Browsing by Author "Räfså, Tomas"

More than half of the agricultural land in Finland is cultivated with cereals, and on many farms, cereals are also grown in monoculture. Studies have shown that crop rotation can decrease the need of inputs and also increase crop yields. At the same time more knowledge is needed about qualities and benefits of different crops. The aim of this study was to investigate the qualities of white lupin as a one year green manure crop, and to investigate its impact and nitrogen effect on barley yield formation and yield quality during the subsequent growth period. The aim was furthermore to investigate if white lupin affected soil mineral nitrogen content. A two year long field experiment was established during the growth season of 2010 at Viikki research farm in Helsinki. In year 2010 white lupin, barley and fallow was cultivated as precrops for the following growth period. In year 2011 only barley was cultivated and different nitrogen treatments were included in the experiment to be able to evaluate precrop nitrogen effect. In year 2011 cultivation of white lupin and barley was also repeated in a second field experiment. In the experiments, white lupin lenght development, ground coverage and biomass accumulation were recorded and compared with barley. The total amount of nitrogen that white lupin accumulated was also determined. In year 2011 precrop and nitrogen treatment effects on barley yield formation and yield quality was determined. Precrop and nitrogen treatment effects on soil mineral nitrogen was investigated from fall 2010 to fall 2011. White lupin was successfully cultivated without any input of fertilizers. White lupin showed less ground coverage in early summer, and therefore showed inferior weed competition compared with barley. White lupin achieved the same plant lenght and total biomass as barley, but accumulated over 200 N kg/ha. In the precrop and nitrogen treatments, barley grain yield did not indicate any need of nitrogen fertilizer, where white lupin had been used as precrop. Grain protein content, however, showed that even with white lupin as precrop, a 20 kg/ha nitrogen starter was not sufficient. Soil mineral nitrogen content was clearly increased by white lupin only before sowing in year 2011.