TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The membrane (a) is the membrane formed from a mixture of polar natural polymer, derivatives and polyvinyl fluoride and its ramification, Kynar (RTM: Polyvinylidene fluoride) and its ramification, polyvinyl acetate and its ramification, polyacrylate and its ramification, acrylonitrile butadiene styrene, nitrile rubber, polyurethane, epoxy resin, unsaturated polyester, phenolic resin, glycerol-phthalic resin and/or a non-polar polymer. The non-polar polymer is polyolefin, polystyrene, butadiene rubber, natural rubber, polyisoprene rubber, butadiene styrene rubber, butyl rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene-butadiene-styrene segmented copolymer and/or styrene-isoprene-styrene segmented copolymer. The membrane (b) is formed from a polar organic compound and/or a non-polar organic compound. The polar organic compound is polyvinyl chloride and its copolymer, polyvinylidene chloride and its copolymer, polyvinyl acetate and its copolymer, polyacrylate and its copolymer, acrylonitrile butadiene styrene, nitrile rubber, polyurethane, epoxy resin, an unsaturated resin, a phenolic resin, glycerol-phthalic resin, coumarone-indene resin, asphalt, colophony and/or an ester. The non-polar organic compound is polyolefin, polystyrene, butadiene rubber, natural rubber, polyisoprene rubber, butadiene styrene rubber, butyl rubber, ethylene propylene rubber, ethylene-propylene diene rubber, segmented copolymer, styrene-isoprene-styrene segmented copolymer, aromatic resin, petroleum resin and/or an olefin. The mass fraction of polar natural polymer and its derivatives in membrane (a) is 25-50%. The mass fraction of polar natural polymer and its derivatives in membrane (b) is 0. The polar natural polymer and its derivatives are at least one of starch and its derivatives. The total thickness of cover is 22-200 mu . The total thickness of membrane (a) is 20-180 mu . The total thickness of membrane (b) is 2-30 mu . ACTIVITY - Fertilizer.