Legume Genomics and Genetics 2025, Vol.16, No.6, 288-296 http://cropscipublisher.com/index.php/lgg 291 in the early stage and allows roots to grow better. Studies have found that in plots covered with plastic film, the root dry weight and root length in the upper soil layer increased, and the root vitality was stronger at maturity, which is important for early development and nutrient absorption (Pei et al., 2024). Plants are more likely to survive and more resistant to environmental stress when roots grow more vigorously, especially when there is less water or low temperature (Zhao et al., 2023). 5.2 Increased pod formation and biomass accumulation After covering the ground with mulch, the photosynthesis and transpiration of plants will become stronger, so that plants can accumulate more biomass and grow pods more easily. Because the mulch improves the water and heat conditions and increases the utilization rate of nutrients, key factors of yield such as the number of pods and particle weight will increase (Zhao et al., 2020). Some studies have also found that compared with land without mulch, mulch can increase biomass by more than 20% on average (Han et al., 2020). 5.3 Yield enhancement under both rainfed and irrigated conditions Whether in plots that rely solely on rain or in plots that are irrigated, mulching can steadily increase yields. Studies and data analysis have shown that the yield increase brought by mulching is generally between 20% and 50%, and the effect is particularly obvious in arid or semi-arid areas (Li et al., 2019; Zhang et al., 2022). With mulch, water is used more effectively, the root system develops better, and the surrounding microclimate is more suitable for plant growth, all of which increase yields significantly and make them more stable. Therefore, mulch is a very practical solution for broad beans in various planting environments (Shen et al., 2023). 6 Environmental and Agronomic Considerations 6.1 Biodegradable vs. conventional plastic film: sustainability concerns Traditional plastic mulch works immediately, but over time it leaves a lot of fragments. These fragments slowly turn into tiny plastic particles and can introduce harmful substances such as phthalates (PAE) into the soil (Liu et al., 2023). These substances are difficult to decompose and will remain in the environment for a long time, which may harm soil health, reduce yields, and even enter the human body through the food chain (Rizvi et al., 2022). For farmers who want to farm for a long time, these problems are troublesome. Degradable mulch is a promising alternative. It is designed to decompose after use, so it can reduce long-term pollution. Studies have found that degradable film has similar planting effects as polyethylene film, providing similar yields and insulation effects, and is more environmentally friendly (Flury et al., 2021). 6.2 Residue management and soil health implications It is difficult to pick up all the plastic film left in the fields, and over time it will accumulate into microplastics. These small particles will change the physical, chemical and biological properties of the soil, and may also slowly reduce yields. As the amount of residual film increases, the field surface will become harder and farming will become more laborious. The residual film can also absorb chemicals in pesticides and fertilizers, further affecting the soil and ecology. Degradable film saves most of the cleaning work, but because it decomposes quickly, it may affect soil microbial activity and nutrient cycling in the later stages of the crop (Feng et al., 2023). Recycling old plastic film is currently the best way to deal with it, which is more environmentally friendly than burning or burying it. Unfortunately, many places do not implement it properly, which also adds extra labor and costs to many farmers (Zheng et al., 2023). 6.3 Economic cost-benefit analysis for broad bean growers Once plastic film is applied to the fields, the yield increases, the harvest is earlier, and water is saved. At first, everyone will say "it's worth it." This is how the data of Schaefer et al. (2016) came from. But don't forget that there are troubles behind the harvest: the residual film must be picked up, the ground must be cleaned, and the regulations are becoming stricter year by year. In the end, the original profit may be swallowed up by these invisible accounts. So some people turned their attention to degradable film-no need to go to great lengths to clean it, the processing fee is low, and it looks greener. But things are not that simple. Di Mola et al. (2022) mentioned that this type of film degrades quickly, and some plots have to be replaced frequently. If the frequency is high, it
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