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Research article2006Peer reviewed

Yield and nitrogen uptake in organic potato production with green manures as pre-crop and the effect of supplementary fertilization with fermented slurry

Bath B, Ekbladh G, Ascard J, Olsson K, Andersson B

Abstract

Differences in yield and N uptake in cultivation systems using autumn or full-season green manures as a pre-crop in organic potato (Solanum tuberosum L.) production were studied in five trials carried out on two sites, one on a poor soil and the other on a more fertile soil, in southern Sweden in 2000-2002. The effects of supplementary fertilization with fermented slurry after the autumn green manure were also studied. Using a one-year green manure as the pre-crop did not increase yields compared with the autumn green manure, probably due to poor growth. The cut biomass contained 36-44 kg N ha(-1). However, a two-year green manure (107 kg N ha-1) as the pre-crop increased yields. Yields were not affected by how the full-season green manures were managed; the cut biomass was either removed or left on the soil surface. The fermented slurry contained between 37 and 94 kg NH4-N ha(-1). On the site with the poorer soil, supplementary fertilization with fermented slurry increased N uptake by approximately 50% and, in one season, yields by approximately 40%. On the site with the more fertile soil, fertilization with fermented slurry had no effect on N uptake or yield. On both sites, there was a positive correlation between potato yield and total N uptake, and on the site with the poor soil also with the amount of N in the soil one week after emergence. In November, residual mineral N in the soil at 0-0.9 in depth was lower in the poor soil (25-60 kg N ha(-1)) than in the more fertile soil (50-90 kg N ha(-1)). There were no indications of N leaching between harvest in September and the last soil sampling occasion in November for any of the fertilization regimes studied, but high N-min values in two of the experiments posed a risk of leaching later in the crop rotation

Published in

Biological Agriculture and Horticulture
2006, Volume: 24, number: 2, pages: 135-148
Publisher: AB ACADEMIC PUBLISHERS