Effects of clinker ash on the properties of Jagaru soil, and growth and mineral composition of lettuce [Lactuca sativa]
2006
Kubotera, H.(National Agricultural Research Center for Kyushu Okinawa Region, Koshi, Kumamoto (Japan))
A gray Terrestrial Regosol called "Jagaru" that corresponds to Udorthent in the Soil Taxonomy is widely distributed in the southwestern islands of Japan. Jagaru is a heavy-textured smectitic soil and shows problematic physical properties such as severe hardening by air-drying. In order to improve the physical properties, the effects of clinker ash, which is the coarse fraction of coal ash, on the properties of Jagaru, and growth and mineral composition of lettuce were investigated. Physical and chemical analysis of clinker ash revealed that it is a mixture of grains of various particle sizes and chemical composition. Total elemental composition of bulk clinker ash was similar to Jagaru. Application of clinker ash increased available water content and reduced solid ratio, bulk density and the strength of air-dried soil blocks of Jagaru, and clinker ash was more effective for the improvement of these physical soil properties than river sand of the same quantity. On the other hand, pot cultivation experiments showed that the application of clinker ash does not increase the yield of lettuce, and heavy application of the ash caused a slight reduction of yield. The yield was remarkably small in the plot that was not watered before planting in order to reduce the salinity caused by ash. According to the effect of clinker ash for improvement of the physical properties of soil greater than usual sand and the inverse effect for lettuce growth and cost for the transportation of ash, a suitable amount of application was assumed to be around 10% of topsoil which corresponds to 240 t ha(-1). No problematic effect such as heavy metal accumulation in the plant was caused by ash application.
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