JWSS - Journal of Water and Soil Science

---

Peat is the best known and the most widely used rhizobial carrier, but unfortunately, it lacks of sufficient sources in Iran. This research aimed at using some inexpensive materials as carrier instead of peat for producing the rhizobial inoculant for alfalfa. For this purpose, the physical and chemical properties of some materials to be used as carriers were determined and the viability of Sinorhizobium meliloti on these carriers during 6 months at +4 ºC was evaluated. The selected carriers were 1) Peat (control) 2) Vermicompost 3) Bilogical Filter Waste (BFW) 4) Vermiculite+Vermicompost (1:1w/w), and 5) Vermiculite+BFW (1:1w/w). Also to determine the suitable moisture content of carriers on prolongation of bacterial survival, two matric potential levels including –10 and –30 kpa were applied on the carriers. The results showed that vermiculite+BFW (1:1w/w) not only maintained a standard number of bacteria compared to the other treatment, but also caused good nodulation on alfalf seedling at the end of the 6^th month. Although BFW carrier maintained a high number of bacteria after six months storage, it can not be recommended as a suitable carrier because of its negative effect on nodulation. In this study, higher number of bacteria was maintained in the matric potential of –30 kpa than –10kpa.

---

Certain microorganisms in soil have phosphate solubilizing ability. Phosphorus has an important role in plant nutrition and N₂ fixation in legumes. The interactive effect of three phosphate solubilizing bacteria (PSB) and Bradyrhizobium japonicum on yield and N, P, K uptake and nodulation of soybean root (Glycin max L. CV. Harcor) was studied under greenhouse conditions. In greenhouse experiment treatments consisted of a factorial combination of four levels of PSB (without PSB M₀ ,Pseudomonas putida M₁ , Aeromonas hydrophila M₂ , Pseudomonas fluorescens M₃) and two levels of B.japonicum (without bacterium B₀ and with bacterium B₁) and three levels of P(P₀ = 0 , P₁=29, P₂ = 58 mg triple superphosphate/Kg soil) in a randomized complete block design with four replications. At harvest, shoot dry weight, seed weight, nodule number, dry and fresh weight of nodules and concentrations of N, P, K in shoot dry matter were measured. PSB significantly increased shoot dry weight, N, P, K concentrations in shoot, fresh and dry weight and number of root nodules. B.japonicum had positive significant effect on these parameters as well as on seed weight. Dual inoculation of plants with PSB and B.japonicum had significant effect on shoot dry weight, P and N concentrations in shoot. Increasing phosphorus levels significantly increased plant dry weight, shoot P concentration and seed weight. Highest P concentration in shoot was obtained at P₂ level but in plants inoculated with P.putida, dry weight at P₁ level was not significantly different from P₂ level.