Effects of Different Plastic Mulching Film on Soil Hydrothermal Status and Water Utilization by Spring Maize in Northwest China

The problem of residual film pollution in farmland caused by polyethylene mulching films is serious. The application effects of different mulching films combined with drip irrigation on maize planting in the Ili area, Xinjiang, China, were explored. In this study, four types of mulching films and non-mulching treatment were used to study the degradation properties of different plastic mulching and their effects on the dynamic changes of soil moisture, heat, and crop yields of maize under drip irrigation. The results showed that after 160 days of mulching film, only small cracks appeared in polyethylene mulching films. The degradation performance of white oxo-biodegradable film treatment was optimal than the black oxo-biodegradable film treatment. The quality loss rate of the two biodegradable films were 52.26 and 48.48%, respectively. Various mulching film treatments could increase soil moisture in the early stage of maize growth. At the 0–60 cm soil layer, the soil moisture under the white oxo-biodegradable mulching film and black oxo-biodegradable mulching film treatments were lower by 2.75 and 2.66% (p < 0.05) than the white polyethylene mulching film and black polyethylene mulching film treatments. The soil water consumption was highest in the non-mulching treatment, followed by biodegradable film, and the small least value was observed in the polyethylene film treatment. The average soil temperature at depth of 0–15 cm in white polyethylene mulching film, black polyethylene mulching film, white oxo-biodegradable mulching film, and black oxo-biodegradable mulching film treatments were 1.43, 1.16, 0.72 and 0.64°C higher than the non-mulching treatment, respectively. Mulching films treatment played a critical role in increasing production and improving water use efficiency. The black polyethylene mulching film treatment had the highest yield and the best water use efficiency. The black oxo-biodegradable mulching film treatment only reduces the yield by 0.33% compared to the black polyethylene mulching film treatment, and the water use efficiency was only reduced by 0.90% (p > 0.05). Comprehensive analysis showed that black oxo-biodegradable mulching film could be used as a substitute for polyethylene mulching film and can be applied to the production practice of drip irrigation maize in the Ili area.

Degradation Mode of PBAT Mulching Film and Control Methods During Its Degradation Induction Period

: The plastic film plays an important role in China's agricultural production. However, the large-scale use of plastic film has also produced a very serious problem of agricultural film pollution. Biodegradable polymers have attracted much attention because of the environmental pollution caused by traditional plastic mulching film. The most typical one is poly (butylene adipate co butylene terephthalate, PBAT). Poly (Butylene Adipate-co-Terephthalate) (PBAT) is a kind of aliphatic–aromatic polyesters with excellent biodegradability and mechanical processing properties. Therefore, it has been rapidly developed and widely used in the industry. However, there are clear requirements for the degradation period of agricultural film. At present, the degradable materials available on the market are difficult to meet the requirements of all crops for their degradation period. In this paper, the basic properties，degradation process and ways to delay the degradation of PBAT are reviewed to improve the degradation period of plastic film prepared by using this kind of material. Among them, the degradation process includes photodegradation, biodegradation and hydrolysis. The ways to delay the degradation include adding chain extender, light stabilizer, anti-hydrolysis agent and antibacterial agent. These can provide a theoretical basis for the research and development of biodegradable film with controllable degradation cycle. The future research and development of biodegradable polymers mainly focus on controllable degradation rate, stable degradation cycle, new materials and reducing research and development costs.

Photosynthetic characteristics of cotton are enhanced by altering the timing of mulch film removal

Background The photosynthetic parameters of cotton plants may be modified by the timing of film removal during their growing period. This study was undertaken during 2015–2017 in Xinjiang, China, to determine to what extent the film mulching removal time, 1 and 10 days before the first irrigation and 1 day before the second irrigation after seedling emergence, influenced cotton’s photosynthetic characteristics. The control group (CK) was film-mulched throughout the growth stages. Results The results suggested the following: (1) Removing mulching-film within 50 days since seedling emergence had adverse effects on soil temperature and moisture. (2) Film-removal before the first or second irrigation after emergence improved the net photosynthetic rate in cotton’s later flowering stage and its transpiration rate in mid and later flowering stages while enhancing the actual electron transport rate (ETR) and maximum electron transfer rate (ETRmax) between cotton photosystems I and II. (3) Film-removal treatment also increased cotton plants’ tolerance to high irradiation after emergence, the trend was more pronounced in the early flowering stage in wetter years. (4) Leaf area index (LAI) of cotton was reduced in the film-removal treatment for which the least accumulation of dry matter occurred in a drought year (i.e., 2015). (5) Film removal caused a yield decrease in the dry year (2015), and the earlier the film was removed, the more seriously the yield decreased. Removing mulching film before the second irrigation could increase the yield of XLZ42 in the rainy year (2016) and the normal rainfall year (2017). Early film removal can increase the yield of XLZ45 in the rainy year (2016). Conclusions Collectively, our study’s experimental results indicate that applying mulch film removal at an appropriate, targeted time after seedling emergence had no adverse effects on soil moisture and temperature, and improved the photosynthetic performance of cotton, thus increased cotton yield and fiber quality, but no significant difference was reached.

Preparation and Properties of CA/γ-Poly(glutamic acid)/ZnO Electrospun Membranes

Cellulose acetate (CA) fibrous membranes blended with poly-(γ-glutamic acid) (γ-PGA) and ZnO were produced via electrospinning. The performance of the obtained composite membrane was investigated by scanning electron microscopy (SEM), Fourier transform IR spectroscopy, tensile test, water contact angle, and thermogravimetric analysis. The corn plant height, leaf area and SPAD (soil and plant analyzer development) were compared with plants covered with CA/γ-PGA and CA/γ-PGA/ZnO fibrous membranes at room temperature. Simultaneously, the water absorption and degradation rate were also studied. The results obtained indicate the potential use of these fibrous membranes for mulching film applications. The fibrous membranes could also find potential use as a material for food packing, facial mask and as antimicrobial films for wound dressing.

Feasible management of non-degradable agricultural mulching film wastes into functional flame-retarded materials

A feasible procedure was proposed to convert agriculture mulching film wastes into functional flame-retarded cotton stalk particles-polyethylene-sandy soil composites (CS-PE-SSx) by simple compounding and injection molding. Due to the uniform dispersion of solid particles in polymer matrix and the promising interfacial combination and the potential interacting forces between cotton stalk and sandy soil particles, the resultant composites showed promising mechanical strength (a flexural strength of approximately 29.0 MPa, a tensile strength of approximately 15.8 MPa, and an impact strength of approximately 3.17 kJ/m2) and improved thermal stabilities. The addition of sandy soil particles endowed materials with favorable flame-retarded properties, which can be resistant to fire ignition and flame out within 55 s. Moreover, the actual agriculture wastes containing mulching film residues, cotton stalk, and soil from different areas of China were also successfully transformed into functional composites, which exhibited promising mechanical, thermal, and flame-retarding properties. This study provided a simple, green, and low-cost strategy to convert agriculture mulching film wastes into functional materials, which can be recommended as a viable option to solve the problem of agriculture mulching film wastes.