Influence of sodium lignosulfonate on loamy soil and cucumber plants

Abstract

Sodium lignosulfonate is a water-soluble by-product obtained by the sulfite method of cellulose production. In a model experiment, the authors investigated the effect of sodium lignosulfonate on certain agrochemical parameters of sod-podzolic loam soil and on the physiological parameters of cucumber plant development. Sodium lignosulfonate was added to the soil in concentrations 0 %, 1 %, 2,5 %, 5 % and 10 % of the dry soil weight. The samples were incubated at a constant temperature (23 °С) and a constant humidity of 70 % for 90 days. Adding lignosulfanate to the model soil in small concentrations (1 and 2.5 %) significantly increased the content of potassium (from 169.7 mg/kg in the control to 389.1–431.6 mg/kg, respectively) and exchange cations, but reduced the nitrogen content regardless of the dose. The concentration of Mg, CA and Na increased by 3.9…7.8 times, which had an alkalizing effect on the soil. At a concentration of 2.5 % lignosulfonate, the pH of the salt solution increased by 1.26 units. At the same time, the concentration of the buffer solution significantly increased, which was manifested in the physiological response of plants. Lignosulfonate reduced the accumulation of plant biomass and proportion of roots in the total mass. With an increase in the concentration of lignosulfonate in the soil, the degree of inhibition of growth processes increased. Lignosulfanate did not affect the stomatal regime of leaves and transpiration losses of water, but it reduced the water content in the leaf depending on the concentration. Photosynthetic activity of plants was partially suppressed in conditions of high lignosulfonate content in the soil. Lignosulfonate did not enhance plant tolerance to low temperature.