A Degradable Mulch Film with Fertilizer Slow-Release Function Enhanced by Lignin

Mulch film and slow-release fertilizers are widely usedin agriculture and horticulture, and it has become a trend to usedegradable materials for the preparation of mulch films using slow-releasematerials. However, most degradable materials have poor performanceor relatively high cost. In this study, three types of degradablematerials, namely, poly(vinyl alcohol) (PVA), corn starch (CS), andalkali lignin (AL), were used as degradable materials to obtain amulch film with a slow-release fertilizer function (MSRF). MSRF hadexcellent performance when 10% AL was added. The properties consistedof elongation at break (180.14%), water vapor permeability (203.8g m(-2) day(-1)), water resistance(its morphology remained good for 50 days), water absorption (300%),and urea release efficiency (cumulative release of 70.63% in 30 days).Rapid plant growth trials demonstrated that the MSRF had excellentfunctionality and that the MSRF could reduce the amount of fertilizerapplied by about 70%. These excellent performances were due to thecombination of chemical cross-linking (chemical bonding) between ALand PVA/CS molecular chains, the hydrogen bonding between the AL,PVA, and CS molecules, and the aggregation properties of AL. Thisprovided a green and efficient strategy for the preparation and applicationof dual functions of mulching and the slow release of fertilizer.