Thick polyethylene films lessen pollution footprint while highlighting environmental merit and maize yielding in drylands

It is crucial to lessen secondary pollution of plastic film mulching (PFM) in drylands, where high and stable yielding of crops are highly dependent on PFM. To explore the solution, field investigations were conducted in dryland maize using the plastic films with four different thicknesses (0.015, 0.010, 0.008 and 0.006- mm) in an arid oasis site of northwest China (no-mulching as control group - CK). The results indicated that the release rate of phthalate acid esters (PAEs) tended to decline with increasing film thickness, up to the lowest in 0.015-mm films (19.7 %), significantly lower than others (p < 0.05). It was significant negatively associated with surface integrity of plastic films after aging, since the damaged area was only 3.5 % in 0.015-mm film, but up to 17.3 % in 0.010-mm, 19.2 % in 0.008-mm and 32.2 % in 0.006-mm thick films, respectively. Thicker PFM was observed to have less plastic fragment residues in soils, due to the higher recycling rate. Moreover, it optimized soil hydrothermal status across two growing seasons, and 0.015-mm plastic film significantly improved the accumulations of soil microbial biomass carbon and nitrogen by 1.4–15.5 % and 3.5–22.6 % relative to CK, also superior to others. The concentrations of easily oxidizable organic carbon and dissolved organic carbon in soils were improved by 8.9–9.8 % and 3.4–6.2 % in 0.015-mm plastic film respectively, relative to CK, significantly greater than others. Under conventional irrigation regime, the grain yield was the highest in 0.015-mm film group, up to 18,091 kg/ha, significantly greater than that of other groups. Thus, thick plastic film acted as a promising solution to lessen secondary pollution footprint while boosting environmental and productive merits in arid areas.