Modification of Calcareous Soil with Sulfur to Improve Tomato Yield and Nutrition

A large part of the cultivated soils in western Iran is calcareous. This is effective in reducing the availability of essential nutrients in the soil and their uptake by plants. This study's aim was to investigate the effect of different levels of sulfur on chemical properties of a calcareous soil and tomato yield. The experiment was carried out in a greenhouse using sulfur at five levels of 0, 1, 2, 3, and 4 g/kg soil with the bacterium Thiobacillus thioparus with three replications (15 pots in total). Tomato seeds were sown two weeks after adding sulfur to the potting soil. At the end of the 60-day growth period, leaf samples and tomato crops were harvested to measure nutrient concentrations and determine the yield, respectively. The results showed that the application of sulfur significantly affected soil pH (19.9 to 20.4%), electrical conductivity (18.7 to 21.5%), and the availability of P (16.2 to 21.2%), Cu (16.6 to 22.8%), Zn (16.8 to 21.9%) and Fe (18.2 to 22.5%) in the soil. The concentrations of these elements were also affected in the plant tissue due to soil sulfur application in the range of 17.7 to 21.3% for P, 18.6 to 21.4% for Cu, 16.4 to 22.9% for Zn and 21.5 to 22.6% for Fe, respectively. Plant height was influenced similarly with an increase from 17.2 to 22.7%. In general, the results of this study showed that applying sulfur up to three grams per kilogram of calcareous soil could increase the uptake of nutrient elements by the plants through improving their availability which in turn resulted in the growth and yield increase of tomato.