Improving P-efficiency in Crops Through the Management of Highly Effective Beneficial Soil Microorganisms

Arbuscular mycorrhizal fungi (AMF) form a symbiosis with 80% of plant species. Plants benefit from association with AMF by enhanced P absorption and they supply photosynthetically produced carbon substrate to AMF as a food source for the fungi. The objectives of this research initiative are to assess the effects of using a commercial AMF innoculant (trade name MYKE®PRO) containing a reported superior AMF strain sold for field crops since 2011, compared to indigenous AMF fungi in the uninoculated treatments. Variable effects of MYKE®PRO on commercial crop yields have been reported in the Prairie farming community, but the value of MYKE®PRO in field crops has rarely been appropriately assessed through independent tests. In our study, the effects of MYKE®PRO on nutrients (N and P) absorption, crop yield and microbial diversity, and its persistence in pulse-based rotation systems are being examined in 2-year crop sequence experiments. Trials are conducted on P-deficient soils, on two experimental farms, in Swift Current, Saskatchewan and Beaverlodge, Alberta, and on two commercial organic farms in the Swift Current area. These trials also test the value of fertilizing materials and the interaction between MYKE®PRO and fertilization. Inoculation with MYKE®PRO or a sterilized innoculant at five different fertilization levels (0%, 75%, and 150% of the recommended rate of P) have been applied to the pulse phase of the rotations.

On one organic farm, MYKE®PRO increased mycorrhizal root colonization slightly and yield by 28%, but no inoculation effects were detected on the other organic farms, perhaps due to the severe drought experienced by lentil at this location. Results showed that the application of MYKE®PRO had no significant effect on yield at the experimental farms of Swift Current (lentil) and Beaverlodge (pea), but reduced indigenous mycorrhizal colonization of plant roots. We conclude that MYKE®PRO did not work well under the majority of experimental sites conditions, and that the commercial AMF strain competed with resident indigenous AMF.

There is on-going research to select improved performing strains of indigenous AMF from prairie soils that could be propagated and commercially used on prairie farms. Data on the microbial communities of roots and rooting soil at the four experimental sites is being generated. It will show how inoculation influenced soil biological resources. Plant nutrient uptake (N and P) is also being determined by laboratory analysis of crop and soil samples. Flax will be planted in the experimental plots in 2016 to assess the legacy effect of MYKE®PRO AMF and P fertilization.