Rice residues decomposing

The unharvested parts of rice plants are generally mixed with the soil because this has been thought to be beneficial. It has been observed however, that productivity of the second crop of rice in a paddy is less than that of the first crop. Chou and Lin (45) found that aqueous extracts of decomposing rice residues in soil retarded radicle growth of rice seedlings and growth of rice plants. Maximum toxicity occurred in the first month of decomposition and declined thereafter. Some toxicity persisted for four months in the paddies. Five inhibitory phenolic acids were identified from decaying rice residues and several unidentified allelochemicals were isolated. 

CHOU C.H. and LIN H.J. 1976. Auto-intoxication mechanism of Oryza sativa, 1. Phytotoxic effects of decomposing rice residues in soil. Journal of Chemical Ecology, 2, 353-367. 

Yakle GA, Cruse RM (1984) Effects of fresh and decomposing com plant residue extracts on com seedling development. Soil Sci Soc Am J 48 1143-1146 Young CC, Zhu Thoume LR, Waller GR (1989) Phytotoxic potential of soils and wheat straw in rice rotation cropping systems of subtropical Taiwan. Plant Soil 120 95-101 Yu JQ (2001) Autotoxic potential of cucurbit crops phenomenon, chemicals, mechanisms and means to overcome. J Crop Prod 4 335-348... 

This compound is one of the more important furan derivatives, and is commercially available from pentosans (polysaccharides) which are present in rice husks, oats and corn residues (furfur is the Latin name for bran ). When treated with sulfuric acid, pentosans decompose into pentoses, which then undergo dehydration to the aldehyde (Scheme 6.31). 

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