连续施用土壤改良剂对砂质潮土团聚体及作物产量的影响

Effects of organic and inorganic amendments on aggregation and crop yields in sandy fluvo-aquic soil

【目的】研究施用无机和有机土壤改良剂对团聚体形成和作物产量的影响,为新型土壤改良剂的应用提供理论依据。【方法】以河北廊坊砂质潮土为研究对象,以虾头蟹壳废弃物为核心材料的有机土壤改良剂(SC)和以凹凸棒土为核心材料的无机土壤改良剂(SA)为试材,进行4年(2015—2019)定位试验。试验设4个处理:单施化肥(CK)、化肥+无机改良剂(SA)、化肥+有机改良剂(SC)、化肥+无机改良剂+有机改良剂(SCA)。种植方式为小麦–玉米轮作。2019年小麦和玉米收获后,测定作物产量并采集耕层土壤,测定土壤理化指标、微生物量碳氮含量、团聚体组成及其碳氮含量。【结果】在小麦季和玉米季,SCA处理均可显著提高作物产量,较CK处理分别提高了54.16%和24.26%;在小麦季,SC处理较CK处理显著提高土壤全氮(TN)、有机碳(SOC)、速效钾(AK)和有效磷(AP)含量,微生物量碳(MBC)显著提高8.82%,pH显著降低3.19%;在玉米季,SCA处理较CK显著提高了土壤TN、SOC、AK、AP含量,MBC显著提高了33.65%,土壤pH显著降低了5.92%;在小麦季和玉米季,土壤团聚体均以粒径0.053~0.25 mm为主;与CK处理相比,小麦季SC处理土壤粒径>0.25 mm的大团聚体含量、平均重量直径(MWD)和几何平均直径(GMD)分别显著提高42.51%、22.41%和20.35%,玉米季SCA处理3个指标分别显著提高68.71%、35.47%和29.65%;各粒级团聚体中SOC和TN含量都以粒径>0.25 mm大团聚体最高,且SCA处理显著增加土壤各级别团聚体SOC和TN含量;施用土壤改良剂增加粒径>0.25 mm大团聚体SOC和TN贡献率,小麦季SC处理较CK处理分别增加了29.06%和69.24%,玉米季SCA处理较CK处理分别增加了61.62%和114.20%;通过冗余分析和结构方程模型分析发现,粒径>0.25 mm大团聚体与pH呈负相关关系,与AP、MBC、SOC以及各粒级团聚体中碳含量呈正相关关系;稳定的团聚体结构会影响SOC含量和pH,改善土壤C/N,进而影响作物产量。【结论】在砂质土壤上,单独施用以虾头蟹壳废弃物为核心材料的有机土壤改良剂或与无机土壤改良剂配施均可改善土壤理化性质,促进大团聚体形成,提高团聚体稳定性,稳定的土壤团聚体可通过改善土壤碳氮比以提高作物产量。

【Objectives】This study was carried out to compare the effects of inorganic and organic amendments on aggregate formation and crop yields in sandy fluvo-aquic soil,and to provide a theoretical basis for the application of new soil amendments.【Methods】A 4-year field experiment was carried out under a wheat-maize rotation system in Langfang,Hebei Province.The experiment included four treatments:chemical fertilizer only(CK),chemical fertilizer+inorganic soil amendment(SA),chemical fertilizer+organic soil amendment(SC),and chemical fertilizer+organic soil amendment+inorganic soil amendment(SCA).Following wheat and maize harvest in 2019,soil samples were collected from the surface layer(0–20 cm)and soil chemical characteristics,microbial biomass,water-stable soil aggregate distributions and stability were measured.【Results】Wheat and maize yields significantly increased by 54.16%and 24.26%,respectively,under SCA compared to CK.Soil chemical properties(total N,soil organic C,readily available K and available P)significantly increased under SC than CK in wheat season and under SCA than CK in maize season.Microbial biomass C also increased significantly under SC by 8.82%in the wheat season and 33.65%under SCA in the maize season.Furthermore,soil aggregate significantly increased under SC and SCA than CK in both wheat and maize season,with the major particle sizes ranging from 0.25~0.053 mm.Compared to CK,a(P<0.05)higher percentage of water-stable aggregates(20.35%),aggregate stability(mean weight diameter=22.41%)and aggregation(42.51%)was recorded in particle sizes>0.25 mm under SC in wheat season.However,in the maize season,these parameters respectively increased by 29.65%,35.47%,and 68.71%under SCA.SCA was the best treatment for aggregate formation and stability.SCA increased soil organic C and total N contents the most in the particle sizes>0.25 mm aggregate.Aggregates in the particle sizes>0.25 mm fraction had significantly higher contribution rate to SOC and TN,while aggregates in the particle sizes<0.053 mm fraction significantly decreased the contribution rate under both inorganic and organic amendments.Both redundancy analysis and structural equation model showed that aggregate composition was positively correlated with soil available P,microbial biomass carbon and organic carbon content of aggregates and negatively correlated with soil pH.【Conclusions】Application of organic amendment or combined application of organic and inorganic amendment in sandy fluvo-aquic soil is an important method for improving soil chemical properties,macro-aggregate formation and aggregates stability.Aggregate stability can improve crop yield by changing soil C/N.