Phosphorus source, organic matter, and arbuscular mycorrhiza effects on growth and mineral acquisition of chickpea grown in acidic soil

Plants grown in acidic soil usually require relatively high amounts of avai lable phosphorus (P) to optimize growth and productivity, and sources of av ailable P are often added to meet these requirements. Phosphorus may also b e made available at relatively high rates in native soil when roots are col onized with arbuscular mycorrhizal fungi(AMF). Addition of P to soil usuall y reduces root-AMF colonization and decreases beneficial effects of AMF to plants. In glasshouse experiments, soil treatments of P [0 P (Control), 50 mg soluble-P kg(-1) as KH2PO4 (SP), and 200 mg P kg(-1) as phosphate rock ( PR)], organic matter (OM) at 12.5 g kg(-1), AMF (Glomus clarum), and variou s combinations of these (OM+SP, OM+PR, AMF+SP, AMF+PR, AMF+OM, AMF+OM+SP, a nd AMF+OM+PR) were added to steam treated acidic Lily soil (Typic Hapludult , pH(W) = 5.8) to determine treatment effects on growth and mineral acquisi tion by chickpea (Cicer areitinum L.), The various treatment applications i ncreased shoot dry matter (DM) above the Control, but not root DM. Percenta ge AMF-root colonization increased 2-fold or more when mycorrhizal plants w ere grown with AMF, OM+SP, and OM+PR. Regardless of P source, plant acquisi tion of P, sulfur (S), magnesium (Mg), calcium (Ca), and potassium (K) was enhanced compared to the Control, and mineral enhancement was greater in PR compared to SP plants. Mycorrhizal plants also had enhanced acquisition of macronutrients. OM+SP and OM+PR enhanced acquisition of P, K, and Mg, but not Ca. Concentrations of Fe, Mn, Cu, and Al were generally lower than Cont rols in SP, RP, AMF+PR, AMF+SP, and OM plants, and mycorrhizal plants espec ially had enhanced micronutrients. Relative agronomic effectiveness values for shoot DM and shoot P, Ca, and Mg contents were considerably higher for PR, including OM+PR AMF+PR, and AMF+OM+PR, than for SP. PR and OM applicati ons to AMF plants are low-cost attractive and ecologically sound alternativ es to intensive use of P fertilizers for crops grown in acidic soils.