Effects Of Biochar And Silicon Fertilizers On Soil Properties In Paddy Fields Under Nighttime Warming

The temperature increase at nighttime is greater than that at daytime,which is one of the salient features of climate warming.The effect of applying biochar and silicon fertilizer under nighttime warming on the properties of paddy soil needs to be studied.In this paper,a field simulation experiment was conducted to study the effect of adding biochar and silicon fertilizer on paddy soil properties under nighttime warming.The field experiment adopted a 3-factor and 3-level orthogonal design,and nighttime warming was set at 3 levels,namely W0(normal temperature control),W1(covered with 5 mm aluminum foil film)and W2(covered with 11 mm aluminum foil film),biochar addition was set at 3 levels,namely B0(not applied),B1(7.5t/ha biochar)and B2(17.5 t/ha biochar),silicate apply was set at 3 levels,namely Si0(not applied),Si1(200 kg/ha steel slag powder)and Si2(200 kg/ha mineral powder).Four key growth periods of rice were selected for testing.The main conclusions are listed as follows:(1)Physical and chemical properties of soilBoth W1 and W2 treatments reduced the average organic matter,available potassium and ammonium nitrogen content in the paddy soil,and increased soil available phosphorus content.The application of biochar and silicon fertilizer increased soil organic matter,ammonium nitrogen and nitrate nitrogen content,and alleviated the adverse effects of nighttime warming on soil nutrient content.The best treatment combination was W0B1Si1,that is,without covering the aluminum foil film at night,applying 7.5 t/ha of biochar and steel slag powder.(2)Soil enzyme activityW1 treatment increased the activities of urease,invertase and cellulase in non-rhizosphere soil during the the key growth period of rice.The activities of soil urease,invertase and nonrhizosphere cellulase were decreased significantly in W2 treatment.Nighttime warming had little effects on protease activity.Application of biochar and silicate fertilizer increased urease activity.Application of biochar reduced soil invertase and protease activity.The best treatment combination was W1B0Si1,that is,5 mm aluminum film cover at nighttime,adding steel slag powder without biochar.(3)Soil microbial biomass carbon and nitrogen content(MBC and MBN)Both W1 and W2 treatments reduced MBC and MBN content in the rhizosphere soil during the key growth period of rice,and the MBC content in the non-rhizosphere soil increased first and then decreased.The application of biochar and silicon fertilizer significantly reduced MBC and MBN content in the rhizosphere soil during the key growth period of rice.The effects of applying biochar and silicate fertilizer on MBN content in non-rhizosphere soil reached significant levels.The best treatment combination was W1B2Si0,that is,5 mm aluminum film cover at nighttime,adding 17.5 t/ha biochar without silicate fertilizer.