0023-6152

AA00697606

4546

査読無

0023-6152

AA00697606

The field experiment on the long-term application of organic residues was started in 1988 at the farm of Bangabandhu Shekh Mujibur Rahamn Agricultural University (BSMRAU; named as Institute of Postgraduate Studies in Agriculture (ISPA)until 1998) and is continued until now. Five kinds of organic residues (no-application, rice straw green manure, compost and cowdung) were applied every June to cover soil surface uniformly as a thin layer and incorporated into soil to the depth of 10cm. Rice(July to October) and wheat (mid-November or December to March) have been cultivated in rotation under the combination of five organic-residue treatments and three levels of inorganic N fertilizer. Improvement of chemical and physical properties of soils during the first 5 years was summarized and already reported along with the yields of rice and wheat (Karim et al., 1995). Soil samples were taken in April 2003 an analyzed for total C and N, and cation exchange capacity to evaluate the accmulation of organic matter and the improvement of soil chemical properties after 15 years sinec the start of the experiment.