化肥减施对冬小麦土壤呼吸的影响

Effect of fertilizer reduction on soil respiration of winter wheat

为探明化肥减施对冬小麦土壤呼吸特征的影响,在新疆农业科学院奇台麦类试验站进行田间试验,以当地常规施肥量(N_(5)P_(3))为对照,设置化肥不同减施量处理(N_(4)P_(2)、N_(3)P_(2)、N_(3)P_(1)、N_(2)P_(1)、N_(1)P_(1)、N_(0)P_(1)、N_(3)P_(0)、N_(0)P_(0)),采用土壤碳通量测量系统LI-8100测定和分析氮、磷减施下冬小麦在灌浆期与成熟期的农田土壤呼吸及影响因子。结果表明,各处理冬小麦在灌浆期与成熟期的土壤呼吸速率变化范围为1.11~3.22μmol/(m^(2)·s),随着氮、磷施用量的减少呈先增加后减少的趋势,与N_(5)P_(3)处理相比,灌浆期N_(2)P_(1)处理与成熟期N_(4)P_(2)、N_(3)P_(2)、N_(3)P_(1)、N_(2)P_(1)、N_(1)P_(1)、N_(3)P_(0)处理均显著促进了土壤呼吸(P<0.05),且在N_(2)P_(1)处理时达到最大,灌浆期与成熟期分别为2.77和3.22μmol/(m^(2)·s)。氮、磷配施(N_(4)P_(2)~N_(1)P_(1))的土壤呼吸速率显著大于不施肥(N_(0)P_(0))、单施氮(N_(3)P_(0))、单施磷(N_(0)P_(1))处理(P<0.05),且单施氮(N_(3)P_(0))处理的土壤呼吸速率显著大于单施磷(N_(0)P_(1))处理(P<0.05)。土壤呼吸速率与10 cm土壤温度存在显著指数相关(P<0.001),与土壤含水量、pH、电导率、有机质、碱解氮、有效磷无显著性相关,各处理土壤温度可解释土壤呼吸变异量的53.38%~90.16%。各处理土壤呼吸的温度敏感系数(Q_(10))为1.51~2.58,少量减施氮、磷处理(N_(4)P_(2)、N_(3)P_(2))以及过量减施氮、磷(N_(1)P_(1))和单施氮(N_(3)P_(0))、单施磷(N_(0)P_(1))处理对土壤呼吸Q_(10)无明显影响,在一定范围内减施氮、磷(N_(3)P_(1)、N_(2)P_(1))则会抑制土壤呼吸Q_(10),较N_(5)P_(3)处理降低了30.77%~35.47%。综上,在一定范围内减施氮、磷会增加冬小麦在灌浆期与成熟期的土壤呼吸速率,促进土壤碳排放,过量减施则会降低土壤碳排放,且氮、磷配施对土壤呼吸的影响大于单施氮、磷处理;在一定范围内减施氮、磷会降低土壤呼吸的Q_(10),而少量或过量减施氮、磷对Q_(10)无明显影响。

A field experiment was carried out to study the effect of fertilizer reduction on soil respiration characteristics of winter wheat in Qitai wheat experiment station of Xinjiang Agricultural Science Academy.With the local conventional fertilization rate(N_(5)P_(3))as control,different fertilizer reduction application amounts(N_(4)P_(2),N_(3)P_(2),N_(3)P_(1),N_(2)P_(1),N_(1)P_(1),N_(0)P_(1),N_(3)P_(0),N_(0)P_(0))were set up.The soil carbon flux measurement system LI-8100 was used to measure and analyze soil respiration and its influencing factors of winter wheat at grain filling and mature stages under reduced nitrogen and phosphorus application.Results showed that the soil respiration rate of winter wheat in all treatments ranged from 1.11 to 3.22μmol/(m^(2)·s)at grain filling and mature stages,and it first increased and then decreased with the reduction of nitrogen and phosphorus.Compared with the N_(5)P_(3) treatment,the soil respiration of N_(2)P_(1) in grain filling stage and treatments of N_(4)P_(2),N_(3)P_(2),N_(3)P_(1),N_(2)P_(1),N_(1)P_(1),N_(3)P_(0) in mature stage were significantly promoted(P<0.05),and it reached the maximum at N_(2)P_(1),which was 2.77 and 3.22μmol/(m^(2)·s),respectively,in grain filling and mature stages.The soil respiration rate of nitrogen and phosphorus combined application(N_(4)P_(2)~N_(1)P_(1))was significantly higher than those of no fertilizer(N_(0)P_(0)),single nitrogen(N_(3)P_(0))and single phosphorus(N_(0)P_(1))treatments(P<0.05),and the soil respiration rate of single nitrogen(N_(3)P_(0))treatment was significantly higher than that of single phosphorus(N_(0)P_(1))treatment(P<0.05).Soil respiration rate was significantly correlated with soil temperature(P<0.001).Soil temperature could explain 53.38%~90.16% of soil respiration variation in all treatments.Soil respiration had no significant correlation with soil moisture content,pH,electrical conductivity,organic matter,alkaline nitrogen,and available phosphorus.The temperature sensitivity coefficient(Q_(10))of soil respiration was between 1.51 and 2.58.A small amount of nitrogen and phosphorus reduction(N_(4)P_(2),N_(3)P_(2)),excessive nitrogen and phosphorus reduction(N_(1)P_(1)),single nitrogen application(N_(3)P_(0))and single phosphorus application(N_(0)P_(1))treatments had no significant effect on Q_(10) of soil respiration,while within a certain range of nitrogen and phosphorus reduction(N_(3)P_(1) and N_(2)P_(1))soil respiration was inhibited,which Q_(10) was 30.77%~35.47% lower than the N_(5)P_(3) treatment.To sum up,within a certain range,the soil respiration rate of winter wheat at the grain filling and mature stages was increased by nitrogen and phosphorus application reduction,which promoted soil carbon emission,while the soil carbon emission was decreased by excessive application reduction,and the effect of combined application of nitrogen and phosphorus on soil respiration is greater than that of single application of nitrogen and phosphorus.In a certain range,the soil Q_(10) will be reduced by nitrogen and phosphorus application reduction,while a small amount or an excessive amount of nitrogen and phosphorus application has no obvious effect on Q_(10).