The influence of organic and mineral fertilization on nutrient status, nitrate accumulation, and yield of head chicory

The influence of different fertilizer forms and rates on nitrogen, phosphorus and potassium contents, nitrate accumulation and yield in red head chicory (Cichorium intybus var. foliosum L.) was investigated. Field fertilization trials were set up at two localities inNorthwest Croatia in 1999 and 2000. Trials were laid out according to the Latin square scheme in five fertilization treatments: manure 5 kg/m2, three rates of complex mineral fertilizer NPK (5:20:30) - 50, 100 and 150 g/m2, and an unfertilized control variant. The results of investigations indicate that there were no significant differences between treatments in the plant nitrogen and phosphorus contents. Significant fluctuations of the chicory potassium content (3.27-4.75% K) depending on the fertilization variant were recorded only in 1999 while in 2000 all values (4.13-5.12% K) were uniform. Plant nitrate levels were influenced by weather conditions more significantly than by the form and rates of fertilizers. All the recorded values are within the limits tolerated for leafy vegetables. Comparing the trial years, yields were generally higher in 1999 (1.58-4.95 kg/m2) than in 2000 (0.40-2.70 kg/m2). No significant differences in yield were recorded between the application of stable manure and the lowest mineral fertilizer rate.