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

Arbuscular mycorrhizal fungi (AMF) forms a symbiosis with 80% of plant species. In the context of the Prairie Provinces of western Canada, this includes most field crops except for canola and mustard. Plants benefit from association with AMF by enhanced phosphorus (P) absorption. Plants 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 inoculant (trade name MYKE®PRO) containing a reported superior AMF strain (sold for field crops since 2011), compared to an indigenous AMF community in the uninoculated treatments. Variable effects of this product on commercial crop yields have been reported in the prairie farming community, but its value in field crops has rarely been appropriately assessed through independent tests. In our study, its effects on nutrient (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 P-containing fertilizer materials and the interaction between the inoculant and fertilization. Inoculation with the product or a sterilized inoculant at five different fertilization levels (0%, 75%, and 150% of the recommended rate of P), in the forms of composted manure, finely ground rock phosphate, and commercial mono ammonium phosphate fertilizer (11-52-0) has been applied to the pulse phase of the rotations at the two Agriculture and Agri-Food Canada (AAFC) Research Stations over the past four years. The organic farms had only composted manure and rock phosphate.

During the four years of research, 2014 through 2017, inoculation with the commercial AMF inoculant had little effect on flax and pulse yields. An incompatibility of this inoculant with local soil biotic or abiotic conditions may limit its function at these sites. The agronomic data, including crop density, crop biomass, crop yield, and plant nitrogen (N), P, potassium (K) and carbon (C) content at blooming stage, soil moisture, and N and P concentrations in the spring at different depths have been collected and analyzed. However, the N, P, K, and C content of seed and straw at maturity and soil N and P concentrations are still being determined from the last year of research. Soil microbial analyses are also in progress. A final report will be prepared and available in late 2018.