A comparison of organically and conventionally grown vegetable crops: results from a 4-year field experiment

Summary

A four-year field trial (2004-2007) was carried out to compare performances of organic and conventional farming systems in the Po Valley (Northern Italy). Four vegetable crops were grown in the sequence: 2004 – processing tomato; 2005 – bean followed by savoy cabbage; 2006 – processing tomato; and 2007 – zucchini. The experimental design was a split-plot with four replicates, the management system being the main factor (OF, organic farming vs. CF, conventional farming) with the rate of nitrogen fertilisation as the secondary factor. N efficiency of the organic fertilizers was assumed as being 50-75%). In all four of the years studied, the two farming systems did not show significant differences in marketable yields for any vegetable crops. The reduction in OF compared with CF was 17% for tomato-2004 and 2% for zucchini; in contrast, for cabbage and tomato-2006 the yields in OF were 10% and 3% higher respectively.