化肥与有机肥配施对设施土壤团聚体稳定性及其有机碳、全氮含量的影响

Effects of combined application of chemical fertilizer and manure on soil aggregate stability and its organic carbon and total nitrogen contents in greenhouse

为探究设施栽培条件下化肥与有机肥配施对0~20 cm土层土壤团聚体稳定性及其有机碳、全氮含量的影响。以设施栽培连续7年定位施肥田间试验为依托,选择4个施用化肥处理(N0PK、N1PK、N2PK和N3PK)和4个化肥与有机肥配施处理(N0PKM、N1PKM、N2PKM和N3PKM),其中,N0、N1、N2和N3氮用量分别为0、187.5、375.0和562.5 kg·hm-2,磷(P2O5)和钾(K2O)用量分别为225.0和450.0 kg·hm-2,有机肥(M)为75000kg·hm-2,研究单施化肥及化肥与有机肥配施土壤团聚体稳定性及其有机碳、全氮含量。结果显示,与单施化肥相比,化肥与有机肥配施显著提高了土壤有机碳和全氮含量(P<0.05),提高幅度分别为93.21%~119.13%和106.69%~139.42%,均以N2PKM处理提高幅度最大,但单施化肥和化肥与有机肥配施的有机碳、全氮含量受施用化学氮量的影响均不显著。化肥与有机肥配施可使土壤大团聚体(>0.25 mm)的比例上升,微团聚体(<0.25 mm)的比例下降,提高了土壤团聚体平均重量直径及其稳定性,其中N1PKM、N2PKM、N3PKM处理土壤团聚体稳定性提高显著(P<0.05)。化肥与有机肥配施提高了大和微团聚体的有机碳和全氮含量,其含量的增幅以>2 mm团聚体为最大(285.30%和470.83%),其次为0.25~2 mm团聚体(235.32%和267.25%)和0.053~0.25 mm团聚体(113.69%和130.54%),<0.053 mm团聚体为最小(35.13%和34.10%);土壤有机碳(全氮)含量与各粒级团聚体有机碳(全氮)含量关系密切(P<0.05),但0.25~2和0.053~0.25 mm团聚体是赋存有机碳(全氮)的主要粒级,也是土壤有机碳(全氮)提升的关键。设施栽培田间试验条件下,连续7年化肥与有机肥配施促进了土壤大、微团聚体的形成,提高了土壤团聚体的稳定性,同时也显著增加了大团聚体(>0.25 mm)有机碳和全氮含量,提高了土壤有机碳(氮)库。

To evaluate the effects of combined application of chemical fertilizer with manure on soil aggregate stability and its organic carbon and total nitrogen contents in 0~20 cm soil layer in greenhouse,a field experiment was carried out for seven consecutive years.There were four chemical fertilizer treatments(N0PK,N1PK,N2PK and N3PK)and four combined applications of chemical fertilizer with manure(N0PKM,N1PKM,N2PKM and N3PKM).Rate of nitrogen of N0,N1,N2 and N3 were 0,187.5,375.0 and 562.5 kg·hm-2,respectively,rate of phosphorus(P2O5)and potassium(K2O)were 225.0 and 450.0 kg·hm-2,respectively,and rate of manure was 75000 kg·hm-2.Wet-sieving was applied to extract different aggregate size fractions for studying the aggregate stability,and its organic carbon and total nitrogen contents.Compared with the application of chemical fertilizer,combined application of chemical fertilizer with manure significantly increased the soil organic carbon and total nitrogen contents(P<0.05),by 93.21%~119.13%and 106.69%~139.42%,respectively,while N2PKM had the largest increase range,but their contents of application of chemical fertilizer and combined applications of chemical fertilizer with manure were not significantly affected by nitrogen application rate.Combined application of chemical fertilizer with manure increased the proportion of macro aggregates(>0.25 mm)and decreased that of micro aggregates(<0.25 mm),and the mean weight diameter and stability of soil aggregates for N1PKM,N2PKM and N3PKM significantly improved(P<0.05).Combined application of chemical fertilizer with manure increased the contents of organic carbon and total nitrogen of macro-and micro-aggregate size fractions,the>2 mm aggregates were the largest increase range(285.30%and 470.83%,respectively),and then 0.25~2 mm aggregates(235.32%and 267.25%,respectively)and 0.053~0.25 mm aggregates(113.69%and 130.54%,respectively),and<0.053 mm aggregates were the smallest(35.13%and 34.10%,respectively).The content of soil organic carbon(total nitrogen)correlated significantly with the content of organic carbon(total nitrogen)in different aggregate size fractions(P<0.05).The 0.25~2 and 0.053~0.25 mm aggregates were the main carrier of organic carbon and total nitrogen sequestration,which were the key contributor for the improvement of soil organic carbon and total nitrogen.The combined addition of chemical fertilizer with manure in the greenhouse for seven consecutive years not only promotes the formation of macro aggregates and micro aggregates and consequently improves soil aggregate stability,but also increases the organic carbon and total nitrogen contents of soil aggregates(>0.25 mm)and therefore improves the soil organic carbon(nitrogen)pool.