Linking sorghum nutrition and production with arbuscular mycorrhizal fungi and alternative soil amendments

Abstract

Mounting fertilizer costs are disproportionally affecting farmers in developing countries. Alternative soil fertility amendments [worm compost, pyrolyzed carbon (biochar)] and arbuscular mycorrhizal fungi have the potential to reduce these costs while promoting soil health. Our greenhouse study investigated the role of mycorrhizal associations and alternative fertility amendments on the productivity and plant nutrition of grain sorghum. We assessed sorghum (Sorghum bicolor cv. Macia) grown with ten different treatments (combinations of biochar, worm compost, and commercial N and P fertilizers) plus a non‐amended control. An amendment blend containing worm compost, biochar, and 50% of the typically recommended commercial fertilizer rate produced similar plant biomass and protein, similar total tissue mineral contents (Ca, Fe, K, Mg, P, and Zn), and supported ≈ 60% more mycorrhizal fungi in the host plant's roots, compared to sorghum grown with the recommended rate of commercial fertilizer (N and P). Our results indicate the potential of biochar and worm compost to enhance the benefits of mycorrhizal fungi for grain sorghum production and plant nutrition while reducing commercial fertilizer applications.

Influence of alternative soil amendments on mycorrhizal fungi and cowpea production

“…Our previous research with sorghum ( Sorghum bicolor ) showed similar improvements in plant tissue mineral contents, particularly P, for plants amended with reduced commercial fertilizer rates + biochar + worm compost; however, root colonization was also ∼60% greater for those plants ( Cobb et al., 2018 ). While root colonization does not always indicate improved nutrient uptake ( Klironomos, 2003 ), it is often correlated, such that greater colonization tends to improve plant nutrient uptake ( Treseder, 2013 ; Cobb et al., 2016 ).…”

Utilizing mycorrhizal responses to guide selective breeding for agricultural sustainability

“…Selective breeding for improved host‐plant partnership with mycorrhizal fungi is a necessary step, setting the stage for additional efforts to use soil amendments and agroecosystem management to support effective microbial symbioses (Cobb, Wilson, & Goad, 2018; Cobb, Wilson, Goad, & Grusak, 2018; Duhamel & Vanderkoornhuyse, 2013; Smith et al., 1992). Mycorrhizal symbioses are widespread and typically beneficial, suggesting that evaluation of mycorrhizal relationships is critical groundwork for disentangling additional plant‐associated microbial dynamics of the total holobiont.…”