Plant diversity shapes microbe‐rhizosphere effects on P mobilisation from organic matter in soil

Abstract

Plant species richness ( PSR ) increases nutrient uptake which depletes bioavailable nutrient pools in soil. No such relationship between plant uptake and availability in soil was found for phosphorus (P). We explored PSR effects on P mobilisation [phosphatase activity ( PA )] in soil. PA increased with PSR . The positive PSR effect was not solely due to an increase in C org concentrations because PSR remained significant if related to PA :C org . An increase in PA per unit C org increases the probability of the temporal and spatial match between substrate, enzyme and microorganism potentially serving as an adaption to competition. Carbon use efficiency of microorganisms (C mic :C org ) increased with increasing PSR while enzyme exudation efficiency ( PA :C mic ) remained constant. These findings suggest the need for efficient C rather than P cycling underlying the relationship between PSR and PA . Our results indicate that the coupling between C and P cycling in soil becomes tighter with increasing PSR .

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