Biodegradable mulch controls weeds and increases water use efficiency in lettuce crops

ABSTRACT Vegetable cultivation requires high water use and weed control. Soil cover using recycled paper, can be an alternative to polyethylene film to reduce weed incidence, soil temperature and increase water use efficiency beyond reduces costs and environmental pollutions. The objective of this study was to evaluate the use of biodegradable mulch in weed management and water use efficiency (WUE) in lettuce crop. The treatments were composed of brown recycled paper (RP), black polyethylene film (PF) and soil without cover with weed removal (WR) and without weed removal (WW). RP and PF were efficient to control weeds. The soil temperature with RP was 8.2 and 2.1ºC lower than with PF and WR, respectively. The lettuce yield with RP was 14.5 and 28.3% higher than WR, and with PF, respectively. The water volume applied with RP was 26.5% lower, and WUE was 55.6% higher compared to WR. Soil cover with recycled paper controlled weeds, reduced soil temperature and water consumption and increased yield and water use efficiency in lettuce crop.

Mulch films based on poly(butylene adipate-co-terephthalate)/carnauba wax/sugar cane residue: Effects on soil temperature and moisture

Polymers were introduced in agriculture in the 1950s and, nowadays, mulching is one of major applications of plastics in this sector. In the last decades, difficulties in recovery of non-degradable plastic films have prompted the intense use of biodegradable mulch films. Therefore, the aim of this work was to develop mulch films based on a biodegradable polymer (poly(butylene adipate-co-terephthalate)), sugarcane and carnauba wax. Mulch films containing 2.5 and 5.0% of sugarcane residue, with and without 2% w/w carnauba wax were prepared by flat extrusion. To evaluate the performance of mulch films during application to the soil, they were maintained for 60 days under real conditions of use. During this period, the temperature and humidity of the soil protected by mulch were measured. In addition, the chemical, physical and morphological properties of the films, after weathering, were determined. Results show that the mulch films developed have promising properties. When larger moisture retention is needed, PBAT mulch films containing 2.5% and 5.0% sugarcane residue are the most indicated and, when higher temperatures are demanded, PBAT mulch films containing carnauba wax and 2.5% and 5.0% residue are the best option. After being exposed to high temperatures and moisture, the mulch films photo degraded and their transmittance was reduced. Besides, the sugarcane residue added to the polymer swelled, which led to breakage of the polymeric matrix.

Degradation and Stabilization of Poly(Butylene Adipate-Co- Terephthalate)/Polyhydroxyalkanoate Biodegradable Mulch Films Under Different Aging Tests

The degradation and stability of biodegradable films determine the service length of mulch films in actual use. Most biodegradable polymers degrade too fast to meet the required durability of mulch films. The objective of this work is to investigate the degradation behaviors of poly(butylene adipate-co-terephthalate) (PBAT) /polyhydroxyalkanoate (PHA) blend mulch films. Several different types of stabilizers were incorporated in the biodegradable blends to provide protection for the PHA/PBAT films during thermal processing and aging on agricultural fields. The degradation process of the films was systematically studied under an Accelerated Aging Test (AAT) and a Soil Aging Test (SAT). Adding a light stabilizer, UV stabilizer, or antioxidant to the mulch films led to significant improvement in the retention of mechanical properties of the films under both AAT and SAT. Morphological evolution of the films with or without a UV stabilizer as a function of aging times was studied by Scanning Electron Microscopy (SEM). The results of thermal properties and crystallinity revealed damage of crystal structure of the films during AAT. Spectrocopic results indicated that the films underwent both hydrolysis and photodegradative chain scissions (Norrish Type I/II reactions and photo-oxidation). The degradation mechanisms of the PHA/PBAT biodegradable mulch films were proposed.

Agricultural, Ecological, and Social Insights: Residual Mulch Film Management Capacity and Policy Recommendations Based on Evidence in Yunnan Province, China

Mulch film contaminates the environment while increasing agricultural yield. As such, the factors that impact the residual film management capacity of farmers must be identified, which would also be helpful for the sustainable development and security of agriculture. We investigated 10 counties across nine cities (states) by surveying 1284 households. The improved entropy-weighted composite index and the grey correlation analysis model were employed to measure the residual film management capacity from five dimensions: human capital, use behavior, management skills, public policy, and willingness. The entropy-weighted composite index results showed that residual film being harmful to the environment had the highest overall rate of 0.0745, followed by the effectiveness of mulch film, which was 0.0715. The results of the grey correlation analysis model showed that willingness to use biodegradable mulch film had the highest correlation of 0.8960, followed by educational level of the laborers, which was 0.8824. We found that residual film being harmful to the environment, effectiveness of mulch film, willingness to use biodegradable mulch film, and educational level of the laborers were the major factors influencing the residual mulch film pollution knowledge of households. Based on this finding, the government should increase subsidies for promoting biodegradable mulch film and publicize the hazards of residual films using diversified means in multiple channels.