The effect of adding residual humic acid biodegradable film on agronomic performance of potted tomato under greenhouse conditions

Abstract

Biodegradable plastic film provides a new way to solve “white pollution”. However, there is an urgent need to solve the problems of residual plastic film and tail vegetable pollution after planting. Currently, the continuous degradation of polyethylene plastic film and biodegradable plastic film after returning to the field and their impact on soil environment and vegetable crop growth need further research. This study is expected to provide some theoretical support through residual membrane addition experiments. We uniformly buried PBAT/PLA humic acid biodegradable film (BIO1), PBAT/PLA-lignin biodegradable film (BIO2), and polyethylene film (PE) at 200 kg film residue per ha in potted soil. After burial 120 d, the crystallinity of BIO1 and BIO2 residue decreased by 7.37 % and 3.91 % respectively, compared to that of PE. Additionally, the water contact angle of BIO1 and BIO2 film was lower, and the weight loss rate significantly increased. Microplastics (polyethylene) abundance in the PE treatment substrate was 166.67 ± 169.96 n kg−1 after 150 days of burial, and microplastics (PBAT/PLA) were not found in BIO1 and BIO2 treatments in this study. Residual film reduced the percentage of 2-1 mm and >2 mm water-stable agglomerates and increased the percentage of <0.25 mm water-stable agglomerates, ledto soil compaction and water upward migration; reduced urease and sucrase activities in substrate, further reduced root vigor and increased leaf proline content, eventually reduced tomato yield. However, compared with PE, BIO1 have lower substrate volumetric weight, higher aeration porosity, alleviated soil compaction, stronger substrate enzyme activity and root activity, residues significantly increased soil Ascomycota relative abundance and decreased Zoopagomycota relative abundance; reduced leaf proline content, significantly increased tomato yield, and improved tomato quality by significantly increasing lycopene content by 12.80 %. Overall, 200 kg ha−1 of residual humic acid biodegradable plastic film can improve tomato quality, reduce “white pollution”, and reduce microplastic residues caused by residual film in a solar greenhouse.