Agroecological practices improve soil biological properties in an organic vegetable system

Redesigning organic vegetable systems through the introduction of agroecological service crops (ASCs) terminated by the in-line roller crimper (RC) has attracted great interest, although the effects on soil quality are poorly known. In a two-year field experiment in Southern Italy, two ASCs winter cereal/legume-based mixtures were terminated by RC (ASC–RC treatment) and as green manure before organic tomato (Solanum lycopersicum L.) and compared with two tilled controls without ASCs, one of which with Mater-Bi mulch (six treatments: two ASCs, two terminations, two controls). Soil chemical and biological attributes and yields were compared to assess whether ASCs and ASC–RC can enhance the soil functioning in semi-arid environment. Tomato yield showed no differences in 2017, while in 2016 it decreased by 67% in ASC treatments compared to the controls. The ASCs didn’t significantly increase soil P and N availability until midpoint of the tomato cycle. Soil mineral N increased by 200% in the ASC with higher legume presence at harvest in 2017. In the distance-based redundancy analysis, total soil organic carbon significantly predicted distribution pattern between ASCs and controls of enzyme activities, fostered by the ASCs (+ 159% for nonanoate-esterase in ASC–RC, compared to controls), although microbial biomass didn’t show differences. The ASC–RC effect in improving soil biological attributes was enzyme- and ASC species-specific. Despite the results on tomato yield, agroecological management seems a promising strategy to improve soil quality in a long-term perspective, supporting soil metabolic activity and improving its self-regulating capacity.