Document Type : Research Paper
Authors
1
Scientific Staff, Safiabad Agricultural Research Center
2
Assistant Professor, Soil and Water Research Institute
3
Associate Professor, Molla Sani-e Ahvaz University
4
Assistant Professor, Soil and water Research Institute
Abstract
In order to evaluate rock phosphate direct application as a source of phosphorus for canola, a randomized complete block experiment with 8 treatments and 3 replications was carried out at Safiabad Agricultural Research Station of Dezful on a calcareous soil. The treatments included: T1= the control; T2= triple superphosphate (80 kg/ha); T3= rock phosphate (160 kg/ha); T4= rock phosphate + organic material; T5= rock phosphate + organic material + inoculum of phosphate solubilizing bacteria; T6= rock phosphate + sulfur + Thiobacillus inoculum; T7= rock phosphate + sulfur + organic materials; T8= rock phosphate + sulfur + Thiobacillus inoculum + organic materials. After preparing soil for cultivation plots were made measuring 37m followed by the application of experimental treatments as described. The major nutrients, nitrogen (as urea), potassium (as potassium sulfate) and zinc (as zinc sulfate) were applied at rates based on soil tests equally on all plots. Canola seeds were planted 20 cm apart on ridges 60 cm a part. Cultivation practices were applied uniformly in each plot during the growing season. Plants were harvested at the end of the growing season when the seed yield, straw yield, number of bushes per plot, number of pods per plant; number of seeds per pod, thousand kernel weight, the oil and protein content of seeds as well as the concentrations of phosphorus, potassium, sulfur, iron, zinc, copper, and manganese in the seeds and shoots were determined.The highest seed and straw yields were obtained with triple super phosphate (T2) which increased the seed and straw yields by 60 and 92% respectively as compared with the control. Treatment 8, rock phosphate + sulfur + organic matter + Thiobacillus inoculum increased the seed and straw yield by 37.7 and 70 per cent respectively as compared to the control, which was the only treatment being statistically in the same category as triple superphosphate treatment but significantly different from other treatments. There were no significant treatment effects on the thousand kernel weight, number of seeds per pod, number of plants per square meter, number of pods per plant, or the protein content of the seeds. Treatment 8 increased seed oil content by 39.04% and was second only after treatment 2 with respect to improving seed oil content. As a whole treatments that contained sulfur, produced seeds with greatest percent oil which were significant in some cases. There were no significant differences with respect to the leaf and seed concentrations of nitrogen, potassium, sulfur, zinc, iron, copper and manganese among different treatments, however T8 and T2 performed superior to the other treatments with respect to the indices mentioned. T8 and T2 performed the best and were in the some statistical group with regard to significantly improving the uptake, by seeds, of nitrogen, phosphorus, potassium, sulfur, zinc, iron, copper and manganese as compared with the control. Data analysis on the trend of changes in soil available phosphorus also showed that 2 months after the application of the treatments available phosphorus reached a maximum level followed by a small decrease in every treatment and then followed a rather similar trend there after.
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