施用生物炭6年后对稻田土壤酶活性及肥力的影响

利用田间定位试验,研究0(BC₀)、7.5(BC₁)、15(BC₂)和22.5(BC₃)t·hm^-2水稻秸秆生物炭及3.75 t·hm^-2水稻秸秆(STR)一次性施加6年后对稻田土壤肥力及酶活性的影响.结果表明: 施用生物炭6年后土壤有机碳、有效磷和速效钾含量显著增加,增幅分别为34.6%、12.4%和26.2%,土壤pH值和容重显著降低,但对土壤全氮含量无显著影响.土壤脲酶和酸性磷酸酶的活性显著增加,土壤荧光素二乙酸酯酶(FDA水解酶)和芳基硫酸酯酶的活性受到不同程度的抑制,其中,BC₂处理的土壤脲酶活性增加量最大,增幅为36.5%.土壤酸性磷酸酶活性随着生物炭施加量的增加而增加,与土壤速效磷含量呈显著正相关关系;土壤FDA水解酶和脲酶主要与土壤速效钾含量有关;酸性磷酸酶和芳基硫酸酯酶与土壤容重呈显著正相关.施用生物炭6年后土壤脱氢酶和多酚氧化酶活性明显升高,增幅分别为48.8%和27.5%,而过氧化氢酶活性逐渐下降,且显著低于对照BC₀.STR处理显著增加了土壤脲酶、FDA水解酶、脱氢酶、酸性磷酸酶和芳基硫酸酯酶的活性,降低了过氧化氢酶和多酚氧化酶的活性,降幅分别为23.4%和15.9%.     

New approaches to establish optimum moisture content for compostable materials

This paper reports on the persistence of total and immobilised enzyme activities (urease and phosphatase) in a soil amended with organic wastes containing high levels of total-urease and phosphatase activity. Fresh organic materials showed the highest values for both total-enzymatic activities. The addition of organic waste to soil increased both total-enzymatic activities in the soil, which, after 360 days, showed values above those of the control. Immobilised enzymes were also higher in the fresh wastes than in the soil with compost, while the specific enzymatic activity levels (enzymatic activity per unit of carbon) were similar. The immobilised urease activity was greater in the amended soil than in the control. At the beginning of the incubation period, the immobilised urease activity was significantly higher in the soil amended with fresh organic wastes than with compost. However, this activity decreased with incubation, whilst the compost-immobilised urease activity increased with time. The effect of organic amendment on immobilised phosphatase activity was similar to that shown by immobilised urease but less pronounced. The persistence of both enzymes was significantly higher in the soil amended with compost than in that amended with fresh materials.     

铜川煤矿区重金属污染对土壤微生物群落代谢和酶活性的影响

研究了陕西省铜川煤矿矿区的重金属污染状况以及不同程度的重金属污染对土壤微生物代谢、微生物群落功能以及土壤酶活性的影响.结果表明： 铜川矿区土壤中重金属Cu、Zn、Cd、Pb全量及有效量均显著高于非矿区土壤,其中Cd污染最为严重.采用Biolog方法结合主成分分析和聚类分析发现,随着污染程度的增加,不同土壤微生物群落间的代谢特征发生显著变化,而且这种变化主要体现在糖类和氨基酸类碳源的利用差异.在轻度、中度污染情况下,土壤微生物群落对碳源的利用表现出激活效应;而在重度污染的情况下,土壤微生物群落对碳源的利用表现出抑制效应.随着污染程度的增加,脲酶、蛋白酶、碱性磷酸酶和过氧化氢酶的活性均呈现降低的趋势,矿区土壤脲酶、蛋白酶、碱性磷酸酶和过氧化氢酶活性分别是非矿区土壤中相应酶活性的50.5%～65.1%、19.1%～57.1%、87.2%～97.5%、77.3%～86.0%;蔗糖酶和纤维素酶在中等污染程度以下的土壤中表现为激活效应,而在重度污染的土壤中表现为抑制效应.     

种植转Bt基因水稻对土壤酶活性的影响

转Bt基因及非Bt基因水稻的盆栽试验研究表明,转Bt基因水稻在生长发育过程中可以向土壤中释放杀虫晶体蛋白,而且杀虫晶体蛋白的释放量与水稻生长发育时间有关;与非Bt基因水稻相比,转Bt基因水稻生长15d时,土壤脲酶活性显著下降(降幅为2．47％),土壤酸性磷酸酶活性显著升高(增幅为8．91％),而土壤芳基硫酸酯酶、蔗糖酶和脱氢酶活性的变化差异不显著;生长30d时,土壤脲酶活性仍显著下降(降幅为16．36％),土壤酸性磷酸酶、芳基硫酸酯酶和脱氢酶活性显著升高(增幅分别为35．69％,19．70％和16．83％),而土壤蔗糖酶活性变化差异仍不显著。     

Application of a green manure and green manure composted with beet vinasse on soil restoration: effects on soil properties

Beet vinasse (BV), a green manure constituted by Trifolium pratense L. uncomposted (TP) and composted with beet vinasse (at 1:1 rate, (TP+BV)1, and 2:1 rate, (TP+BV)2) at 10t organic matter ha(-1) rate were applied during a period of four years for purpose of restoration of a Xelloric Calciorthid located near Seville (Guadalquivir Valley, Andalusia, Spain). The effect on the plant cover, soil physical (structural stability and bulk density), chemical (exchangeable sodium percentage), and biological properties (microbial biomass, soil respiration and enzymatic activities such as dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase) were determined. The application of BV had a detrimental impact on soil physical (structural stability decreased 16.5% and bulk density increased 18.7% respect to the control soil), chemical (exchangeable sodium percentage increased 87.3% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities decreased by 53.5%, 24.5%, 27.8%, 15%, 39.7%, 42.7%, and 65.6%, respectively with respect to the control soil), probably because high quantities of monovalent cations (Na principally) were introduced into the soil by the vinasse, thus destabilizing its structure. The application of TP had a positive impact on soil physical (structural stability increased 5.9% and bulk density decreased 6.1% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased by 66.3%, 45.6%, 97.7%, 98.9%, 97.7%, 87.2%, and 89.4%, respectively with respect to the control soil). However, when BV was co-composted with a green manure, principally at a 2:1 rate, the resulting compost had a positive effect on soil physical (structural stability increased 10.5% and bulk density decreased 13.5% respect to the control soil), and biological properties (microbial biomass, soil respiration, and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased by 68.9%, 46.2%, 97.5%, 98.4%, 99.1%, 90.5% and 91.6%, respectively with respect to the control soil). After four years, the percentage of plant cover decreased 64.3% in the BV-amended plots respect to the control soil, whereas increased 82.8%, 81.6% and 81% in the (TP+BV)2, (TP+BV)1 and TP treatments, respectively. While the application of BV deteriorates the soil and therefore does not contribute to its restoration, the application of TP, and BV composted with TP protects the soil and will contribute to its restoration.     

Effects of different green manures on soil biological properties and maize yield

The utilization of green manures as alternatives to reduce the use of mineral fertilizers is considered a good agricultural practice. However, the effect of each green manure on soil properties and crop yield depends upon its chemical composition. The main objective of this work was to study the effect of incorporating three green manures originating from residues of Trifolium pratense, L. (TP), Brassica napus, L. (BN), and the mixture of TP+BN at rates of 5384 and 8973 kg C ha(-1), on soil biological properties (soil microbial biomass-C, soil respiration and soil enzymatic activities), nutrition (leaf N, P and K concentration, pigments and soluble carbohydrate concentrations) and yield parameters of maize (Zea mays cv. Tundra) crop for four years on an Typic Xerofluvent located near Sevilla (Guadalquivir Valley, Andalusia, Spain). All green manures had a positive effect on the soil biological properties, plant nutrition an crop yield parameters, although at the end of the experimental period and at the high organic matter rate, the soil microbial biomass and dehydrogenase, urease, beta-glucosidase, phosphatase and arylsulfatase activities increased more significantly in the TP amended soils (79.2%, 92.1%, 93.9%, 99.3%, 87.9% and 96%, respectively) respect to the control soil, followed by TP+BN amended soils (77.3%, 90.9%, 92.8%, 99.1%, 84.4% and 95.7%, respectively) and BN amended soils (76%, 90.1%, 91.7%, 99%, 83.2% and 95.2%, respectively). Since these soil enzymatic activities measured are responsible for important cycles such as C, N, P and S, an increase of leaf N, P an K contents and pigments and soluble carbohydrate contents were highest in TP amended soils, followed by TP+BN and BN treatments. The application of TP in soils at high doses increased the grain protein concentration, number of grains corncob(-1) and crop yield 44.6%, 6.3% and 22.1%, respectively, compared with the control soil, followed by TP+BN treatment (41.7%, 5.7% and 20.8%, respectively) and BN treatment (39%, 5.3% and 20%, respectively). The explanation of these results can be a consequence to the different chemical composition of the green manures applied to the soils and its mineralization, aspect controlled by the soil C/N ratio.     

镉、汞复合污染对土壤脲酶和酸性磷酸酶活性的影响

通过土壤培养试验, 研究了重金属镉（Cd）、汞（Hg）复合污染对小粉土和黄红壤脲酶和酸性磷酸酶活性的影响.结果表明：整个培养过程中,Cd、Hg单一及复合污染都对两种土壤中脲酶和酸性磷酸酶的活性具有明显抑制作用,且随重金属浓度增强而增强（浓度≤1 mg·kg^-1Cd除外）.与单一Cd或Hg污染相比,同剂量Cd和Hg复合污染时两种酶活性的净变化量均大于0,表明Cd和Hg复合污染在两种土壤中对土壤脲酶和酸性磷酸酶活性的抑制作用均表现为一定的协同作用.所有处理黄红壤脲酶和酸性磷酸酶活性均高于小粉土,这可能与黄红壤有机质和粘粒含量相对较高有关.     

Biodegradation of waste-lubricating petroleum oil in a tropical alfisol as mediated by animal droppings

This study evaluated the applicability of some organic wastes from animal droppings as bioremediation alternative for soils spiked with waste-lubricating oil (spent oil). The total hydrocarbon contents (THC) with time of sampling were markedly reduced with addition of cow dung (CD), poultry manure (PM) and pig wastes (PW). The general trend in the first year indicated that PW stimulated the highest net percentage loss in THC for soils polluted with 5000 mg kg⁻¹ (0.5%SP) and 50,000 mg kg⁻¹ (5%SP) oil levels. Poultry manure induced the highest reduction in soils polluted with medium, i.e. 2.5%SP (25,000 mg kg⁻¹) oil concentration. The overall net loss mediated by each organic waste in the 2nd year showed that PM addition was better irrespective of total oil loading. For example, at 3 months PM led to 16.1% and 14.6% net reduction in THC for soils treated with 50,000 mg kg⁻¹ (5%) and 100,000 mg kg⁻¹ (10%) total oil loading, respectively; whereas at same period, the performance of the organic wastes were relatively similar in soils with 10,000 mg kg⁻¹ oil loading. At 6 and 12 months, PM reduced the oil levels better than CD and PW. Further evaluation by first-order kinetic model which utilized combine data for the entire periods for each year indicated that PW was better at low oil pollution level, while PM performed better at high oil pollution levels. Overall, the differential performance of these organic amendments followed PM > PW > CD.     

秸秆和生草覆盖对桃园土壤养分含量、微生物数量及土壤酶活性的影响

以秸秆(覆盖重量分别为小麦(Triticum aestivum)秸3.25 kg·m^-2、玉米(Zea mays)秸1.97 kg·m^-2、禾本科杂草3.67 kg·m^-2)和生草(白三叶草(Trifolium repens)、高羊茅(Festuca arundincea)和紫花苜蓿(Medicago sativa), 播种量均为50 kg·hm^-2)为覆盖材料, 以不覆盖为对照, 研究了不同覆盖材料对桃园土壤微生物数量和酶活性的影响, 及其与土壤养分的关系。结果表明, 与对照相比, 除覆盖生草根际和非根际土壤全磷和速效磷含量差异均不显著外, 其他处理根际和非根际土壤碱解氮、速效钾、全氮、全钾和有机质含量差异均达到显著水平; 所有处理根际和非根际土壤氨化细菌、真菌和放线菌数量、土壤含水率和pH值、土壤脲酶和磷酸酶活性差异均达到显著水平。白三叶草处理的根际和非根际土壤碱解氮、速效钾、全氮、全钾、有机质含量, 土壤氨化细菌和真菌数量, 土壤脲酶和磷酸酶活性的平均升幅均最高, 分别为99%、270%、267%、117%、272%、158%、141%、156%和64%。氨化细菌、真菌、放线菌、脲酶和磷酸酶分别与土壤碱解氮、速效钾(放线菌和磷酸酶除外)、全氮、全钾和有机质呈显著或极显著的正相关。通径分析表明, 在3种土壤微生物和2种酶对养分含量的影响中, 脲酶是影响土壤碱解氮、速效钾、全氮、全钾和有机质的主要因子。     

土壤微生物生物量氮对不同腐熟度有机肥的响应及对土壤矿质氮的调控作用

为探究化肥配施不同腐熟度有机肥对土壤微生物生物量氮(MBN)的影响及土壤MBN调控土壤矿质氮的作用,将堆肥过程与土壤培养试验相结合,设置常规化肥对照(CK)、化肥+腐熟度为50%(种子发芽指数为50%,下同)的有机肥(CO1)、化肥+腐熟度为80%的有机肥(CO2)、化肥+腐熟度为100%的有机肥(CO3)共4个处理,测定土壤MBN、矿质氮(NH₄⁺-N、NO₃^--N)、净硝化速率、微生物生物量碳(MBC)、可溶性有机碳(DOC)、脲酶和蛋白酶,并揭示土壤MBN对矿质氮的调控作用。结果表明: 到培养结束时,与CK处理相比,有机肥处理(CO1、CO2、CO3)的土壤MBN、NH₄⁺-N含量显著提高50.1%～62.4%、109.9%～147.1%,土壤NO₃^--N、净硝化速率显著降低23.3%～46.8%、26.2%～51.5%,土壤MBC、DOC含量、脲酶和蛋白酶活性分别显著提高33.8%～69.6%、7.4%～20.8%、11.2%～69.0%、9.4%～25.1%,且CO2、CO3的变化幅度均显著高于CO1。冗余分析和结构方程模型显示,较高腐熟度有机肥(腐熟度≥80%)对MBC、MBN、NH₄⁺-N含量、脲酶和蛋白酶活性具有正向调控作用,对土壤净硝化速率具有负向调控作用。化肥配施较高腐熟度有机肥可以明显增加土壤MBN,提升脲酶、蛋白酶活性,增加NH₄⁺-N含量,降低土壤净硝化速率。因此,在实际应用中,建议采用腐熟度为80%的有机肥与化肥配施,减少有机肥生产成本及时间,实现有机固体废弃物的资源化利用。     

Variations in soil culturable bacteria communities and biochemical characteristics in the Dongkemadi glacier forefield along a chronosequence

The variations in the soil culturable bacterial communities and biochemical parameters of early successional soils from a receding glacier in the Tanggula Mountain were investigated. We examined low organic carbon (C) and nitrogen (N) contents and enzymatic activity, correlated with fewer bacterial groups and numbers in the glacier forefield soils. The soil pH values decreased, but the soil water content, organic C and total N significantly increased, along the chronosequence. The soil C/N ratio decreased in the early development soils and increased in the late development soils and it did not correlate with the soil age since deglaciation. The activities of soil urease, sucrase, protease, polyphenol oxidase, catalase, and dehydrogenase increased along the chronosequence. The numbers of culturable bacteria in the soils increased as cultured at 25°C while decreased at 4°C from younger soils to older soils. Total numbers of culturable bacteria in the soils cultured at 25°C were significantly positively correlated to the soil total N, organic C, and soil water content, as well as the activities of soil urease, sucrase, dehydrogenase, catalase, and polyphenol oxidase. We have obtained 224 isolates from the glacier forefield soils. The isolates were clustered into 28 groups by amplified ribosomal DNA restriction analysis (ARDRA). Among them, 27 groups and 25 groups were obtained from the soils at 25°C and at 4°C incubation temperatures, respectively. These groups are affiliated with 18 genera that belong to six taxa, viz, Actinobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, Alphaproteobacteria, and Betaproteobacteria. The dominant taxa were Actinobacteria, Gammaproteobacteria, and Bacteroidetes in all the samples. The abundance and the diversity of the genera isolated at 25°C incubation temperature were greater than that at 4°C.     

马尾松人工林土壤有机层和矿质土壤层酶活性随雨旱季的变化

土壤酶活性随雨旱季的变化特征对于深入理解人工林土壤物质循环具有重要意义。2014年6月至2017年4月,采用原位土柱培养方法,研究了长江上游低山丘陵区的马尾松人工林土壤有机层和矿质土壤层转化酶、脲酶和酸性磷酸酶活性随关键时期（雨季初期;雨季中期;雨季末期;旱季初期;旱季末期）的变化特征。结果表明：土壤有机层和矿质土壤层酶活性随关键时期的变化显著,总体表现为雨季高于旱季。土壤有机层转化酶和脲酶活性呈现逐年降低的趋势;矿质土壤层酸性磷酸酶活性呈现逐年增加的趋势。土壤有机层转化酶和酸性磷酸酶活性显著高于矿质土壤层。土壤有机层三种酶活性年际变化幅度及随关键时期的变化幅度均高于矿质土壤层。偏最小二乘分析（PLS）表明,土壤含水量、微生物量和底物含量对土壤酶活性具有显著影响,但其影响大小强烈取决于土壤层次和酶的种类。可见,马尾松人工林土壤有机层酶活性对环境因子变化的响应更敏感,而且驱动土壤有机层和矿质土壤层酶活性动态的主导因子也存在差异。     

新型磷酰胺类脲酶抑制剂对不同质地土壤尿素转化的影响

施用脲酶抑制剂是降低尿素水解、减少氨气挥发损失、提高作物氮(N)肥利用率的重要途径之一.采用室内恒温、恒湿模拟试验方法,在25 ℃黑暗条件下培养,研究新型磷酰胺类脲酶抑制剂N-丙基磷酰三胺(NPPT)的脲酶抑制效果,比较其与N-丁基磷酰三胺(NBPT)在不同尿素用量条件下不同质地土壤中对脲酶的抑制差异.结果表明: 在壤土和黏土中,尿素作用时间≤9 d,添加抑制剂可以将尿素水解时间延长3 d以上.砂土中,尿素分解过程相对缓慢,添加抑制剂显著降低土壤脲酶活性,抑制NH₄⁺-N生成.在培养期间,不同尿素用量条件下,脲酶抑制剂在不同质地土壤中的抑制效果表现为高施N量优于低施N量.培养第6天,在尿素用量250 mg N·kg^-1条件下,NBPT和NPPT在砂土中脲酶抑制率分别为56.3%和53.0%,在壤土中分别为0.04%和0.3%,在黏土中分别为4.1%和6.2%;尿素用量500 mg N·kg^-1,NBPT和NPPT在砂土中脲酶抑制率分别为59.4%和65.8%,在壤土中分别为14.5%和15.1%,在黏土中分别为49.1%和48.1%.不同质地土壤中脲酶抑制效果表现为砂土>黏土>壤土.不同抑制剂处理在培养期间土壤NH₄⁺-N含量呈现先上升后下降的趋势,而NO₃^--N含量和表观硝化率均呈现逐渐上升的趋势.与单施尿素处理相比,添加脲酶抑制剂NBPT和NPPT显著增加土壤中的残留尿素态N,降低NH₄⁺-N生成.新型脲酶抑制剂NPPT在不同质地土壤中的抑制效果与NBPT相似,是一款有效的脲酶抑制剂.     

Microbiological indicators of soil quality and degradation following conversion of native forests to continuous croplands

Deforestation resulting from forest conversion to agricultural land use is an important issue worldwide. This phenomenon is known to influence the activity and size of soil microbial community due to changes in environmental conditions with subsequent losses of soil organic matter (SOM) and soil quality degradation. The objective of this study was to investigate the relationship between soil organic carbon (SOC) losses and enzyme activities following land use conversion from native forests to continuous croplands. The amount of soil microbial biomass carbon (SMBC) and the activity of five soil enzymes (i.e., urease, invertase, alkaline phosphatase, acid phosphatase and arylsulfatase) were measured in croplands derived from forests and adjacent natural forests all on similar soil type at Gorgan site located in Northeast Iran. The content of SMBC decreased (47–83%) with deforestation at both soil sampling depths (0–20 and 20–40 cm). With the exception of phosphatases, the absolute activities of soil enzymes (activity on a soil mass basis) tended to decrease significantly (15–35%) with continuous cultivation. However, the specific enzyme activities expressed either per unit of SOC or SMBC tended to increase (about 1.5–5.5 times) with conversion of forestlands to croplands. The significant positive correlation between enzyme activity per SMBC and C turnover rate may imply that a faster C cycle and loss due to deforestation is related to a greater enzymatic activity by a smaller size of microbial biomass in cropland soils. In brief, the specific activities of soil enzymes could be used to reveal SOM losses and soil degradation in natural forest ecosystems, and to identify changes in soil quality and fertility following deforestation. Changes or improvements in soil management such as cessation of cultivation or implementing agricultural practices that stop or minimize soil disturbance are most likely needed to stop further soil degradation, restore soil quality and rebuild SOC stocks to offset CO₂ emissions in these ecosystems.     

施用生物有机肥对黄瓜连作土壤有机碳库和酶活性的持续影响

采用田间定位试验和室内培养试验相结合的方法,研究了一次性施用生物有机肥对黄瓜连作土壤有机碳组分、有机碳矿化和酶活性的持续效应.结果表明: 连续种植4季黄瓜过程中,与对照处理(CK)相比,施用生物有机肥可明显增加黄瓜连作土壤总有机碳、活性碳库、缓效碳库和惰性碳库的有机碳含量,且随着黄瓜连作季数的增加,土壤惰性碳库比例逐渐增加;连续种植4季黄瓜后,施用生物有机肥处理中土壤有机碳累计矿化量和日均矿化量与CK相比分别增加了17.3%～31.0%和7.8%～43.0%,且在同一季黄瓜成熟期,施用生物有机肥还能提高黄瓜连作的土壤脲酶、过氧化氢酶、蔗糖酶和磷酸酶(中性)的活性,增幅分别为10.5%～62.1%、4.8%～25.5%、3.9%～21.4%和4.6%～66.4%.相关分析和通径分析结果表明,黄瓜连作过程中4种酶的活性与土壤有机碳各组分动态变化均呈显著相关,且黄瓜连作过程中土壤脲酶和蔗糖酶活性是影响有机碳矿化的主要生物酶.施用生物有机肥可提高黄瓜连作过程中土壤有机碳各组分含量和酶活性,增加土壤惰性碳库比例、有机碳累计矿化量和矿化速率,从而增强土壤固碳能力.     

Influence of olive oil solid waste applications on soil pH, electrical conductivity, soil nitrogen transformations, carbon content and aggregate stability

Some of the agricultural wastes have important economic potentials to be used as a plant nutrition and/or soil conditioner. Olive oil solid waste (OSW) is one of them. The aim of this study was to determine effects of OSW on soil pH, electrical conductivity (EC), improving soil nitrogen (N) status, soil aggregate stability and soil carbon contents. Different rates of OSW (control, 2%, 4% and 8%, w/w) were applied to coarse soils and incubated for 2 months. OSW applications decreased soil pH values. The mean EC value of soil measured 2 months after the incubation was greater than that of the first month. Application of OSW at the rate of 8% has significantly increased soil total organic nitrogen contents. OSW applications at the rate of 8% (w/w) significantly increased both mean SOC content (3.5%) and aggregate stability (88%) after 2 months of incubation (p<0.01). Therefore, OSW has great potential to improve soil structure of coarse textured soil in short term.     

Effect of water deficit on microbial characteristics in soil amended with sewage sludge or inorganic fertilizer under laboratory conditions

The potential impact of different types of organic (sewage sludge) or inorganic (mineral fertilizer) amendments to a basic soil was investigated under dry conditions. A soil incubation experiment was carried out over 64 days; there were two fertility treatments: sewage sludge (SS) (140 t ha(-1)), mineral fertilizer (M) and an unamended control (C). Two levels of irrigation were imposed: (1) well-watered, kept at 60% of its water holding capacity, and (2) water-deficit at 6%. Available N-NO3-, N-NH4+ and P, and electrical conductivity (EC) increased in SS and M-treated soils. Under well-watered conditions activities of some enzymes (protease-BAA, phosphatase and beta-glucosidase), and microbiological properties (microbial biomass carbon, basal respiration and dehydrogenase activity) were stimulated in SS-treated soils. Under water-deficit conditions, protease-BAA, phosphatase and beta-glucosidase activities, and basal respiration were more reduced in SS than in C and M. Results showed that under severe dry conditions, soil microbial activity always remained higher in organic amended soils than when mineral fertilizer was added.     

砷对土壤脲酶活性影响的研究

采用模拟方法对As污染土壤脲酶特征进行了研究．结果表明,土壤中As浓度在0～200mg·kg^-1浓度范围内,反应初期脲酶活性变化无明显规律;一年后砷激活土壤脲酶活性,二者达到显著或极显著正相关．随As浓度增加,土壤脲酶Km值基本不变或略有增加,Vmax增大,从机制上揭示出As加速脲酶-尿素复合物的解离．厩肥和无肥土样脲酶对As的反应类似,只是变化幅度有所差异．     

Municipal solid waste compost amendment in agricultural soil: changes in soil microbial biomass

Agricultural application of Municipal Solid Waste (MSW), as nutrient source for plants and as soil conditioner, is the most cost-effective option of MSW management because of its advantages over traditional means such as landfilling or incineration. However, agricultural application of MSW can lead to a potential environmental threat due to the presence of pathogens and toxic pollutants. Composting is an attractive alternative of MSW recycling. Application of MSW compost (MSWC) in agricultural soils can directly alter soil physico-chemical properties as well as promote plant growth. The soil microbial biomass, considered as the living part of soil organic matter, is very closely related to the soil organic matter content in many arable agricultural soils. Numerous studies, with different MSWC amendment doses on different soil types and under different water regimes revealed no detrimental effect on soil microbial biomass. In this review, we show the state of art about the effects of MSWC amendment on soil microbial biomass.     

模拟氮沉降增加条件下土壤团聚体对酶活性的影响

氮沉降增加改变了森林土壤生态系统物质输入,影响土壤生物及酶活性,而土壤团聚体内相对稳定的微域生境可能减弱或延缓土壤生物和酶对氮沉降增加的响应强度。以广东省东莞大岭山森林公园荷木人工林为研究对象,用模拟N沉降方法,分析了2011年12月到2012年11月一年内氮沉降增加条件下表层混合土壤和土壤团聚体内脲酶、蔗糖酶和酸性磷酸酶活性的变化及影响因素,旨在理解氮沉降增加条件下土壤团聚体对酶活性的影响。结果表明:氮沉降增加对表层混合土壤中脲酶和蔗糖酶的抑制作用不显著,而酸性磷酸酶受氮沉降显著影响,表现为低氮(50 kg N hm-2a-1)促进,高氮(300 kg N hm-2a-1)抑制的规律。表层土壤团聚体内脲酶活性随氮沉降增加而降低,N300处理显著低于对照;蔗糖酶和酸性磷酸酶活性随氮沉降增加先降低后增加,N100处理最低,分别比其他处理降低了6.46%—25.53%和42.33%—68.25%。试验区内各粒径土壤团聚体内酶活性高于混合土壤,且随团聚体粒径增加酶活性均为先增加后降低。不同粒径土壤团聚体的3种酶活性均以2—5 mm最高,但脲酶、酸性磷酸酶在各团聚体粒径间差异不显著,蔗糖酶活性2—5 mm显著高于5—8 mm。土壤酶相对活性指数和相对活性综合指数结果显示,超过85%的团聚体粒径内的相对酶活性指数大于1,而土壤酶相对活性综合指数均大于1。以上结果表明,氮沉降增加条件下土壤团聚体对其团聚体内的土壤酶活性有隔离保护作用,但其隔离保护效果与酶的种类和土壤团聚体粒径有关。