Poorly crystalline iron and aluminium oxides contribute to the carbon saturation and sorption of dissolved organic carbon in the soil     

Tania Khandakar  Chris Guppy  Sheikh M. F. Rabbi  Heiko Daniel 《Soil Use and Management》2021,37(1):120-125

Soil carbon (C) saturation implies an upper limit to a soil's capacity to store C depending on the contents of silt + clay and poorly crystalline Fe and Al oxides. We hypothesized that the poorly crystalline Fe and Al oxides in silt + clay fraction increased the C saturation and thus reduced the capacity of the soil to sorb additional C input. To test the hypothesis, we studied the sorption of dissolved organic carbon (DOC) on silt + clay fractions (<53 µm) of highly weathered oxic soils, collected from three different land uses (i.e., improved pasture, cropping and forest). Soils with high carbon saturation desorbed 38% more C than soils with low C saturation upon addition of DOC, whereas adsorption of DOC was only observed at higher concentration (>15 g kg^?1). While high Al oxide concentration significantly increased both the saturation and desorption of DOC, the high Fe oxide concentration significantly increased the desorption of DOC, supporting the proposition that both oxides have influence on the DOC sorption in soil. Our findings provide a new insight into the chemical control of stabilization and destabilization of DOC in soil.  相似文献   

王正非林火蔓延模型改进研究     

张晓婷  刘培顺  王学芳 《山东林业科技》2020,50(1):1-6,40

王正非林火蔓延模型是目前国内比较先进的森林火灾蔓延模型,但是由于林火行为的复杂性,此模型在准确率和普适性方面仍存在许多不足。本文结合已有的成果进一步改进王正非模型,增加了可燃物湿度对林火蔓延速度的影响,改进了林火初始速度的计算方式。针对各种坡度对林火蔓延行为的影响给出了一个计算公式。与改进前相比,改进后的模型使其对林火蔓延情况的预估更为精准。  相似文献   

酸碱对低活力苜蓿种子萌发及初期生长的影响   总被引：2，自引：0，他引：2  

赵树兰 《黑龙江畜牧兽医》2003,(9):13-14

以H2SO4，HCl，HNO3及NaOH为激活荆，研究其对低活力苜蓿种子萌发及初期生长产生的影响。结果表明：不同酸碱处理及其时间不同，效果差异明显，但各处理在不同程度上均对苜蓿种子萌发和初期生长有促进作用；尤其是短时间HNO3处理，对激发苜蓿种子活力效果最佳。  相似文献   

冻融中土壤的水热动态     

张转放  赵小雯  华孟 《中国农业大学学报》1992,(3):287-292

根据在北京郊区的试验,认为土壤水冻融过程可分为三阶段,其中第二阶段有聚墒现象,平均聚墒8.6mm,所聚的墒在融化过程中又逐渐消失。气温回升至-2℃左右是冻层下部由冻到融的转折温度。冬灌水保存到来年春季的数量有限,本试验中1m 土层内平均不足20mm。  相似文献   

Periodicity and gradients in dispersal ofAlternaria linicola in linseed crops     

I. Vloutoglou  B. D. L. Fitt  J. A. Lucas 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(6):639-653

Conidia ofAlternaria linicola produced on infected linseed crops were mainly dispersed by wind. The numbers of conidia in the air above linseed crops collected by a Burkard spore sampler were greatest between 1200 h and 1300 h, when the relative humidity was lowest. Although numbers of conidia collected decreased with increasing height within and above the crop canopy, air-borneA. linicola conidia were present up to 80 cm above the crop canopy. Conidia ofA. linicola were transported by wind up to at least 40 m downwind from an artificial line inoculum source, but their numbers decreased with increasing distance from the source. In 1991, 1992, and 1993, the dispersal ofA. linicola conidia above linseed crops followed a seasonal periodicity which was influenced by weather conditions and cultural practices. The greatest numbers of conidia were collected during July, August and early September and coincided with periods favourable for sporulation and with an increase in the incidence of the disease in the senescent crop. Air-borneA. linicola conidia produced on point or line inoculum sources (naturally infected linseed stem debris) were responsible for the spread of the disease in linseed crops. In 1992 and 1993, the disease was first detected downwind from the sources, but by the end of the growing seasons, it had spread in all directions and up to 20 m and 60 m from the sources, respectively. Disease gradients were initially steep near the inoculum sources but they became flatter with time due to the secondary spread of the disease.  相似文献   

营养补偿初期苏尼特母羊对NDF、ADF消化能力的研究     

苗志国  侯先志  敖长金  吴庶青 《中国饲料》2005,(21):15-16

将45只处于妊娠后期(90～150d)的苏尼特母羊随机分成4组,以不同的营养水平(代谢能:0.20、0.33、0.44、0.86MJ/kgW0.75·d)分组饲养,分娩后进行补偿生长试验,研究妊娠后期不同营养限制程度的母羊在补偿初期(分娩后0～6周)对中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)消化率的影响。结果表明:在补偿初期,各组母羊对ADF、NDF的消化率随着营养限制程度的增强而下降。  相似文献   

Detection of Colletotrichum coccodes and Helminthosporium solani in soils by bioassay   总被引：1，自引：0，他引：1  

S. F. Carnegie †  J. W. Choiseul  A. M. I. Roberts 《Plant pathology》2003,52(1):13-21

The sensitivity of a bioassay in detecting soil inoculum of Colletotrichum coccodes and Helminthosporium solani was examined using potato minitubers and microplants. Tests were conducted on soils which were collected from fields in which the interval after a previous potato crop differed, and which were also artificially infested with conidia or microsclerotia. For C. coccodes , determining plant infection based on the occurrence of infected roots after 9–12 weeks was a sensitive method for detecting and quantifying the amount of inoculum in soil. Infestations of less than 0·4 microsclerotia per g soil were detected in artificially infested soils. A semiselective medium, developed for isolating C. gloeosporioides from pepper, detected soil infestations by C. coccodes as low as nine conidia or one microsclerotium per g soil in artificially infested soil. For H. solani , infection on minitubers was a sensitive measure, with soil inoculum of fewer than 10 conidia per g soil being detected. Soil infestation could be quantified by assessing the percentage surface area of minitubers covered by sporulating lesions, which was strongly related to the amount of soil infestation. The results of these bioassay tests were compared with published results for real-time quantitative PCR assays on the same soils. The two methods were in good agreement in artificially infested soils, but the bioassay appeared to be more sensitive with naturally infested soils.  相似文献   

Ovary colonization by Claviceps africana is related to ergot resistance in male-sterile sorghum lines     

B. Komolong  S. Chakraborty †  M. Ryley  D. Yates 《Plant pathology》2003,52(5):620-627

Ergot, caused by Claviceps africana , has emerged as a serious threat to sorghum hybrid seed production worldwide. In the absence of gene-for-gene-based qualitative resistance in commercial cultivars, varieties with high pollen production that can escape ergot infection are preferred. Recent demonstration of differences in ergot susceptibility among male-sterile lines has indicated the presence of partial resistance. Using chitin-specific fluorescin-isothiocyanate-conjugated wheat germ agglutin and callose-specific aniline blue, this study investigated the process of sorghum ovary colonization by C. africana . Conidia germinated within 24 h after inoculation (a.i.); the pathogen was established in the ovary by 79 h a.i., and at least half of the ovary was converted into sphacelial tissue by 120 h a.i. Changes in fungal cell wall chitin content and strategic callose deposition in the host tissue were associated with penetration and invasion of the ovary. The rate of ovary colonization differed in three male-sterile lines that also differed in ergot susceptibility. This work demonstrates a possible histological basis for partial resistance in male-sterile sorghum lines that could lay the foundation for variety improvement through further breeding and selection.  相似文献   

微生物菌剂肥对超级杂交水稻生长和产量的影响   总被引：3，自引：0，他引：3  

郭夏宇  艾治勇 《湖南农业科学》2015,(4)

以两优959为供试水稻,设计了0、150、300和450 g/667m2 4种不同施用量处理,考察微生物菌剂肥对超级杂交水稻生长发育及产量的影响。结果表明,以常规施肥+300 g/667m2微生物菌剂肥的处理效果最好,与对照相比,其单株平均分蘖数多了2.4个,有效穗多了11.05%,产量增加了10.3%。这说明微生物菌剂肥在超级杂交水稻生产上具有较高推广应用价值。  相似文献   

Effect of Partial Replacement of Steam Rolled Corn With Soybean Hulls or Prickly Pear Cactus in the Horse's Diet in the Presence of Live Saccharomyces cerevisiae on In Vitro Fecal Gas Production     

《Journal of Equine Veterinary Science》2016

The aim of the study was to evaluate the fecal fermentation of partial replacing steam rolled corn with soybean hulls (SH) or prickly pear cactus (PC) as energy source in horse diets, in the presence of Saccharomyces cerevisiae. Steam rolled corn was replaced with SH at 0% (control), 7.5% (SH75), and 15% (SH150) in the first trial, whereas it was replaced with PC at 0% (control; the same of the first trial), 7.5% (PC75), and 15% (PC150) in the second trial. Yeast of S. cerevisiae was added at 0, 2, and 4 mg/g dry matter (DM) of incubated substrates. Fecal inoculum was obtained from four adult English Thoroughbred horses fed on an amount of commercial concentrate and oat hay ad libitum. Interactions observed between PC rations and yeast doses for the asymptotic gas production (GP), the rate of GP and carbon dioxide (CO₂) production during some incubation hours. Moreover, with no effect due to SH rations (P > .05), increased (P < .05) rate of GP was observed with the ration PC75 compared with other rations. Besides, PC75 and PC150 rations with 0 mg yeast/g DM linearly decreased (P < .05) CO₂ production at some incubation hours. However, SH75 and SH150 ration had increased (P = .005) DM degradability (DMD). Yeast addition at 2 mg/g DM increased the asymptotic GP (P = .048) with the SH75 and PC150 rations. The level of 4 mg yeast/g DM increased the asymptotic GP (P = .048) from the SH150 ration. Yeast addition at 2 and 4 mg/g DM increased (P < .05) ​the asymptotic GP from PC75 and PC150 rations, respectively, with increasing DMD with the both doses. Yeast addition increased (P < .05) CO₂ production from SH75, SH150, PC75, and PC150 rations. It could be concluded that SH and PC can replace steam rolled corn at levels of 7.5% to 15% without negative effect of fermentation kinetics and with better fermentation performance in the presence of yeast at 2 mg/g DM of substrates.  相似文献