Assessing the Decomposition Speed of Residual Vegetation under Haplic Acrisols in Lang Giang district, Bac Giang Province

Improvement of Haplic Acrisols by residual vegetation is an effective and easily applied measure in the condition of Vietnam. In the Summer season the decomposition speed of residual vegetation is more rapid than last ones in the Spring - Winter season. In the Summer all of residual vegetation were decomposed after 5-6 months. From 3 residuals vegetation, the ground nut stem having most rapid speed of decomposition, then is wild chrysanthemum of Thailand and the last one is straw. Addition of lime with 1 tan CaO per hectare with microorgarnism products (CT4) led to the acceleration of decomposition speed of residual vegetation. In the summer season, in CT4 the decompositioned percentage of ground nut stem, straw and wild chryssamthemum of Thailand after 150 days of their buries was 87.2 -90.0%, 78.3 -81.1% and 79.1% respectively. In the spring winter the speed of vegetation residue decomposition is reduced approximate by a half but in CT4 its still highest.