STUDIES ON THE LAND IMPROVEMENT IN THE SALINE SOIL AREA

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1. In 1996, we, the scientists of the Agronomy Department of Iwate University and Jilin Agricultural University, chose an experimental region of typical saline-soil at the western area of Taonan city, Jilin province, and conducted the field investigation. As the results of physical and chemical analyses of the soil, bulk density was 1.6 - 1.7, percentage of solid phase was 60%, soil showed high alkalinity at 9 - 10 pH, and the salts accumulated in the topsoil was mainly sodium carbonate, the soil texture was silty clay or heavy clay. There was no problem in water quality including pH and EC for paddy fields but water temperature was low.2. In 1997 and 1998, the following three experiments were conducted at Shenjiangzi village being a typical saline-soil region, Daan city, Jilin province.Experiment to recover grassland : One of the most important factors that caused the degeneration of grassland is overgrazing in this area. So, the effect of keeping-off livestock temporally from grassland were investigated using natural grassland of 650 ha. From the control plot, great effect was observed in recovering vegetation and in the productivity of the grassland.Experiment to improve saline-soil field : The relationships between the amount of soil conditioner and crop growth were investigated for corn cultivation. A combined treatment of multing film and applying aluminum sulfate or gypsum improved corn yield drastically even in the areas where were not suitable for crop production.Experiment to improve saline-soil paddy-field : The effect of irrigation to the leaching of saline, to rice growth and productivity were investigated. When subterranean water pumped up from 8O m below ground was used, rice production rose up to 6,000 kg / ha. High productivity can be expected in the areas where subterranean water is plenty enough for rice cultivation and drainage canal are equipped.