牛粪堆肥化中氮素形态与微生物生理群的动态变化和耦合关系

在强制通风静态垛装置中研究了牛粪堆肥化中氮素形态和微生物生理群的动态变化。在堆制的56d里,根据堆温变化分阶段采集堆肥样品,测定各种氮素组分的含量和氮素微生物生理群的数量。结果表明,堆肥过程中,总氮减少了21．6％;有机氮是堆肥中的主要氮素形态,其含量降低了19．1％;氨基酸态氮和氨态氮的含量分别降低了20．9％和86．4％,在有机氮和总氮中的比例分别降低了2．2％和5．2％;氨基糖态氮和硝态氮含量分别增加了147％和79％,在有机氮和总氮中的比例分别增加了2倍和1．3倍。氨气的挥发占总损失的63％,高温期的释放量占总挥发量的69％。堆肥中氨化细菌数量较高,在高温期大幅度增加,其数量变化与堆肥中氨气和氨态氮含量都呈极显著正相关关系。在堆肥过程中,硝化细菌数量总体较小,在降温期增加幅度较大;反硝化细菌数量逐渐增加,堆制结束时达到堆肥初期的2．45倍;固氮菌数量总体增加1．8倍,其中降温期数量较多。堆肥过程中存在的反硝化作用,是氮素损失的另一个重要原因。     

长期施肥条件下栗褐土碱性磷酸酶活性及其与磷形态的关系

利用长期定位试验研究了长期不同施肥对土壤碱性磷酸酶活性的影响及碱性磷酸酶与土壤磷素形态间的相关关系.结果表明:与不施肥的对照处理相比,长期施肥特别是有机肥与化肥配施可以显著提高土壤碱性磷酸酶活性;碱性磷酸酶活性与土壤速效磷、有机磷总量、中活性有机磷、中稳性有机磷、Ca2-P和Ca8-P含量相关性均达到极显著水平(P＜0.01),与A1-P、Fe-P和O-P相关性达显著水平(P＜0.05);各形态磷对碱性磷酸酶活性直接影响的大小顺序为Ca8-P(-5.706 9)＞Fe-P(4.180 5)＞Ca2-P(2.760 4)＞Ca10-P(0.980 0)＞中稳性有机磷(0.892 4)＞Al-P(-0.567 5)＞O-P(-0.294 4)＞活性有机磷(0.268 1)＞中活性有机磷(0.210 3)＞高稳性有机磷(-0.165 2).     

Humus macro-morphology and soil microbial community changes along a 130-yr-old Fagus sylvatica chronosequence

We aimed to characterize humus macro-morphology and the associated soil microbial community within the unmodified litter (OL), the fragmented and humified layers (FH) and the organo-mineral (A) layer along a beech (Fagus sylvatica L.) forest chronosequence with four stand age-classes (15-, 65-, 95-, 130-yr-old) in Normandy, France. Humus macro-morphology was described with 36 quantitative and semi-quantitative variables. We measured microbial biomass N (N_mic), microbial N quotient (N_mic-to-N_t), fungal ergosterol, bacterial and fungal DNA using 16S and 18S rDNA real-time qPCR and evaluated the potential metabolic profile of heterotrophic bacteria within each soil layer and stand age-class. The log-transform ergosterol/fungal DNA ratio (EFR index) was used as an indicator related to active fungal biomass and the fungal/bacterial (F/B) ratio was calculated from qPCR results. There was a shift from mull (mainly dysmull) to moder humus forms along the chronosequence. While the N_mic did not change significantly, the N_mic-to-N_t decreased along the chronosequence in the OL layer. Ergosterol content increased in FH and A layers and the F/B ratio increased in the FH layer with increasing beech forest age. The EFR index was significantly higher in the OL and A layers of the oldest stands, whereas the highest EFR index in the FH layer occurred in the 15-yr-old stands. The functional diversity of heterotrophic bacteria was greater within OL and FH layers of 130-yr-old stands, but highest in the A layer of 15-yr-old stands while the Average Well Color Development remained stable for all soil layers. We found significant correlations between macro-morphology and microbial variables, especially between FH-based morphology and fungal biomass. Our main results are that beech forest maturation is accompanied by (1) an increase in fungal biomass in the FH layers and, (2) an increase in heterotrophic bacteria functional diversity in the organic layers. We have identified key macro-morphology variables that are good predictors of the structural and functional profile of the soil microbial community during beech forest development.     

溶解氧等环境因素对Alafia河表层沉积物磷释放影响的模拟研究

在实验室条件下,采用混合均匀的Alafia河表层沉积物并以蒸馏水为上覆水进行沉积物磷释放模拟试验,研究了溶解氧、有机碳和金属铝对沉积物磷（PO4-P）释放的影响。结果表明,试验期间厌氧条件下沉积物磷释放量明显高于好氧条件下。厌氧条件下,未添加金属铝、添加有机碳源的试验组中沉积物释放平衡时水中磷浓度为5.93mg.L-1;好氧条件下,平衡时水中磷浓度为2.39mg.L-1。研究还发现,未添加金属铝的试验组,无论好氧还是厌氧条件下,未添加有机碳源时,沉积物磷释放量高于添加碳源条件;而在添加金属铝后,添加有机碳源的试验组中磷释放量略高于未添加碳源的试验组。添加金属铝能够明显抑制沉积物中磷的释放。未添加金属铝,厌氧条件下,平衡时水中磷浓度为6.91mg.L-1,好氧条件下,释放平衡时水中磷浓度为3.70mg.L-1;而添加金属铝的试验组,无论厌氧还是好氧条件下,上覆水中磷浓度均很小,接近于0mg.L-1。     

Long-term Potassium Contribution of Potassium Forms of Udic Haplustept and Sustainability of Growing Crops

A balance sheet of potassium (K) was prepared in a long-term experiment that was started in 1985 on a loamy sand Udic Haplustept at the Potash Research Institute of India, Gurgaon, Haryana, India, involving a sorghum (fodder)–wheat cropping system. During the 20 cycles of sorghum and wheat, as much as 2,404 kg K ha^?1 was released from the structural form of soil K that contributed 77.3% K to the total K removed by growing sorghum and wheat. However, this K released from the structural form could no longer sustain the growth of sorghum and wheat. Both water-soluble and exchangeable soil K forms contributed 3% K and nonexchangeable K contributed 6.6% K. Groundwater used in irrigation contributed 13.1% K. Potassium fertilizer is needed for the growth of sorghum and wheat on a loamy sand Udic Haplustept as in this long-term experiment and other representative soils both to sustain yield and maintain soil K fertility.     

冀中南棉区土壤钠的形态与棉花吸收的关系

对河北省中南部棉区36个地块土壤钠形态和含量进行了测定。结果表明,冀中南棉田土壤020cm全钠含量为10.7～24.6g.kg;交换性钠含量为48～10250mg.kg,水溶性钠含量为21.5～10400.5mg.kg。土壤全钠含量与交换性钠含量、水溶性钠含量之间及土壤交换性钠含量与水溶性钠含量之间均呈正相关关系;土壤全钠含量与土壤有机质含量、土壤阳离子交换量之间呈负相关关系;土壤交换性钠含量、水溶性钠含量与土壤阳离子交换量之间呈负相关关系;水浇地棉田土壤全钠含量与水溶性钠含量之间呈负相关关系。从供试土壤全钠含量为14.1～17.6g.kg,交换性钠含量为39.0～189.0mg.kg,水溶性钠含量为19.5～114.0mg.kg条件下的盆栽试验结果看出,棉花苗期干物质积累量与土壤交换性钠含量、土壤水溶性钠含量之间以及棉花苗期钠吸收量与土壤交换性钠含量、水溶性钠含量之间均呈曲线相关关系。     

硅藻土有机肥对Cd-Zn复合污染土壤重金属形态和有效性的影响

通过室内土壤培养试验研究硅藻土有机肥对Cd、Zn复合污染土壤重金属形态和有效性的影响。结果表明,添加硅藻土有机肥可提高Cd、Zn复合污染土壤的pH值,降低土壤有效态Cd、Zn的含量。硅藻土有机肥对Cd、Zn复合污染土壤Cd、Zn形态有明显的影响,表现为明显降低土壤交换态、松结有机态Cd、Zn含量,提高紧结有机态和残渣态Cd、Zn含量。相关分析表明,土壤交换态、松结有机态Cd、Zn的含量与土壤有效态Cd、Zn的含量均呈极显著相关,氧化锰结合态Cd与土壤有效态Cd含量显著相关。硅藻土有机肥用量(土壤重量的5%和10%)对土壤有效态Cd、Zn和不同形态Cd、Zn含量无显著差异。     

模拟氮沉降对毛竹林土壤生化特性和酶活性的影响

以亚热带毛竹林为研究对象,以长江三角洲地区实际氮沉降量40 kg/(hm~2·a)为参照,设置2种形态(铵态氮(NH_4Cl)和硝态氮(KNO_3))和3种水平(对照、低氮和高氮(0,40,120 kg/(hm~2·a))的氮添加试验。结果表明:(1)氮添加显著降低了土壤pH,不同氮水平和形态对pH均有显著影响(P=0.001和P=0.010);(2)高水平氮处理下,硝态氮处理的土壤NO_3~--N和DON含量分别高于铵态氮处理的40.06%和50.10%,土壤NH_4~+-N含量低于铵态氮处理的12.33%,在同一氮形态下,高氮处理的土壤NO_3~--N和DON含量分别高于低氮处理的47.12%和78.12%,土壤NH_4~+-N含量低于低氮处理的24.24%。说明氮水平和形态均对土壤NH_4~+-N、NO_3~--N和DON含量有显著影响(P0.05);(3)与对照相比,高水平氮处理下土壤脲酶和蔗糖酶活性分别提高了14.16%和8.11%,氮形态对土壤脲酶和蔗糖酶活性没有显著影响。氮水平和形态对过氧化氢酶活性均无显著影响(P0.05);(4)土壤脲酶、蔗糖酶和过氧化氢酶活性均呈现显著的季节变化,脲酶和蔗糖酶活性夏季高,冬季低,春秋居中,过氧化氢酶则秋冬季节较高。氮添加没有改变酶活性的季节分异规律。通过Pearson分析发现,土壤酶活性(脲酶、蔗糖酶和过氧化氢酶)与土壤生化特性显著相关(P0.05)。氮水平和形态对土壤生化特性和酶活性的影响存在一定差异,研究结果可为氮沉降背景下亚热带毛竹林的管理提供理论依据。     

腾格里沙漠沙坡头地区旱季沙层含水量

[目的]研究腾格里沙漠沙坡头地区旱季沙层含水量、水分来源、水分存在形式、水分平衡等问题,为沙漠地区水分合理利用、沙漠化防治、沙地改良以及沙地农业生产提供科学依据。[方法]利用轻型人力钻打孔取样,进行水分测定。[结果]腾格里沙漠沙坡头地区旱季沙层平均含水量为1%~3%,一般具有分为3层的特点;沙层含水量存在明显的空间差异,洼地平均含水量最大,平坦高地和半固定沙丘中部含水量较低,流动沙丘中上部含水量最低;旱季时期沙层水分以薄膜水形式存在;研究区旱季沙层水分仍为正平衡,主要是由沙层的高入渗率和受蒸发影响深度小决定的;研究区有植被发育之处,在根系的吸水作用下沙层剖面中下部的含水量比无植被的剖面含水量低。[结论]研究区旱季沙层含水量低,空间差异较大,沙层水分仍保持正平衡状态。     

三峡库区消落带沉积物与土壤磷形态及分配特征研究

应用沉积物中磷形态的标准测试程序(SMT)对三峡库区典型消落带表层新生沉积物及土壤中形态磷进行分级测定,并探讨形态磷之间及其与有效磷和样品理化性质(有机质和铁)之间的相关性。结果表明:消落带沉积物及土壤中总磷(TP)含量分别在435.1~970.0,152.8~1 022.7mg/kg之间,均值分别为(713.6±124.3),(547.5±169.7)mg/kg,沉积物中TP含量远高于土壤,显示了新生沉积物吸附磷的能力高于土壤。无机磷(IP)是沉积物及土壤中磷的主要形态,分别占TP的78.2%,74.2%;有机磷(OP)只占较小的比例。沉积物及土壤中钙磷(Ca—P)是IP的主要赋存形态,Ca—P/IP均值为73.6%,74.1%,而铁/铝磷(Fe/Al—P)占IP比重仅为26.4%,25.9%。沉积物及土壤中有效磷(Olsen—P)含量分别在4.43~45.50,2.88~41.84mg/kg之间,其中分别有29.6%,11.1%的样品超过土壤磷素淋失的Olsen—P临界突变点(25mg/kg)。回归分析表明,沉积物中Fe/Al—P和OP是Olsen—P的主要贡献者,而Ca—P对Olsen—P的贡献很小;土壤中仅Fe/Al—P对Olsen—P有较大贡献。相关分析表明,有机质与OP呈极显著正相关,说明有机质的输入可促进OP的累积;TP、Fe/Al—P、Ca—P与无定形态铁(Fe_o—Fe_p)、有机络合态铁(Fe_p)呈显著正相关,表明Fe_o—Fe_p和Fe_p可促进沉积物及土壤的固磷作用。