“Liquid mulching film is one kind of degradable mulching film. Due to the land pollution caused by the residues of polyethylene (PE) mulching films, China actively encourages growers to use degradable mulching films. There are four major kinds of mulching films in China. They are PE/PP degradable mulching film able to be oxidized under light, starch-based PE mulching film, degradable mulching film based on polyester materials and liquid mulching film, of which the first three are solid mulching films. Currently, for its shortage of scientific strength, slow commercial progress and immature technologies, liquid mulching film is an unpopular mulching film in China.
1. Scientific strength
– The study of liquid mulching films started late. It was from 1994 that China started to study the liquid mulching films. At that time, it was first proposed by the State Key Laboratory of Heavy Oil Processing to use degradable liquid mulching films to replace the current PE mulching films. On China Patent Net, the patent of liquid mulching films was earliest recorded in 1998 while that of solid degradable mulching films was earliest recorded in 1985. It can be predicted that the study of liquid mulching films is ten years later than that of solid degradable mulching films.
– The scientific achievements of liquid mulching films are still in a small number. On China Patent Net, with key words of “liquid mulching film”, 61 patents related to liquid mulching films can be found. With key words of “liquid” and “mulching film”, 90 patents related to mulching films can be found out while with key words of “degradable mulching films”, 1,796 patents related to degradable mulching films can be presented.
2. Commercial development
– Commercial development proceeds in a slow pace. At present, Zhejiang Bolong Ecological Technology Co., Ltd. (Zhejiang Bolong) and Yangling Mingrui Ecological Technology Co., Ltd. are the enterprises engaged in producing liquid mulching films. Among the 90 patents based on the key words of “liquid” and “mulching film” when searching on the Internet, 56 patents are concerning the inventions of liquid mulching films, of which 31 patents are from 12 companies. However, only one company in these 12 ones exploited its patents in a commercial way. In searching the key words of “liquid mulching films” on Baidu.com, there are 201 pieces of news about liquid mulching films and 90 of them are readable. Among these readable news, about 35% is related to the patent popularization of liquid mulching films, nearly 33% is about the introduction, promotion and generalization of the study progress of the liquid mulching films and about 20% is concerning Zhejiang Bolong. So far, the liquid mulching film is still remaining undeveloped.
– The development of leading enterprises did not go well. Before 2008, part of scientific institutions and oil refineries put liquid mulching films into small-scale production and liquid mulching film was in a test phase. In 2008, Zhejiang Bolong was founded with registered capital reaching USD8.17 million (RMB50 million). Until 2010, this company has owned two major production bases in Xuzhou City, Jiangsu Province and Binzhou City, Shandong Province, production capacity given at 700,000 t/a. In 2008-2011, Zhejiang Bolong popularized liquid mulching films in over 20 provinces in China. After 2012, the company took less efforts in publicizing the liquid mulching films. Now, according to the data from the State Enterprise Credit Information Publicity System, Zhejiang Bolong is running unusually, whose business scope has shifted to many other agricultural products from the liquid mulching films.
– Target enterprises lack confidence. In 2014, Jiangxi Shuangjia Science and Technology Development Co., Ltd. (Jiangxi Shuangjia) cooperated with Jinggangshan University in inventing new patents of liquid mulching film, but this company did not conduct commercial development for the liquid mulching films. On 8 July, 2015, Jiangxi Shuangjia bought two patents, a kind of modified solid degradable film mixing humic acid/polyvinyl alcohol and a kind of modified solid degradable mulching film mixing humic acid/EVA resin from Jinggangshan University and planed to put solid degradable mulching films (production capacity: 10,000 t/a) into production in March 2016. Although Jiangxi Shuangjia invented the patent of liquid mulching film, it did not commercially develop it. Instead, it bought the patents of solid degradable mulching films and put them into commercial production. All these can be seen that Jiangxi Shuangjia is short of confidence to the prospect of the liquid mulching films.
3. Technological drawback
– Short film-forming time. This problem generally exists in current liquid mulching films sold in the market. Thus the liquid mulching film is of poor performance in helping crops to resist drought in later period.
– Weak covering ability. Since the liquid mulching film is of no toughness after taking shape, as a result the ground will crack easily and weed will grow easily too.
– Incomplete technological equipment. Now China’s technology of spraying machinery for liquid mulching films is immature and farmers lack good-quality tools to exercise agricultural operations.
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