生物炭添加和灌溉对温室番茄地土壤反硝化损失的影响

生物炭添加和灌溉是番茄地常用的田间管理措施,然而其对反硝化的影响还不清楚.本研究种植试验设置3个灌溉量水平分别为估算作物生育期需水量ET0的50%(W50%)、75%(W75%)、100%(W100%)和3个生物炭添加水平分别为B0(折合纯碳,0)、B25(折合纯碳,25 t·hm-2)、B50(折合纯碳,50 t·hm-2),在2014年和2015年番茄收获后,每个试验小区采集具有代表性的土样进行室内培养试验,采用乙炔抑制法来研究土壤的反硝化损失和不加乙炔研究N_2O的排放量.结果表明生物炭和灌溉量显著改变了土壤的理化性质.与B0相比,添加生物炭能够提高土壤全碳、全氮含量和pH值,降低铵态氮、硝态氮含量,而灌水量降低了土壤中全氮和全碳的含量.因此,与B0/W50%相比,B25/W75%和B50/W100%处理显著减少了反硝化损失量(P0.05).生物炭和灌溉量的交互作用对土壤无机氮含量和反硝化损失的影响均达到显著水平(P0.05),且对硝态氮的影响表现为灌溉量生物炭添加量两者交互作用,对铵态氮的影响表现为生物炭添加量灌溉量两者交互作用,对反硝化损失的影响表现为灌溉量生物炭添加量两者交互作用.反硝化损失量与土壤中无机氮含量、(CO_2-C)矿化量与N_2O排放量均呈正相关关系.不同生物炭添加量和灌溉量处理后明显影响了N_2O/DN(P0.05),培养结束时,各处理下的N_2O累积排放量/DN累积排放量差异较大,介于0.31%~1.88%.

Effects of Biochar Amendment and Irrigation on Denitrification Losses in Greenhouse Tomato Fields

Biochar addition and irrigation are normal farm practices for tomatoes management, while their impacts on denitrification are less known. In this study, three irrigation treatments(hereafter main plots)were set as 50% (W50%), 75% (W75%) and 100% (W100%) of reference evapotranspiration (ET₀), and the subplots coupled three biochar treatments at the rates of 0 (B0), 25 t·hm^-2 (B25) and 50 t·hm^-2 (B50). Typical soil samples in each plot were collected when tomatoes were harvested in 2014 and 2015. We used acetylene inhibition method to study the denitrification loss, and also measured N₂O emissions of tomato soil without acetylene amendment. The results showed that biochar and irrigation significantly changed the physical and chemical properties of the soil. Adding biochar improved total carbon, total nitrogen content and pH of the soil, while reduced the content of NH₄⁺-N and NO₃^--N compared to B0. On the contrary, irrigation reduced the amount of total nitrogen and total carbon content. As a result, both biochar and irrigation significantly reduced denitrification losses (P<0.05). Moreover, the interaction of biochar and irrigation significantly reduced soil inorganic nitrogen and denitrification losses (P<0.05),and the orders of the influencing factors of NO₃^--N were irrigation, biochar, their interactions in turn, the orders of the influencing factors of NH₄⁺-N were biochar, irrigation, their interactions in turn, the orders of the influencing factors of denitrification losses were irrigation, biochar, their interactions in turn. Denitrification losses were positively related to inorganic nitrogen content in the soil, CO₂mineralization rates and N₂O emission rates. The ratio of N₂O/D_N, ranging from 0.31% to 1.88%, was significantly affected by biochar and irrigation treatment in the fields (P<0.05).