Source: Sotrafa Global Solutions
Exploring Mulching Films: Types, Benefits, and Environmental Considerations in Agriculture
by Al Mamun
In modern agriculture, mulch films have emerged as indispensable tools for farmers seeking to optimize crop yield, conserve soil moisture, and suppress weed growth. Mulch films are thin sheets of plastic or biodegradable material applied to the soil's surface around crops. They effectively modify the microenvironment in which plants grow, leading to a range of benefits that contribute to the sustainability and profitability of farming operations.
This blog explores the different types of mulch films available, their applications, benefits, and potential environmental impacts. Additionally, I will discuss best practices for their use and how they can be integrated into sustainable agricultural systems.
Types of Mulching Films
Mulch films come in several types based on their material composition, color, and intended use. The most common types include:
1. Conventional Plastic Films: Conventional plastic mulch films are the most widely used due to their cost-effectiveness and durability. Typically made from polyethylene (PE), these films are highly effective in increasing crop yields and are available in various colors, each influencing soil temperature and weed control differently. For example, black PE films absorb sunlight, warming the soil, while silver or white films reflect sunlight, helping to lower soil temperatures. Despite their advantages, conventional plastic films pose significant environmental challenges due to their non-biodegradable nature, contributing to soil contamination with microplastics (Huang et al., 2020).
2. Bio-based Plastic Films: These films are derived from renewable resources and are designed to biodegrade in the soil. They offer a sustainable alternative to conventional plastics, with satisfactory functionality in terms of water vapor permeability and tensile strength (Briassoulis & Giannoulis, 2018).
3. Biodegradable Plastic Mulch: Biodegradable plastic mulch films are made from materials that degrade over time through microbial activity. They are typically composed of starch-based polymers or other bioplastics. These films are gaining popularity due to their environmental benefits: They decompose naturally, reducing the need for disposal and enhancing soil fertility (Akhir & Mustapha, 2022). As environmentally friendly alternatives to traditional plastic films, biodegradable mulch films help minimize plastic waste while eliminating the need for film removal and disposal, making them a sustainable option for modern agriculture.
4. Bamboo-derived Liquid Films: An innovative approach using bamboo-derived carboxymethyl cellulose to create a biodegradable liquid film. This film can be sprayed onto the soil, forming a protective layer that retains moisture and biodegrades within 60 days (Xu et al., 2021).
Benefits of Mulching Films
Mulching films provide numerous advantages that contribute to improved agricultural productivity and sustainability:
1. Enhanced Crop Yield and Quality: Mulching films significantly boost crop yields by optimizing soil temperature and moisture conditions. The combination of weed suppression, moisture retention, and soil temperature regulation results in healthier plants, earlier harvests, and increased yields. Studies have shown that plastic film mulching can enhance maize yields by up to 29% in semi-arid regions (Zhang et al., 2017).
2. Water Use Efficiency: By minimizing evaporation, mulching films help conserve water, making them particularly valuable in water-scarce regions (Chen et al., 2017).
3. Soil Health Improvement: Bio-based and biodegradable mulch films decompose over time, enriching the soil with organic matter and enhancing microbial activity, which supports long-term soil fertility (Akhir & Mustapha, 2022).
4. Weed Control: Mulch films physically block sunlight from reaching the soil, inhibiting weed growth. This reduces competition for essential nutrients and water, allowing crops to thrive.
5. Moisture Retention: By covering the soil, mulch films reduce evaporation, maintaining soil moisture levels. This is especially beneficial in arid or drought-prone areas.
6. Soil Temperature Regulation: The color and material of mulch films influence soil temperature. Black mulch films, for instance, absorb heat and warm the soil, benefiting early planting, while reflective films, such as silver or white, help cool the soil for crops that require lower temperatures.
7. Soil Erosion Prevention: Mulch films protect the soil from erosion by reducing the impact of raindrops and wind, preserving soil structure, and preventing nutrient loss.
8. Reduced Pest and Disease Incidence: Mulch films can act as a physical barrier to prevent certain pests and soil-borne diseases from reaching crops, reducing the need for chemical pesticides.
Environmental Impacts
While mulch films offer significant agricultural benefits, they also pose environmental challenges, particularly in the case of conventional polyethylene (PE) films. The widespread use of non-biodegradable plastic mulch has raised concerns regarding soil health, pollution, and broader ecological consequences. The key environmental impacts associated with mulch films include:
1. Microplastic Pollution: Conventional plastic mulch films degrade over time into microplastic particles, which persist in the soil for years. These microplastics can alter soil structure, disrupt microbial communities, and potentially enter the food chain through plant uptake (Huang et al., 2020). Long-term accumulation of microplastics in agricultural fields can lead to reduced soil fertility and water retention capacity, affecting crop productivity.
2. Greenhouse Gas Emissions: The use of plastic mulch films influences greenhouse gas (GHG) emissions from the soil. Studies have indicated that certain plastic mulches, particularly PE films, can increase nitrous oxide (N₂O) emissions—a potent greenhouse gas contributing to global warming (Yu et al., 2021; Chen et al., 2017). Additionally, the production and disposal of plastic mulch require fossil fuel resources, further exacerbating carbon emissions and environmental degradation.
3. Phthalate Contamination: Plastic mulch films can release harmful chemicals such as phthalates, which are used as plasticizers to improve flexibility. Over time, these chemicals leach into the soil and can be absorbed by crops, posing potential health risks to humans and animals (Wang et al., 2021). Phthalate contamination has been linked to endocrine disruption and other adverse health effects, raising concerns about food safety in agricultural systems reliant on plastic mulch.
Best Practices for Using Mulch Films
To maximize the benefits of mulch films while minimizing environmental impact, consider the following best practices:
1. Choose the Right Type of Mulch Film: It is crucial to select the appropriate film for your specific crop, climate, and soil conditions. Consider factors such as color, material, and durability.
2. Proper Installation: Ensure the mulch film is installed smoothly and securely, with edges buried to prevent wind uplift. Proper installation will enhance the film's effectiveness and longevity.
3. Timely Removal and Disposal: Plan for the removal and disposal of non-biodegradable films at the end of the growing season. This prevents them from becoming environmental hazards.
4. Monitor Soil Health: Regularly assess soil health and fertility, as the use of mulch films can alter soil pH and nutrient levels over time.
5. Integrated Pest Management (IPM): Combine mulch films with other IPM practices to maintain a balanced ecosystem and reduce reliance on chemical inputs.
Conclusion
Mulching films play a crucial role in modern agriculture by enhancing crop yields and improving soil conditions. However, the environmental impacts of conventional plastic films necessitate a shift towards more sustainable alternatives, such as biobased and biodegradable films. Innovations such as bamboo-derived liquid films offer promising solutions to mitigate the environmental challenges associated with traditional mulching practices. As research continues, the development of eco-friendly mulching technologies will be vital for sustainable agricultural practices.
References
Briassoulis, D., & Giannoulis, A. (2018). Evaluation of the functionality of bio-based plastic mulching films. Polymer Testing, 67, 99-109. https://doi.org/10.1016/J.POLYMERTESTING.2018.02.019
Yu, Y., Zhang, Y., Xiao, M., Zhao, C., & Yao, H. (2021). A meta-analysis of film mulching cultivation effects on soil organic carbon and soil greenhouse gas fluxes. Catena, 206, 105483. https://doi.org/10.1016/J.CATENA.2021.105483
Akhir, M., & Mustapha, M. (2022). Formulation of Biodegradable Plastic Mulch Film for Agriculture Crop Protection: A Review. Polymer Reviews, 62, 890 - 918. https://doi.org/10.1080/15583724.2022.2041031
Huang, Y., Liu, Q., Jia, W., Yan, C., & Wang, J. (2020). Agricultural plastic mulching as a source of microplastics in the terrestrial environment. Environmental pollution, 260, 114096. https://doi.org/10.1016/j.envpol.2020.114096
Chen, H., Liu, J., Zhang, A., Chen, J., Cheng, G., Sun, B., Pi, X., Dyck, M., Si, B., Zhao, Y., & Feng, H. (2017). Effects of straw and plastic film mulching on greenhouse gas emissions in Loess Plateau, China: A field study of 2 consecutive wheat-maize rotation cycles. The Science of the Total Environment, 579, 814-824. https://doi.org/10.1016/j.scitotenv.2016.11.022
Zhang, P., Wei, T., Cai, T., Ali, S., Han, Q., Ren, X., & Jia, Z. (2017). Plastic-Film Mulching for Enhanced Water-Use Efficiency and Economic Returns from Maize Fields in Semiarid China. Frontiers in Plant Science, 8. https://doi.org/10.3389/fpls.2017.00512
Wang, D., Xi, Y., Shi, X., Zhong, Y., Guo, C., Han, Y., & Li, F. (2021). Effect of plastic film mulching and film residues on phthalate esters concentrations in soil and plants, and its risk assessment. Environmental pollution, 286, 117546. https://doi.org/10.1016/j.envpol.2021.117546
Xu, Y., Li, Q., & Man, L. (2021). Bamboo-derived carboxymethyl cellulose for liquid film as renewable and biodegradable agriculture mulching. International journal of biological macromolecules. https://doi.org/10.1016/j.ijbiomac.2021.09.152
