Evidence for a nutritional disorder of Oxalis acetosella L. on acid forest soils: control situation and effects of dolomitic liming and acid irrigation

摘要

The mean cover, biometric and vitality parameters and mineral nutrient status of wood-sorrel (Oxalis acetosella) was monitored during 1983-95 at Hoglwald, southern Germany, on the control and experimental plots of a mature Picea abies stand on acidsoil. On the control plot O. acetosella exhibited relatively poor leaf growth and chlorosis on young and older leaf blades. Mineral analyses indicated a very good or good supply of N and P, a moderate Ca nutrition and very high Mn concentrations in the leaves. The input of dolomitic lime led to a significant propagation and vitalization of O. acetosella, the long-lasting effect of treatment being independent of pH dynamics in the root zone. The leaf chlorosis disappeared completely after liming and thelevel of Ca and Mg supply clearly improved, whereas the concentrations of P, N, Mn and Zn diminished. Surprisingly, K nutrition also improved after liming. O. acetosella reacted to acid irrigation (sulfuric acid; pH 2.7-2.8) in comparison to normal watering (pH 5.0-5.5) with a continuous decrease in cover, but without visible leaf necrosis. The concentrations of total sulfur, SO4-S and Sorg were raised, while the concentrations of Ca, Mn and Zn in the leaf blades decreased. After termination of acid input, a recovery of nutrition occurred and a slow recolonization began. Previous lime application prevented the growth-inhibiting effect of the acid irrigation. It is suggested that Ca nutrition may be the controlling factor for leaf growth and vegetativepropagation of Oxalis acetosella.