Allelopathy Journal

Indole-3-acetic acid (IAA) contents in soils from two shelterbelts of different age and plant composition as well as in adjoining soils of cultivated fields were studied. During the entire vegetative growth, the concentrations of IAA were significantly higher in soils under the old shelterbelt (64.4 to 241.5 μg.kg⁻¹) than in soil under the young shelter belt and adjoining cultivated fields (5.8 to 21.8 μg.kg⁻¹). These differences may be due to the contents of organic carbon and total nitrogen and associated roots of Robinia pseudoacacia. The IAA contents in soils from the young shelterbelt and adjoining cultivated fields were lower than in soils under old shelterbelt.