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1.
BACKGROUND: Proquinazid is a new quinazolinone fungicide from DuPont registered in most European countries for powdery mildew control in cereals and vines. The aim of this paper is to present baseline sensitivity data in populations of Blumeria graminis f. sp. tritici EM Marchal and Erysiphe necator (Schw) Burr as well as results from cross‐resistance studies with other fungicides. RESULTS: Proquinazid exhibited a high intrinsic activity on B. graminis f. sp. tritici isolates at rates ranging from 0.000078 to 0.02 mg L?1. Erysiphe necator isolates were comparatively less sensitive to proquinazid, with EC50 values ranging from 0.001 to 0.3 mg L?1. Proquinazid controlled equally well B. graminis f. sp. tritici isolates sensitive and resistant or less sensitive to tebuconazole, fenpropimorph, fenpropidin, cyprodinil and kresoxim‐methyl. A positive correlation (r = 0.617) between quinoxyfen and proquinazid sensitivities was found among 51 B. graminis f. sp. tritici isolates. Quinoxyfen‐resistant B. graminis f. sp. tritici isolates were slightly less sensitive to proquinazid than the quinoxyfen‐sensitive isolates; however, proquinazid remained much more active than quinoxyfen on these isolates. A stronger sensitivity relationship (r = 0.874) between proquinazid and quinoxyfen was found among 65 E. necator isolates tested in a leaf disc assay. The sensitivity values for proquinazid were significantly lower than those for quinoxyfen, confirming the higher intrinsic activity of proquinazid on both pathogens. CONCLUSION: Given the history of resistance development in powdery mildew and the observed sensitivity relationship with quinoxyfen, specifically in E. necator, we conclude that the risk of resistance developing to proquinazid might be influenced by the use of quinoxyfen. Based on these results, the authors recommend that proquinazid and quinoxyfen be managed together for resistance management. Copyright © 2009 Society of Chemical Industry 相似文献
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3.
Derek W. Hollomon Ian Wheeler Keith Dixon Christopher Longhurst George Skylakakis 《Pest management science》1997,51(3):347-351
The new powdery mildew fungicide quinoxyfen belongs to the novel quinoline class of chemistry. Although its biochemical mode of action is unknown, quinoxyfen does not act in the same way as other cereal fungicides. It is a systemic protectant which inhibits the early stages of mildew infection on a wide range of crops, and provides season-long protection from a single early-season spray applied around GS 31. The base-line sensitivity profile of quinoxyfen was defined for barley powdery mildew (Erysiphe graminis f.sp. hordei) from over 340 field isolates collected from different parts of the UK from 1991 onwards. Sensitivities ranged from <0·0001→0·16 mg litre-1 with a mean of 0·003 mg litre-1. Current work is extending the base-line sensitivity studies to wheat powdery mildew (E. graminis f.sp. tritici), and includes isolates from European trials, but so far this new data set has shown no differences from barley powdery mildew. Quinoxyfen-resistant mutants were generated in the laboratory, and some similar resistant strains were obtained from treated field crops. These laboratory and field strains were always defective, in some way, for sporulation and, curiously, all required the presence of quinoxyfen for survival in culture. Attempts to generate resistant mutants that sporulated normally were unsuccessful. These studies suggested that the resistance risk for quinoxyfen is low. The recommended anti-resistance strategy accompanying introduction of quinoxyfen avoids seed treatments and late-season applications. Instead, a single early (GS 31) treatment using either pre-formulated mixtures or alternating with a fungicide with different mode of action is recommended. This strategy will be supported by continued monitoring of wheat and barley powdery mildew. ©1997 SCI 相似文献
4.
Leo J
T van der Pas Arriënne M Matser Jos J
T
I Boesten Minze Leistra 《Pest management science》1999,55(9):923-934
The behaviour of the herbicide metamitron and of the main transformation product, hydroxy-chlorothalonil (HTI), of the fungicide chlorothalonil was studied to assess the risk of leaching from low-humic sandy soil. The adsorption of metamitron corresponded to a Kom value of about 60 dm3 kg−1 (moderate adsorption). The half-life of metamitron in soil at 15 °C was only three days, presumably due to adaptation of the micro-organisms. In the autumn, the residue of metamitron in the soil profiles corresponded to less than 1% of the cumulative dosage. The half-life of chlorothalonil at 15 °C was about 12 days and about 45% of it was transformed to HTI. The adsorption of HTI to the soils corresponded to a Kom value of 260 dm3 kg−1. The incubation study (15 °C) showed the transformation of HTI in the soils to be very slow. The amounts of HTI remaining in the soil profiles in the autumn corresponded to 4 and 16% of the cumulative dosage of chlorothalonil. In winter, the HTI residue decreased by 40% relative to the autumn level. Occasionally, HTI could be detected in the upper ground-water level (at a depth of about 1 m), at an average concentration of 0.1 to 0.2 µg dm−3. © 1999 Society of Chemical Industry 相似文献
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Amrith S Gunasekara Imma Donna P dela Cruz Matthew J Curtis Victor P Claassen Ronald S Tjeerdema 《Pest management science》2009,65(6):711-716
BACKGROUND: Clomazone is a herbicide used to control broadleaf weeds and grasses. Clomazone use in agriculturally important crops and forests for weed control has increased and is a potential water contaminant given its high water solubility (1100 µg mL?1). Soil sorption is an environmental fate parameter that may limit its movement to water systems. The authors used model rice and forest soils of California to test clomazone sorption affinity, capacity, desorption, interaction with soil organic matter and behavior with black carbon. RESULTS: Sorption of clomazone to the major organic matter fraction of soil, humic acid (HA) (Kd = 29–87 L kg?1), was greater than to whole soils (Kd = 2.3–11 L kg?1). Increased isotherm non‐linearity was observed for the whole soils (N = 0.831–0.893) when compared with the humic acids (N = 0.954–0.999). Desorption isotherm results showed hysteresis, which was greatest at the lowest solution concentration of 0.067 µg mL?1 for all whole soils and HA extracts. Aliphatic carbon content appeared to contribute to increased isotherm linearity. CONCLUSION: The results indicate that clomazone does not sorb appreciably to sandy or clay soils. Its sorption affinity and capacity is greater in humic acid, and consequently clomazone has difficulty desorbing from soil organic matter. Sorption appears to follow processes explained by the dual‐mode model, the presence of fire residues (black carbon) and a recently proposed sorption mechanism. Copyright © 2009 Society of Chemical Industry 相似文献
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Fast BJ Ferrell JA MacDonald GE Sellers BA MacRae AW Krutz LJ Kline WN 《Pest management science》2011,67(7):825-830
BACKGROUND: Bahiagrass (Paspalum notatum Flueggé) is a poor host of several soilborne pests of vegetable crops; therefore vegetable crops are commonly grown in a rotation with bahiagrass pastures in Florida. The herbicide aminopyralid provides foliar and soil residual weed control and increases forage production in bahiagrass pastures; however, the soil residual activity of aminopyralid makes carryover injury likely in subsequent sensitive vegetable crops. Field research was conducted to determine the sensitivity of five vegetable crops to soil residues of aminopyralid. RESULTS: At an aminopyralid soil concentration of 0.2 µg kg?1 (the limit of quantitation for aminopyralid in this research), crop injury ratings were 48% (bell pepper), 67% (eggplant), 71% (tomato), 3% (muskmelon) and 3% (watermelon), and fruit yield losses (relative to the untreated control) at that concentration were 61, 64, 95, 8 and 14% in those respective crops. CONCLUSIONS: The crops included in this research were negatively affected by aminopyralid at soil concentrations less than the limit of quantitation (0.2 µg kg?1). Therefore, it was concluded that a field bioassay must be used to determine whether carryover injury will occur when these crops are planted on a site where aminopyralid has been previously applied. Copyright © 2011 Society of Chemical Industry 相似文献
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BACKGROUND: The purpose of this work was to determine residues of acaricides in recycled Spanish beeswax. RESULTS: Chlorfenvinphos, fluvalinate, amitraz, bromopropylate, acrinathrin, flumethrin, coumaphos, chlorpyrifos, chlordimeform, endosulfan and malathion residues were determined by GC‐µECD/NPD/MS detection. Owing to the extreme instability of amitraz, this analyte was transformed into the stable end‐metabolite 2,4‐dimethylaniline, later derivatised with heptafluorobutyric anhydride and determined by GC‐µECD/MS. Recoveries from spiked samples ranged from 86 to 108%, while quantification limits varied from 0.10 to 0.30 mg kg?1 using GC‐µECD/NPD, and from 12 to 85 µg kg?1 by GC‐MSD. Of a total of 197 samples analysed, only eight samples (4%) were free of residues of chlorfenvinphos (0.019–10.6 mg kg?1), fluvalinate was present in 93.6% of samples analysed (0.027 –88.7 mg kg?1), while coumaphos was confirmed in only five of the 134 samples analysed at concentrations of less than 195 µg kg?1. The remaining acaricides were identified with different levels of incidence at concentrations from 12 to 231 µg kg?1. CONCLUSIONS: Residues of acaricides were found in an extensive number of beeswax samples. The contamination with chlorfenvinphos and tau‐fluvalinate was very relevant, particularly as chlorfenvinphos is not legally authorised for use in beekeeping. The possible impacts of the main acaricides detected on larval and adult honey bees are discussed. Copyright © 2010 Society of Chemical Industry 相似文献
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小麦白粉病菌对喹氧灵和苯菌酮的敏感基线及药剂的生物活性 总被引：3，自引：0，他引：3
采用离体叶段法,分别测定了从河北、河南、湖北、陕西和四川5省分离的53个小麦白粉病菌单孢菌株对苯菌酮和喹氧灵的敏感性,并分析了白粉病菌对三唑酮和苯菌酮以及喹氧灵之间的 交互抗性。结果表明:小麦白粉病菌群体对苯菌酮和喹氧灵的平均EC50值分别为(0.001 9±0.000 6) 和(0.013 1±0.002 0) mg/L,苯菌酮比喹氧灵具有更高的抑菌活性;小麦白粉病菌对三唑酮和苯菌酮与喹氧灵之间均不存在交互抗性(R2值分别为0.102 6和0.491 9);室内盆栽试验结果显示:接种前1 d和接种后1d施药,苯菌酮和喹氧灵对小麦白粉病的保护与治疗作用防效分别为92.21%、84.25%和82.43%、70.25%,表明这2种药剂不仅具有优异的保护作用,同时还具有较好的治疗作用。 相似文献
9.
为研究不同苹果种植模式下土壤养分变化情况,在陕西省千阳县2种不同种植模式(矮化和乔化种植)的苹果园区采集土样,通过测定0~100 cm土层土壤中的全氮、全磷和有效磷含量,分析和比较其土壤氮磷养分含量差异及剖面分布特征。结果表明：在0~100 cm深度的土层中,除全磷外,矮化苹果园土壤各养分含量显著低于乔化苹果园(P<0.05),矮化富士、嘎啦苹果园和乔化富士苹果园全氮含量分别为0.60、0.63、0.76 g·kg-1,全磷含量分别为0.58、0.56、0.63 g·kg-1,有效磷含量分别为6.98、3.48、51.00 mg·kg-1;矮化苹果园全氮、全磷以及有效磷含量主要在0~10 cm的表层土壤中聚集显著(P<0.05);土壤养分含量与土层深度相关性显著(P<0.05),矮化苹果园和乔化苹果园土壤养分含量与土层深度的变化过程分别符合幂函数和对数函数的变化趋势。 相似文献
10.
Biodegradation of [ring-14C] mecoprop (2-(4-chloro-2-methylphenoxy)propionic acid) was determined in surface and sub-surface soil at concentrations of 0·0005, 0·05, 0·5, 5, 50, 500, 5000 and 25000 mg kg-1. The kinetics of mineralisation were evaluated from the mineralisation rates as a function of time and by non-linear regression analysis. In the sub-surface soil, degradation was 6–8 times slower than in surface soil, but the shape of the curves was the same in both layers. At concentrations between 0·0005 and 0·5 mg kg-1, in both surface and sub-surface soil, degradation was initially zero-order followed by first-order kinetics. At 5 to 500 mg kg-1 in surface soil and 5 to 50 mg kg-1 in sub-surface soil the degradation rate was initially either constant or decreasing followed by exponential degradation indicating increasing populations of mecoprop decomposers in the soil. At 5000 and 25000 mg kg-1 in the surface soil and at 500, 5000 and 25000 mg kg-1 in the sub-surface soil, the degradation was negligible, as determined by the percentage [14C] carbon dioxide evolved. By non-linear regression, the three-half order model was found to describe the mineralisation. © 1998 SCI 相似文献
11.
为探讨关中平原小麦-玉米水分高效利用的栽培技术方式,采用田间定点观测方法,研究秸秆还田+接种蚯蚓处理对土壤含水量的影响。设置CK(对照)、S1(秸秆还田3 000 kg·hm-2)、S2(秸秆还田6 000 kg·hm-2)、E(接种蚯蚓)、S1E(秸秆还田3 000 kg·hm-2+接种蚯蚓)、S2E(秸秆还田6 000 kg·hm-2+接种蚯蚓)共6个处理。结果表明：各处理较CK处理均提高了土壤含水量,S1、S2、E、S1E、S2E处理下土壤含水量分别增加0.21%～27.47%、0.43%～32.85%、1.00%～15.53%、3.25%～36.52%、2.97%～51.24%。CK、S1、S2、E、S1E、S2E处理下土壤含水量分... 相似文献
12.
潮棕壤速效磷产量临界值和淋溶临界值的计算 总被引：4，自引：0，他引：4
确定合理磷肥用量对取得高产、提高经济收益和保护环境都有重要意义,而明确土壤速效磷产量临界值与淋溶临界值是界定施肥量适宜与否的必要前提。本文基于下辽河平原长期定位试验,使用直线-平台、双直线和米氏模型计算土壤速效磷产量临界值,通过土柱淋溶试验确定土壤速效磷淋溶临界值。结果表明：该地区玉米和大豆的速效磷产量临界值分别为12.0 mg·kg-1和10.8 mg·kg-1;三个模型中以米氏模型计算的值最高,以直线-平台模型计算的值最低;通过6次淋溶试验,计算的土壤速效磷淋溶临界值在74.6 mg·kg-1到82.0 mg·kg-1之间,均值为80.2 mg·kg-1。在农业生产中应将土壤速效磷控制在12.0～80.2 mg·kg-1之间,可据此指导施肥,达到保证作物生长所需养分,并减少施肥对环境影响的目标。 相似文献
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Quinoxyfen is a protectant fungicide that provides excellent control of many powdery mildew diseases. Prior to the launch of quinoxyfen in vines in 1998, a leaf disc sporulation assay was developed to assess the sensitivity of Uncinula necator (Schw) Burr to quinoxyfen. The distribution of EC(50) values from 56 monoconidial U. necator isolates collected from six countries between 1993 and 1996 was found to range from less than 0.03 to 2.6 mg litre(-1). Although this range of EC(50) values was quite broad, the inability to establish a minimum inhibitory concentration (MIC) for the majority of these isolates, including some of the most sensitive isolates, was unexpected and suggested that the leaf disc sporulation assay may not reflect the true activity of quinoxyfen in the field. In 2002, following the detection of isolates resistant to quinoxyfen in Blumeria graminis Speer f. sp. tritici Marchal, a discriminatory dose screen was developed to test large populations of U. necator for rare individuals with significantly decreased sensitivity to quinoxyfen. The individual isolates selected by this method were tested with the leaf disc sporulation assay. Although a significant proportion were found to have EC(50) values within the original distribution, a number of isolates with apparent reduced sensitivity to quinoxyfen were also detected. However, further examination of a subset of these isolates in a more quantitative germination/germ tube elongation inhibition assay suggested that the magnitude of the reduction in sensitivity for some of these isolates was much less than predicted by the sporulation assay. Thus, for an exclusively protectant fungicide such as quinoxyfen, a leaf disc sporulation assay may overestimate the frequency of isolates with significantly reduced sensitivity and the threat of decreased performance due to resistance. 相似文献
14.
James D Hansen Charles R Sell Harold R Moffit James G Leesch Preston L Hartsell 《Pest management science》2000,56(6):555-559
Methyl bromide fumigations are used to treat apples, Malus domestica Borkh, and sweet cherries, Prunus avium (L), before export to Japan. In order to expand existing markets, additional cultivars are being prepared for export to Japan. As part of the approval process, residue analyses must be conducted and residues must be at acceptable levels. Five apple cultivars (‘Braeburn,’ ‘Fuji,’ ‘Gala,’ ‘Jonagold,’ and ‘Granny Smith’) were fumigated at 40 g m−3 for 2 h at 10 °C, and six sweet cherry cultivars (‘Brooks,’ ‘Garnet,’ ‘Lapin,’ ‘Rainier,’ ‘Sweetheart,’ and ‘Tulare’) were fumigated for 2 h with 64 g m−3 at 6 °C, 48 g m−3 at 12 °C, 40 g m−3 at 17 °C, and 32 g m−3 at 22 °C. Three replicates of fruit from each fumigation were analyzed for methyl bromide and bromide ion residues periodically with time. Methyl bromide residues for both apples and cherries were the highest immediately after fumigation, but rapidly declined so that only ‘Braeburn’ had residues >8 µg kg−1 after 13 days and, except for ‘Lapin,’ all cherries were <1 µg kg−1 after seven days. Average bromide ion residues were between 3.3 and 4.9 mg kg−1 among apple cultivars, and between 3.7 and 8.0 µg kg−1 among cherry cultivars. Published in 2000 for SCI by John Wiley & Sons, Ltd 相似文献
15.
渭干河—库车河三角洲绿洲棉田土壤盐分估算及遥感反演 总被引：1，自引：0，他引：1
基于研究区的野外采样数据与Landsat 8遥感影像提取的增强型植被指数,构建渭干河—库车河三角洲绿洲棉田土壤盐分估算模型,并对土壤盐分的空间分布格局进行预测。结果表明:(1)由土壤含盐量与增强型归一化植被指数(ENDVI)构建的线性回归模型(y=-56.494x+22.687)拟合效果最好(R2=0. 886,RMSE=0. 907)。(2)通过选取的82个采样点,依据最佳遥感反演模型,预测出研究区土壤含盐量在9.33～26.99 g·kg-1之间变化,平均值为17.42 g·kg-1,标准差为2.30 g·kg-1,预测结果与土壤盐分的实测值较为一致。(3)利用地统计分析方法制作研究区棉田土壤盐分的空间分布图,分析可知土壤盐分从绿洲内部向外围呈逐渐增加的趋势。 相似文献
16.
Helvi Heinonen-Tanski Hilkka Siltanen Sisko Kilpi Paavo Simojoki Christina Rosenberg Seppo Mkinen 《Pest management science》1986,17(2):135-142
The study deals with the effect of common, annually-used pesticides on soil microorganisms, pesticide residues in soil, and carrot (Daucus carota) yields in Central Finland. Linuron residues in carrot roots were also analysed. Thiram+lindane and dimethoate were applied from 1973–1981 at the commercially recommended doses on experimental plots of carrots, linuron was applied at twice the recommended rate from 1973–1979 and at the normal rate thereafter and in addition TCA was applied in 1978. Maleic hydrazide was used in the years 1973–1976, and glyphosate after 1977. The numbers of different soil microorganisms, their activities and the pesticide residues were studied from autumn 1978 to 1981. The pesticide treatments reduced the growth of soil algae but increased the total number of microorganisms and the number of aerobic spore-forming bacteria. Linuron residues in the soil were 0.9–2.8 mg kg?1 in the growing season and 1.2–1.7 mg kg?1 in the autumn, 3 months after application. The residues of glyphosate in the soil were 0.7 mg kg?1 in the autumn, 41 days after the treatment, and had declined to a level of about 0.2 mg kg?1 by the following summer. In the pesticide-treated plots the carrot yield was only 20–60% of the yield in the hand-weeded plots. The herbicide programme controlled most of the annual weeds but not couchgrass Elymus repens and milk sow-thistle Sonchus arvensis. 相似文献
17.
Sanitation from harvest to storage is a key factor in eliminating sources of infection and reducing levels of mycotoxigenic fungal invasion, and thereby mycotoxin contamination. This study was conducted at Haramaya University, Eastern Ethiopia to investigate the effects of threshing methods on fungal invasion and mycotoxin contamination of sorghum grain. The methods included threshing on bare ground, cow-dung-painted ground, concrete asphalt and canvas. The threshed grain was kept separately in bags in three replications in a completely randomized design and stored for five months. The results revealed that all the sorghum grain samples taken from different threshing methods were contaminated with both Aspergillus and Fusarium species. There were variations in fungal invasion between samples taken immediately after threshing and stored samples. The level of Aspergillus spp. invasion was much higher in the latter in sorghum grain threshed on bare ground. The concentration of aflatoxin B1 was gradually increased, whereas the total fumonisin concentration was decreased with the storage duration both in 2013 and 2014. On stored sorghum grain, the highest (1.97 µg kg?1) and the lowest (0.70 µg kg?1) mean aflatoxin B1 concentrations were recorded from sorghum grains threshed on bare ground and on canvas, respectively. Sorghum grain obtained from canvas threshing method had significantly lower mean total fumonisin content (142.5, 54.9 µg kg?1) than grain from the other methods at threshing. The current work clearly demonstrated the effect that threshing might have on fungal invasion and mycotoxin contamination of sorghum grains. . 相似文献
18.
Daniel A Potter Carl T Redmond Kumudini M Meepagala David W Williams 《Pest management science》2010,66(4):439-446
BACKGROUND: Earthworm casts are a worldwide problem on golf courses and sports fields when they disrupt the playability, aesthetics and maintenance of closely mowed playing surfaces. Currently, no pesticides are labeled for earthworms in the United States. Tea seed pellets (TSPs), a saponin‐rich byproduct of Camellia oleifera Abel oil manufacture, were tested for expelling earthworms and reducing casts on creeping bentgrass turf. The fate of expelled worms, methods for removing them and impacts on pest and beneficial arthropods were also evaluated. RESULTS: Application of TSPs at 2.93 kg 100 m?2, followed by irrigation, quickly expelled earthworms from the soil. A single application reduced casts by 80–95% for at least 5 weeks. Mowing or sweeping removed expelled earthworms from putting green surfaces. Most expelled earthworms burrowed down when transferred to untreated turf, but few survived. Bioassay‐guided fractionation confirmed the vermicidal activity results from a mix of saponins. TSPs did not reduce the abundance of beneficial soil arthropods, nor did they control black cutworms or white grubs in treated turf. CONCLUSION: TSPs are an effective botanical vermicide that could be useful for selectively managing earthworm casts on closely mowed turfgrass. They might also be used to suppress earthworms in grassy strips alongside runways to reduce bird strike hazard at airports. Copyright © 2009 Society of Chemical Industry 相似文献
19.
Dimitrios G Karpouzas Allan Walker Donald S
H Drennan Robert J Froud‐Williams 《Pest management science》2001,57(1):72-81
Carbofuran was incubated in top‐soil and sub‐soil samples from a pesticide‐free site at a range of initial concentrations from 0.1 to 10 mg kg−1. Amounts of the incubated soils were removed at intervals over the subsequent 12 months, and the rate of degradation of a second carbofuran dose at 10 mg kg−1 was assessed. An applied concentration as low as 0.1 mg kg−1 to top‐soil resulted in more rapid degradation of the fresh addition of carbofuran for at least 12 months. The degree of enhancement was generally more pronounced with the higher initial concentrations. When the same study was conducted in sub‐soil samples from the same site, an initial dose of carbofuran at 0.1 mg kg−1 resulted in only small increases in rates of degradation of a second carbofuran dose. However, degradation rates in the sub‐soil samples were, in many instances, considerably greater than in the corresponding top‐soil samples, irrespective of pre‐treatment concentration or pre‐incubation period. Initial doses of 0.5 mg kg−1 and higher applied to sub‐soil successfully activated the sub‐soil microflora. Application of the VARLEACH model to simulate carbofuran movement through the soil profile indicated that approximately 0.01 mg kg−1 of carbofuran may reach a depth of 70 cm 400 days after a standard field application. The results therefore imply that adaptation of the sub‐soil microflora (c 1 m depth) by normal field rate applications of carbofuran is unlikely to occur. In experiments to investigate this in soils exposed to carbofuran in the field, there was no apparent relationship between top‐soil exposure and degradation rates in the corresponding sub‐soils. The results further confirmed that some sub‐soil samples have an inherent capacity for rapid biodegradation of carbofuran. The high levels of variability observed between replicates in some of the sub‐soil samples were attributed to the uneven distribution of a low population of carbofuran‐degrading micro‐organisms in sub‐surface soil. There was no apparent relationship between soil microbial biomass and degradation rates within or between top‐soil and sub‐soil samples. © 2001 Society of Chemical Industry 相似文献
20.
以民勤不同年限(1、2、4、8、13 a)退耕地为研究对象,以当年耕地作为对照,采用时空替代法及通径分析法研究不同年限退耕地土壤理化性质、土壤酶活性变化特征及二者的相关关系.结果表明:(1)随着退耕年限的增加土壤速效钾含量表现为缓慢上升趋势,在退耕13 a达到峰值(411 mg·kg-1);其余理化指标均在退耕13 a... 相似文献