School of Agriculture, Food and Ecosystem Sciences - Theses
Permanent URI for this collection
Search Results
1 - 10 of 18
-
ItemSpecies composition of improved dairy pastures in Bumthang, Bhutan( 2005)Multilocation studies of forage mixtures since 1970s identified white clover, cocksfoot, tall fescue and Italian ryegrass as appropriate pasture mixture for Bhutanese temperate environments. To date, there has been limited evidence on the long-term sustainability of these mixtures in farmer managed environments. Forty-one grazed pastures and fifty cut pastures were sampled in the elevation range of 2500-3500 m asl. Species composition was expressed in terms of tiller/growing point density of grass and legume species. Tiller core technique was used to measure plant densities. Soil samples were collected from depth profile of 5- 15cm. The dried soil samples were analysed for P, K, pH and texture. Dairy farmers were interviewed to obtain paddock histories and information on defoliation management. The tiller density of cocksfoot was higher in cut pastures though cocksfoot was negatively associated with cutting frequency. Cocksfoot was negatively associated with white clover and Italian ryegrass for both cut and grazed pastures. Soil pH was negatively associated with pasture age. Negative associations between K and pasture age was observed for both cut and grazed pastures. White clover was positively associated with P in grazed pastures. Italian ryegrass was positively associated with P, soil pH and moisture in grazed pastures. Available P was negatively associated with elevation. Cocksfoot abundance in cut pastures has been attributed to cocksfoot being a well adapted hay type species. The lower tiller density of cocksfoot in grazed pastures may be the consequence of continuous grazing without adequate rest period. White clover is positively associated with available P due to white clover being a well known plant that requires adequate levels of available P. The positive association between Italian ryegrass and pH has been explained by the greater availability of P with increasing pH. A decline in the levels of available K in older pastures was related to repeated defoliation without K inputs to replace the losses.
-
ItemA study of the effects of high stocking rates on the production of perennial pasture and its utilization by dairy cattle( 1973)The work in this thesis consists of a study of the effects of increasing the stocking rate from 2.2 to 3.2 cows per hectare on the production of dairy cattle and perennial pastures from 1966-70. (a) Milk production per cow was significantly reduced (P < 0.05) by the increase in.:stocking rate with the exception of the first year. (b) The yield of milk and milk components per hectare was increased (P< 0.05) by the increase in stocking rate except for 1968-69 when a drought occurred and the increases were not large enough in most components to attain significance (P)00.05). The yield of nitrogen in milk per hectare was significantly increased (p<0.05) in all years with stocking rate. (c) There was a tendency for the high stocking rate to lower the percentage of all components in milk with the exception of nitrogen which remained unaltered. However significant differences were not recorded consistently in any one component over the four lactations studied. (d) No significant differences (p>0.05) in seasonal or annual net pasture production were recorded between stocking rates. (e) The increase in stocking rate caused significant increases (1).<0.01) in grazing pressure, reductions in pasture availability (P<0.01) and higher contents of crude protein (1).<0.01) in pasture excepting spring and on two occasions in winter. (f) Estimates of feed intake at the higher stocking rate showed a significant increase in pasture harvested (P < 0.01) per unit area every year. However with the exception of the first year feed intake per cow was significantly reduced (P<0.01). (g) The ratio of pasture consumed per hectare to milk production per hectare was not significantly affected (P>0.05) by the increase in stocking rate.
-
ItemSome effects of botanical composition of pasture on the liveweight and wool production of sheep( 1972)Until recently, the main evidence on which to base pasture mixture. recommendations in Victoria, has been district experience and the results from dry matter ( "mowing") experiments. The grazing experiments described in this thesis, were initiated by Messrs. R. Twentyman, R. Newman, R. Allen and K. Maher of the Department of Agriculture during the period, 1960-196. Their aim was to develop some objective appreciation of the relative value for animal production of some of the sown and unsown species in Western district pastures. In addition to pasture species evaluation, they sought information on the relationship between pasture growth and animal production. Such information is needed so that Agrostologists can better evaluate the many pasture management factors (such as fertilizers, seeding rates, seed. treatments, herbicides, insecticides and defoliation treatments) that affect pasture growth and for which advice is frequently sought.
-
ItemThe economic evaluation of forage research results( 2004)Three economic analyses were conducted on the results of dairy forage production experiments undertaken in Victoria. The first analysis investigated the level of pasture production increases that would have to be achieved to warrant the investment in different soil modification options. This analysis took pasture production data and using a computer program "UDDER" (Larcombe 1990) generated farm data which was then applied to development budgets. The increase in pasture growth rate required was such that it is unlikely that investment in the soil modification systems tested here will produce a satisfactory return on investment. The second analysis investigated the use of different pasture species combinations on a dairy farm in northern Victoria. A linear programming model was developed that balanced the energy requirements of the milking herd with the energy supplied from pasture and supplements. The results showed that the most profitable mix of pasture depended on the energy supply profile of the pasture and the requirements of the herd. The proportion of autumn and spring calving cows in the herd in part determined the most profitable pasture mix. The effect of grazing management on profit was the subject of the third study. A farm model was constructed that balanced the energy, protein and neutral detergent fibre requirements of the milking herd with that supplied by pasture and supplements and optimised operating profit. The results of a grazing trial conducted in south-west Victoria were entered into the model and the operating profits for each treatment compared. The results suggested that while Operating profit was related to total pasture consumption, the timing of the pasture consumption impacted on operating profit. The results also suggested that grazing frequency may have affected operating profit more than grazing intensity.
-
Item
-
ItemThe effect of applied N and P under mowing and grazing on the yield and botanical and chemical composition of irrigated pasture and on the nutrient status of a red-brown earth at Kyabram( 1978)A split plot experiment was conducted over 4 years to study the effect of method of harvesting (grazing and mowing) and applied N and P (5 rates of nitrogen ranged from 0 to 112 kg N ha -1 cut-1 and 6 rates of superphosphate ranged from 0 to 188 kg P ha 1 year year-1) on the yield, botanical and chemical composition of irrigated phalaris (Phalaris tuberosa x Phalaris arundinacea)/white clover (Trifolium repens L. cv. Irrigation) pasture and nutrient status of a red-brown earth at Kyabram. A second experiment was conducted over 2 years to find out the effect of rates (0 to 112 kg N ha. 1) and frequency of N application (2, 4 or 8 times year ) o n dry matter production, botanical composition and crude protein content of paspalum (Paspalum dilatatum)/white clover pasture. Results: Mowed plots significantly out-yielded grazed plots in the first two years. However, grazed plots significantly out-yielded mowed plots in the following two years. Nitrogen application significantly (P <0.01) increased dry matter production of grass/clover mixtures. The size of response was governed by the growth rate of pasture species, clover percentage in the sward, climatic conditions and the status of other nutrients in the soil. Splitting N rates in smaller but more frequent applications had no effect on total herbage yield or seasonal distribution. Response to N (kg D.M. kg N-1 ) declined as N rates increased. Phosphorus application up to 94 kg P ha -1 year -1 significantly (P,(0.01) increased pasture production and relative response was greater in winter. Occasionally, the P and N requirements for maximum production were higher for grazing than for mowing. Both methods of defoliation and fertilizer applications affected pasture composition and IT, P and K content in the herbage. Nitrogen application decreased N in the herbage before increasing it and P application up to 141 kg P ha- 1 year -1 increased it. The return by the grazing animal increased total soil N by 106 kg ha 1 year 1 and soil P (Colwell) by 1:0 p.p.m. in four years compared with the start of the experiment. The relationship between plant P and soil P and P rates were significant (P < 0.01). The available soil P decreased with P withdrawal or the application of 23.5 kg P ha-1 year -1 under grazing and 47 kg P ha -1 year-1 under mowing. Phosphorus and nitrogen application significantly affected available soil P. 60-80% of the available P accuminulated in the 0-5 cm and the downward movement increased by increasing P rates. The continuous mowing and P application significantly reduced available soil K. Defoliation method affected C/t:N ratio. Phosphorus application increased soil N whereas N application decreased it. P application at the rate of 23.5 kg ha-1 year-1 increased total soil N by 0.068% which is equivalent to 952 kg N ha-1 in five years. It was estimated that 4 to 4.7 p.p.m of P was required to be removed or added to the soil to change the available soil P by 1 p.p.m. The application of 196 kg N ha-1 year -1 as NH4 NO3 did not change the soil pH and 784 kg N ha 1 year 1 reduced soil pH by an average of ').4 unit.
-
ItemFactors influencing the purchases of Pivot fertilisers and Prescription Farming program /cIwan Dhaniyarso( 2000)This study is about the factors influencing the purchases of fertiliser and prescription farming in general and Pivot fertilisers and the Pivot Prescription Farming in particular. The purchase of Pivot fertilisers in this study is defined to be a decision about Pivot as the main fertiliser company. Meanwhile, the purchase of Pivot Prescription Farming is defined as whether or not farmers purchase the Pivot Prescription Farming for the on going activities of their farms. Prescription farming, in this study, refers to services associated with farm inputs such as soil testing and plant analysis. Farmers' decision-making process on the farm inputs, including the choice within a product class, might be dominantly influenced by the problem-solving process. However, the human factors in the farmers' decision is also important. Thus, the farmer's decision-making process is likely to be based on a combination of cognitive and emotional models. In the context of farm income, farmers normally face three stages on the problem of their income allocation. First, allocation to production, consumption and savings. Second, allocation to the categories of generic products in farm activities such as tractors, compound feed and fertilisers. Third, allocation within a product class such as a particular product type or brand. Since the purchase of fertiliser and prescription farming might be categorised as an out-stock situation, the buying process for these inputs only involves stage three. Past research has indicated that the purchase of fertilisers from a particular firm might be affected by quality, price, service, availability of fertiliser, distribution coverage and a specific relationship with the firm. Past studies on the use of soil testing and plant analysis, which are some elements of prescription farming, have shown that price, turnaround time, reliability of results, service and follow up of the service have influenced the use of these services. Additionally, knowledge about available providers, which reflects the amount of information possessed, may influence the purchase. The quantitative analyses in this study use existing data from Pivot Ltd. The method used in this study is logistic regression. The decision on the purchase of Pivot Prescription Farming is involved in the model for the decision on Pivot as the main fertiliser company, and vice versa. For this particular sample, the results revealed that no variable was found to be significant in explaining the decision about Pivot as the main fertiliser company. Only the purchase of Pivot Prescription Fanning and some dummy variables for types of farm and states were significant. The result may indicate that subjective norm appears in the outcome. For the decision about the purchase of the Pivot Prescription Farming, knowledge about service provider, follow up, turnaround time and the decision on Pivot as the main fertiliser company significantly affected the purchase. Those results indicated that farmers who chose Pivot as their main fertiliser company were more likely to purchase the Pivot Prescription Farming, and vice versa. The results also revealed that there is a need to do further research to incorporate with the important issues such as brand loyalty, consumer attitude formation, and the multipersonal influence in farm enterprise, in a better survey with more exhaustive data collection methods.
-
Item
-
ItemEffects of irrigation on the roots of pastures( 1969)An experiment was conducted in order to investigate the effects of wetting the soil to a range of depths, on the root growth and top growth of some pasture species. The experiment was done within a glasshouse, using a sandy loam soil; the pasture species studied were white clover, ryegrass and subterranean clover. Gypsum block readings, and visual assessment of the moisture status of the soil (as seen through the transparent walls of the containers) were used to decide when to apply water. The soil was maintained within the wetter 2/3 of the available moisture range, so that the effects of drying cycles were avoided. For each species the depth of wetting had a marked effect on the depth of roots; in all treatments, the roots completely occupied the depth of wetted soil. With the deeper wetting treatments both of the perennial species showed a marked increase in the weight of tops, but the annual subterranean clover showed no significant differences. On the other hand, the effect of deeper wettings on the weight of roots was significantly greater for white clover; it was not significantly different for ryegrass; but it was significantly less for subterranean clover.
-
Item