Yield and quality of carrots as affected by soil moisture and N-fertilization

Summary High yield and quality are important factors for growers of carrots (Daucus carota L.). The objective of this study was to determine optimum soil moisture and N-fertilization to maximize carrot yield and external quality (i.e. the quantity of split and forked roots). The experiment was carried out in a microplot field installation with three levels of soil moisture (75, 50 and 25 vol% available field capacity (AFC)) on a sandy and a loamy soil over the last 16 and 11 weeks of the cropping period, respectively. Two movable roofs covered with polyethylene foil were used to maintain the three soil moisture levels, which were measured in all combinations with two levels of nitrogen fertilization (0 and 150 kg N ha-1). The highest total yields were reached at both soil types at 75 vol% AFC and 150 kg N ha-1. The quantity of forked carrots was more affected by reduced soil moisture on the sandy soil than on the loamy soil. The mass fraction of split roots increased with increasing soil moisture on both soil types and a significant interaction was calculated between soil type and fertilization. The mass of split roots on the sandy soil was significantly increased by fertilization.