tablelands Rural Lands Protection Boards located in the Southern Tablelands agricultural region of New South Wales. The projects were conducted in Yass in 2005 and in the Central Tablelands in 2006. A random sample of weaners from four flocks in the Yass board and 11 flocks in the Central Tablelands board were regularly weighed, growth rates were calculated after weaning and survival was determined by the continuing presence of an individual weaner at subsequent weighing activities. Weaning weight was the most important factor in determining postweaning liveweight, growth rates and survival with the significant impact of weaning weight on liveweight persisting for up to 6 months after weaning. Despite the lightest weaners being capable of considerable compensatory growth given sufficient postweaning nutrition, the lightest 25% of weaners were more than twice as likely to die as heavier weaners. A focus on ewe nutrition and parasite control during late pregnancy and lactation will allow Merino producers to achieve higher weaning weights that will set their weaners up for strong postweaning growth with a decreased likelihood of mortality.
Ten paired irrigated dairy farms under biodynamic (BD) and conventional (CV) management were compared over a 3-year period (1991–93). The paired farms were located in the irrigation districts of northern Victoria and southern New South Wales and were matched for soil type, cattle breed and farm area. The BD farms practised BD principles for an average of 16 years before the study. The effects of farm management on milk yields and composition and animal health were examined by annually surveying farm managers regarding disease incidence and chemical treatment of animals, and by measuring milk yield and composition and faecal egg counts over the experimental period. The two hypotheses tested were that (1) milk volume and milk solids per cow would be lower under BD management, and (2) the incidence of internal parasitic infection and disease would be lower under CV management. Milk production and milk components produced, both on a per hectare and per cow basis, were 24–36% higher (P < 0.01) under CV management, due to significantly higher pasture intakes (P < 0.001). Although the incidence of parasitic infection was similar for mature cows, CV farms consistently used a greater number of chemical treatments (P < 0.05). Although BD heifer calves <8 months in age had significantly (P < 0.05) higher faecal egg counts, the results highlight the risk of reduced growth rates in calves due to high rates of parasite infection, under both management systems. Somatic cell counts were higher (P < 0.05) under BD management, with this being consistent with the use of significantly less chemical treatments under this management system. The implications of these findings for both CV and BD management for milk production and animal health are discussed.
These studies were made in the Inverleigh district of Victoria where a sheep breeding problem has occurred among summer-mated ewes in some years since 1947. The possibility of onion grass (Romulea rosea L.) poisoning being responsible for this problem was investigated. The botanical composition of the diet selected by four sheep, fitted with oesophageal fistulas and grazing an onion grass dominant pasture on a problem property, was determined approximately every two weeks during the late summer and autumn of two years. One year (1965) was a problem year and the other year (1966) was a non-problem year for sheep reproduction on this property and in this district. The experimental sheep ate appreciable amounts of both dry and green onion grass, especially in the late summer and immediately after the autumn rains. The mean percentage of dry onion grass in the diet before the autumn break was 20 in 1965 and 31 in 1966 ; and after the autumn break the mean per cent of green onion grass was 16 in 1965 and 28 in 1966. Overall, the sheep did not show a dietary preference for onion grass as twice these levels were present in the dry or green pasture species. The major difference in onion grass intake between the two years was that, because of the late autumn break in 1965, the fistulated animals ate dry onion grass (and onion grass seed) for six weeks longer than in 1966.
1. Attention is drawn to the remarkable dissimilarity between the cacao and the grapefruit tree in their nutrient requirements, indicating that grapefruit is calcicolous in physiological habit. This conclusion is mainly based on a consideration of the results of chemical analysis of representative leaf material produced by trees grown on soil of known chemical and physical characteristics, under the same climatic conditions in Trinidad.2. The nutrient relationships that obtain between the cacao and the grapefruit tree respectively and the soil in which they are growing have been gauged by means of chemical analysis of representative leaf material.3. For this purpose, leaf material was obtained from trees growing on the differently manured plots of two large-scale field experiments in Trinidad.
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