| Regulation of soil moisture, temperature and nutrient by mulching farmland plays an important role in affecting crop growth and yield. Nowadays, there are many kinds of materials be used in mulching on the farmland, such as plastic film, biodegradable film, crop straw, liquid film and so on. Different materials lead to different effect on improving soil environment, crop water use efficiency and yield. This thesis, by fixed-place experiment, compared the effects of different mulching materials on maize growth and soil environment in dryland, so as to provide a theoretical basis and application model of water-saving cultivation in arid and semi-arid areas.The experiment, carried out in the experiment region of Northwest A & F University in Heyang county in Shaanxi Province from April, 2009 to September, 2010, with randomized block design, three replications, measured and compared the effects of different mulching materials which included plastic film (PM), biodegradable film (BM), maize straw (SM), liquid film (LM), the check (CK) is bare land. The study focused on the effects of different mulching materials on soil moisture, temperature, nutrient and maize shape, dry biomass accumulation, growth process, photosynthetic characteristics, yield and water use efficiency. The main conclusions are as follows:1. Straw mulching is proved to be the best on soil moisture throughout the whole growth period of maize, which increased the average water retaining by 37.62 mm and average mass water content by 7.2% in 0-200 cm layer of soil in two years. Plastic film and biodegradable film mulching, which is better on water retention in the wet year (2010), increased the water retaining by 5.70 mm and 26.00 mm in 0-200 cm layer of soil respectively. Liquid film mulching is better in the drought year (2009), which increased the water retaining of soil by 12.41 mm in 0-200 cm layer.2. It was obvious that the effect on warming by plastic film and biodegradable film mulching, and the former was better than the latter, the average soil temperature in 5-25 cm layer before heading stage increased 2.4℃and 1.4℃respectively in two years; straw mulching had significant cooling effect, which decreased 2.7℃in two years; climate factors affected the thermal insulation effect of liquid film mulching seriously, especially from rainfall in different growth stages of maize, the average soil temperature in 5-25 cm layer decreased 0.9℃and increased 1.3℃respectively in two years.3. Plastic film, biodegradable film and liquid film mulching treatments enhanced the organic carbon, available nitrogen, phosphorus and potassium content in 0-20 cm layer of soil, especially in liquid film mulching, which increased the organic carbon, available nitrogen, phosphorus and potassium content by 0.55 g·kg-1, 5.17 mg·kg-1, 1.75 mg·kg-1 and 13.93 mg·kg-1 respectively. Organic carbon and available nutrient content accumulation of straw mulching treatment decreased in 2009 and increased in 2010 respectively.4. Plastic film, biodegradable film and liquid film mulching treatments enhanced net photosynthetic rate of maize in bell-mouthing stage in different degrees. Plastic film mulching treatment was significantly (P<0.01) higher than bare land in two years, which increased 4.99μmol CO2·m-2·s-1 and 8.51μmol CO2·m-2·s-1 respectively. Treatment of biodegradable film mulching was evidently (P<0.05) higher than bare land, increased 8.57μmol CO2·m-2·s-1. Liquid film mulching was similar with bare land. Straw mulching treatment was 4.22μmol CO2·m-2·s-1 evidently (P<0.05) lower than bare land and 4.09μmol CO2·m-2·s-1 evidently (P<0.05) higher than that.5. Plant height, stem diameter and dry biomass of shoot of maize were all enhanced by plastic film, biodegradable film and liquid film mulching treatments in two years, but straw mulching treatment showed effect in the late stage of maize growth in 2010. The whole growing period of maize could be shortened by plastic film and biodegradable film mulching treatments, and were proved to be similar with each other. The whole growing period of plastic film and biodegradable film mulching treatments was 134 d and 136 d respectively, and shortened 11 d and 9 d compared with that of bare land respectively. Owing to extending of stage from bell-mouthing to heading, the time for vegetative growth was extended and the reproductive stage was relatively shorter. Straw mulching treatment extended 3 d in the whole growing period in 2009, and was similar with bare land in 2010. Liquid film mulching treatment had no effect on whole growth period of maize.6. Biodegradable film mulching treatment was proved to be the best on average growth rate of economical output, which was 21.0% in two years; straw mulching treatment was proved to be the worst on average yield in two years. Yield of plastic film, biodegradable film and liquid film mulching treatments increased 34.7%, 26.9% and 2.4% respectively in 2009, that of straw mulching treatment decreased 10.5%. The yield of plastic film, biodegradable film, straw and liquid film mulching treatments increased 6.6%, 15.4% , 9.8% and 0.5% respectively in 2010. It showed a significant effect on yield increasing in plastic film and biodegradable film mulching treatments, and it was better for yield increasing to mulch straw in the whole growing in two years, and it was not obvious for that of liquid film mulching treatment. Plastic film mulching treatment increased yield by increased ear length, ear diameter, Kernels per row and hundred-kernels weight; that of biodegradable film mulching treatment by increased ear length, ear diameter, rows per ear and kernels per row; straw mulching treatment by increased ear length and hundred-kernels weight. Based on the yield and effects on soil moisture, temperature, nutrient in long-term, biod egradable film and straw mulching is conducive to sustainable production of dryland which rainfed. |
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