Impact of Fire on Soil Nitrogen Forms in Central Semiarid Argentina

Burning effects on soil N are particularly important in the Caldenal region of Argentina because N is likely to be limited and is easily lost by volatilization during fire. Burning may cause an initial increase in the mineral N content of the surface soil and, perhaps more important, can reduce the proportion of N in hydrolyzable (that is, more mineralizable) forms. The modification in soil N fractions by fire is directly related to the degree of soil heating and to the proportion and amount of N fractions remaining in the ash. This research was aimed at studying the effects of a controlled burn on total N, inorganic (NO3 and NH4+) and organic (amino acids, ammonium, hexosamines) N forms, as well as hydrolyzable and nonhydrolyzable N compounds of top soils of the southern Caldenal. Soil samples were taken from beneath the canopy of shrubs and from the areas with herbaceous cover, before and after burning. In order to show that a greater proportion of N added to regularly burned soils will result in lower levels of mineralizable N, differences in the changes of the various pools of plant tissue N upon burning at different ignition tem peratures are also reported. The initial unburned top soils had no significant differences in total, inorganic, and organic N form concentrations between shrub and herbaceous vegetation-covered soil. Burning did not affect the net content of total N in soil under woody vegetation, but in the grassland soil a decrease of total N concentration was observed. Nitrate concentration increased and NH4+ concentration decreased in both shrub and grassland soils after burning. Controlled burning caused losses of amino acid and ammonium organic N forms from the soil under grass plants and gains of hexosamine N in both shrub-and herbaceous-coveredsoils. There was an observed tendency to increase the relative proportions of non hydrolyzable N forms in both the shrub and grassland soils after burning. Inorganic and organic N form concentrations were similar in initial shrub litter and grass, but litter had higher concentrations of total and nonhydrolyzable N than those of grass. Shrub litter ash obtained after muffling at 300 C contained higher NH4+-N, aminoacid N, ammonium N, and total and nonhydrolyzable N concentrations than those from grass. An increase of 100 C in the ignition temperature produced clear ashes, rich in mineral N with little concentration of total N and C. The organic N forms affected most by the ignition temperature increase were amino acid N and ammonium N, respectively, particularly in woody litter. The most striking feature was the constituent increase in the percentages of nonhydrolyzable N forms of the vegetation covers on passing from initial to 300 C to 400 C, particularly for the litter and its ashes. These results suggest that the soil mineralizable N pool may be reduced by frequent burning or by more severe burning than observed presently in the Caldenal region.     

施肥对新建日光温室番茄产量及土壤养分含量的影响

在陕西杨凌选择3个新建大棚,采用田间试验方法研究了不同施肥处理(常规施肥、配方施肥1和配方施肥2)对番茄产量,及番茄种植前和收获后土壤有机质、全氮、速效氮、有效磷、速效钾和电导率等基本性质的影响。与农户常规施肥相比,配方施肥1和2处理氮、磷及钾肥用量分别减少9%～40%、26%～46%和18%～47%时,番茄产量并未显著变化,说明常规施肥处理存在肥料过量施用问题;与种植前相比,种植一季番茄后耕层(0～20 cm)土壤有机质、全氮、有效磷及速效钾含量均有不同程度增加,其中有机质和有效磷含量均达显著水平,增加幅度分别为25%和460%;0～100 cm土层电导率也有不同程度的增加;0～100 cm土层矿质氮含量显著增加,平均增加幅度为182%;0～200 cm土层硝态氮累积量平均达727 kg/hm2。新建日光温室存在过量施肥现象,由此带来的硝态氮及有效磷在土壤中的大量累积问题值得关注。     

Formation,Distribution, and Physicochemical Properties of Plant Litter in Shrub Patches of Northeastern Patagonia

The objective of this study was to assess the formation, distribution, and physicochemical properties of litter in two types of shrub patches, featured by the dominant species (Atriplex lampa and Prosopis alpataco). These species are important components of the Monte Phytogeographic Province . The surface layers of the shrub-steppe have been classified into four soil condition classes using attributes that are easily observable in the field. These classes provide an estimate of litter spatial patterns and of potential dry matter production. Litter differs greatly in chemical content. The P. alpataco patch presents higher quality in organic matter , based on its elemental composition of carbon , nitrogen , and phosphorus . The patterns of the lignin studied in both patches were different . The sum of phenolic oxida tion species was higher in summer for P. alpataco than in A. lampa, indicating higher contents of lignin components in the former and a slight oxidation in the latter . The strongest peaks in 1 3 C NMR spectra are present in the rank of poly saccharides and sharper aliphatic structures . Seasonal differences between patches correlate to the results obtained in polysaccharides and lignin and might be ascribed to the high mineralization of the former . The results of this study indicate that the shrub structure in terms of patch types and patch dynamics controls the content , distribution , and composition of litter materials and has a major impact on litter decomposition . Thus the formation , distribution , and function of litter in shrub steppe soils can be studied through the structural characterization of patches and classes of soil surface conditions.     

Influence of some biologically active compounds on microbial activity and on the availability of plant nutrients in soils. II. Nitrapyrin,dazomet, 2-chlorobenzamide and tributyl-3-chlorobenzylammonium bromide

The effect of the nitrification inhibitor nitrapyrin (2-chloro-6-trichloromethylpyridine), the soil partial sterilant dazomet (tetrahydro-3,5-dimethyl-1,3,5-thiadiazine-2-thione), the quaternary ammonium growth retardant tributyl-3-chlorobenzylammonium bromide, and the pre-emergent herbicide 2-chlorobenzamide on total microbial activity and available plant nutrient content of an acid and an alkaline soil during an incubation period of 6 weeks under aerobic conditions has been studied in comparison with untreated soils. The compounds were incorporated with the soils at normal application rates. At intervals determinations were made of carbon dioxide liberated, the content of ammonium and nitrate nitrogen and of some available plant nutrient mineral elements. All four compounds were found to influence these quantities. Nitrapyrin increased carbon dioxide production throughout and dazomet did so after initial depression. 2-Chlorobenzamide and the growth retardant reduced carbon dioxide liberation especially in the early stage of incubation. All the compounds retarded nitrification in both soils; an increase in ammonium nitrogen resulted in treated soils except in the alkaline soil containing the growth retardent, where ammonification was also reduced. A reduction in the content of available mineral nutrient elements was usually found suggesting interference with the biological oxidation of these elements to less available forms. However, available manganese was increased by dazomet, as were available iron and manganese by the growth retardent and 2-chlorobenzamide.     

艾比湖自然保护区土壤酶活性及理化性质

以艾比湖自然保护区荒漠生态系统不同土壤类型为研究对象,分析各土壤类型酶活性及理化性质,探讨理化性质对酶活性影响的强度。结果表明：黑钙土酶活性较高,营养元素丰富,水分和盐分条件较好;而棕漠土、栗钙土酶活性相对较低,理化条件相对较差;灰钙土、灰漠土则表现为土壤酶活性极差,营养元素贫乏。从通径分析和决定系数得出：土壤有机质是影响该地区酶活性的主导因子;速效磷对过氧化氢酶活性的直接通径系数较大,较大程度影响过氧化氢酶活性;全氮对脲酶活性直接通径系数较大,是直接影响脲酶活性的主导因子;碱解氮对磷酸酶和蔗糖酶活性有强烈的直接作用,是影响磷酸酶和蔗糖酶活性的主导因子;土壤总盐对蔗糖酶存在较大的直接负效应,是制约蔗糖酶活性的主导因子。     

Response of soil nitrogen,phosphorous and organic matter to vegetation succession on the Loess Plateau of China

 Revegetation is a traditional practice widely used for soil protection. We evaluated the effect of natural revegetation succession on soil chemical properties and carbon fractions (particulate organic carbon (POC), humus carbon (HS-C), humic acid carbon (HA-C) and fulvic acid carbon (FA-C)) on the Loess Plateau of China. The vegetation types, in order from the shortest to the longest enclosure duration, were: (a) abandoned overgrazed grassland (AbG3; 3 years); (b) Hierochloe odorata Beauv. (HiO7; 7 years); (c) Thymus mongolicus Ronnm (ThM15; 15 years); (d) Artemisia sacrorum Ledeb (AtS25; 25 years); (e) Stipa bungeana Trin Ledeb (StB36; 36 years) and (f) Stipa grandis P. Smirn (StG56; 56 years). The results showed that the concentrations of soil organic carbon, total nitrogen and available phosphorus increased with the increase of restoration time except for ThM15. The concentration of NH₄-N increased in the medium stage of vegetation restoration (for ThM15 and AtS25) and decreased in the later stage (for StB36 and StG56). However, NO₃-N concentration significantly increased in the later stage (for StB36 and StG56). Carbon fractions had a similar increasing trend during natural vegetation restoration. The concentrations of POC, HS-C, FA-C and HA-C accounted for 24.5%–49.1%, 10.6%–15.2%, 5.8%–9.1% and 4.6%–6.1% of total carbon, respectively. For AbG3, the relative changes of POC, HS-C and FA-C were significantly higher than that of total carbon during the process of revegetation restoration. The higher relative increases in POC, HS-C and FA-C confirmed that soil carbon induced by vegetation restoration was sequestrated by higher physical and chemical protection. The increases of soil C fractions could also result in higher ecology function in semiarid grassland ecosystems.     

不同植被覆盖度沙垄土壤化学性质的空间分异

为了研究温带固定半固定沙漠土壤化学性质与地表植被的关系,本文以古尔班通古特沙漠西南缘莫索湾地区沙漠–绿洲过渡带为研究区,分别选取植被覆盖度为10%和15%的半固定沙垄及植被盖度为30%的固定沙垄。采集了各沙垄不同地貌部位的土壤样品,室内测试了土壤pH、电导率、有机质、全氮和全磷等指标。结果表明：① 随着植被覆盖度下降,沙垄西坡、坡顶和东坡,土壤pH、电导率、有机质、全氮和全磷呈逐渐降低趋势;② 不同地貌部位的分布格局各沙垄表现不一致,沙垄A和沙垄B的 pH、电导率、有机质、全氮和全磷含量最大值均出现在垄间地,其他部位之间没有明显的规律,沙垄C 的pH和电导率最大值出现在垄间地,而土壤养分含量于坡顶部位富集;③ 各沙垄不同土层土壤性质分布规律相对一致,土壤pH、电导率随着土层深度的增加呈上升的趋势,而土壤养分随着土层深度的增加而降低;④ 土壤化学性质空间分布异质性与植被的分布格局密切相关,相互影响,当植被覆盖度较高时,生物作用起主导作用,当植被覆盖度较低时,风蚀、地形等非生物因素作用加强,影响生物作用,植被对土壤颗粒和养分的拦截及富集作用逐渐减弱或消失。     

短期N、P添加对荒漠草原土壤非保护性有机碳的影响

以干旱、半干旱地区荒漠草原土壤为研究对象,研究N、P养分添加对荒漠草原0～30 cm土层土壤颗粒有机碳和轻组有机碳含量、分配比例、敏感指数的影响,探讨荒漠草原土壤非保护性有机碳分配比例及其向保护性有机碳的转化速率对N、P添加的响应.研究结果表明:短期N、P添加能促进荒漠草原表层土壤(0～10 cm)土壤颗粒有机碳和轻组...     

不同植被覆盖度沙垄土壤化学性质的空间分异

为了研究温带固定半固定沙漠土壤化学性质与地表植被的关系,本文以古尔班通古特沙漠西南缘莫索湾地区沙漠-绿洲过渡带为研究区,分别选取植被覆盖度为10%和15%的半固定沙垄及植被覆盖度为30%的固定沙垄。采集了各沙垄不同地貌部位的土壤样品,室内测试了土壤pH、电导率、有机质、全氮和全磷等指标。结果表明:①随着植被覆盖度下降,沙垄西坡、坡顶和东坡,土壤pH、电导率、有机质、全氮和全磷呈逐渐降低趋势;②不同地貌部位的分布格局各沙垄表现不一致,沙垄A和沙垄B的pH、电导率、有机质、全氮和全磷含量最大值均出现在垄间地,其他部位之间没有明显的规律,沙垄C的pH和电导率最大值出现在垄间地,而土壤养分含量在坡顶部位富集;③各沙垄不同土层土壤性质分布规律相对一致,土壤pH、电导率随着土层深度的增加呈上升的趋势,而土壤养分随着土层深度的增加而降低;④土壤化学性质空间分布异质性与植被的分布格局密切相关,相互影响,当植被覆盖度较高时,生物作用起主导作用,当植被覆盖度较低时,风蚀、地形等非生物因素作用加强,影响生物作用,植被对土壤颗粒和养分的拦截及富集作用逐渐减弱或消失。     

外源铅在土壤中的年际变化及对土壤有机碳矿化和速效养分的影响

以关中土为供试土样进行田间试验,向耕层土壤中添加不同浓度外源铅(Pb0:背景值,CK;Pb1:175 mg·kg~(-1)+背景值;Pb2:350 mg·kg~(-1)+背景值),进行小麦—玉米轮作试验。分别于2011—2013年小麦收获季采集耕层(0~20 cm)土壤,分析土壤中铅全量及有效态铅含量的年际变化,以及铅对小麦-玉米轮作模式下土壤有机碳(SOC)、溶解性有机碳(DOC)、微生物量碳(MBC)、碱解氮、速效磷、速效钾含量的影响。结果表明,三年中,施铅处理下土壤中铅全量及有效态铅含量分别下降13.22%和30.65%,总体呈现逐年下降趋势。与对照(CK)相比,Pb1、Pb2处理下SOC平均含量分别下降了16.30%和11.86%;DOC平均含量分别下降了4.05%和7.34%,与土壤铅含量呈现显著负相关关系;低浓度铅污染下土壤微生物商(q M)显著高于对照土壤,微生物量碳含量变化不显著。此外,土壤速效养分的分析显示,土壤碱解氮含量在外源铅加入初期下降明显,且在Pb1处理下碱解氮减少量最大;土壤速效磷含量随土壤铅含量增加而呈现下降趋势;土壤速效钾含量则随土壤铅含量的增加而增加。试验表明,外源铅的加入影响了土壤有机碳的稳定性,对土壤碳、氮循环产生了一定的影响;能够与土壤溶液中的磷酸根生成难溶性盐,与土壤胶体或土壤矿物晶格中的K+发生置换,加大土壤速效养分的流失风险。     

生物质炭对盐土改良效应研究

采用小麦、糜子连续盆栽种植试验方法,研究了添加不同用量的生物质炭后,盐土中基础养分含量、Ph值、阳离子交换量、水溶性盐及其他盐分离子含量的变化,以期为生物质炭在盐土改良中的应用提供参考.结果表明:随生物质炭用量的增加,盐土中有机碳含量明显提高,矿质态氮、有效磷及速效钾变化很小;Ph值略有降低,但各处理间差异不显著;阳离子交换量大幅度增加;水溶性盐含量降低明显,其中Na+、K+、Mg2+及Ca2+降低幅度较大,C1-和SO42-含量也显著降低.在该盆栽试验中,生物质炭对盐土具有良好的改良效果.     

乌鲁木齐城市土壤性质及污染研究

通过对乌鲁木齐城市土壤基本理化性质、营养盐特征、重金属污染的研究,结果表明:乌鲁木齐市城市土壤较自然土壤碱性更强、有机质丰富;氮素缺乏,磷有明显的累积特征;Cr,Cu,Pb,Zn含量很高,Mn,Fe含量不高;除Mn和Fe以外,其他重金属及有机质、总氮、总磷在不同功能区的空间分布差异都很大;重金属形态均以残渣态为主,但各重金属形态分布规律并不完全相同,Pb的活性最大,Fe的活性最小.     

无定河流域植被恢复对土壤团聚体及碳固定的影响

对无定河流域坡耕地和4、5、10、30、50年植被恢复样地土壤水稳性团聚体含量,全土样及不同直径水稳性团聚体中的有机质、速效磷含量进行了测定分析,计算了土壤有机碳密度,旨在评价植被恢复对土壤结构、养分及土壤固定的影响。结果表明:各样地全土样有机质和速效磷含量分别介于6.73~31.83 g·kg-1和1.93~14.72 mg·kg-1之间,不同直径团聚体有机质和速效磷含量分别介于7.15~26.03 g·kg-1和3.71~16.64 mg·kg-1之间。相对农地,植被恢复能明显增加表层土壤有机质含量和有机碳密度,杜梨群落增加幅度最高,增加值分别为24.93 g·kg-1和91.98 mg·cm-2;水稳性团聚体以0.05 mm和0.05~0.1 mm为主,含量分别在37.06%~57.22%和21.71%~29.76%之间;不同直径水稳性团聚体中有机质含量表现为2 mm至0.2~0.5 mm之间,直径愈小,有机质含量愈高,0.2~0.5 mm至0.05 mm之间,粒径愈小,有机质含量愈低;除1~2 mm团聚体中的速效磷含量最高外,2 mm至0.05 mm团聚体之间,粒径愈小,速效磷含量愈低。土壤有机碳密度与植被恢复年限呈线性正相关关系。相对于土壤碳固定,土壤抵抗水力侵蚀的能力需更长时间才能显著提高。相对慢速湿润,快速湿润条件下各直径水稳性团聚体有机质含量均较高。研究区大雨或暴雨是造成该区域土壤结构恶化和有机碳损耗的主要原因。     

Responses of soil nitrogen,phosphorous and organic matter to vegetation succession on the Loess Plateau of China

Revegetation is a traditional practice widely used for soil protection. We evaluated the effect of natural revegetation succession on soil chemical properties and carbon fractions(particulate organic carbon(POC), humus carbon(HS-C), humic acid carbon(HA-C) and fulvic acid carbon(FA-C)) on the Loess Plateau of China. The vegetation types, in order from the shortest to the longest enclosure duration, were:(a) abandoned overgrazed grassland(Ab G3; 3 years);(b) Hierochloe odorata Beauv.(Hi O7; 7 years);(c) Thymus mongolicus Ronnm(Th M15; 15 years);(d) Artemisia sacrorum Ledeb(At S25; 25 years);(e) Stipa bungeana Trin Ledeb(St B36; 36 years) and(f) Stipa grandis P. Smirn(St G56; 56 years). The results showed that the concentrations of soil organic carbon, total nitrogen and available phosphorus increased with the increase of restoration time except for Th M15. The concentration of NH4-N increased in the medium stage(for Th M15 and At S25) and decreased in the later stage(for St B36 and St G56) of vegetation restoration. However, NO3-N concentration significantly increased in the later stage(for St B36 and St G56). Carbon fractions had a similar increasing trend during natural vegetation restoration. The concentrations of POC, HS-C, FA-C and HA-C accounted for 24.5%–49.1%, 10.6%–15.2%, 5.8%–9.1% and 4.6%–6.1% of total carbon, respectively. For Ab G3, the relative changes of POC, HS-C and FA-C were significantly higher than that of total carbon during the process of revegetation restoration. The higher relative increases in POC, HS-C and FA-C confirmed that soil carbon induced by vegetation restoration was sequestrated by higher physical and chemical protection. The increases of soil C fractions could also result in higher ecological function in semiarid grassland ecosystems.     

不同比例羊粪与化肥配施对土壤质量及甜菜含糖率和效益的影响

为了解决长期施用化肥导致土壤质量下降,甜菜产量低,品质差的问题,在甘肃省张掖市甘州区明永镇甜菜种植基地,采用田间试验方法,连续3a进行了不同比例羊粪与化肥配施对土壤质量及甜菜含糖率和效益影响的研究.结果表明:施用100％羊粪比其他处理有利于改善土壤质量,提高甜菜含糖率,与100％化肥比较,土壤容重、pH值和全盐降低10...     

吴起县退耕还林后主要植被类型土壤质量评价

为明确吴起县退耕还林后形成的主要植被类型土壤质量状况,文中以吴起县王洼子典型退耕植被作为研究对象,对比分析不同植被类型土壤理化性质差异,并综合主成分分析法、敏感性以及相关性分析法,建立了研究区土壤质量评价指标最小数据集.结果表明:1)不同植被类型间土壤物理、化学性质差异显著(P＜ 0.05);山桃×沙棘混交林在土壤孔隙...     

有机物料组合肥还田对耕地质量及甜菜品质和效益的影响

在甘肃省张掖市甘州区明永乡甜菜种植基地上,采用田间试验方法,连续3a进行了有机物料组合肥还田对耕地质量及甜菜品质和效益影响的研究.结果表明:羊粪+改性糠醛渣+葵花籽饼组合肥有利于提高土壤的总孔隙度、>0.25 mm团聚体、持水量和CEC,降低容重、pH值和全盐含量,与传统化肥比较,土壤总孔隙度和>0.25 mm团聚体分...     

长期秸秆还田对褐土农田土壤有机碳、氮组分及玉米产量的影响

基于1992—2022年连续30 a的长期定位试验,研究秸秆不还田（CK）、秸秆覆盖还田（SM）、秸秆粉碎直接还田（SC）和秸秆过腹还田（CM）4种不同秸秆还田方式对土壤有机碳、氮组分和作物产量的影响。结果表明：（1）不同秸秆还田方式均可增加耕层土壤有机碳、全氮及其组分含量;与CK相比,CM处理0~20 cm土层土壤的总有机碳（SOC）、轻组有机碳（LFOC）、微生物量碳（MBC）、水溶性有机碳（DOC）和颗粒有机碳（POC）的含量分别显著增加42.85%、93.51%、80.09%、190.42%和123.38%;土壤全氮（TN）、轻组有机氮（LFON）、微生物量氮（MBN）、水溶性有机氮（WSON）和颗粒有机氮（PON）的含量分别显著增加49.37%、34.26%、69.49%、172.73%和129.29%。（2）各活性有机碳组分与土壤有机碳的比值表现为LFOC>POC>MBC>DOC;各氮组分与土壤全氮的比值表现为LFON>PON>MBN>WSON。（3）CM和SC处理下敏感指数最高的指标为DOC,DOC可作为CM和SC处理早期有机物变化的指示物;SM处理下敏感指数最高的指标为LFOC,LFOC可作为SM处理早期有机物变化的指示物。（4）土壤有机碳、氮组分间均呈显著正相关关系,其中DOC可以较好地反映SOC的变化情况,WSON可较好地反映TN的变化情况。（5）与CK相比,长期秸秆还田均可以显著提高玉米产量,SM、SC和CM处理30 a累计产量分别增加6.38%、7.82%和23.00%。综上,长期秸秆还田是提高土壤有机碳氮组分含量和作物产量的有效耕作措施,以秸秆过腹还田效果最为突出,可在黄土高原旱地玉米种植区域推广。     

连续施用农业废弃物组合肥制种玉米田理化性质及酶活性和重金属变化特征

在甘肃省进行了连续4 a施用农业废弃物组合肥制种玉米田理化性质及酶活性和重金属变化特征研究。 结果表明：农业废弃物组合肥施用量比例为秸秆组合肥18 t·hm^-2∶畜禽粪便组合肥36 t·hm^-2∶废渣组合肥15 t·hm^-2。施用农业废弃物组合肥4 a与不施肥比较,制种玉米田容重、pH值和真菌数量分别降低6.77%、6.20%和26.19%;总孔隙度、水稳性团聚体、总持水量、EC值、可溶性盐和CEC分别增加6.63%、18.95%、6.62%、5.23%、5.36%和36.10%;有机质、有机碳、有机碳密度、碱解氮、速效磷和速效钾含量分别增加23.72%、24.10%、15.48%、28.44%、49.92%和27.97%;细菌数量、放线菌数量、蔗糖酶、 脲酶、磷酸酶和多酚氧化酶活性分别增加38.20%、86.60%、63.46%、38.89%、61.48%和58.82%;Hg、Cd、Cr、Pb和Zn含量分别增加21.74%、30.00%、24.49%、27.55%和31.81%。农业废弃物组合肥施用年限与制种玉米田容重、pH值和真菌数量之间呈显著负相关关系,与总孔隙度、水稳性团聚体、CEC、EC值、可溶性盐、总持水量、有机质、有机碳密度、速效氮磷钾含量、细菌数量、放线菌数量、酶活性、重金属含量之间呈显著正相关关系。 虽然连续4 a施用农业废弃物组合肥重金属含量比不施肥高,但重金属含量小于土壤污染临界值,说明研究区域农业废弃物组合肥重金属含量较低,不会对作物造成风险。     

不同覆膜连作年限对玛纳斯县棉田土壤质量的影响

为研究不同覆膜连作年限对玛纳斯县棉田土壤质量的影响,以新疆玛纳斯县覆膜连作0、5、10、20、30 a的棉田为研究对象,分别采集0~10、10~20、20~30 cm土层土壤,测定其土壤理化性质、土壤酶活性、土壤微生物量碳、氮含量等指标,并对不同覆膜连作年限玛纳斯县棉田的土壤质量进行综合评价。结果表明：（1）随覆膜连作年限的增加,土壤含水率和有机质含量逐渐增加,以覆膜连作30 a时最高,分别为11.52%和21.60 g·kg^-1,土壤速效磷呈先升高后降低趋势,在覆膜连作10 a时含量最高（49.60 mg·kg^-1）,土壤电导率、总盐、速效钾和碱解氮总体呈降低趋势,在覆膜连作年限30 a时含量最低,分别为0.50 mS·cm^-1、0.69 g·kg^-1、148.28 mg·kg^-1和25.27 mg·kg^-1;同一覆膜连作年限下,随着土层深度的增加,土壤含水率、电导率和总盐逐渐增加,pH值、有机质、速效磷、速效钾和碱解氮含量逐渐降低。（2）在不同覆膜连作年限下,土壤蔗糖酶、脲酶、碱性磷酸酶活性随覆膜连作年限的增加呈先升高后降低趋势,在覆膜连作10 a时活性最高,分别为10.57 mg·g^-1·d^-1、0.86 mg·g^-1·d^-1、0.40 mg·g^-1·d^-1,土壤过氧化氢酶活性随不同覆膜连作年限并无显著变化,为1.80~2.20 mL·g^-1;在同一覆膜连作年限下,土壤脲酶、碱性磷酸酶活性均表现为表层>深层,且差异显著。随覆膜连作年限的增加,土壤微生物量碳含量呈现先增加后减少的趋势,最高为205.26 mg·kg^-1,微生物量氮含量逐渐降低,最低在覆膜连作30 a时为11.40 mg·kg^-1,且不同土层土壤微生物量碳、氮表现为表层>深层。（3）土壤速效磷与过氧化氢酶、脲酶、碱性磷酸酶活性和微生物量碳呈极显著正相关关系,与蔗糖酶活性呈显著正相关关系,表明土壤速效磷是影响土壤酶活性和微生物量碳、氮的主要因素。土壤质量综合评价表明,以覆膜连作10 a的土壤质量最佳,0 a和30 a的土壤质量相对较低。