1 مربی پژوهش، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی قم، سازمان تحقیقات، ترویج و آموزش کشاورزی، تهران، ایران
2 استاد پژوهش، موسسه تحقیقات خاک و آب، سازمان تحقیقات، ترویج و آموزش کشاورزی، تهران، ایران
3 استادیار پژوهش، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی قم، سازمان تحقیقات، ترویج و آموزش کشاورزی، تهران، ایران
عنوان مقاله [English]
One of the major problems in calcareous soils is low efficiency of phosphorous (P) fertilizers due to rapid precipitation. Lowering soil pH is mentioned as a solution for solubility of precipitated P. In order to investigate the effect of sulfur (S) and thiobacillus sp. bacteria and P fertilizer on canola (Brasica napus L. cv. Hayola-401) yield and nutrient concentrations in soil and plant, an experiment was carried out during cropping season 2012-13, in a calcareous soil which was generally poor in P content. The experimental factors were designed in a complete randomized blocks with factorial arrangement in three replicates. The first factor consisted of S, in 4 levels (0, 500, 1000 and 2000 kg.ha-1) as pastille form as elemental sulfur with sulfur oxidizing bacteria (in 2% rate of sulfur weight) and the second factor including 3 P levels (0, 72 and 110) kg.ha-1)as triple superphosphate. There was a positive and significant interaction between S and P levels on seed and aerial part yield and yield component (p<0.05). The maximum seed and aerial part yield was obtained with applying 2000 kg.ha-1 S (inoculated with Thiobacillus sp. bacteria) along with 110 kg.ha-1 P by 3141 and 3710 kg.ha-1 respectively in which showed 1.9 and 1.5 fold increase in comparison with control. With increasing P applied in each inoculated S levels, aerial P, Zinc (Zn) and iron (Fe) concentration decreased but their uptake increased which in some S levels were much more notable. Increasing P applied in all S levels, raised Zn and Fe available in soil. Applying different levels of S and P had significant interaction in lowering of soil pH after harvesting. The minimum pH of soil was observed in combined use of S (2000 mgkg-1) and P (110mgkg-1) which had a 5% decrease compared to the control. According to the positive and significant effect of sulfur inoculated with oxidizing Thiobacillus sp. bacteria on increasing seed yield, in one side, and lowering soil pH, in the other side, application of them recommend in calcareous soils. Although, determining of the optimal period of sulfur application in these soils should be investigated.