Temporal and spatial variation of soil respiration under mulching in a greenhouse cucumber cultivation

The objective of this work was to determine the temporal and spatial variations of soil respiration (Rs) in a greenhouse, as well as the factors causing them, in a soil covered with different mulching types and cultivated with cucumber (Cucumis sativus). Four mulching treatments were applied to a soil cultivated with cucumber: CK, conventional practice without mulch; FM, plastic film mulch; CM, combined mulch of plastic film with wheat straw; and SM, wheat straw mulch. Rs was measured by a soil respiration chamber connected to a portable infrared gas analyzer, and the differences of Rs between mulchings were evaluated. Rs was significantly lower in the control than in the treatments with mulch. In addition, Rs was higher in the position on the soil near plants (5.4 mu mol CO2 m(-2) s(-1)) than in the positions between plants (4.7 mu mol CO2 m(-2) s(-1)) and rows (3.9 mu mol CO2 m(-2) s(-1)). Soil water content and temperature had an interacted effect on Rs. Cucumber root biomass and root vigor should also be incorporated as predictor variables for Rs in the succession crops, mainly for accurately estimating carbon cycling in agroecosystems in a greenhouse.