Effet des racines vivantes sur la decomposition d' une litiere racinaire marquee au 14C.
1981
Billes G. | Bottner P.
Wheat was ('14)C-labelled by cultivation on soil in pots, from seedling to maturity, in a chamber with constant CO(,2) and ('14)CO(,2) levels. The ('14)C-distribution was constant amongst the aerial parts, the roots and the soil in the whole pots. After cutting the plant tops, the pots were dried without disturbing the soil and root system. The pots were then incubated under controlled humidity and temperature conditions for 62 days. In the same time a second wheat cultivation was grown on one half of the pots in normal atmosphere without plant cultivation. The purpose of the work is to study the effect of living roots on decomposition of the former ('14)C labelled roots litter. The CO(,2) and the ('14)CO(,2) released from the soil were continuously measured. On incubation days 0, 18, 33 and 62, the remaining litter was separated from soil, and the organic matter was fractionated by repeated hydrolysis and NaOH extraction. Root litter disappeared faster when living roots were present than in bare soil. The accumulation and mineralization rates of humified components in soil followed two stages. While the roots of second wheat cultivation grew actively (until earing), the strong acid hydrolysable components accumulated in larger amount than in the case of bare soil. After earing, while roots activity was depressed, these components were partly mineralized and the ('14)CO(,2) release was then higher with plants than with bare soil. The humification and mineralization rate were related to living plant phenology stages.
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