Effects of water soluble polyphenols in Eucalyptus grandis trees and their effects on crops and soil water repellency

Abstract

The water soluble polyphenols extracts from the Eucalyptus grandis litter and leaves inhibited the germination of beans but the soil extract was not inhibitory. Germination of beans inside the Eucalyptus trees plantations under natural conditions was 90 %, 92 % and 86 % in 1.5, 3 and 6 years old trees, respectively. Bean production under 1.5 years old trees canopy significantly differed from both 3 and 6 years old canopies. The amount of water soluble polyphenols in the soil under Eucalyptus increased with tree age but was less than that present in litter or leaves. Soil water repellency increased with age of Eucalyptus tree and was strong during the dry spells and decreased with soil depth in the soil profile. The contents of water soluble polyphenols and moisture in the soil were the key factors influencing the soil water repellency under Eucalyptus grandis trees. Mixing of the soils with litter during crop cultivation under Eucalyptus trees reduced the soil water repellency.