Assessing plant-microbial competition for 33P using uptake into phospholipids

A novel method of estimating soil microbial P uptake, using 33P incorporation into the phospholipids in soil microbial biomass, was used in a study of P-competition between plants and microorganisms. The microbial biomass, and thus the competition for the added 33P, was altered by using different glucose treatments in a microcosm set-up. There was obvious competition for 33P, as shown by the negative relationship between 33P uptake by the plant and 33P incorporation into microbial phospholipids. The data thus indicate that soil microorganisms partly control 33P uptake by the plant. The suggested method of measuring 33P in phospholipids appears to have the potential to provide a rapid alternative to techniques such as chloroform fumigation-extraction for the determination of microbial P uptake, although at present the method will only give relative estimates of P uptake.