The Effect of adding different levels of sulfur on the growth of canola Brassica napus L.
Abstract
An experiment was conducted in the fields of Al-Shuhaymiya district, Wasit Governorate, during the 2021-2022 winter growing season. Agricultural sulfur was added at different levels, along with the bacterium Thiobacillus thioparus, to investigate the soil pH and its effect on the growth of rapeseed (Brassica napus L.). A factorial experiment was conducted using a completely randomized block design (RCBD). The experiment included two factors: the first factor was the addition of four sulfur concentrations (0%, 12%, 24%, and 36%), and the second factor was the addition of two levels of T. thioparus bacteria (5 ml and 10 ml of bacteria per planting hole). Three replicates were performed for all treatments, which were randomly distributed among the treatments, resulting in a total of 36 experimental units. Rapeseed seeds were sown on October 20, 2021. The results showed that the treatment with 36% sulfur and 10 ml/hole of T. thioparus bacteria resulted in the highest average number of bacterial colonies in the field experiment after 30 days of germination, which is considered the peak growth of T. thioparus bacteria. This reached 1866.66 x 10⁴ cells/g of soil, compared to 1066.66 x 10⁴ cells/g in the control treatment. The results also showed that the treatment with 36% sulfur and 10 ml/hole of T. thioparus bacteria at harvest time resulted in the greatest decrease in soil pH within the experiment, reaching 6.89 compared to 7.86 in the control treatment. Furthermore, the treatment with 36% sulfur and 10 ml/hole of T. thioparus bacteria recorded the highest level of available sulfur in the soil at harvest time, reaching 42 mg/kg of soil in the field experiment, compared to the control treatment. 20.44 mg/kg of soil. The treatment of adding 36% sulfur and 10 ml/hole of T. thioparus bacteria recorded the highest concentration of nitrogen, phosphorus and potassium in rapeseed plants, where the NPK concentration rates reached 3.81, 0.85 and 2.66% respectively in the field experiment, while the NPK rates in the control treatment were 1.13, 0.51 and 1.20% respectively.
