Resumen de Soil water content during and after plant growth influence nutrient availability and microbial biomass
Ran Xue, Yuying Shen, Petra Marschner
Two experiments were conducted to study the effect of soil water content on soil respiration, microbial biomass and nutrient availability in planted and unplanted soil. In the first experiment, wheat was grown in pots for four weeks in soil that was kept dry between one and four weeks. In the second experiment, soil was maintained at 50% of water-holding capacity (WHC) for four weeks and either planted with wheat or left unplanted. After removal from the pots, soil was kept at 50% WHC or quickly dried to 40, 30, 20 or 10% of WHC. The soils were incubated four weeks during which soil respiration, microbial biomass and nutrient availability were measured. In the first experiment, shoot and root biomass and microbial biomass carbon were higher in constantly moist than constantly dry soil, but the reverse was true for available N. In the second experiment, cumulative respiration was two-fold higher in planted than unplanted soil and decreased with water content, with a smaller decrease in planted soil. Microbial biomass carbon on days 5 and 10 was higher at 10% than at 50% WHC in planted soil, but not affected by water content in unplanted soil. We conclude that soil microbes can maintain higher respiration at low water content despite low biomass because activity per unit biomass is high.
