Application of Compost from Sugarcane Filter Cake to Alleviate Al Toxicity and to Improve Sugarcane Production on Acid Sulfate Soils.
Vien Minh Duong, Thi Guong Vo, Minh Dong Nguyen, and Thi Kim Phuong Nguyen. Cantho University, 3/2 street,, Cantho, Vietnam
Filter cake, a muddy residual from sugarcane manufacture, has been produced about tens of thousands of tons per year from each sugar factory in the Mekong Delta. This by-product has been deposited in enormous heap where it released organic liquid causing foul smell and death of fishes and plants in surrounding areas. Filter cake was composted in mixing with sugarcane bagasses to produce organic fertilizer in order to solve the problem of environmental pollution and to apply back to sugarcane for growth promotion. Sugarcane has been an important crop on acid sulphate soils in the Mekong Delta because of its tolerance to acidity and Al toxicity. This study evaluated the possibility of using filter cake compost to reduce soil Al-toxicity and chemical fertilizers for sustainable sugarcane production on acid sulphate soils. Pot trial with application of filter cake compost to sugacane on acid sulphate soils showed that active aluminium species as water extractable and exchangeable Al reduced significantly with the increasing amounts of compost applied. Part of active Al after application of compost might enter into complexed forms of organic matters or insoluble forms with phosphates, which were not able extracted even by Cu2+. Considerable reduction of active soil Al in pot trial after application of compost increased root length density of sugarcane. Application of this compost to sugarcane on acid sulphate soil in two field crops showed no effects on reduction of Al toxicity and increase of yield. The most reason likely related to frequent supply of water containing soluble Al through soil capillaries from sulfuric layer that neutralized the effects of compost. Key words: sugarcane filter cake, compost, Al toxicity, water extractable Al, exchangeable Al, acid sulphate soil, root length density.