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Phosphorus change point indicating the threshold related to P leaching, largely depends on soil properties. Increasing data have shown that biochar addition can improve soil retention capacity of ions. However, we have known little about weather biochar amendment influence the change point of P leaching. In this study, two soils added with 0, 5, 10, 20, and 50 g biochar kg-1 were incubated at 25℃ for 14 d following adjusting the soil moisture to 50% water-holding capacity （WHC）. The soils with different available P values were then obtained by adding a series of KH2PO4 solution （ranging from 0 to 600 mg P kg-1 soil）, and subjecting to three cycles of drying and rewetting. The results showed that biochar addition significantly lifted the P change points in the tested soils, together with changes in soil pH, organic C, Olen-P and CaC12-P but little on exchangeable Ca and Mg, oxalate-extractable Fe and Al. The Olsen-P at the change points ranged from 48.65 to 185.07 mg kg-1 in the alluvial soil and 71.25 to 98.65 mg kg^-1 in the red soil, corresponding to CaCl2-P of 0.31-6.49 and 0.18-0.45 mg L~, respectively. The change points of the alluvial soil were readily changed by adding biochar compared with that of the red soil. The enhancement of change points was likely to be explained as the improvement of phosphate retention ability in the biochar-added soils. 相似文献
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The potassium-releasing characteristics of a bacterium from different minerals were studied through pure culture and soil column experiments. The results showed that the strain NBT of tested strains had the highest potassium-releasing capacity. It released 35.2 mg/L after 7days of pure culture incubation at 28℃, 31.8% - 1203.7% more than other tested strains. Potassium released from the minerals was obviously affected by pH, aerobic condition, soil and mineral properties. The strain NBT had a much higher potential to release potassium in the pH 6.5 - 8.0 than other pHs. Living cell inoculation resulted in an increase of 84.8%- 127.9% compared with that of the dead cell inoculation. More aerobic condition produced more K than a less aerobic one. The potassium-releasing order was as follows: illite ＞ feldspar＞ muscovite. Soil column experiment showed that the bacterial number increased from (2.6 - 3.0) × 106/g to (6.8 - 7.4) × 107/g. Soil available potassium content increased by 31.2- 33.6mg/kg in yellow-brown soil and 21.7mg/kg in paddy soil, when inoculated with the strain NBT, 290.6% and 185.5% increment of the dead cell inoculation soils respectively. 相似文献
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选取黄壤、紫色土和石灰性土3种土壤为研究对象,采用一次平衡吸附法,研究了pH、有机质对镁吸附的影响.结果表明,不同pH和有机质条件下,土壤对镁的最大吸附量有较大差异,黄壤和紫色土受pH影响较明显,在pH3.5～7.5这个范围,黄壤对镁的最大吸附量变化在1 336.25g～2 054.77 mg/kg,紫色土在1 417.04～2 025.38 mg/kg,石灰性土变化不大.去有机质后,黄壤、紫色土和石灰性土对镁的吸附能力下降,最大吸附量分别减少363.31,148.72,120.00 mg/kg.Langmuir方程能很好的拟合土壤对镁的吸附过程.Abstract： The effects of pH and organic matter on adsorption of magnesium in yellow soil, purple soil and calcareous soil were studied in a batch adsorption experiment. Considerable differences were observed among the three soils in their maximum Mg adsorption under different pH and organic matter conditions.The adsorption of magnesium was mainly related to the changes in pH in yellow soil and purple soil. In the pH range of 3.5-7.5, the maximum magnesium adsorption varied from 1 336.25 to 2 054.77 mg · kg-1 in the yellow soil and from 1 417.04 to 2 025.38 mg · kg-1 in the purple soil, while little change was detected in the calcareous soil. The ability of Mg adsorption decreased after the removal of organic matter in the above three soils and the maximum Mg adsorption decreased by 363.31 mg· kg-1 , 148.72 mg · kg-1 and 120.00 mg · kg-1, respectively. Magnesium adsorption in soils was well fitted with the Langmuir equation. 相似文献
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ANDRY Henintsoa INOUE Mitsuhiro MORITANI Shigeoki UZOMA Kingsley Chinyere 《东北农业大学学报(英文版)》2010,17(4):30-36
The property of hydrophilic polymers capable absorbing huge volumes of water led to many practical applications of these new materials in arid regions for improving the water retention in sandy soils. Effects of four carboxymethylcelluloses (CMC), mixed at various rates with the sandy soil, on the water-holding capacity and hydraulic conductivity (KS ) when leached with distilled water (simulating rain), tap water, and saline water were evaluated. The maximum water absorption of CMCs ranged between 80 and 100 kg ? kg-1 of polymer; however, the absorbent swelling capacity decreased significantly with increasing the salt concentration in the solution. The water absorption capacity of CMCs decreased significantly when incorporated in the sandy soil compared to that of the absorbent alone. Application of CMC increased significantly the available water content up to 3 ± 0.5 times. All soils treated with CMCs showed a significant lower in KS compared to the control soil. Meanwhile, KS was found increased with increasing the salt concentration in the leaching solution. This understanding of characteristics of the absorbents and the interactions among absorbents, soil, and irrigation water quality would be of help in water management of sandy soil. 相似文献
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聚丙烯酰胺处理土壤不同粒径团聚体中磷吸附和解析特性的研究(英文) 总被引：5，自引：1，他引：4
[Objective]The research aimed to provide scientific reference for reasonable utilization of polyacrylamide(PAM).[Method]After PAM treatment,the soil aggregates were classified through dry sieve analysis and the adsorption capacity and desorption capacity of all soil aggregates to phosphorus at different phosphorus concentrations were analyzed.[Result] The phosphorus adsorption and desorption of soil sample treated by PAM declined. The amount of phosphorus adsorption increased with the increase of phosphorus concentration and this increase was fast in low phosphorus concentration area but slow in high phosphorus concentration area.At different phosphorus concentrations,adsorption showed a へ shape changing trend.The phosphorus adsorption was related to phosphorus concentration and the 2-3 mm aggregate had the highest desorption rate while 0.1-0.25 mm aggregate and 0.45-1 mm aggregate had lowest desorption rate.[Conclusion]The PAM treatment generated significant influence on phosphorus adsorption and analytic features of aggregate in all size fractions. 相似文献
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PAM的土壤保水性能研究 总被引：9，自引：0，他引：9
有机高分子聚合物能对土壤水分特征产生重要影响,为阐明聚丙烯酰胺(PAM)对黄土高原主要土壤类型(黄绵土、黑垆土和塿土)的保水作用,采用土柱法研究了PAM用量分别为54.5,112.9,169.4和225.8 mg/kg对3种土壤的持水性能、土壤饱和导水率和土壤蒸发量的影响,并以不添加PAM为对照。结果表明,PAM提高了黄绵土和黑垆土的持水量,而对土娄土效果不明显。在土壤导水率方面,PAM对黄绵土的改善效果最明显,除添加225.8mg/kg PAM的处理外,土壤饱和导水率随PAM用量的增加而增大;黑垆土的饱和导水率与对照相比也有一定提高,但添加225.8 mg/kg PAM的处理除外;土娄土的饱和导水率在施入PAM后降低。在一定土壤含水量条件下,保水剂抗蒸发作用明显,随PAM用量的增加,各土壤的蒸发量均减少,其中土娄土、黑垆土和黄绵土添加225.8 mg/kg PAM的处理与对照相比,蒸发量分别减少24.5%,55.8%和33.7%。说明在一定用量范围内,PAM可以提高黄土高原主要类型土壤的持水和导水性能,并且可以减少土壤水分的蒸发。 相似文献
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The North China Plain(NCP) is one of major breadbaskets in China. Crop growth and grain yield differ significantly with spatial variations of soil properties. This study aims to identify the key soil properties in relation to the grain yield for the winter wheat(Triticum aestivum L.)-maize(Zea mays L.) cropping system in a high-productivity farmland of the NCP. The field trials were conducted in three fields with different grain yield levels in Tai’an City, Shandong Province, China, during the 2009–2012 period. Consistent field management strategies were applied in the three fields. Fifty-one physical and chemical indicators of the soil profile as related to grain yield were evaluated. An approximate maximum of 17.8% annual average grain yield difference was observed in the fields during the period of 2009–2012. The soil indicators were classified into three clusters with specific functions using cluster analysis, and three key indicators were extracted from each cluster to characterize the different soil properties of three fields. The first cluster represented soil water retention capacity, and the key indicator was available soil water(ASW), which ranged from 153 to 187 mm in the 1.2 m profile and was correlated positively with grain yield. The second cluster represented soil water conductivity, as measured by saturated hydraulic conductivity(K s). The higher yield field had a greater capacity to retain topsoil water for its lower K s(1.9 cm d–1) in the 30–70 cm soil layer as compared to the lower yield field. The third cluster represented nutrient storage and supply, as indicated by the ratio of nutrient content to silt+clay content of the top soil layer. The ratio of soil organic matter(OM), total nitrogen(TN), available P, exchangeable K+ to silt+clay content in the 0–20 cm soil layer were 19.0 g kg–1, 1.6 g kg–1, 94.7 mg kg–1, 174.3 mg kg–1 in the higher yield field, respectively, and correlated positively with the grain yield. By characterizing the differences in soil properties among fields with different yield levels, this study offers the scientific basis for increasing grain yield potential by improving the soil conditions in the NCP. 相似文献
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通过对重庆石漠化区2种植物群落凋落物层和土壤层的持水性能进行研究,结果表明:马尾松群落的蓄积量高于樟树群落,蓄积量高达48.3 t/hm2,不同分解层次的蓄积量,因植物群落类型不同而有别,测定结果显示针叶林的凋落物的蓄积量、鲜质量、干质量明显高于阔叶林;在两种群落中同种凋落物的不同分解层次的最大持水量、持水率,均是半分解层高于未分解层,马尾松群落持水总量高于樟树群落,达71.5 t/hm2,相应的持水深度也是马尾松群落高于樟树群落;马尾松群落凋落物的吸水量明显高于樟树群落,且每一种凋落物的半分解层的吸水量均大于未分解层,在持水过程中,两种凋落物呈现相同的变化趋势,在前4 h内吸水速率降低幅度大,4 h后吸水速度减缓,20 h后趋向于零.凋落物吸水量和浸水时间之间存在对数关系(y=aln(x)+b),凋落物吸水速率与浸水时间的关系按照反函数方程变化(y=a+bx-1);马尾松群落的总拦蓄量(98.18 t/hm2)大于樟树群落的总拦蓄量(59.26 t/hm2);马尾松群落可截留9.818 mm的林内降雨,樟树群落可以截留5.925 mm的林内降雨.且不同分解层次上也表现为半分解层的有效拦蓄量大于未分解层.表层土壤的持水性能也和凋落物层的持水性能呈现相同的规律,也表现为马尾松林高于樟树林.Abstract： The water-holding capacities in 2 main forest types (Pinus tabulaeformis Lamb and Cinnamomum (L.)Presel) in mountainous eco-system in Karst area of Chongqing were studied. The results showed that the litter storage of P. tabulaeformis (48.3 t/ha) was higher than that of Cinnamomum. Different vegetation types and different decomposition levels resulted in different storages. The litter storage, the wet litter standing crop and the dry litter standing crop of conifers were higher than those of broadleaf forests. The maximum water-holding percentage and water holding capacity of the semi-decomposed layer was higher than those of the non-decomposed layer of the same vegetation type, and the total water holding capacity and the water holding depth of P. tabulaeformis was much higher than that of Cinnamomum. In the water holding process, the litter of the two vegetation types showed a similar trend. Water absorption rate dropped sharply in the first 4 hours, and slightly thereafter and approached zero after 20 hours. The total water holding capacity increased logarithmically with increasing immersion time in water (y = aln(x)+b),and water absorption rate in all plantations decreased with increasing immersion time according to the equation y= a+bx-1. The total interception amount of P. tabulaeformis and Cinnamomum was 98.18 t/ha and 59.26 t/ha, respectively; and their total interception depth was 9. 818 mm and 5. 925 mm. The modified interception amount of the semi-decomposed layer was higher than that of the non-decomposed layer.Like the litter layer, the topsoil showed a similar pattern of the water-holding properties. i.e. the waterholding capacity of the soil of P. tabulaeformis forests was better than that of Cinnamomum forests. 相似文献
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采用盆栽试验法,研究了高羊茅对污染土壤中菲、芘的去除效果与修复机制.结果显示:在试验浓度范围(0～322 mg/kg)内,植物-微生物系统对土壤中芘、菲的去除效果明显.种植高羊茅60 d后,土壤-高羊茅系统(TD3)对土壤中菲、芘去除率分别为52.82%～82.27%(m=67.96%)、47.27%～75.4%(m=60.06%);平均去除率分别比对照组TD1(无植物,不加NaN_3)高45.41%,41.63%,比对照组TD_2(无植物,加0.1% NaN_3)高62.89%,57.5%.高羊茅能吸收积累土壤中的菲和芘,根部和茎叶部菲、芘含量随土壤中菲、芘浓度的提高而增大;生物浓缩系数随土壤中菲、芘含量的增加而减小,且根部大于茎叶部、芘大于菲.修复过程中,非生物因子、植物积累对菲、芘的去除率分别只有5.07%,0.017%和2.56%,0.11%;微生物降解、高羊茅-微生物间的交互作用对菲、芘的平均去除率分别为19.21%,62.87%和15.87%,57.5%.说明微生物降解作用、植物-微生物交互作用是土壤中菲、芘去除的主要途径.Abstract： Pot experiments were carried out to investigate the mechanisms of the removal and accumulation of phenanthrene and pyrene by tall fescue (Festuca arundinacea). The results showed that plantation of tall fescue significantly removed phenanthrene and pyrene from the soils at their initial concentrations of 0 to 322 mg/kg. Sixty days after the plantation of tall fescue, 52.82%～82.27% (m=67.96%)of phenanthrene and 47.27%～75.4% (m=60.06%) of pyrene were removed from the soils of TD3. On the average, tall fescue removed more phenanthrene (by 45.41%) and more pyrene (by 41.63%) from the soils as compared to TD1, and more phenanthrene (by 62.89%) and more pyrene (by 57.5%) from the soils as compared to TD2. The bioconcentration factors (BCFs) for phenanthrene and pyrene tended to decrease with increasing concentrations of these contaminants in soil, the BCFs for pyrene were larger than those for phenanthrene, and the BCFs for phenanthrene and pyrene in the shoots were much lower than those in the roots in the same treatments. Though the plantation of tall fescue markedly enhanced the remediation of phenanthrene and pyrene in soils, contributions of biotic and abiotic factors to phytoremediation process were distinctly different. Abiotic loss and plant accumulation accounted for 5.07% and 0. 017% of the total removal of phenanthrene and for 2.56% and 0. 11% of pyrene from thesoils, respectively. In contrast,an average of 19.21% of the total removal of phenanthrene and 15.87% of pyrene were attributed to the contributions of microbial degradation, and 62.87% of phenanthrene and 57.5% of pyrene to plant-microbial interactions. Microbial degradation and plant-microbial interactions are thus considered to be the main mechanisms of the remediation of soil PAHs pollution. 相似文献
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任琪 《安徽农业大学学报》2008,(3):132-134
国家贫困生资助政策实施以来,对贫困生帮助很大,同时在实际运行中还存在着一些问题。本文提出贫困生认定工作仍需要进一步采取各种相关配套措施,以推动和保障贫困生资助工作更好地开展。 相似文献
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《河北农业大学学报》创刊年代考 总被引：3，自引：0，他引：3
清光绪二十八年(1902)河北农业大学前身—直隶农务学堂诞生,经几易其名,于1958年更名为河北农业大学至今。清光绪三十一年(1905)直隶高等农业学堂时期创办了《北直农话报》,清光绪三十四年(1908)更名为《直隶农务官报》,中华民国七年(1918)改出《农学月刊》,中华民国十七年(1928)易名为《河大农刊》,中华民国二十三年(1934)更名为《河北通俗农刊》,中华民国二十四年(1935)易名为《河北农林学刊》,1948年更名为《河北农学院研究专刊》,1959年更名为《河北农业大学学报》至今。《河北农业大学学报》前身诸刊都与现时的《河北农业大学学报》有着一脉相承的历史渊源,各刊之间联系紧密,连续性、继承性强。因此,《河北农业大学学报》的创刊时间应追溯至1905年创办的《北直农话报》。 相似文献
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生态旅游潜在客源市场特征的调查研究--以湖南永州金洞森林旅游开发为例 总被引：5，自引：2，他引：3
李慧云 《湖南农业大学学报(自然科学版)》2004,30(2):165-168
为探明客源市场生态旅游消费的潜在特征,采用问卷调查的形式,就长沙市居民对湖南金洞生态旅游开发的意向等问题进行抽样调查．结果显示,生态旅游符合人们“回归自然”的旅游新时尚,有着极大的开发空间,指出生态旅游的开发要注重环境保护和可持续发展．开发的产品要以休闲度假类的大众产品为主,开发生态旅游都市客源市场还要多种渠道并用,尤其是要注重媒体的宣传． 相似文献
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动物疫病是畜牧业生产的大敌,要发展畜牧业生产就要防治动物疫病。但在疫苗接种时,经常出现正常反应外的其他不利于机体的反应,如废食、皮疹、休克、死亡等,正确处理或避开这些问题,对推行动物疫病的计划免疫,实施强制免疫,保护人畜安全具有十分重要的现实意义和作用。 相似文献
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为了预测厚胶合板弹性模量,通过简化层合板理论,该文建立了胶合板弹性模量预测模型,并以单板条、经过涂胶热压处理的单板条和相同工艺条件下的单板层积材的弹性模量,采用4种不同铺层方式的19层桉树胶合板对模型进行了验证。结果表明:3种预测值与实测值的趋势一致,相关系数R2顺纹在0.86以上,横纹在0.88以上,但是精度不同。采用单板条弹性模量预测的胶合板弹性模量比实测值偏低;采用经过涂胶热压处理后的单板条弹性模量预测的胶合板弹性模量比实测值偏高;采用相同工艺条件下的单板层积材弹性模量预测的胶合板弹性模量与实测值偏差较小,顺纹平均误差为4.64%,横纹平均误差10.94%。因此,采用相同工艺条件下的单板层积材的弹性模量来预测胶合板的弹性模量是可行的。 相似文献
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分析了入世4年来,我国水果出口在量上实现了突破,但并没有实现质变的主要原因,指出我国水果业存在的问题。论述了引进外资对发展我国水果业的意义,并提出了具体可行的对策与建议。 相似文献
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采用L（934）正交设计试验,对山茱萸浸提液中山茱萸多糖的酶水解法提取工艺进行了优化研究,并对浸提液的中有效成分马钱苷含量进行了HPLC法分析。结果表明,山茱萸多糖浸提的最佳工艺为：液料比1∶5,浸提时间4 h,浸提温度80℃,果胶酶添加量0.55 g/L。用HPLC法测定出的山茱萸浸提液中马钱苷平均含量为0.512 ... 相似文献
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甘肃省设施农业发展历史悠久,古代创造了麦草覆盖生产韭 黄及泥碗护苗等传统设施农业技术,至今仍然受到农民欢迎,在 甘肃省中部应用面积约5万多hm2。建国后,甘肃设施农业获得 了新生,大致经历了三个阶段;第一阶段为引进应用北京改良式 温室阶段,时间在20世纪50-60年代;第二个阶段为塑料拱棚 与地膜覆盖栽培阶段,时间在20世纪70-80年代:第三阶段为 相似文献