Browsing by Author "Nurmi, Elina"

Agriculture and other human activity has considerably affected the nitrogen cycle, which initially doubled the amount of nitrogen on the planet. The most well-known consequence of this phenomenon is eutrophication. The objective of this thesis was to study nutrient balances and their usefulness in evaluating the nitrogen usage in beef cattle farms, the nitrogen load and nitrogen use efficiency in those farms as well as how well the farms utilize their inputs. This study based on three organic beef cattle farms which took part in BERAS Implementation –project in 2010-2013. All farms specialized in suckler cow production. The data was collected in July-August 2013 when the farmers were interviewed about their inputs and outputs during the years 2010-2012. On the basis of this information different type of nitrogen balances were calculated. The farm gate nitrogen balances were 27, 36 and 70 kg/ha. Except for the last one, the feed self-sufficiency of the farms was very high, more than 90 %. The farm with the largest nitrogen surplus utilized a considerable amount of input from outside the farm which reflected in low feed self-sufficiency (64 %). The other two with smaller surpluses received excellent primary nutrient ratios (1,38 and 1,40) which indicates active nutrient recycling. However, despite of these results, it is important to remember that nutrient balances should be viewed with a critical eye. The uncertainties primarily concern the amount of biologically fixated nitrogen and the amount of yields of cultivated plants. These variables were taken into consideration in sensitivity analysis. Instead of nutrient balances, it would more useful to draw attention to other indicators such as feed self-sufficiency or animal unit density when evaluating nitrogen load of farms. The efficiency of beef cattle production depends also on how the production is actually implemented. It is especially important to acknowledge the importance of feeding and manure handling. The feed conversion ratio is always low in beef production since it is less than 10 %. Nevertheless, there are other benefits in cattle breeding such as utilization of natural pastures and cultivation of perennial grasses which not only are excellent for soil fertility, but also decrease nutrient leaching.