Influence of soil pH and contents of organic carbon and clay on the volatilization of [14C]fenpropimorph after application to bare soil

The behaviour of the morpholine fungicide fenpropimorph applied to soil was investigated in a laboratory chamber. The volatility and metabolism of a ¹⁴C-labelled fenpropimorph formulation (Corbel^®) was studied after application to three soils (sandy loam, loamy clay and loamy sand), simulating a four-day weather scenario in the volatilization chamber. Additional experiments were conducted under standard climatic conditions over a period of 24 h using sandy soils with different pH values. The results of the first experiments showed that most of the radioactivity applied remained in the soils as unchanged fenpropimorph four days after application. In the experiments with the sandy loam and loamy clay, less than 5% of the applied radioactivity was removed by volatilization whereas 11·4% volatilized from the surface of the loamy sand. The comparatively higher volatilization of the fungicide from the loamy sand was confirmed by the later experiments indicating that higher soil pH favoured volatilization of [¹⁴C]fenpropimorph from sandy soils. Thus 5·6% (pH 5·0), 18·9% (pH 5·8) and 28·3% (pH 6·6) of the radioactivity applied volatilized within one day after application. The overall recoveries were between 93·8% and 111·3% in these experiments. © 1998 SCI     

不同施肥土壤对尿素NH3挥发的影响

经过6a长期不同施肥定位试验,使同一土壤形成肥力上的差异,对此土壤进行室内氨挥发模拟试验。研究结果表明,施用等量尿素条件下,不同施肥土壤氨挥发损失具有明显差异,长期施N土壤,可缩短氨挥发时间3～4d,并且可明显降低挥发损失量。长期施用P肥土壤也能降低氨挥发损失量。并且氨挥发损失量与土壤有机质含量显著相关。     

施氮量对库尔勒香梨园氨挥发和氧化亚氮排放的影响

为了解库尔勒香梨园土壤氮素气态损失,采用密闭式集气法和静态箱气相色谱法对不同氮肥用量下的土壤氨挥发和氧化亚氮排放进行研究,并设置了5个处理：不施肥（N₀P₀K₀）、不施氮肥（N₀PK）、施氮150 kg·hm^-2（N₁PK）、施氮300 kg·hm^-2（N₂PK）、施氮450 kg·hm^-2（N₃PK）。结果表明：氨挥发速率和氧化亚氮排放通量均在施基肥和施追肥后第4天出现峰值和次峰值,且氨挥发速率和氧化亚氮排放通量均随着施氮量的增加而增大;各处理氨挥发累积量达到27.886～44.416 kg·hm^-2·a^-1,施氮处理氨挥发净损失量达到6.726～16.197 kg·hm^-2·a^-1,各处理氧化亚氮累积量达到341.616～531.960 g·hm^-2·a^-1,施氮处理氧化亚氮净损失量达到90.452～185.412 g·hm^-2·a^-1,氨挥发累积量和净损失量与氧化亚氮累积量和净损失量均随着施氮量的增加而增加;施氮处理氨挥发净损失率为2.720%～4.480%,氧化亚氮净损失率为0.038%～0.060%,氨挥发和氧化亚氮净损失率随着施氮量的增加均表现为先减小再增大;施用氮肥能显著增加0～20 cm和20～40 cm土层中铵态氮和硝态氮含量;相关分析表明,氨挥发速率和氧化亚氮排放通量与施氮量和土壤温度呈极显著正相关关系;N₂PK处理的库尔勒香梨产量最高,达到6 213.5 kg·hm^-2,且氨挥发净损失率和氧化亚氮净损失率均最小,为2.720%和0.038%。从库尔勒香梨园土壤氮素气态损失和生产角度看,纯氮用量为300 kg·hm^-2时最佳。     

秸秆粉碎带膜还田对玉米氮肥追施过程土壤氨挥发的影响初探

为探讨河西绿洲灌区玉米秸秆粉碎带膜还田对春玉米氮肥追施过程土壤氨挥发的影响,设置不还田（CK）、传统粉碎全地翻压覆膜还田(CM)、全量粉碎带状翻压覆膜还田(CB)、全量整株带状覆盖覆膜还田(WM)4个处理,采用密闭法测定各处理在追肥过程中土壤氨挥发的动态过程。结果表明,拔节期追肥后,CM和CB处理的氨挥发肥料损失累积量分别为76.94 g·hm^-2和85.49 g·hm^-2,占追肥量的0.06%和0.07%,相比不还田CK处理差异显著,降幅达到了71.24%和68.04%;WM处理的氨挥发肥料损失累积量为253.50 g·hm^-2,占追肥量的0.21％,相比不还田CK处理差异不显著,降幅仅为0.96％。大喇叭口期追肥后,CM、CB、WM处理的氨挥发肥料损失累积量分别为37.92、33.45、40.88 g·hm^-2,分别占追肥量的0.02%、0.02%、0.03％,相比不还田CK处理差异不显著,CM和CB处理的降幅仅有3.76%和15.09%,WM处理的增幅为1.04％。整个追肥过程中CM、CB、WM处理的的氨挥发肥料损失累积量分别为114.86、118.94、294.39 g·hm^-2,分别占追肥量的0.08%、0.10%、0.20％,相比不还田CK处理的降幅分别达到了61.58%、61.25%、0.91％。综上所述,全量粉碎带状翻压覆膜还田和传统粉碎全地翻压覆膜还田对土壤氨挥发的抑制作用显著且基本相当,全量整株带状覆盖覆膜还田对土壤氨挥发的抑制无显著效果。可见,在河西绿洲灌区,采用秸秆粉碎带膜还田措施来抑制玉米全生育期化学氮肥追施后的氨挥发效果显著。     

垄作覆膜条件下冬小麦田的氨挥发研究

为了解垄作覆膜下氨挥发特点,采用密闭法研究了垄作覆膜条件下冬小麦田间氨挥发的动态过程,并结合室内模拟比较了覆膜和氮肥深施对氨挥发的影响.大田实验结果表明,垄作覆膜处理可显著减少田间氨挥发.垄作覆膜180 kg N/hm2和240 kg N/hm2处理下的氨挥发量分别为:1.9±0.2 kg N/hm2和2.4±0.7 ...     

Influence of Compost Addition to Soil on the Behaviour of Herbicides

The transformations of eight herbicides (atrazine, simazine, terbutryn, pendimethalin, carbetamide, 2,4-D, metsulfuron-methyl and dimefuron) in soil after compost addition were monitored during long-term laboratory incubations. The herbicides were applied to soil, compost and soil-compost mixtures. Herbicide sorption, their kinetics of mineralisation and the extractability of residues were compared in the different treatments. Compost addition to soil generally decreased herbicide mineralisation and favoured the stabilisation of herbicide residues. A fraction of the stabilised residues remained extractable and potentially available. However, most of them were unextractable and formed bound residues. Sorption could be at the origin of a kinetically limited biodegradation, mainly for the most highly-sorbed herbicides (atrazine, simazine, terbutryn, pendimethalin and dimefuron). Compost addition had little effects on the less sorbed herbicides (carbetamide, 2,4-D and metsulfuron- methyl). © 1997 SCI.     

Surface application of ammonium thiosulfate fertilizer to reduce volatilization of 1,3‐dichloropropene from soil

Atmospheric emission of the soil fumigant 1,3‐dichloropropene (1,3‐D) is of environmental concern because of its toxicity and carcinogenicity. Thiosulfate fertilizers have been found to rapidly transform 1,3‐D in soil to non‐volatile ions which are less toxic. We investigated the use of surface application of ammonium thiosulfate (ATS) for reducing 1,3‐D volatilization. In packed soil columns, emission of 1,3‐D applied by sub‐surface injection decreased with increasing ATS application rate and the amount of water used for delivering ATS. When ATS was applied in 9 mm water at 64 g m⁻², total 1,3‐D emission was reduced by 61%. The reduction was 89% when ATS was applied at 193 g m⁻². Bioassays showed that ATS application did not affect the effectiveness of 1,3‐D for controlling citrus nematodes. In field plots where a 1,3‐D emulsified formulation was applied via sub‐surface drip, surface spray of ATS reduced 1,3‐D emissions by 50%, and by 71% when the surface was also covered with polyethylene film. ATS application had no effect on the efficacy of root‐knot nematode control or tomato yields. These results suggest that surface application of thiosulfate fertilizers may be a feasible and effective strategy for minimizing 1,3‐D emissions. © 2000 Society of Chemical Industry     

有机无机肥配施对宁夏引黄灌区露地菜田土壤氨挥发的影响

为了探讨宁夏引黄灌区露地菜田土壤氨挥发损失特征,于2013年5—9月在该区域露地花椰菜-大白菜轮作体系下,采用田间小区试验,研究了不同有机无机肥配施对土壤氨挥发速率、氨挥发损失通量及其损失率的影响。结果表明:露地花椰菜和大白菜基肥后,不同有机无机肥配施处理下土壤氨挥发损失高峰通常出现在第1~4天,而追肥后提前到1~2天,在高量施氮处理下,氨挥发延续时间在10天以上;花椰菜季大多数施肥处理的氨挥发损失发生在追肥阶段(占总氨挥发损失通量的50.2%~60.3%,单施有机肥和低氮处理除外),大白菜季各处理的氨挥发损失主要在基肥阶段(占总氨挥发损失通量的57.0%~73.6%);露地花椰菜基肥和追肥后,不同施肥处理下土壤氨挥发最大速率分别在0.79~4.56、1.00~5.34 kg·hm-2·d-1之间,而露地大白菜季分别为3.49~13.09、1.54~7.03 kg·hm-2·d-1;不同有机无机肥配施下,花椰菜和大白菜全生育期内土壤氨挥发损失通量分别为5.15~35.82、11.11~70.60 kg·hm-2,其随总施氮量的增加而增加;花椰菜和大白菜季不同施肥处理的土壤氨挥发损失率分别为4.02%~4.87%和2.54%~10.55%,其化肥贡献率分别为62.0%~100.0%和85.5%~100.0%,且化肥贡献率随化学氮肥用量的增加而增加。因此,在同等施用有机肥的情况下,合理降低化肥氮用量是减少该地区露地菜田土壤氨挥发损失的重要措施。     

Study on the behaviour of imazapyr in two Moroccan soils

Imazapyr owes its importance in Morocco to its success in controlling the perennial weed Solanumelaeagnifolium Cav., which infests the Tadla area. Persistence and mobility of imazapyr has been studied in two Moroccan soils from the Rabat area, with differing organic matter content (red and organic soils), under laboratory conditions at 75% of their field capacities and 25–28 °C. Residue analysis was performed on the basis of a bioassay test using lentil (Lens culinaris Medic.) as indicator species. The residual activity of imazapyr accounted for 69%, 25%, 50% and 62%, 46%, 66% of the initial activity for the red and organic soils at 1, 5 and 10 mg L^?1 respectively. The half-lives varied between 25 and 58 days for the red soil and 55 and 58 days for the organic soil. In the organic soil, imazapyr was highly mobile under the irrigation regime applied. Most of the activity was found in the first 3 × 75 mL of the effluents. A following biotest with the leached soil showed low remaining residual activity.     

C/N比对好氧堆肥中NH3挥发损失和含氮有机物转化的影响

利用牛粪和不同比例玉米秸秆的混合,设置5个不同C/N比处理(T1=15、T2=20、T3=25、T4=30、T5=35),研究其对条垛式好氧堆肥过程中的NH₃挥发损失和含氮有机物转化的影响。结果表明:在肥堆前24 d有11.1%～23.1%的总氮损失,堆体C/N比越低,总氮损失率越高。堆肥结束时,T1～T5处理的总氮损失率为10.1%～24.1%,其中由NH₃挥发造成的氮损失占总氮损失的30.9%～40.5%。堆肥过程的NH₃挥发主要发生在升温期和高温期,此期的NH₃挥发量占总挥发量的95%以上,是总氮损失的主要途径。堆肥前6 d各处理堆体铵态氮积累并达到最高值,导致pH值迅速升高,是造成堆肥NH₃挥发的直接原因。堆体C/N比越低,pH值越高,NH₃挥发量越大,由此造成的氮损失占总氮损失的比例越大。堆肥材料总氮的90%以上为有机氮,其降解主要发生在堆肥前24 d,堆体初始C/N比越低,有机氮矿化越快。不同有机氮组分的降解速率不同,以氨基酸态氮和酰胺态氮的降...     

Behaviour of sulcotrione and mesotrione in two soils

The behaviour of sulcotrione, a recently introduced triketone herbicide, in various soil types was studied under laboratory conditions. In particular, degradation and sorption processes were examined on Ghent and Perpignan soils. Kinetics showed that the degradation of sulcotrione was influenced by biotic and/or abiotic factors. Half-lives ranged between 45 and 65 days. Among the degradation compounds identified were 1,3-cyclohexanedione (CHD) and 2-chloro-4-mesyl benzoic acid (CMBA), previously described as hydrolysis products, and, under special conditions, a derivative of phenylheptanoic acid (PHD). This new degradation product suggested that sulcotrione could follow two possible pathways in the soil, as in water. During the sorption study, a moderate retention of sulcotrione and CMBA relative to CHD and PHD, which were highly adsorbed whatever the soil type, was reported. Experiments carried out under the same conditions for sulcotrione and mesotrione, another triketone herbicide recommended in maize culture, made it possible to compare the two triketones and to conclude that they exhibited relatively similar behaviour in the soil, i.e. that their leaching potential needs to be properly addressed and risks evaluated. Copyright (c) 2007 Society of Chemical Industry.     

Influence of nitrogen fertilisers on the persistence of carbaryl and carbofuran in flooded soils

Ammonium sulphate and urea, but not potassium sulphate, increased the persistence of carbaryl in a flooded laterite soil with a low native nitrogen content (0.04%), but not in an alluvial soil with a higher nitrogen content (0.11%). Thus, NH₄⁺ but not SO₄^2-, contributed to the increased persistence of carbaryl. Likewise, ammonium sulphate increased the persistence of carbofuran in the laterite soil, but not in the alluvial soil. Significant accumulations of 1-naphthol and 2,3-dihydro-2, 2-dimethylbenzofuran-7-ol (‘carbofuran phenol’), in soils treated with carbaryl or carbofuran, suggested hydrolysis as the major pathway of degradation. Treatment of the two soils with ammonium sulphate, urea or potassium sulphate led to a decrease in soil-bound residues and an increase in the respective hydrolysis products, compared with untreated soils. Sorption studies indicated that NH₄⁺ and SO₄^2- compete with carbaryl, 1-naphthol and carbofuran for sorption and exchange sites in the complex soil system. Evolution of [¹⁴C]carbon dioxide from ring-¹⁴C in carbaryl and carbofuran was negligible. Consequently, after 40 days, more than 50% of the ¹⁴C in [¹⁴C]carbaryl and [¹⁴C]carbofuran remained in the soils as hydrolysis products (1-naphthol or 2,3-dihydro-2,2-dimethylbenzofuran-7-ol) plus soil-bound residues.     

载体中蓟马聚集信息素组分的释放速率测定及其储藏温度筛选

为明确蓟马聚集信息素组分在2种常用载体中的释放规律,应用固相微萃取(SPME)和气相色谱-质谱联用技术测定不同聚集信息素剂量(1、10、100μg)和萃取时间(30、60、120 min)下SPME萃取头对载体中3种蓟马聚集信息素组分的萃取效率,筛选最佳萃取条件,并分析储藏温度对载体中蓟马聚集信息素组分释放速率的影响。结果表明,在橡胶塞和PVC管2种载体中,相同聚集信息素剂量下,与萃取30 min处理相比,萃取60、120 min时SPME萃取头对载体释放的3种聚集信息素组分的萃取效率或无显著差异,或随萃取时间增加而呈现降低趋势;相同萃取时间下,SPME萃取头对载体释放的3种聚集信息素组分的萃取效率均随剂量增加而显著增大。因此,测定载体中聚集信息素释放速率的最佳条件为萃取时间30 min、剂量100μg。室温25℃储藏条件下,橡胶塞和PVC管中3种聚集信息素组分的释放速率均在存储2 d时最高,之后随存放时间的延长而逐渐降低;-20℃储藏条件下,载体中3种聚集信息素组分的释放速率随着存放时间的延长相对稳定,56 d内释放速率均处于较高水平,且显著高于室温下储藏载体中聚集信息素组分的释放速率。表明-20℃储藏可有效减少载体中聚集信息素组分的损耗,即-20℃是聚集信息素载体储藏的适宜温度。     

Influence of plastic mulching and disinfection on the fungal flora of soils in Belgium1

Plastic mulching was tested in Belgium over several years as a method for modifying the population of pathogens and saprophytic fungi in the soil, both in the glasshouse and in the field. The plastic film was kept on the soil for 3 or 6 months, and treatments with formaldehyde, methyl bromide or dazomet were also applied. In the glasshouse the fungal flora was decreased after 6 months’plastic cover without disinfectants, especially for Mucor and Rhizoctonia, but Trichoderma was favoured. The plastic layer together with formaldehyde resulted in 50% killing of soil fungi. In the field with plastic layer only, there was a slight decrease in some fungi and an average increase in bacteria. With plastic combined with formaldehyde (250 ml m^-2), methyl bromide (100 gm^-2) or dazomet (80 g m^-2), better results were obtained. Fungi were reduced 75% with formaldehyde and 80–100% with methyl bromide or dazomet depending on soil depth. Qualitatively there was a clear shift towards Trichoderma, while pathogenic fungi such as Verticillium and Fusarium were nearly 100% killed.     

Co‐solvent effects on the adsorption of carbofuran by two Indian soils

The adsorption of carbofuran on soils from water‐methanol mixtures has been evaluated by batch shake testing. Two uncontaminated soils having different physicochemical properties were used in these experiments. The volume fraction of methanol in the liquid phase (f_s) was varied from 0.25 to 1.0. Higher adsorption of carbofuran was observed in medium black (silt loam) soil than in alluvial (sandy loam) soil; calculated values of the Freundlich constant (K^m) and distribution coefficient (K_d) showed that adsorption of carbofuran in both soils decreased with increase in f_S values. The decreased carbofuran adsorption in methanol–water mixtures meant a greater potential of ground‐water contamination through leaching from potential sites. The data have been used to evaluate the co‐solvent theory for describing adsorption of carbofuran in methanol–water mixtures. The aqueous phase partition coefficient K_dw (mol g⁻¹) normalized with respect to f_oc and the aqueous phase adsorption constant K_w for carbofuran were evaluated by extrapolating to f_S = 0. © 2000 Society of Chemical Industry     

红火蚁入侵对荔枝园土壤性理化质的影响

对红火蚁Solenopsis invicta Buren荔枝园发生区土壤理化性质进行了研究,结果表明:3类红火蚁不同发生区之间、红火蚁蚁巢4个不同方位之间以及距红火蚁蚁巢中心不同距离之间的土壤各项理化性质均有显著的差异(p<0.01)。从对照区、轻度发生区到重度发生区土壤粘粒变得越来越细,酸性逐渐升高。土壤有机质、碱解N、有效P的含量在轻、重度发生区较对照区分别下降了29.0%与39.9%、42.1%与53.6%、43.3%与52.6%,但速效K的含量在轻、重度发生区较对照区则分别升高了8.5%与34.0%。此外,在红火蚁发生区,蚁巢上的土壤理化性质与蚁巢以外的土壤理化性质明显不同(p<0.01)。蚁巢上的土壤明显比蚁巢以外的土壤酸性强。土壤有机质、碱解N、有效P的含量在蚁巢上明显最小,但土壤速效K的含量在蚁巢上明显最高。蚁巢不同方位上土壤的理化性质相对差异较小,红火蚁在荔枝园的分布存在一定的空间随机性。     

Effect of freezing and thawing on microbial activity and glyphosate degradation in two Norwegian soils

Little research has been done on pesticide dissipation in cold climates and there is a need to focus on the influence of climate on pesticide degradation in soil. Glyphosate, N-(phosphonomethyl)glycine, is a herbicide frequently used for controlling perennial weeds through application after harvest and was used as a model compound for this study. The effect of freeze-thaw activity on the availability of glyphosate in soil, and consequently its mineralization by soil microorganisms, was studied through laboratory incubations of repacked soil cores treated with 14C-labelled glyphosate and subjected to different freeze-thaw treatments. Winter simulation regimes applied were constant thaw (+5 degrees C), constant freezing (-5 degrees C), unstable conditions with short fluctuations (24 h of -5 degrees C followed by 24 h of +5 degrees C), and long duration fluctuations (3 weeks of -5 degrees C followed by 3 weeks of +5 degrees C). Distribution of 14C-glyphosate was followed during the incubation through measurements of the mineralized fraction (14CO2), soil water fraction, KOH extractable fraction, and non-extractable fraction. Microbial parameters used to characterize the soils were estimates of size of microbial biomass, overall microbial activity and microbial diversity. The constant freezing treatment exhibited the lowest amount of glyphosate mineralization. The constant thawed treatment and the treatments with fluctuating temperature exhibited significantly increased mineralization. These results were in accordance with the observed concentration of glyphosate in soil water; the higher the activity, the lower the concentration. The amount of glyphosate extractable with KOH and the resulting non-extractable fraction, however, were not significantly affected by soil type or temperature regime. The glyphosate mineralization pattern was comparable with the overall microbial activity in the soils. Observed different levels of diversity might explain some of the difference in total glyphosate mineralization between soils.     

土壤温、湿度对两种微胶囊杀虫剂毒力的影响

以华北大黑鳃金龟幼虫为生测对象,在常规毒力测定的基础上研究土壤温、湿度对35%辛硫磷和30%毒死蜱微囊悬浮剂毒力的影响。结果显示:35%辛硫磷微囊悬浮剂对华北大黑鳃金龟幼虫的毒力高于30%毒死蜱微囊悬浮剂,约是其毒力的3～9倍;在试验湿度和温度范围内,35%辛硫磷和30%毒死蜱微囊悬浮剂对供试幼虫的杀虫效果随着温度的升高而逐渐增强;在相同温度条件下,2种微囊制剂在含水量为10%的土壤中杀虫效果高于含水量20%的土壤。     

Influence of temperature and storage conditions on the hatching behavior of cereal cyst nematodes (Heterodera avenae Wollenweber) from Egypt

Journal of Plant Diseases and Protection - The cereal cyst nematode Heterodera avenae has been reported in wheat fields in Egypt; however no information is available on the hatch of second-stage...     

Influence of temperature and soil moisture on the relation between Tylenchorhynchus dubius and Lolium perenne

The relation between the ectoparasitic nematodeTylenchorhynchus dubius and the growth and production ofLolium perenne during the first month after sowing, was studied in pot experiments at several temperatures, and moisture levels.The nematode reduced the growth of the grass, mainly as a result of activity during the first weeks after seeding. The percentage decrease of dry matter yield was smaller when temperature was more favourable for plant growth. Decreased moisture content of the soil enhanced the effect of nematodes at 10°C.Samenvatting De relatie tussen de ectoparasitaire nematodeTylenchorhynchus dubius en de groei en produktie vanLolium perenne gedurende de eerste maand na inzaai werd bestudeerd in potproeven bij verschillende temperaturen en vochtgehaltes van de grond.De nematode veroorzaakte groeireductie die vooral een gevolg was van nematoden-activiteit in de eerste weken na inzaai. Het procentuele effect op de droge-stofopbrengst was kleiner naarmate de temperatuur dichter bij de optimumtemperatuur voor de groei van de plant lag. Bij 10°C versterkte een lager vochtgehalte van de grond het effect van de nematoden.