Effects of Bacterial and Fungal Inoculants in a Loess Soil Amended with Various Phosphorus Sources on Pea Growth and Phosphorus Uptake

We evaluated the effects of microbial inoculants in a loess soil amended with various phosphorus (P) sources on pea growth and P uptake (PU). Treatments included factorial combinations of three treatments (noninoculation, NI; bacteria, BA; and fungi, FU) and three P sources (no P, NP; calcium superphosphate, SP; and rock phosphate, RP). Compared with NI, soils inoculated with BA and FU and receiving NP and SP increased pea shoot and total biomass, with greater increases with BA than with FU. Both BA and FU stimulated root growth, regardless of P addition. Compared to NI, PU with BA increased by 26, 59, and 83% in soils amended with RP, SP, and NP, respectively, whereas with FU it increased by 25% with SP and 48% with NP, with no effects with RP. The results indicate that BA can increase bioavailability of soil P, whereas FU may promote plant utilization of bioavailable P existing in soil.