Mulch films biodegradation rate in different types of soil

Abstract

Nowadays, the use of polyethylene (PE) mulch on horticultural crops leads to negative environmental impacts. To overcome these problems, biodegradable mulches were developed once they can be incorporated at the end of the crop cycle, towards a more sustainable agriculture. The aim of this study was to perform respirometric tests in standardized aerobic conditions using two methods: one in batch conditions (at 28°C) and the other in continuous mode (at 25°C). Biodegradation tests were developed in three types of soils: Ferralsols (T1), Calcisols (T2) and Arenosols (T3) with: 21 g kg(-1) organic matter (OM), sandy-loam texture, 5.8 pH (H(2)O); 11 g kg(-1) OM, clay texture, 7.6 pH (H(2)O); and 8 g kg(-1) OM, sand texture, 6.9 pH (H(2)O), respectively. Agrobiofilm® (15 µm, black) was used, in Brazil and Portugal, at real scale with same family crops: Asteraceae, Solanaceae and Cucurbitaceae, for that reason biodegradable mulch was selected. At Taubate University, in T1 soil, a respirometric test was developed in batch system to measure CO(2) production. At Lisbon University CO(2) production was measured in a continuous aeration test using the soils T1, T2 and T3. The results obtained regarding the Brazil test showed that CO(2) production was higher on Agrobiofilm® modality with 1.20 against 0.69 mg CO(2) g(-1) soil on bare soil modality. The data obtained from the trials performed in Portugal was for T1, T2 and T3, on Agrobiofilm modality: 3.04, 0.88, 0.74 mg CO(2) g(-1) soil, against bare soil: 1.88, 0.58, 0.50 mg CO(2) g(-1) soil, respectively. From results obtained, CO(2) production on continuous aeration methodology was 2.5 times higher than batch methodology. Overall the correlation between biodegradation rate and different soils' characteristics shows a promising approach emphasising the complex mechanisms involved.