Nitrogen supply to arugula from pig slurry composts in contrasting soils

Resumo

This study aimed to evaluate nitrogen (N) supply to arugula from composts produced by automated composting of pig slurry (PS). During the composting process, retorted oil shale (ROS) and dicyandiamide (DCD) were added to PS to mitigate gaseous N losses. The study was developed in a greenhouse where four treatments were evaluated, three with compost addition (PS compost, PS compost + ROS, and PS compost + ROS + DCD) and one without compost (Control) in two contrasting soils (clay and sandy-loam). The best result was obtained with the compost without additives (PS compost), which increased the arugula dry matter yield by 2.2 times in clay soil and 6.1 times in sandy-loam soil compared to the control treatment. The presence of ROS in composts reduced arugula dry matter yield by 27 % in clay soil and 35 % in sandy-loam, while DCD did not affect arugula dry matter yield. The results of this study show that the addition of ROS to PS during composting reduces N supply to arugula, both in the immediate (first cut) and residual effect (second cut).