Grain mineral concentrations and yield of wheat grown under organic and conventional management

Summary

This comparative study on low-phosphorus soils in southeastern Australia found that organic wheat grain had higher zinc, copper and lower phosphorus and manganese concentrations than conventionally grown grain, though differences were generally minor across most minerals. Conventional management and soluble phosphate fertilisers significantly increased yields (17–84% higher) but reduced mycorrhizal colonisation, with trade-offs between yield performance and certain grain micronutrient profiles. The findings suggest that organic management does not induce dramatic increases in grain mineral concentrations despite claims to that effect, and highlight the importance of regional soil and management variations when generalising across production systems.

Regional applicability

This study was conducted in Australia and may have limited direct applicability to United Kingdom wheat production, which operates under different soil conditions, climates and management traditions. However, the mechanistic findings regarding phosphate fertiliser form, mycorrhizal colonisation and mineral uptake dynamics are likely relevant to UK farming systems; UK soils are often phosphate-adequate rather than phosphate-limited as in the study area, which may modify outcomes. The findings are useful for informing comparative assessments of organic versus conventional grain quality in temperate regions.

Key measures

Grain mineral concentrations (nitrogen, potassium, magnesium, calcium, sulphur, iron, zinc, copper, manganese, phosphorus), wheat yield, mycorrhizal fungal colonisation

Outcomes reported

The study compared grain mineral concentrations (N, K, Mg, Ca, S, Fe, Zn, Cu, Mn, P) and yields between organic and conventional wheat grown on paired farms and in controlled fertiliser experiments on low-phosphorus soils in southeastern Australia.

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