Many studies have reported the effect of SCG on the growth, mineral content and bioactive compounds of several type of plants including edible plants (both for humans and for animals) such as beans, soybeans, broad beans, alfalfa, wheat, corn, clover, sorghum, sunflower, oats, rye, barley, buckwheat, lettuce, basil, ryegrass, tomato and Brassica [12,44,49,51,52,53,54,55,61,62,63,64,65,66,67,68], although inedible plants such as pine have also been studied [69]. In addition, SCG have been studied when fresh, that is, without any type of treatment [12,44,49,54,55,61,64,65,66], composted [44,62,65], combined with other types of waste [67,70], transformed into biochar or hydrochar [68,71,72,73] or supplemented with nitrogen fertilizers [51].

The first reference on the effect of SCG on plant growth is in Kitou and Yoshida [53]. In a trial with pots, they studied the effect of this residue in a concentration of 1 and 2% on the growth of 12 edible plants. These authors found growth inhibition for most plants, attributing this effect to N immobilization, the multiplication of pathogenic fungi or the release of phytotoxins derived from fresh organic matter. Subsequently, many authors found the same detrimental effect of SCG on plant growth [12,49,52,55,61]. Hardgrove and Livesley [52] tested broccoli, leek, radish, sunflower and viola, Cervera-Mata et al. [51] and Cruz and Cordovil [66] tested lettuces, and Yamane et al. [49] tested alfalfa, guinea grass, crotalaria, sorghum, sunflower, oat, barley and rye. Yamane et al. [49] tried to corroborate the negative effect of SCG found in pots in a field trial. SCG displayed a negative effect on different plants, which was attributed to the presence of caffeine, tannins and polyphenols [74]. These authors suggested that SCG were better used for legume species to counteract the possible immobilization of N due to the addition of an untransformed residue. Cruz and Cordovil [66] also …