Deadwood affects the soil organic matter fractions and enzyme activity of soils in altitude gradient of temperate forests

The main objective of our study has been to determine the role of deadwood in the shaping of the amount of soil organic matter fractions in mountain forest soils.For this purpose,a climosequence approach comprising north(N)and south(S)exposure along the altitudinal gradient(600,800,1000 and 1200 m a.s.l.)was set up.By comparing the properties of decomposing deadwood and those of the soils located directly beneath the decaying wood we drew conclusions about the role of deadwood in the shaping of soil organic matter fractions and soil carbon storage in different climate conditions.The basic properties,enzymatic activity and fractions of soil organic matter(SOM)were determined in deadwood and affected directly by the components released from decaying wood.Heavily decomposed deadwood impacts soil organic matter stabilization more strongly than the less decayed deadwood and the light fraction of SOM is more sensitive to deadwood effects than the heavy fraction regardless of the location in the altitude gradient.Increase in SOM mineral-associated fraction C content is more pronounced in soils under the influence of deadwood located in lower locations of warmer exposure.Nutrients released from decaying wood stimulate the enzymatic activity of soils that are within the range of deadwood influence.

Effects of continuous nitrogen addition on microbial properties and soil organic matter in a Larix gmelinii plantation in China

Continuous increases in anthropogenic nitrogen（N） deposition are likely to change soil microbial properties, and ultimately to affect soil carbon（C） storage.Temperate plantation forests play key roles in C sequestration, yet mechanisms underlying the influences of N deposition on soil organic matter accumulation are poorly understood. This study assessed the effect of N addition on soil microbial properties and soil organic matter distribution in a larch（Larix gmelinii） plantation. In a 9-year experiment in the plantation, N was applied at100 kg N ha-1 a-1 to study the effects on soil C and N mineralization, microbial biomass, enzyme activity, and C and N in soil organic matter density fractions, and organic matter chemistry. The results showed that N addition had no influence on C and N contents in whole soil. However,soil C in different fractions responded to N addition differently. Soil C in light fractions did not change with N addition, while soil C in heavy fractions increased significantly. These results suggested that more soil C in heavy fractions was stabilized in the N-treated soils. However,microbial biomass C and N and phenol oxidase activity decreased in the N-treated soils and thus soil C increased in heavy fractions. Although N addition reduced microbial biomass and phenol oxidase activity, it had little effect on soil C mineralization, hydrolytic enzyme activities, d13 C value in soil and C–H stretch, carboxylates and amides, and C–O stretch in soil organic matter chemistry measured by Fourier transform infrared spectra. We conclude that N addition（1） altered microbial biomass and activity without affecting soil C in light fractions and（2） resulted in an increase in soil C in heavy fractions and that this increase was controlled by phenol oxidase activity and soil N availability.

Changes in Soil Enzyme Activity and Nutrient Content in Different Years of Continuous Cropping Tobacco Fields

In order to find out changes in the main fertility indicators of continuous cropping tobacco fields in Henan Province with years of continuous cropping,5 typical tobacco fields( Jia County,Shaoling District,Fangcheng County,Xiangcheng County,and Song County) were studied. Indicators in question included activity of main enzymes( sucrase,urease,catalase,and acid phosphatase),p H value,organic matters,total nitrogen,available phosphorus and available potassium. The results indicate that in most tobacco fields,the activity of sucrase and urease increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping; in some fields,it directly declined with increase in years of continuous cropping; the activity of catalase increased in two years of continuous cropping,later,it showed a declining trend with increase in years of continuous cropping,and it became stable after three years of continuous cropping;generally,the activity of acid phosphatase declined with increase in the years of continuous cropping within 3 years continuous cropping,later,it became stable. Except Fangcheng County,the soil p H value of other districts( counties) generally declined with increase in years of continuous cropping,and it was in the range of 5. 6-6. 8. With the increase in continuous cropping,the soil organic matters( SOM) in tobacco fields of Jia County and Song County declined,changes of SOM in tobacco fields of Fangcheng County and Xiangcheng County were not obvious,and SOM showed the trend of first decline then rise in Shaoling District. In most tobacco fields( Jia County,Xiangcheng County,and Song County),the total nitrogen showed a declining trend; in Shaoling District,it showed a trend of first decline then rise; in Fangcheng County,it showed a rising trend. The available phosphorus firstly slightly declined then rose in tobacco fields of Shaoling District and Song County; it showed a trend of first rise then decline in Jia County; there were no obvious changes in Fangcheng County and Xiangcheng County. Changes in the available potassium were different in tobacco fields. In sum,there are certain rules for changes in soil enzyme activity and nutrient content in tobacco fields in Henan Province,but changes are not completely the same. It is concluded that the site conditions and farming activities exert a certain influence on soil enzyme activity,p H value,organic matters,and nitrogen,phosphorus and potassium content. Therefore,to solve obstacles in continuous cropping of tobacco fields,different regions should take different measures.

Effect of spot burning of logging residues on the properties of mountain forest soils and the occurrence of ground beetles(Coleoptera, Carabidae)

We investigated the relationships between dehydrogenase activity and the physicochemical properties of mountain soils over three and five years from Norway spruce(Picea abies L. Karst) logging residue spot burning and the occurrence of epigeic carabid beetles. Six study sites were utilised, including18 study plots(nine plots in a mixed coniferous mountain forest site and nine plots in a mixed broadleaf mountain forest site), with five replicate pitfall traps at each site located in southern Poland.Soil samples from the organic horizon were taken for p H, organic carbon, nitrogen, base cation content,acidity and dehydrogenase activity determination.Carabid beetles were monitored in weekly intervals during the period of July to August 2016. The burning of logging residues led to modified soil properties,especially the dehydrogenase activity. In all the tested variants, the activity was higher in soil samples after the burning in comparison to the control variants. We show no positive correlation between dehydrogenase activity and the number of carabid specimens. The preferences of dominant predatory hygrophilous carabids to acid habitats with weakly decomposed organic matter were proven. Simultaneously, the soil organic matter content was positively related to the carabid abundance. The significant impact of forest site conditions and the date of logging residue burning on the number of caught specimens were confirmed. In contrast, no relationships between the species richness, species diversity, mean individual biomass and spot burning effect were found. This work supports the recommendation of spruce fine woody debris utilisation by spot burning on mountain regions with rich habitats presenting moderate wet conditions and small land falls.

Biological Soil Quality Indicators and Conditioners in a Plant-Assisted Remediation of Crude Oil Polluted Farmland

Owing to vital roles played by enzymes in the preservation of the make-up of soil ecosystem and functional diversity, the influence of organic manure on the resultant biological quality of a crude oil polluted agricultural soil from a 90 d phytoremediation pot experiment was investigated. A 4-factor phyto-assisted clean-up of crude oil polluted agricultural soil was designed with options of manure amendments, to boost micobial activities. Profiles of β-glucosidases, proteases, dehydrogenases, phosphomonoesterases and respiration were investigated. Analysis of variance of triplicate experiment was carried out. Application of soil conditioner gave no marked dehydrogenase activity, which increased with depletion of available phosphorus. Marked increases in CO2 release and alkaline phosphatase activity with soil conditioning may implicate beneficial relationship with the abundance of microbial populations. Flooding in some pots correlated with β-glucosidase and respiratory acitivities. A direct relationship between cellulose breakdown, measurable with β-glucosidase activity, organic matter and CO2 release, measurable with respiratory activity within all soils was found in the present study. Use of organic manure significantly improved CO2 release by soil biota in hydrocarbon-impacted soil and may be explored for phytoremediation technique.

有机物料还田对黑土胞外酶化学计量特征的影响

冷凉区有机物料(秸秆和有机肥)还田黑土胞外酶计量特征是否受年平均温度的影响,目前缺少定量研究和深入分析。根据气候条件,该研究在黑龙江省西部依据纬度特征选取了12个有机物料还田年限大于5 a的定位试验点,基于有机物料还田种类对土壤胞外酶计量学特征及驱动因子进行了区域性分析。结果表明土壤胞外酶C:N:P在1:0.97:0.61~1:1.13:0.71之间,即有机肥还田(M)和秸秆还田(S)处理下土壤微生物整体面临微生物碳和养分(氮)限制。研究发现随年均温度升高,M和S处理的碳获取酶活性降低,而氮获取酶活性增加。此外,年均温度升高还使得M处理磷获取酶活性降低,而S处理磷获取酶活性增加。总体而言,东北冷凉区有机物料还田黑土微生物能量和养分限制主要受年平均温度直接影响,间接受pH值,土壤C:P等影响。该研究为冷凉区黑土建立合理的碳氮磷施肥模式提供数据支撑,为土壤养分恢复提供理论依据。

冬季覆盖对幼龄柑橘园土壤化学性质及酶活性的影响

为明确冬季不同覆盖模式对幼龄柑橘园土壤化学性质及酶活性的影响,于2020年11月—2021年10月在树龄3 a的柑橘园设置玉米秸秆覆盖(JGF)、白色地膜覆盖(BMF)、黑色地膜覆盖(HMF)、园艺地布覆盖(YDF)4种覆盖模式,以不覆盖为对照(CK),测定柑橘春梢期、夏梢期和秋梢期土壤pH值、有机质含量、速效养分含量及土壤酶活性变化,并进行相关性分析。结果表明,与CK相比,4种覆盖模式均有效提高了柑橘各生育时期土壤有机质、速效养分含量和土壤酶活性。土壤有机质含量除JGF模式呈先减后增趋势外,其他模式均呈逐渐下降的趋势,其中JGF模式在秋梢期较其他3个覆盖模式显著提高18.87%~30.03%。土壤碱解氮和有效磷含量在柑橘生育期均呈不断下降的趋势,土壤速效钾含量除CK不断下降外,其他覆盖模式均呈先降后增的趋势。土壤过氧化氢酶和脲酶活性在柑橘生育期呈先降低后增加的趋势,土壤蔗糖酶活性则呈现先升高后下降的趋势,但不同覆盖模式土壤pH值和酸性磷酸酶活性的变化略有不同。冗余分析(Redundancy analysis,RDA)结果表明,不同覆盖模式柑橘园土壤化学性质因子对土壤酶活性的影响均达到极显著水平(P<0.01),其重要性排序依次为速效钾含量>碱解氮含量>有效磷含量>pH值>有机质含量。比较4种冬季覆盖模式,其中玉米秸秆覆盖模式可显著提高土壤有机质含量,改善土壤养分条件,刺激土壤酶活性,因此可优先作为黄壤土幼龄柑橘园冬季覆盖材料使用。

施用钾肥抑制岗梅镉吸收积累效应研究

重金属污染已成为影响作物品质的重要因素之一。通过土壤镉(Cd)胁迫下施加0.75、1.50、3.00 g/kg三种浓度硫酸钾,研究硫酸钾对岗梅根际土壤理化性质和岗梅植株中镉积累的影响。结果表明,施用高浓度硫酸钾肥会使土壤pH下降,降低幅度最高达8.09%。镉胁迫会使土壤有机质含量降低,施用中(1.50 g/kg)、高(3.00 g/kg)浓度硫酸钾肥可以提高土壤有机质含量、全钾含量和速效钾含量。施用硫酸钾普遍提高了土壤中生物有效态镉含量,只有施用低浓度硫酸钾(0.75 g/kg)第30天,土壤中的生物有效态镉含量相比Cd处理组降低1.94%。在镉胁迫下,施加硫酸钾可以提高岗梅叶的SOD活性,进而提升对镉胁迫的耐受性。低浓度硫酸钾(0.75 g/kg)可以抑制岗梅植株内的镉从根和茎向叶片转运,且可以有效地减少镉在岗梅根和茎中的积累。因此,施用高浓度钾肥会使土壤pH下降;施用中(1.50 g/kg)、高(3.00 g/kg)浓度硫酸钾肥可以提高土壤有机质含量、全钾含量和速效钾含量,从而提高土壤肥力;低浓度硫酸钾可以降低土壤中生物有效态镉含量,可以较好抑制岗梅植株内的镉从根、茎向叶片转运,且可以较好地减少镉在岗梅根和茎中的积累。

有机物料对植烟土壤养分、酶活性和微生物群落功能多样性的影响

【目的】为探究有机物料施用对土壤养分和生物学特性的影响。【方法】采用盆栽试验,研究了草炭、花生壳炭、蒸汽爆破烟梗和玉米秸秆对植烟土壤的影响,采用BIOLOG ECO平板培养技术分析了土壤微生物群落功能多样性。【结果】施用有机物料能够显著提高土壤有机碳、速效氮、速效磷和速效钾含量;汽爆玉米秸秆处理土壤MBC、MBN含量及脲酶、蔗糖酶活性提高幅度最大。BIOLOG分析结果表明,有机物料提高了土壤微生物AWCD和多样性指数。主成分分析结果表明,生物炭促进了以羧酸类和多聚物类物质为碳源的微生物的生长,汽爆玉米秸秆有利于以碳水化合物类、氨基酸类、酚酸类和胺类物质为碳源微生物的生长。【结论】施用有机物料可提高植烟土壤养分含量,改善土壤微生态环境,其中以汽爆玉米秸秆效果最好。

外源有机酸对土壤pH值、酶活性和Cd迁移转化的影响

为了筛选植物修复土壤Cd污染适宜的外源有机酸,采用盆栽试验,在温室内以油菜为试验材料,在模拟重度Cd污染的土壤(原土Cd含量为0.838 mg·kg^-1,人工喷洒CdCl2水溶液,制备成Cd含量为4.838 mg·kg^-1的试验土)中加入5种有机酸:乙酸、草酸、柠檬酸、苹果酸和酒石酸,设置6个浓度:1、2、3、4、5、6 mmol·kg^-1,以不加有机酸为对照(CK),测定了油菜收获时的土壤pH值、酶活性和油菜干物质量以及Cd累积量,并分析了土壤理化指标与土壤Cd形态之间的关系。结果表明:1、3、4、5、6 mmol·kg^-1乙酸处理,4、5、6 mmol·kg^-1柠檬酸处理,3 mmol·kg^-1苹果酸处理,3、6 mmol·kg^-1酒石酸处理可显著增大土壤pH值(P<0.05),草酸处理pH值与CK差异不显著;但施加有机酸对土壤酶活性的影响不明显。1、4、6 mmol·kg^-1乙酸处理显著提高了油菜地上部干物质量,1、6 mmol·kg^-1乙酸处理根干物质量较CK增加了1倍以上,差异显著(P<0.05),4、6 mmol·kg^-1苹果酸处理根干物质量较CK显著增加了77.13%和88.30%(P<0.05),其余处理与CK差异不显著。1 mmol·kg^-1乙酸处理地上部Cd累积量较CK增加了51.52%,2 mmol·kg^-1草酸处理根系Cd累积量较CK增加了1.58倍,1 mmol·kg^-1柠檬酸处理地上部+根系Cd吸收总量高于CK,差异均显著(P<0.05);增加苹果酸量有利于提高根系Cd吸收总量,1、2 mmol·kg^-1酒石酸处理也提高了根系Cd累积量,但与CK差异均不显著(P>0.05)。施加乙酸时,土壤pH值与铁锰氧化物结合态Cd和土壤总Cd显著负相关,施加柠檬酸时,土壤pH值与碳酸盐结合态Cd和试验结束时土壤中的总Cd量显著正相关,施加苹果酸时土壤pH值与可交换态Cd显著正相关,其余处理土壤pH值与Cd形态相关性不显著。在碱性土上种植油菜,施加5种有机酸均会增大收获时土壤的pH值,且不同有机酸施加量对土壤Cd形态的影响不同。5种有机酸中乙酸最有利于提高油菜干物质量和油菜Cd累积量。

生物质炭与有机物料配施的土壤培肥效果及对玉米生长的影响

生物质炭作为一种多功能的土壤培肥材料被广泛应用,但其与传统有机物料的对比及配施研究还比较少。通过盆栽试验,研究了生物质炭与秸秆、发酵鸡粪单施及配施对壤质潮土和砂土养分含量、酶活性及玉米生长的影响,并采用主成分分析方法对3种有机物料的培肥效果进行综合评价。试验设6个处理,分别为不添加有机物料(CK)、添加生物质炭(BC)、小麦秸秆(WS)、发酵鸡粪(CM)、秸秆和生物质炭(WS+BC)、鸡粪和生物质炭(CM+BC)。研究结果表明,各处理均增加了砂土玉米生物量和株高,3种有机物料的提升幅度排序为:鸡粪>生物质炭>秸秆,鸡粪还可增加壤质潮土玉米生物量和株高。添加生物质炭和有机物料还可提高土壤有机质含量,其中生物质炭的提升幅度最大。此外,3种有机物料对土壤养分和酶活性的影响各异,单施鸡粪分别增加壤质潮土和砂土的碱解氮22.08%和26.67%,速效磷91.92%和53.65%,脲酶活性40.54%和36.94%;单施生物质炭分别增加壤质潮土和砂土速效磷83.52%和89.91%,速效钾79.38%和127.02%,过氧化氢酶活性3.41%和11.22%,却降低了土壤碱解氮含量,且与鸡粪配施后会抑制鸡粪中氮的有效性;单施秸秆分别增加壤质潮土和砂土速效钾49.48%和63.02%,β-葡糖苷酶活性51.86%和59.09%;生物质炭与鸡粪或秸秆配施可以更均衡地提升土壤肥力。通过主成分分析和相关分析发现,玉米生物量和株高与土壤氮、磷供应正变化的第2主成分(PC2)得分呈极显著正相关关系。因此,3种有机物料中,鸡粪对土壤氮、磷含量及相关酶活性影响最大;秸秆对土壤钾以及纤维素分解相关酶影响较大,而生物质炭对土壤肥力的提升作用更均衡,且土壤肥力综合得分最高。秸秆或鸡粪配施生物质炭可以更全面地提高土壤肥力。

玉米秸秆腐解对石灰性褐土酶活性和有机质质量分数动态变化的影响

通过室内培养,研究玉米秸秆腐解量与腐解时间的关系,以及不同秸秆添加量对石灰性褐土酶活性和有机质质量分数动态变化的影响。结果表明,玉米秸秆的腐解量随培养时间延长而增加,在培养的第45天,腐解量可达45%左右,而45天后腐解速度明显下降。在腐解的前60d,常规秸秆添加处理的腐解速率小于加倍量秸秆添加量处理,而在培养后期处理间腐解速率无差异,且腐解速率均随腐解时间延长而减小。土壤过氧化氢酶活性随培养时间的延长呈先增加后降低再增加的趋势,但不同秸秆量处理土壤过氧化氢酶活性差异不显著;碱性磷酸酶活性随秸秆添加量增加而增大,且均随培养时间延长而提高。土壤有机质和活性有机质质量分数均随培养时间延长而增加,且随秸秆添加量的增加而显著增加。

不同生物有机肥用量对土壤活性有机质和酶活性的影响

通过盆栽试验研究了不同有机质含量的土壤中,不同用量生物有机肥对棉花苗期土壤活性有机质和5种酶活性的影响。结果表明,不同土壤随着生物有机肥施用量的增加,其活性有机质及碳库管理指数(CMI)均显著增加。其中高有机质含量土壤施用生物有机肥20 g/kg效果显著,中等有机质含量土壤和低有机质含量土壤施用生物有机肥30、40 g/kg效果显著。5种土壤酶活性施肥处理均高于对照(CK),并且土壤酶活性与施用量成正比。脲酶、蔗糖酶、多酚氧化酶在施用生物有机肥10、20 g/kg与其它处理相比变化显著,过氧化氢酶、蛋白酶变化不显著。相关分析表明,有机质与活性有机质和CMI在棉花出苗0 d相关系数分别为0.831**、0.542*;在出苗后60 d相关系数分别为0.928**、0.635**,其中有机质与活性有机质相关性最高。而CMI与有机质和活性有机质在棉花出苗0 d相关系数分别为0.542*、0.896**,在出苗后60 d分别为0.635**、0.842**,说明活性有机质相对于有机质与CMI关系更为密切。蔗糖酶、过氧化氢酶、多酚氧化酶与土壤有机质和活性有机质在棉花出苗0 d和出苗后60 d存在显著相关,表明活性有机质与土壤酶活性能够较好的反映肥力水平。

平菇栽培废料等有机肥对土壤活性有机质和土壤酶活性的影响

通过大田试验研究了不施有机肥（CK）、施用平菇栽培废料（T1）、施用干腐熟牛粪（T2）和烘干鸡粪（T3）在种植黄瓜01-50 d内土壤中活性有机质和4种土壤酶活性的变化。结果表明：施入不同有机肥对土壤总有机质含量的影响为烘干鸡粪〉平菇栽培废料〉干腐熟牛粪〉对照;对活性有机质含量的影响为平菇栽培废料〉烘干鸡粪〉干腐熟牛粪〉对照;施用平菇栽培废料的土壤中脲酶、转化酶和脱氢酶活性最高,施用干腐熟牛粪的土壤中过氧化氢酶活性最高。相关性分析显示,脲酶、转化酶和脱氢酶活性与土壤活性有机质显著相关。用平菇栽培废料做有机肥能有效提高土壤活性有机质含量和土壤酶活性。

土地利用变化对土壤肥力影响研究进展

随着人类活动对土地利用的范围不断扩大、强度不断加剧,不同的土地利用方式改变了土壤的理化性质、养分状况、土壤酶活性,进而对土壤肥力造成了不同程度的影响。文中从土壤微生物、养分状况、土壤酶活性和土壤的物理性质4个方面综述了土地利用变化对土壤肥力的影响。

改良剂施用对干旱盐碱区棉花生长及土壤性质的影响

新疆是中国盐碱土重要分布区,也是棉花等经济作物的主产区,因此探究不同盐碱改良材料对其土壤性质和棉花生长的影响可为干旱区盐碱土壤改良和提高作物产量提供理论依据。以新疆巴音郭楞蒙古自治州水利管理处灌溉试验站盐碱棉田为研究对象,试验设置对照处理(CK)、腐植酸(F)、黄腐酸(H)、石膏(S)和聚丙烯酰胺(P)5个处理,以微区试验的方式开展改良试验,通过对比分析不同处理棉花收获后表层0-20 cm土壤盐分、pH、有机质、土壤过氧化氢酶活性、脲酶活性和碱性磷酸酶活性及对棉花株高和产量的影响,探究干旱区最适盐碱改良材料。结果表明:F、S、H和P处理,棉花产量较CK处理分别增产24.8%、11.1%、8.5%和4.8%。各改良措施处理均降低了土壤盐分含量,以F处理降低最多,较CK处理降低26.2%;S和F处理下土壤pH值较CK降低最多,分别降低0.1和0.09个单位;H、P和F处理下土壤有机质质量分数显著高于CK处理,分别增加26.5%、23.9%和23.6%;除S处理土壤过氧化氢酶活性低于对照处理外,其他改良措施均提高了土壤过氧化氢酶、碱性磷酸酶和脲酶活性及土壤酶活参数,其中腐植酸处理土壤酶活参数较CK处理提高77.2%。综合各改良材料对土壤性质和棉花产量的影响,腐植酸改良剂是该试验区较适宜改良剂。

小麦秸秆焚烧对土壤有机质积累和微生物活性的影响

【目的】焚烧作物秸秆是常见的处理农业废弃物减少病虫害和增加土壤养分的方法。但秸秆焚烧污染大气,妨碍农业健康发展。前人对秸秆焚烧造成大气污染已研究颇多,而对土壤环境所受影响的探究较少。本文选取焚烧不同小麦秸秆量的耕层土壤为研究对象,分析秸秆焚烧在短期内对土壤有机质积累和土壤微生物活性的影响。【方法】利用田间试验,设置对照（CK）、秸秆减量焚烧（0.24 kg/m^2,A1）、全量焚烧（0.48 kg/m^2,A2）和增量焚烧（0.72 kg/m^2,A3）4种处理。将秸秆均匀覆盖在地表进行焚烧,并对残留较多的部分进行补充焚烧,以确保秸秆焚烧完全。焚烧完成5 h后,待土壤温度恢复正常,采集0—5 cm、5—10 cm、10—20 cm土壤样品,分析各层次土壤有机质含量、含水量、微生物数量和土壤酶活性。【结果】秸秆焚烧对0—5 cm土层的有机质含量、含水量、微生物数量及土壤酶活性影响显著,各处理均表现出减少的趋势。有机质含量下降了6.37%-19.47%,含水量减少22.15%-39.19%;细菌数量减少52.26%-75.25%,真菌减少45.21%-63.29%,放线菌减少46.87%-68.26%。蔗糖酶活性降低14.19%-30.75%,脲酶活性降低7.81%-25.48%,过氧化氢酶活性降低9.63%-39.53%,磷酸酶活性降低11.36%-40.44%;各处理与CK间大多呈显著差异。5—20 cm土层中各指标无显著变化。焚烧处理各指标的减少量均表现出A3〉A2〉A1的趋势,不同秸秆焚烧量之间大多差异显著。相关性分析表明,秸秆焚烧量与有机质含量、含水量、土壤微生物数量和酶活性之间呈显著负相关关系。【结论】小麦秸秆焚烧在短期内显著降低了0—5 cm土层中的有机质含量和微生物活性,而对5—20 cm土层的土壤影响不显著。小麦秸秆焚烧对土壤环境的影响强度随秸秆量的增多而加大。焚烧量与有机质含量、含水量、土壤微生物数量和酶活性之间呈显著负相关关系。鉴于秸秆焚烧对土壤肥力的长期效应以及对土壤理化性质影响的复杂性,焚烧对土壤有机质积累和微生物群落的影响还需要长期定位试验来探讨。

渭北果园土壤有机质及酶活性研究

为了探讨渭北果园土壤生物质量演化趋势,分析制约地区苹果可持续发展的土壤因素,在渭北旱塬果区选择了〈10 a、10~20 a、〉20 a园龄段苹果园各3个,选用农田土壤作为对照,研究0~100 cm范围内土壤有机质、过氧化氢酶、脲酶、碱性磷酸酶活性的变化趋势。结果表明,随着果树种植年限的增加,果园土壤有机质含量仅在表层0~20 cm有不同程度地累积趋势,且在〉20 a果园累积较为明显;20~40 cm土层处有机质呈现在植果初期递减,20 a后逐渐增加的趋势;果园土壤3种酶活性变化差异主要体现在0~40 cm土层范围,过氧化氢酶活性在0~40 cm呈现递减趋势,且在0~100 cm土层显著高于农田土壤;脲酶活性在0~40 cm有不同程度递增过程,碱性磷酸酶活性在0~40 cm也呈现出相对增高的态势。相关性分析表明土壤有机质与3种酶之间存在着极显著相关。由此得出,渭北地区果树对土壤生物质量的影响主要体现在0~40 cm范围,果园土壤过氧化氢酶活性显著递减和表层土壤脲酶活性增加可能会对苹果树生长产生一定影响。

不同土地利用方式下Cd、Pb复合污染对土壤酶活性的影响

为探寻合理的土地利用方式,减轻重金属污染,以上海市崇明岛为研究对象,结合室内盆栽模拟试验,研究了不同土地利用方式下Cd、Pb复合污染对土壤酶活性的影响,以期为合理规划土地功能和提高土壤健康程度提供科学依据。试验结果表明,农田、生活用地等受人类活动影响较明显的地区,其土壤酶活性低于湿地、林地、河道旁等人为扰动较少且水分充足的地区;土壤脲酶、磷酸酶和脱氢酶活性两两之间呈显著正相关(P<0.01),且土壤脲酶对Cd、Pb较敏感;土壤有机质与土壤酶活性呈显著正相关(P<0.05);Cd、Pb复合污染在低含量(Cd:0～1mg.kg-1;Pb:0～60mg.kg-1)时对土壤酶活性表现为促进作用,而高含量(Cd:0～20mg.kg-1;Pb:0～100mg.kg-1)时则表现为抑制作用。

施用给水厂残泥对南北方不同类型农田土壤质量的影响

为评估WTR（给水厂残泥）在农业区污染控制领域的土地应用风险,从土壤理化性质、土壤养分含量、有机质活性、微生物生长和土壤酶活性等五方面,考察了不同WTR添加量（w为0%、2%、5%、10%）对3个南北方农田（土壤）（常州水稻田、寿光和天津蔬菜种植区土壤,依次记做常州土壤、寿光土壤和天津土壤）质量的影响.结果表明：1WTR添加后,各土壤中CEC（阳离子交换容量）提高了23.7%-63.9%;添加WTR有利于调节酸性和碱性土壤p H,使之更适合作物生长,随着WTR添加量由0%增至10%,常州土壤p H由5.45升至6.69,寿光和天津土壤p H则分别由7.57、7.88降至7.26、7.64.2添加适量WTR不会造成土壤中P、K、Fe、Al、Ca、Mg、Cu、Mn和Zn等多种有效态元素含量的缺失,特别是在富P（〉50 mg/g）土壤中施加2%-10%的WTR,既能满足植物生长对有效P的需求,又能降低P的淋溶风险.3在施肥和不施肥条件下,WTR添加量≤5%时均能增加土壤w（活性有机质）,促进土壤微生物生长,提高土壤脱氢酶和总磷酸酶活性.由于WTR对有机P底物的强吸附作用,不施肥条件下,WTR添加量达到10%时,土壤总磷酸酶活性降低了55%;而施加有机肥会削弱或抵消这种不利影响,土壤总磷酸酶活性可提高至未添加WTR时的1.7倍.因此,添加适量WTR能有效改善我国南北方不同类型农田土壤质量.