Effects of Bio-organic Fertilizer Application Rate on the Degradation of Biodegradable Mulch Films of Different Colors and the Soil Environment
This study demonstrates that increasing bio-organic fertilizer application rates differentially accelerate the degradation of black versus white biodegradable mulch films while significantly enhancing soil nutrient availability, enzyme activities, and the abundance of polyester-degrading microbes, with the black film combined with the highest fertilizer dose (90 g) yielding the most favorable outcomes.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
In the modern world of farming, plastic sheets are a common sight, draped over fields to trap warmth, hold moisture, and keep weeds at bay. These films act like a protective blanket for crops, helping them grow faster and stronger. However, the most common type of plastic used for this purpose does not break down naturally. Over time, these sheets shatter into tiny, invisible pieces that remain in the soil, damaging its structure and choking plant roots. This accumulation of plastic waste, often called "white pollution," poses a serious threat to the long-term health of the land. To solve this, farmers have turned to biodegradable films, which are designed to decompose into harmless substances like water and carbon dioxide when buried in the earth. Yet, the speed at which these films disappear depends heavily on the environment around them. Just as a piece of fruit rots faster in a warm, damp kitchen than in a cool, dry pantry, the soil's temperature, moisture, and the tiny living creatures within it determine how quickly the plastic vanishes.
Researchers in China set out to understand how to make this decomposition happen faster and more reliably. They focused on a specific type of farming practice: combining these biodegradable films with a special kind of fertilizer known as bio-organic fertilizer. This fertilizer is not just a source of food for plants; it is packed with living, beneficial microorganisms that can help break down tough materials in the soil. The scientists wanted to know if adding more of this fertilizer would speed up the breakdown of the plastic, and whether the color of the plastic sheet itself—black or white—would change the outcome. They chose cucumber plants for their experiment, planting them in pots covered with three different types of biodegradable film: one black, and two different shades of white. They applied the bio-organic fertilizer at two different amounts, 60 grams and 90 grams per pot, and waited fifty days to see what happened.
The results revealed that the color of the film mattered immensely. For the black film, the relationship was straightforward and encouraging. As the researchers increased the amount of bio-organic fertilizer, the film broke down faster and faster. When they used the higher dose of 90 grams, the black film degraded by nearly 23 percent, a significant improvement over the lower dose. The black film creates a unique environment underneath it; it blocks sunlight but holds heat and moisture well, creating a stable, damp home for the microorganisms. The added fertilizer provided these tiny decomposers with extra energy and a boost of new helpers, allowing them to work more efficiently on the plastic.
The story was quite different for the white films. These films let more light through, which warms the soil during the day but allows it to cool down quickly at night. When the researchers applied a small amount of fertilizer to the white films, the decomposition actually slowed down compared to using no fertilizer at all. It was only when they increased the fertilizer to the higher dose of 90 grams that the breakdown rate began to recover, though it still did not reach the high levels seen with the black film. This suggests that the fluctuating temperatures under the white film might stress the microorganisms, and a small dose of fertilizer was not enough to overcome this challenge. Only a larger supply of nutrients and microbes could partially restore their ability to eat the plastic.
Beyond just the speed of decomposition, the study showed that combining the film with the fertilizer improved the soil itself. The soil under the combined treatments was richer in nutrients and more active with enzymes, which are the tools living things use to break down food. The black film, in particular, helped the soil retain more potassium, a vital nutrient for plants, while the white films were better at helping the soil release nitrogen and phosphorus. The researchers also looked at the microscopic life in the soil and found that the black film treatments encouraged the growth of specific bacteria known for their ability to digest plastic. These bacteria thrived in the stable, moist conditions created by the black film and the extra food from the fertilizer.
This work highlights that there is no single solution for every field. The effectiveness of biodegradable plastic depends on a delicate balance between the film's color, the type of fertilizer used, and the resulting soil environment. While the black film proved to be the most responsive to increased fertilizer, creating a perfect storm for rapid decomposition, the white films showed that the relationship is more complex and sensitive to change. The findings suggest that farmers can actively manage the breakdown of their plastic sheets by choosing the right combination of film color and fertilizer amount, turning a potential waste problem into a manageable part of the farming cycle.
Drowning in papers in your field?
Get daily digests of the most novel papers matching your research keywords — with technical summaries, in your language.