Effects of irrigation treatment on pear trees on the Loess Plateau in western Shanxi Province

Given the conditions of water shortage, low fertilization and low yield in pear orchards in arid farming areas on the Loess Plateau in western Shanxi Province, the authors tried to determine the causes of low yield and suggested an appropriate treatment combination. In an orthogonally designed experiment of three factors, each at three levels, authors analyzed the effects of subsurface irrigation water (factor A), fertilizer (B) and coverage measures (C) on the following variables: soil humidity, photosynthetic rate, yield and increased net income.Resultsshowed that the order of importance of the three factors on these variables was: the amount of subsurface irrigation (A), coverage measure (C) and fertilizer application (B). The optimum disposition was the combination A₃B₂C₃, which indicated that water was more important to pear trees than fertilizers in this dry area. Comparing the results of different levels of the three factors, authors arrived at the following inferences: the differences between the medium (A₂) and high irrigation (A₃) amounts, straw coverage (C₂) and pellicle coverage (C₃), reasonable (B₂) and a high fertilizer dose (B₃) were statistically not significant. This shows that it is unnecessary to conduct the experiment at high levels of irrigation and fertilization in order to obtain high yields in the area. It is concluded that the disposition of a water saving irrigation system, a reasonable application of fertilization and coverage can obtain high yields and recommend the treatment combination A₂B₂C₃, ie subsurface irrigation at 27 m³/hm², fertilizer application at 202.5 kg/hm² and plastic pellicle coverage.