不同农业废弃物还田对土壤碳排放及碳固定的影响

在玉米生长季,采用静态箱法,在氮磷钾等养分量(N 240kg/hm~2,P2O5100kg/hm~2,K2O 120kg/hm~2)的条件下,研究秸秆、牛粪、鸡粪与化肥配施还田,对土壤CO_2排放及碳固定的影响。研究结果表明:施肥促进土壤CO_2排放,其中100%秸秆粉碎还田配施化肥(S1)对土壤CO_2排放的促进作用最为明显,平均排放通量达389.0mg/(m~2·h);其次为单施化肥(S4)。S1、S2、S3和S4处理在6,7,8三个月份CO_2平均排放通量表现为S4S1S3S2,分别占整个生长季排放总量的80.1%,78.9%,78.8%和83.7%,表明单施化肥处理(S4)在玉米生长旺季CO_2排放通量最高达624.9mg/(m~2·h)。各施肥处理在玉米生长季出现2个CO_2排放高峰阶段,与2次氮肥(尿素)追施密切相关,2次追施氮肥后CO_2排放通量平均值均表现为S4S1S3S2,表明用农业废弃物中的氮部分代替化肥氮,可减少CO_2排放量。50%牛粪有机氮还田配施50%化肥氮(S2),能明显提高土壤有机碳含量。50%鸡粪有机氮还田配施50%化肥氮(S3)可明显提高玉米各器官及植株含碳量,其中S3处理植株含碳量最高为9.59t/hm~2,促进玉米碳固定;而100%秸秆粉碎还田配施化肥氮(S1),并不能提高玉米各器官及植株含碳量,甚至低于单施化肥(S4)。

Effects of different agricultural residues on soil carbon emission and carbon sequestration

Returning agricultural waste is the important way of developing circular agriculture and low-carbon economy. In maize growth season, this study adopts the static method, such as NPK keep weight (N 240 kg/hm2, P2O5 100 kg/hm2, 120 kg K2O/hm2) conditions, straw, cow muck, chicken manure and chemical fertilizer was studied with soil and its influence on soil CO2 emissions and carbon fixation. The results show that the fertilizer promoted the soil CO2 emissions, 100% straw crushing returning NPK fertilizers (S1) promoting effect of soil CO2 emissions is most obvious, the average emission flux of 389.0 mg/m2?h; Followed by chemical fertilizer fertilization (S4). S1, S2, S3 and S4 handling in 6, 7, 8, three month average CO2 emission flux performance for S4 > S1 > S3 > S2, accounted for 80.1% of total emissions throughout the growing season, 78.9%, 78.8% and 78.9%, showed that fertilization of chemical fertilizer treatment (S4) in the maize growth season CO2 emission flux of up to 624.9 mg/m2?h. Various fertilizer treatments on maize growth season two CO2 emissions peak stage, is closely related to the two nitrogen fertilizer (urea) topdressing, twice topdressing nitrogen after CO2 flux values of performance for S4 > S1> S3 > S2, that use agricultural waste of nitrogen instead of nitrogen fertilizer, can reduce CO2 emissions. 50% cattle manure organic nitrogen application in the field with 50% nitrogen fertilizer (S2) can obviously increase soil organic carbon content. 50% chicken manure organic nitrogen application in the field with 50% nitrogen fertilizer (S3) can obviously improve the maize organs and plant carbon content, among them, the S3 processing plant carbon content up to 9.59 t/hm2, promoted the corn carbon fixation; While 100% straw crushing returning NPK fertilizer nitrogen (S1) does not improve maize organs and plant carbon content, and even lower than that of single chemical fertilizer (S4).