Investigating the Possibility of Using Enriched Rock Phosphate to Supply Phosphorus in Tea Plantations

Direct use of rock phosphate is considered as one of the alternatives to superphosphate, however, its use in acidic soils in the north of Iran has received less attention.This experiment was conducted as randomized complete block design. The treatments included: 1) control, 2) triple superphosphate (Tsp) fertilizer (based on soil test), 3) rock phosphate (to the extent that P addition was the same as Tsp), 4) compost at the rate of 10 tons per hectare, 5) rock phosphate+phosphate solubilizing fungi, 6) rock phosphate+phosphate dissolving fungi (Glomos), 7) rock phosphate + 10 tons per hectare compost, 8) rock phosphate + compost + phosphate solubilizing fungi (Pseudomonas), 9) rock phosphate+phosphate solubilizing fungi +compost. The results indicated the possibility of substituing rock phosphate for Tsp  in acidic soils of tea plantations, and organic matter plays an important role in better dissolution of rock phosphate by microorganisms in acidic soils. Application of bacteria, fungi, and compost treatments along with rock phosphate significantly increased the yield of green tea leaves as well as soil available P, compared to the control. Also, the concentration of trace elements in treatments containing compost showed a significant increase. The use of rock phosphate alone significantly increased the soil available P compared to the control, but the highest amount of soil P was obtained by simultaneous application of rock phosphate with compost and microorganisms (biofertilizers).