| Agricultural sciences |
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| Biological effect of biodegradable mulch films on maize and their degradation properties. |
| Hu Hongliang, Han Zhigang, Zhang Guoping* |
| (College of Agriculture and Biotechnology, Zhejiang University, Hangzhou 310058, China) |
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Abstract Over the past few decades, the use of traditional mulch film made of poly-ethylene enhanced agriculture production worldwide, and meanwhile raised a range of agricultural and ecological concern associated with degradation of soil fertility due to residue accumulation. It has become an increasingly challenging issue for agricultural sustainability. As a consequence, biodegradable films are proposed as an effective solution to alleviate this issue. Among them, poly (butyleneadipate-co-terephthalate) (PBAT), a biodegradable aliphatic-aromatic polyester, possesses similar mechanical properties to polyethylene and therefore is generally considered an ideal substitute for conventional films. This study aimed at making a comprehensive evaluation of several recently developed biodegradable films by comparing their biological effects and field degradation properties. Five biodegradable films with a main component of PBAT were applied to cover the beds of maize in an experimental field, and then the soil temperature, plant growth indices and yield components of maize were investigated. Meanwhile, the field degradation of both biodegradable and conventional films was assessed by a standard of degradation degree. The results showed that the biodegradable films, compared to bare plot, markedly raised soil temperatures at three observation depths (5 cm, 10 cm and 15 cm) and this heat capturing effect was as pronounced as the conventional polyethylene film. The temperature boosting effect varied with soil depth and time, i.e., the biggest diurnal fluctuation of temperature occurred at the depth of 5 cm in each treatment, while the least was at the depth of 15 cm. The growth of maize was significantly stimulated in all mulched plots, with the occurrence of seedling emergence and silking stage being 35 days and 1013 days earlier than bare plots, respectively. A minor advantage of biodegradable film over conventional film was also observed. The highest chlorophyll content (indicated by SPAD) was found in the bare plot, followed by M2, and M1 was the lowest, yet there were no significant differences among mulching treatments. By contrast, leaf area indices (LAI) of the biodegradable films were significantly higher than non-mulched plot, with the highest in M2. At the jointing stage, the plant height under all mulched plots were greater than that under the bare plot. While at the maturity stage, plants in the bare plot had the highest height, and there were no significant differences among the five biodegradable films. The largest accumulation of nitrogen, phosphate and potassium in plants occurred in the bare plot, being significantly higher than in the mulched plots. The fresh yield, kernels per ear and 100-kernel mass were significantly larger in all mulched plots than in the bare plot. The yield per plot of the biodegradable films was higher than that of the conventional film, yet no difference existed between the biodegradable films and the conventional film in terms of kernels per ear and 100-kernel mass. Field observation revealed that the biodegradable films started losing integrity at approximately 20 days after application in the field. The earliest clear disappearance of film started at 90 days after application for M2. While the relatively slow degradation was found in M1 and M5, which were torn into separate subunits with roughly 10 cm cracks after 100 days of field exposure, reaching the 4th period of degradation. In sum, all the biodegradable films are capable of enhancing maize growth by improving soil temperature and even contribute a larger economic yield than the conventional film; moreover, the biodegradable films maintain stability for approximately 20 days after application in the field and disappear after 90100 days, demonstrating the applicable effectiveness for mulching as a substitute of the conventional film.
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Published: 20 March 2015
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生物降解地膜对玉米的生物学效应及其降解特性
通过大田试验，从土壤保温性、作物生长发育与产量、田间降解等方面对5种可降解地膜进行分析比较。结果显示：可降解地膜覆盖能显著提高土壤不同深度的温度，其中M2和M5 2种地膜的整体保温效果最为突出，达到了接近普通地膜的水平；地膜覆盖可显著加快玉米生育进程和增加玉米产量，且部分可降解地膜的促进效果优于普通地膜。在地膜降解方面，5种可降解地膜破裂启动期较为一致，发生于覆膜后约20 d，可基本满足玉米苗期对温度、水分的需要；覆膜90~100 d后可降解地膜从土壤表面基本消失。以上结果显示，供试的5种可降解地膜不仅具有显著的生物学效应和经济学效果，其降解特性也基本符合玉米生长对环境条件的要求，完全可以替代传统地膜。
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