Use of Yard Trimmings Compost For Restoration Of Saline Soil Incineration Ash

Abstract

Removal of organic contaminants from soil by high temperature (circa 900°C) incineration also destroys soil structure, removes all soil organic matter, sterilizes the soil, removes some fine particulates, alters the crystalline structure of soil clay minerals, and adds salts and alkalinity. The resulting soil ash is incapable of supporting plant life, and revegetation is usually done by covering with borrow soil material. A greenhouse experiment was conducted to determine if restoration of saline, alkaline soil incineration ash was possible by amendment with yard trimmings compost and chemical fertilizer. Ash was placed in pots (40 cm tall by 18.5 cm diam) and was mixed to depths of 15 to 30 cm with four rates of compost and NPK fertilizer. Pots were moistened to field capacity, and after two weeks were planted with birdsfoot trefoil (Lotus corniculatus) and tall fescue (Festuca arundinacea). During the 22 week experiment, pots were watered daily to meet plant needs, were leached four times by application of 4 cm of water, and were harvested four times. Seedling establishment and plant yield were measured, and chemical analysis was conducted on leachates and soil. Salinity limited plant establishment and early growth, both of which were improved by compost. Soil electrical conductance (EC) was decreased by leaching, but compost did not decrease either soil or leachate EC. Compost increased final soil organic C, and CEC which appeared to account for the large yield response to compost and a strong positive compost × fertilizer yield interaction. Compost greatly increased NO3− in the first leachates indicating a potential for groundwater contamination with application of large amounts of compost to soil ash. This experiment demonstrated that sustained plant growth could be achieved on soil incineration ash by amendment with yard trimmings compost and fertilizer.