Phosphorus Fertilizer and Stocking Rate Effects on Soil Microbial Biomass of a Long-Term Dairy Farmlet Experiment

The effects of a range of P fertilizer rates and dairy cow stocking rates on microbial biomass carbon and phosphorus were compared in a long-term farmlet trial in southeastern Australia. Pastures were stocked at 2, 3, or 4 cows/ha and received fertilizer at rates of 0, 35, 70 or 140 kgP/ha. There was no effect of either P fertilizer rate or stocking rate on microbial biomass C from 1995 to 1998. Increasing P application rate significantly increased the chloroform-released microbial P flush measured, but stocking rate had no effect on microbial P. There were significant temporal changes, with the seasonal effects of soil temperature and moisture overriding treatment effects on these microbial measurements

Grazing Management Impacts on the Riparian Zone and Water Quality

Inappropriate farm management activities such as stock access to creeks, and poor fertiliser and effluent management can negatively impact riparian zones and waterways, contributing to increased in-stream nutrient, sediment and microbiological loads and loss of riparian biodiversity, amongst other impacts. Nutrient budgets for dairy systems indicate that on-farm nutrient accumulation and redistribution is common (Gourley 2004), which in large part is due to the uneven distribution of dairy cow dung and the nutrients they contain (Aarons et al., 2004). The \u27Gippsland Dairy Riparian Project Environmental Monitoring module\u27 was established in Jan. 2003 to monitor the impact of dairy farm management and changed riparian zone management on the riparian zone and water quality

Contribution of Dairy Cow Manure to Soil Fertility and Nutrient Redistribution in Pastures

The effects of dairy cow manure on soil fertility were investigated at the site of the long-term phosphorus rate by stocking rate farmlet experiment at the Dairy Research Institute, Ellinbank, in Victoria. Manure increased extractable soil P (Olsen) in the 0 - 5 cm layer after 60 days to 61 mg/kg compared with values of 32 mg/kg in the control soils. Extractable soil K (Colwell) almost doubled under manure pads to 5 cm depth from 642 mg/kg in control soils to 1226 mg/kg in manure treated soils. The effects of grazing management on nutrient redistribution and pasture growth within strip-grazed paddocks was also investigated. While soil Olsen P was not different, Colwell K (p \u3c 0.001) and pasture height (p \u3c 0.01) were significantly greater at the front or gate-end of the paddocks compared with the back

Fertiliser Responses and Soil Test Calibrations for Grazed Pastures in Australia

On-farm management of fertiliser is of major economic significance to the Australian grazing industries, based on expenditure on fertiliser and higher farm productivity that fertiliser use supports. However the application of fertiliser has traditionally been an inexact and inefficient process (Peverill et al. 1999) and there is increasing pressure for nutrient losses from agriculture to be minimised. The improved adoption and application of tools like soil testing can make substantial improvements in nutrient use efficiency but interpretation needs to be based on the best available information. This paper reports on the collation of current and historical experimental data relating to pasture production - fertiliser response relationships (nitrogen, phosphorus, potassium and sulphur) for various pasture types, climatic zones and soils across Australia

Investigation of the soil properties that affect Olsen P critical values in different soil types and impact on P fertiliser recommendations

Optimization of phosphorus (P) fertiliser use is desired to ensure more sustainable use of fertiliser, economic food production and reduction of eutrophication of water bodies. Presently, the Olsen P values on which fertiliser recommendations are based to achieve optimum yield are frequently the same for all soils. The aim of this study was to identify the properties of different soils that affect their critical Olsen P values in order to develop better, soil specific P fertiliser recommendations. A pot experiment using 10 soils with low available P with different P additions was carried out to investigate the impact of wide-ranging soil properties on the relationship between P addition, resultant Olsen P values and yield response of ryegrass to Olsen P values. The relationship between added P and Olsen P varied greatly between the individual soils. These relationships were affected by pH, manganese oxide, crystalline aluminium oxide and amorphous iron oxide contents of the soil. Different soils had widely varying critical Olsen P values for ryegrass. However, these could not be related to the measured soil properties. Fertiliser recommendations and critical values for optimum yield of ryegrass based on the Olsen P test should be soil specific. The complexity and lack of clarity over which combination of soil properties governs critical Olsen P values calls for further investigation with more soil types and additional soil property measurements to elucidate the different factors controlling critical Olsen P values in different soils

Statistical Mechanics of Dilute Batch Minority Games with Random External Information

We study the dynamics and statics of a dilute batch minority game with random external information. We focus on the case in which the number of connections per agent is infinite in the thermodynamic limit. The dynamical scenario of ergodicity breaking in this model is different from the phase transition in the standard minority game and is characterised by the onset of long-term memory at finite integrated response. We demonstrate that finite memory appears at the AT-line obtained from the corresponding replica calculation, and compare the behaviour of the dilute model with the minority game with market impact correction, which is known to exhibit similar features.Comment: 22 pages, 6 figures, text modified, references updated and added, figure added, typos correcte

Structure-based design and synthesis of antiparasitic pyrrolopyrimidines targeting pteridine reductase 1

The treatment of Human African Trypanosomiasis remains a major unmet health need in sub-Saharan Africa. Approaches involving new molecular targets are important and pteridine reductase 1 (PTR1), an enzyme that reduces dihydrobiopterin in Trypanosoma spp. has been identified as a candidate target and it has been shown previously that substituted pyrrolo[2,3-d]pyrimidines are inhibitors of PTR1 from T. brucei (J. Med. Chem. 2010, 53, 221-229). In this study, 61 new pyrrolo[2,3-d]pyrimidines have been prepared, designed with input from new crystal structures of 23 of these compounds complexed with PTR1, and evaluated in screens for enzyme inhibitory activity against PTR1 and in vitro antitrypanosomal activity. 8 compounds were sufficiently active in both screens to take forward to in vivo evaluation. Thus although evidence for trypanocidal activity in a stage I disease model in mice was obtained, the compounds were too toxic to mice for further development