Impact of Heating and Rewetting on Soil Respiration and Nutrient Availability Is Enhanced by Prior Growth of Plants

Abstract

The effects of heating and rewetting on nutrient availability and microbial activity have been studied extensively. But little is known about the effect of prior presence of plants on the impact of heating on microbial activity and nutrient availability. Soil was planted with wheat or left unplanted. After 4 weeks, roots were removed from the planted soil, washed and then added to half of the previously planted and unplanted soil at 1 g dw kg−1. Half of the replicates from each treatment were heated and then maintained at 60 °C for 30 min followed by rapid rewetting, while others remained unheated. Soil respiration was measured continuously for 14 days. Soils were sampled 2, 7 and 14 days after rewetting for available N and P pools. Heating and rewetting induced a flush of respiration and increased available N and P. The heating-induced increase in initial respiration rate, cumulative respiration and available N and P was greater in previously planted soil than unplanted soil. Heating increased available N and P three- to fivefold in planted soil, but only twofold in unplanted soil. Plant-induced changes in nutrient availability increase the impact of heating on soil respiration and nutrient availability.