Influence of organic manures on carrot (Daucus carota L.) crops grown in a long-term field experiment in Sweden

Abstract

This study evaluated the effects of organic agriculture manuring systems on carrot (Daucus carota) root morphology and sugar and polyacetylene content. Carrots were harvested three times per season 2006–2007 in a long-term field experiment at Skilleby research farm, Sweden. The effects of pelleted chicken manure, fresh farmyard manure and composted farmyard manure (COM) were compared against control plots left unmanured since the field experiment started in 1991. The carrots were analyzed for root size, root shape, amount of soluble sugars and amount of falcarinol-type polyacetylenes. Differences between manuring systems were found to be smaller than the variation between harvest years and harvest occasions, probably due to the grass-clover ley included in the crop rotation system. On an average for the six harvests, manuring with COM increased root length by 6% compared with fertilizing with pelleted chicken manure. Carrots fertilized with pelleted chicken manure also had 6–7% lower total soluble sugar content than carrots manured with 50 t ha−1 of composted or fresh manure. The falcarinol to total falcarinol-type polyacetylenes ratio was 15.4% in carrots manured with 50 t ha−1 of composted or fresh manure and 14.7% in carrots fertilized with pelleted chicken manure. Seasonal fluctuations in falcarinol-type polyacetylenes were more pronounced in carrots manured with fresh or composted manure than in carrots fertilized with pelleted chicken manure. The results suggest that manuring organic carrots with compost may be the most beneficial strategy, at least in systems where fertilizer is applied only once per crop rotation, whether directly to the carrot crop or in the preceding crop.

Correlations between Polyacetylene Concentrations in Carrot (Daucus carota L.) and Various Soil Parameters

“…Mean total concentration of FaTP was 600 µg FaDOH equivalents/g dry weight (DW) and the mean contribution of the different FaTP to the total concentration was: FaDOH 76.2%, FaOH 16.2% and FaDOAc 7.6% ( Table 1 ). This is in accordance with our earlier findings [ 29 ]. The concentrations of all three FaTP were higher at the first two harvests than at the harvest on 24 September ( Table 1 ).…”

“…Kämpe, an open-pollinated carrot of the Chantenay type, grown from seed obtained from Lindbloms Frö, Sweden, were harvested on three occasions (in total 144 samples) from a long-term field experiment at Skilleby research farm, Sweden (59.2° N, 17.4° E). The field experiment, described more in detail elsewhere [ 29 ], was established in 1991 to compare the influence of different organic manures on the properties of soils and crops. The design of the field trial is given in Figure 1 .…”

“…Some of the carrot samples used were also analysed in our earlier study examining the influence of organic manures on carrot crops [ 29 ]. However, within the framework of that study it was not possible to make a more thorough analysis of the influence of soil chemical composition on FaTP concentrations in carrots.…”

“…In another study, we examined the influence of different organic manures on FaTP concentrations in carrots [ 29 ]. The samples used were collected from a long-term field trial.…”

“…The samples used were collected from a long-term field trial. The results, based on 288 carrot samples, indicated that differences in FaTP concentrations arising from manuring strategies were rather small and inconsistent [ 29 ].…”