| Popis: |
Climate warming has one of important characteristics that the temperature increase at night is greater than that during the day.Many reports have been available regarding the effects of nighttime warming, silicate or biochar application on the growth, physiology and yield in rice, but it is unclear regarding the effects of the three factors on soil enzyme activities in paddy fields.A field simulation experiment was carried out to investigate the effects of biochar and silicate supply on soil enzyme activities in rice soil under nighttime warming. The orthogonal experimental design with three-factor and three-level was adopted in the experiment. The nighttime warming was treated by covering the rice canopy with aluminum foil reflective film at night (19:00~6:00). The nighttime warming was set at three levels, ambient temperature control (W0), covering rice canopy with 5mm aluminum foil film (W1), and with 11 mm aluminum foil film (W2); biochar supply was designed with 3 levels, i.e., control (B0), 7.5 t·hm-2 biochar (B1) and 17.5 t·hm-2 (B2); silicate application had three levels, i.e., control (Si0), steel slag powder (Si1, 200 kg·hm-2), and ore powder (Si2, 200 kg·hm-2). Root bag method was used to separate rhizospheric soil from non-rhizospheric soil. The soil samples were collected at rice main growth periods (elongation, booting, flowering and filling) to determine the activities of urease, invertase, cellulase and protease in the soil. The results showed that, the activities of urease, invertase and cellulase in non-rhizospheric soil increased under nighttime warming with 5 mm reflective film (W1).Soil invertase and protease activities increased in the treatment without biochar application (B0), while urease and cellulase activities enhanced in the treatment with biochar application (B1 and B2).Silicate application increased the activities of soil enzymes mentioned above.This study suggests the treatment with W2B1Si0 is the optimal combination. Soil enzyme activities were inhibited in the treatment with W2B1Si0, implying that thedecomposition of organic carbon and nitrogen in paddy soil will be likely decreased with applying biochar without silicate supply under climate warming. |
