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

A four-year field trial (2004-2007) was carried out to compare performances of organic and conventional farming systems in the Po Valley, at Montanaso Lombardo (LO, Northern Italy). The soil was a fine loamy, mixed, superactive, mesic Ultic Haplustalf. 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 (0 vs. 60-200 kg N ha-1 year-1 depending on the vegetable crop). In all four of the years studied, the two farming systems did not show significant differences in marketable yields for any vegetable crops. The tomato fruit quality was also quite similar between the two farming methods. The choice of a well-adapted genotype is one of the keys to success in organic vegetable growing.