Comparison of plastic films with different optical properties for soil covering in horticulture: test under simulated environmental conditions

Abstract

Covering the soil with plastic film is an important method to modify soil temperature and improve the conditions for plant growth. For the optimal use of films in horticulture, it is necessary to quantify this effect, which depends particularly on the optical properties of the film. Five films, used mainly for soil covering in asparagus cultivation, were tested by measuring the soil temperature as well as the transmittance and reflectance in the short-and long-wavelength bands: 'Taschenfolie schwarz/weiß', a film with black and white surfaces and pockets for fastening; 'Antitaufolie', a film with anti-condensation coating, 'Solartherm plus Folie', a film with black top and transparent sides; 'MaterBi Folie', a biodegradable film; and 'Thermoplus Folie', a black polyethylene with transparent sides. All films were produced in Germany. The temperature measurements were carried out under controlled irradiation (short-wavelength band) and ambient temperature conditions in the laboratory: first, 182 W m −2 and 11 • C at a depth of 0.4 m, and second, 340 W m −2 at 20 • C. A significant relationship between the temperature increase or decrease by covering the soil with the film and the calculated apparent quantities of the reflectance in the short and long-wavelength band was derived (r 2 = 0.85, n = 12). Furthermore, first tests with a physical model were carried out to obtain basic information, which should be used in the development of strategies for film management in the field.

Ring‐Opening Homo‐ and Copolymerization of Cis/Trans‐3‐oxa‐4‐oxobicyclo‐ and Cis/Trans‐4‐oxa‐3‐oxobicyclo[5.4.0]undecane

“…As displayed in Figure 5(a), the melting point shows a linear dependence on the comonomer feed and decreases by %1 8C per percent comonomer from 61 8C for pure polycaprolactone (entry 1) to 36 8C for [CL]: [2] ¼ 80:20 (w/w; entry 4). This result is in accordance with our expectations showing that the cyclohexyl moieties act as internal softener.…”

“…The 1 H NMR chart in Figure 2 shows the spectrum of the copolymer with [CL]: [2] ¼ 80:20 (w/w; entry 4) after precipitation in methanol (methylene and methine groups were named a 1 , a 2 , b 1 , b 2 , etc). As expected, the spectrum is Ring-Opening Homo-and Copolymerization of Cis/Trans-3-oxa-4-oxobicyclo-and .…”

“…Figure 3(a) and 3(b) display the spectrum of a sample prepared with [CL]: [2] ¼ 80:20 w/w and the spectrum of the homopolymer. Signals up to m/z ¼ 16 000 and a maximum at 4 000 for the former and 4 500 and 13 000 for the latter were obtained.…”

“…This result is in accordance with our expectations showing that the cyclohexyl moieties act as internal softener. In the case of [CL]: [2] ¼ 50:50 (w/w; entry 5) and the homopolymer of 2 (entry 6), a melting point was not P. Kerep, H. Ritter Figure 5. Dependence of the melting point (a) and the glass transition temperature (b) on the feeding ratio of 2.…”

“…For example, blends with starch (MaterBi 1 ) exhibit excellent biodegradability and are used in foils, packaging, foams, etc. [2] Moreover, polycaprolactone is nontoxic and shows high biocompatibility, making this polymer an attractive material also for medical purposes such as tissue engineering, drug release, or bone scaffolds. [3][4][5] Due to its versatility, much research has been done in order to alter or fine-tune its properties.…”