Effects of vesicular-arbuscular mycorrhizal inoculation on the yield and phosphorus uptake of field-grown barley

In a field experiment on barley, the effects of soil application of phosphorus fertilizer and inoculum of Glomus mosseae on the mycorrhizal colonization of roots, crop yield and P uptake were evaluated in a natural or methyl bromide fumigated soil. Soil fumigation raised the amount of available nitrogen (NH4-N+NO3-N) in the soil by 13 mg kg(-1). Although both soils were equalized for the N status by adding N fertilizer to non-fumigated soil, fumigated soil gave higher crop yield. The applied P increased the dry matter yield significantly but suppressed mycorrhizal infection. An overall small increase of 3% in total P uptake and a decrease of up to 2% in grain and straw yield were observed as a result of inoculation, which were statistically non-significant at P < 0.05. These trends in results were most likely due to the status of available soil P higher than the threshold limit for a positive mycorrhizal growth response. (C) 2000 Elsevier Science Ltd. All rights reserved.