Impact of organic and conventional cultivation systems on nutrient concentration of broccoli

Organic agriculture relies on intercropping, composts, green and animal manures and is proposed as a sustainable low-input farming system that yields healthier products. However, there is a great concern about whether this system can effectively support vegetable crop production and whether the organic labelled products are more nutritious, especially those with high nutrient requirements, such as Brassica sp. Within this frame, a field experiment was conducted at the open-field facilities of the Laboratory of Vegetable Production, at the Agricultural University of Athens, where one-head broccoli plants were cultivated under organic or conventional farming practices. The aim of this study was to investigate the impact of the organic and conventional fertigation schemes on yield and macro- and micro-nutrient content of broccoli leaves and flowerheads. Prior to the crop establishment farmyard manure was applied in organically cultivated broccoli to provide 120 kg N ha-1, while the fertigation scheme that applied to conventional broccoli crop included inorganic fertilizers that provided 240 kg N ha-1 during the whole cultivation period. The impact of the experimental treatments on yield was assessed by harvesting all the flowerheads and recording their total fresh weight. Leaf samples were collected prior to the flowerhead formation. The results of this study showed that organic farming reduced the mean fresh weight of flowerheads by approximately 20%. In addition to broccoli yield, the organic farming practices restricted also the total-N content of both leaves and flowerheads. On the other hand, organic broccoli flowerheads recorded greater K content, while the different fertigation schemes had no significant impact on P content of both plant parts. Besides macro-nutrients, various significant differences were also observed in micro-nutrient content of broccoli plant grown under the two different cultivation systems. In conclusion, the organic fertigation scheme may have restricted broccoli yield, but produced flowerheads with enhanced nutrient content.