A greenhouse pot experiment on sandy soil was conducted to examine the effects of food waste compost on yield, nitrate content, phosphorus and potassium uptake of carrot (Daucus carota L.) and AL soluble phosphorus and potassium content of soil. Five levels of food waste compost (10 t ha-1; 20 t ha-1; 30 t ha-1; 50 t ha-1; 50 vv% compost), NPK fertilizers and control were tested as treatments. Each treatment was applied in three replications.

Results indicated that besides the positive yield effect of NPK fertilizer significant response to yield was observed for application of food waste compost up to 30 t ha-1 dose. 30 t ha-1 compost dose increased the carrot weights by 85% compared to control. The 50 t ha-1 of compost dose increased the weight of leaves to a greater extent than the weight of roots compared to those found in case of applying 30 t ha-1. The highest compost dose (50 vv% compost) caused significant yield decrease, also increased the number of root branches, while in the small, branched roots the nitrate content significantly increased. The negative effect of the highest compost dose has not fully elucidated, but according to our results, the root growth could be retarded firstly by the higher salt content of food waste compost and secondly by its mechanical inhibitory effect.

The nutrient supply capability of food waste compost was clearly shown. By increasing compost doses up to 30 t ha-1, the phosphorus and potassium uptake of leaves and roots proportionately increased. In addition to the root growth inhibitory effect of doses of 50 t ha-1 and 50 vv%, the potassium and phosphorus uptake of plants was also reduced due to their application. However, due to the mineralization of compost, the increase of phosphorus and potassium in the soil was verified by the increase of the amount of AL-P2O5 and AL-K2O.

Keywords: food waste compost, sandy soil, carrot nitrate, phosphorus, potassium