addition of herbicides and carbon black which provides an economic advantage to the user.On the basis of the above-mentioned results and discussion, the mulch films described here contain an adequate balance of the important properties needed for an agricultural mulch film. These properties include (1) good mechanical properties, (2) the ability to retard weed growth without the incorporation of toxic chemicals such as herbicides, (3) degradability, (4) the incorporation of multinutrirional materials that can be released slowly, (5) harmless to the environments, and (6) clarity.
ConclusionsVarious types of multinutritional, degradable, and slow-release clear agricultural mulch films containing poly(vlny1 alcohol), urea-formaldehyde, Pz05, K20, and other additives were prepared and coated with different water-resistant coating materials. The mechanical properties and the dissolution rates of these films were studied. The mechanical properties of these films are affected by the type of materials involved and the percentage of moisture present. The results also indicate that the presence of starch, ethylene glycol, and urea improves tensile strength, elongation at break, and dissolution rate of these films. The dissolution rate of the mulch film is affected by the type of coating material and its thickness, types of additives present, the temperature, and the type of water used. This information can be used to design suitable films for any crop duration. It was also found that the prepared mulch films can prevent weed growth despite their clarity. Registry Agency of Industrial Sciences and Technology, Japan Kokai Tokyo Bryzgalov, V. A.; Sakova, T. M.; Zakharova, E. I. Plast. Mussy 1984, Clendinning, R. A. U S . Patent 3 929 937, 1975. Clendinning, R.
