有机肥施用对植烟土壤氮素矿化及土壤酶和微生物群落的影响

为探索不同有机肥对植烟土壤氮素矿化及土壤微生态的影响。在等氮(100 mg/kg)投入和30℃条件下对施入不同有机肥(植物源有机肥、芝麻饼肥、生物质炭有机肥)的土壤进行室内培养,分析不同时期土壤NO3–-N和NH4+-N含量、土壤酶活性及细菌群落多样性的变化。结果表明：施用不同有机肥均可提高土壤矿质氮含量,在培养前期以饼肥矿化量最高,矿化速率最快,而后期为生物质炭有机肥处理的氮素矿化量、矿化速率高于其他处理;施用生物质炭有机肥、植物源有机肥均可显著提高土壤脲酶、硝酸还原酶活性,芝麻饼肥对蛋白酶、蔗糖酶活性有显著的提升作用;相较不施有机肥处理,添加不同有机肥的土壤细菌多样性明显提升。优势菌门为变形菌门、酸杆菌门、拟杆菌门、浮霉菌门,优势菌属为Sphingomonas、RB41,Sphingomonas在不施有机肥处理中最高,RB41在生物质炭有机肥处理中最高。Sphingomonas与蔗糖酶活性呈正相关关系,与脲酶、硝酸还原酶均呈负相关关系;PCA分析显示,生物质炭有机肥处理的细菌群落结构与其他处理相比差异较大。施用芝麻饼肥有利于促进早期氮素矿化,提高矿化量,而生物质炭有机肥后期矿化量较...     

生物质炭对旱作土壤生物性状及养分有效性的调控效应

通过盆栽试验研究了生物质炭施用对贵州中部地区旱作土壤微生物群落数量、酶活性和土壤养分有效性的影响。结果表明:对不同类型旱作土施用5%～15%(炭/土质量比)的生物质炭后,黄泥土、黄砂土中真菌、放线菌、细菌数量和硝化细菌、氨化细菌数量以及磷酸酶、过氧化氢酶、脲酶活性均表现出明显的增加,特别是黄砂土;而大泥土中放线菌、真菌数量和硝化细菌数量以及磷酸酶和过氧化氢酶活性出现较明显的提高,但氨化细菌数量及脲酶活性出现大幅度降低。此外,黄泥土、黄砂土施生物质炭后有效N、P、K、Ca、Mg、B含量表现出不同程度的增加,但土壤有效Fe、Mn、Cu、Zn含量则出现不同程度的下降;而大泥土中有效P、K、Fe、Mn、Cu、B的含量呈现不同程度的提高,但土壤有效N、Ca、Mg、Zn的含量出现不同程度的减少;其中这3类旱作土壤施炭后土壤有效Zn含量均表现出显著的下降。黄泥土、黄砂土及大泥土施用5%～15%的生物质炭后均能明显提高白菜及莴笋的产量,其中黄砂土施生物质炭的增产效果最好,其次是大泥土。不同类型旱作土壤施炭后土壤有效性养分数量变化存在较大的差别,施用生物质炭时要根据土壤特性配合使用一定比例的氮、磷、钾及适量的微量元素肥料,更有利于促进作物的生长。     

Nationally Coordinated Evaluation of Soil Nitrogen Mineralization Rate using a Standardized Aerobic Incubation Protocol

Abstract

Aerobic incubation methods have been widely used to assess soil nitrogen (N) mineralization, but standardized protocols are lacking. A single silt loam soil (Catlin silt loam; fine‐silty, mixed, superactive, mesic, Oxyaquic Arguidoll) was subjected to aerobic incubation at six USDA‐ARS locations using a standardized protocol. Incubations were conducted at multiple temperatures, which were combined based on degree days (DD). Soil water was maintained at 60% water‐filled pore space (WFPS; constant) or allowed to fluctuate between 60 and 30% WFPS (cycle). Soil subsamples were removed periodically and extracted in 2 M potassium chloride (KCl); nitrate (NO₃) and ammonium (NH₄) concentrations in extracts were determined colorimetrically. For each location, the rate of soil organic‐matter N (SOMN) mineralization was estimated by regressing soil inorganic N (N_i) concentration on DD, using a linear (zero‐order) model. When all data were included, the mineralization rate from four datasets was not statistically different, with a rate equivalent to 0.5 mg N kg^?1 soil day^?1. Soil incubated at two locations exhibited significantly higher SOMN mineralization rates. To assess whether this may have been due to pre‐incubation conditions, time‐zero data were excluded and regression analysis was conducted again. Using this data subset, SOMN mineralization from five (of six) datasets was not significantly different. Fluctuating soil water reduced N‐mineralization rate at two (of four) locations by an average of 50%; fluctuating soil water content also substantially increased variability. This composite dataset demonstrates that standardization of aerobic incubation methodology is possible.     

Nitrogen‐uptake by plants following soil incubation

Abstract

Many methods of evaluating organic soil nitrogen (N) mineralization and N availability indexes have been proposed. Chemical methods are more rapid but they do not measure the soil microorganisms and plant root activities. Incubation‐leaching procedure may remove some of the readily mineralizable soil organic N compounds. Continuous‐incubation procedure may sometimes increase soil acidity or cause toxins accumulation. The objective of this study was to determine, in a greenhouse experiment, the relative capabilities of 10 soils with organic matter (O.M.) content ranging from 2.38 to 8.63% to supply plant‐available N by combining two procedures, i.e., soil incubation and plant N‐uptake. In method one (M₁), N‐uptake by 3 successive oat crops of 8 weeks each, without soil preincubation was studied. Method two (M₂) involved a soil preincubation of 8 weeks, and the subsequent determination of N‐uptake by two successive crops of oats (Avena sativa L.) of 8 weeks each. No soil‐leaching was used. The results show that there was a large difference in plant N‐uptake according to soil organic matter. The highest correlation between soil O.M. and plant N‐uptake (r = 0.91**) was given by the first crop following incubation. The N‐uptake by the first crop in M₁ (without soil incubation) was much less correlated with soil O.M. (r = 0.74*) and was significantly influenced by soil initial NO₃ and NH₄‐N. The results of this study show that the preincubation of soil samples minimized the influence of soil initial mineral N and that a preincubation was necessary before the plant N‐uptake measurement, even on a 8‐week cropped soil period.     

有机肥对酸性稻田土壤Cd赋存形态的影响途径和机制

以堆肥后的菜籽饼为有机肥,通过水稻田间试验,研究了有机肥对土壤有机质(OM)、pH、微生物量碳、氮(MBC、MBN)、3种酶活性(酸性磷酸酶,ACP、脲酶,UA、脱氢酶,DH)及土壤Cd的赋存形态的影响,利用通径分析研究了有机肥对土壤Cd赋存形态的影响途径和机制。结果表明:(1)施用有机肥能显著提高土壤OM含量和土壤pH,显著增加土壤中可还原态Cd(Red-Cd)和可氧化态Cd(Oxi-Cd)含量,降低土壤酸可提取态Cd(Aci-Cd)含量。(2)施用有机肥能不同程度增加土壤ACP、UA及DH活性,提高土壤MBC和MBN含量。(3)通径分析结果表明,施用有机肥降低土壤Aci-Cd含量主要是通过提高土壤OM含量、DH活性和MBC含量这3个途径完成。土壤OM含量、土壤DH活性和MBC含量的决策系数分别为0.846,0.257,-0.276,均达到显著水平,是有机肥施用下影响土壤Aci-Cd含量的主控因子。     

Effect of different types of organic fertilizers on the chemical properties and enzymatic activities of an Oxisol under intensive cultivation of vegetables for 4 years

The effects of different types of organic fertilizers on the chemical and enzymatic properties of an Oxisol were studied after being fertilized for four consecutive years (26 crops) in a greenhouse under intensive cultivation of vegetables. Seven treatments, consisting of five types of organic fertilizer treatments, one "sequential application" (SA) treatment, and a chemical fertilizer treated plot were compared. The organic fertilizers used were dairy cattle dung compost (DCDC), hog dung compost (HDC), chicken dung compost (CDC), pea residue compost (PRC) and soybean meal (SBM). After 4 years of cultivation, the soils were analyzed for their chemical properties and enzymatic activities. The microbial carbon (C) and nitrogen (N), basal respiration and nitrification rate were also measured. The results showed that the SBM significantly lowered the soil pH, and that the HDC and DCDC raised the soil pH. The SBM and CDC resulted in the lowest soil electrical conductivity. The SBM had no significant effect on soil organic C and total N contents when compared with the CF plot. However, the DCDC resulted in the highest contents of soil organic C and total N. The organic fertilizers applied did not significantly affect the soil available copper, zinc, cadmium, lead and nickel. The effects of the different organic fertilizers on soil enzymatic activities depended on the types of organic fertilizers applied. The SBM and CDC often resulted in a lower microbial C (or N) and respiration rate, while in contrast DCDC and PRC resulted in high measurements. Most of the measured soil enzymatic activities in the SBM treatment, except for acid phosphatase, were the lowest. Differing contents of different heavy metals in the organic fertilizers resulted in different Mehlich III extractable heavy metal contents in the soils. From the point of view of the soil chemical and enzymatic properties, SBM is not an appropriate organic fertilizer for continuous application to an Oxisol.     

冰雪灾害后林窗对杉木林土壤性质的影响

During January–February 2008, a severe ice storm caused significant damages to forests in southern China, creating canopy gaps and changing soil nutrient availability and enzyme activity. To understand the relationships between gap size, changes in the soil environment and the effects that these changes have on soil processes, we investigated the effects of gap size on soil chemical and biological properties in the forest gaps in a Cunninghamia lanceolata stand in northern Guangdong Province, southern China. Ten naturally created gaps, five large(80–100 m~2) and five small(30–40 m~2), were selected in the stand of C.lanceolata. The large gaps showed a significant increase in light transmission ratio and air and soil temperatures and a decline in soil moisture, organic matter,N and P compared with the small gaps and the adjacent canopy-covered plots in the 0–10 cm soil. The differences in organic matter and nutrient levels found between the large and small gaps and the canopy-covered plots may be related to changes in environmental conditions. This indicated rapid litter decomposition and increased nutrient leaching in the large gaps. Moreover, the lowest levels of catalase, acid phosphatase and urease activities occurred in large gaps because of the decline in their soil fertility. Large forest gaps may have a region of poor fertility, reducing soil nutrient availability and enzyme activity within the C.lanceolata stand.     

柳枝稷生物炭对来自不同地区的两种土壤上植物生物量和微生物动态的影响

Biochar amendments to soils may alter soil function and fertility in various ways, including through induced changes in the microbial community. We assessed microbial activity and community composition of two distinct clayey soil types, an Aridisol from Colorado (CO) in the U.S. Central Great Plains, and an Alfisol from Virginia (VA) in the southeastern US following the application of switchgrass (Panicum virgatum) biochar. The switchgrass biochar was applied at four levels, 0%, 2.5%, 5%, and 10%, approximately equivalent to biochar additions of 0, 25, 50, and 100 t ha^-1, respectively, to the soils grown with wheat (Triticum aestivum) in an eight-week growth chamber experiment. We measured wheat shoot biomass and nitrogen (N) content and soil nutrient availability and N mineralization rates, and characterized the microbial fatty acid methyl ester (FAME) profiles of the soils. Net N mineralization rates decreased in both soils in proportion to an increase in biochar levels, but the effect was more marked in the VA soil, where net N mineralization decreased from -2.1 to -38.4 mg kg^-1. The 10% biochar addition increased soil pH, electrical conductivity, Mehlich- and bicarbonate-extractable phosphorus (P), and extractable potassium (K) in both soil types. The wheat shoot biomass decreased from 17.7 to 9.1 g with incremental additions of biochar in the CO soil, but no difference was noted in plants grown in the VA soil. The FAME recovery assay indicated that the switchgrass biochar addition could introduce artifacts in analysis, so the results needed to be interpreted with caution. Non-corrected total FAME concentrations indicated a decline by 45% and 34% with 10% biochar addition in the CO and VA soils, respectively, though these differences became nonsignificant when the extraction efficiency correction factor was applied. A significant decline in the fungi:bacteria ratio was still evident upon correction in the CO soil with biochar. Switchgrass biochar had the potential to cause short-term negative impacts on plant biomass and alter soil microbial community structure unless measures were taken to add supplemental N and labile carbon (C).     

配施不同有机物料对玉米养分积累及土壤微生物特征的影响

目的探究化肥配施不同有机物料对玉米养分积累与土壤酶活性及微生物特征的影响,为维护土壤微生物生态系统和农业可持续发展提供养分管理技术支撑。方法田间定位试验连续两年在黑龙江大庆进行,试验包括1个单施化肥对照(CK)和3个化肥配施有机物料(腐熟秸秆、腐植酸、鸡粪)处理。在玉米收获期,采样测定玉米地上部养分积累、土壤酶活性和土壤细菌与真菌微生物多样性。结果与CK相比,配施有机物料处理提高了玉米地上部氮、磷的积累量。腐熟秸秆处理的细菌和真菌群落结构与其他3个处理差异显著。与单施化肥对照相比,施用鸡粪和腐熟秸秆显著增加了土壤中差异细菌的数量,降低了差异真菌的数量,腐植酸处理降低了差异细菌和真菌的数量。所有处理中,细菌特有的差异微生物种类数量均高于真菌,相对丰度>5%的4个细菌门分别为变形菌门(Proteobacteria)、酸性菌门(Acidobacteriota)、芽单胞菌门(Gemmatimonadota)和放线菌门(Actinobacteriota),3个细菌科分别为鞘脂单胞菌科(Sphingomonadaceae)、芽单胞菌科(Gemmatimonadaceae)和维近单胞菌科(Vicinamibacteraceae),1个细菌属为鞘脂单胞菌属(Sphingomonas);相对丰度>5%的3个真菌门分别为子囊菌门(Ascomycota)、担子菌门(Basidiomycota)和被孢霉门(Mortierellomycota),1个真菌科为毛壳菌科(Chaetomiaceae),1个真菌属为柄孢壳菌属(Podospora)。除腐植酸处理提高了土壤蔗糖酶活性,腐熟秸秆和腐植酸处理提高了过氧化氢酶活性外,其他有机物料处理的酶活性相较于CK没有显著变化。相关性分析表明,细菌中酸性菌门的相对丰度与土壤过氧化氢酶活性呈负相关(P<0.05),放线菌门的相对丰度与磷酸酶活性呈正相关(P<0.01);真菌中担子菌门的相对丰度与玉米植株氮、钾积累呈负相关(P<0.05);被孢霉门的相对丰度与玉米植株钾积累呈正相关(P<0.05)。结论在化肥基础上配施不同有机物料显著增加了玉米地上部的氮、磷养分积累量,提高了玉米产量。腐熟秸秆与化肥配施显著改变了土壤真菌和细菌的组成,施用鸡粪和腐熟秸秆增加了土壤中差异细菌的数量。酶活性与土壤微生物群落组成密切相关,尤其是细菌和真菌属水平上的Sphingomonas和Podospora,并且玉米植株氮、磷积累均与土壤蔗糖酶活性呈显著正相关关系。