Effects of Leonardite on Soil Properties and the Nutrients Concentrations of Tomato Plants

Abstract

ABSTRACT Leonardite is an important source of organic fertilizers and soil amendment. The objective of this study was to determine the effects of increased doses of leonardite (control (L0), 20 (L20), 40 (L40), 60 (L60), and 80 (L80) t ha−1) on soil properties at different incubation times (control (T0), 15 (T15), 30 (T30), 45 (T45), 60 (T60), and 90 (T90) days). Analysis results of soil samples taken during six different incubation periods. Results showed that application of leonardite significantly improved soil organic matter (SOM), total nitrogen (N), exchangeable calcium (Ca) and, available iron (Fe), manganese (Mn) and zinc (Zn), especially with L40 and L60. Prolonged incubation time was significantly increased N, P, K, Ca, Fe, Zn concentrations especially T60 and T90. The nutrient concentration of the tomato plants was not affected by increased doses of leonardite, except for total N, Fe and Cu. By the way, prolongation of the incubation period resulted in fluctuating nutrient concentrations of the plant. As a result, it was determined that leonardite improved the chemical properties of the soils but it was not sufficient in the feeding of the tomato plant. Therefore, leonardite must be used with chemical fertilizers for plant growing.