Pyrolysis of maize,sunflower, grape and tobacco residues

Pyrolysis of four agricultural residues (maize, sunflower, grape and tobacco) has been carried out in order to quantify their energy content. The main characteristics of the charcoals formed and the nature and quantity of gases produced have been determined. The process was studied batchwise by varying the reaction time (15–60 min) and temperature (400–700°C). Reaction times higher than 30 min do not exert any influence while increasing temperature yields high fixed carbon solids, low volatile content and slight increases in ash. The increase in temperature is specially important to increase the production of gas, mainly hydrogen. From gas composition and proximate analysis, the heating power of gas and solid phases have been determined. A kinetic model of pyrolysis based on gas generation has been accomplished. From this model, rate constants of gas formation at different temperatures and activation energies have also been determined. ©1997 SCI     

Effects of cotton plant allelochemicals and nutrients on behavior and development of tobacco budworm

Female moths of the tobacco budworm,Heliothis virescens (F.), oviposit in the terminals of the cotton plant,Gossypium hirsutum (L.). The hatched larvae migrate to the terminal area and then to small squares (buds), on which they feed, finally burrowing into the anthers where they grow and develop. They attempt to avoid gossypol glands as they feed. Chemically related evidence explains, in part, these observations. The calyx crown of resistant lines (which is avoided) is high in the terpenoid aldehydes (TAs) including gossypol. HPLC data showed that the gossypol content of both susceptible and resistant glanded lines is equal, while the hemigossypolone and heliocides H₁ and H₂ are greatly increased in resistant lines and presumably are more closely associated with resistance. Analysis for total amino acids in cotton square tissues showed that there was a gradation from the calyx and calyx crown, which were lowest, to the anthers, the site of final insect development, which were highest. Synthetic diets mimicking amino acid distribution in anthers were found to be successful for larval growth and development.     

Metal availability in contaminated soils: II. Uptake of Cd, Ni and Zn in rice plants grown under flooded culture with organic matter addition

Higher accumulation of toxic heavy metals in rice grown in contaminated soils may lead to health disorder in humans in tropical countries as rice is a staple diet. A pot experiment was conducted in a growth chamber to investigate the effect of flooding and non-flooding conditions in three soils added with4% organic matter on the concentration and uptake of Cd, Ni and Zn by rice plants (Oryza sativa L.). In flooding condition, the level of standing water was at a height of 2.5 ± 0.5 cm above the soil surface and in non-flooded culture80 ± 5% of water holding capacity was maintained. Flooding condition significantly(p < 0.05) reduced the concentration and uptake of Cd, Ni and Zn in rice grown in all three soils. The overall reduction of metal concentration in shoot at vegetative stage, and straw and polished rice at maturity, under flooding conditions was 84, 89, and 79% for Cd; 21,63and 65% for Ni; and 52, 78 and 16% for Zn, respectively. Organic matter addition significantly reduced the Ni concentration in plant parts but no such reduction was seen for Cd and Zn. Accumulation index of Cd and Zn was 82and 55% higher than that of Ni in the plant and the index of all three metals was higher in the tannery soil than the other two soils. Polished rice contained significantly lower amounts of Cd, Ni and Zn than shoot and straw. Cadmium and Ni uptake in polished rice was > 20% of the total uptake and thus it may be a concern for human health. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of different treatments on electrokinetic remediation of Zn,Pb and Cd from a contaminated calcareous soil

Electrokinetic remediation is a promising method to decontamination of the heavy metals from soils.In this paper,the remediation of a contaminated calcareous soil with Zn,Cd and Pb sampled from around Zanjan province of Iran,was investigated using electrokinetic method.In this paper,the soil contain a high concentration of Zn (1400 mg·kg-1),Cd (15 mg·kg-1) and Pb (250 mg·kg-1).Electrokinetic decon-tamination consists of two series of experiments as follows:(1) the effect of five treatments including the use of distilled water,acetic acid and EDTA electrolyte solutions,and approaching anodes systems,and the circulation flow of electrolyte at two different voltage gradient (i.e.1.33 and 2.66 V·cm-1),and(2) the effect of moisture content (saturated,FC and 0.7FC,FC indicated soil moisture at "Field Capacity") with a voltage gradient of 1.33 V·cm-1.After applying electric current for 5 days,the results of experiments indicated that the removal efficiency of heavy metals can be increased by raising the volt-age gradient.In this matter,the highest remediation can be observed among different treatments in EDTA(Ethylene diamine tetra acetic acid) treatment (40.11％,43.10％ and 24.7％ for Zn,Cd and Pb,respectively).Moreover,the heavy metals removal at the saturated moisture was at the highest level so that 32.62％cadmium,31.33％ zinc and 18.82％ lead being removed after 120 h of electric current application.By decreasing moisture to 0.7FC,the removal percentage for the three heavy metals obtained 20.97％,18.44％ and 12.25％,respectively.Furthermore,Cd had the highest removal,and Zn and Pb were next among the three heavy metals in question.     

The effect of fertilizer additions on the solubility and plant-availability of Cd, Ni and Zn in soil

We conducted a pot experiment to investigate the effect of fertilizer additions on the solubility of Cd, Ni and Zn in soil solution and their uptake by plants. Radish (Raphanus sativus cv. Crystal Ball), oat (Avena sativa cv. Thule) and water spinach (Ipomoea aquatica cv. Kangkon) were grown in a naturally metal-rich soil. From day 7 after planting, fertilizers were added daily to each pot. Additions of fertilizer nutrients affected the pH of soil and soil solution, soluble and tissue concentrations of Ca, Mg, K, Cd, Ni and Zn differently in three plant species. The trend of soil and solution pH was in the order: water spinach < radish < oats, that resulted highest soluble and plant tissue concentrations of Cd and Zn in the water spinach followed by radish and then oats. However, Ni concentration in the soil solution increased in all pots and was not affected by pH changes. Soil solution pH increased by more than 1unit in the pots with radish and oats, indicating that mechanisms other than acidification, such as ion exchange and root exudation, may be responsible for the increased heavy metal uptake in these two plant species. Paired t-test showed significantly higher uptake of Cd and Zn in the radish plants resulting in lower concentrations of these elements in the solution. The contribution of mass flow to the supply of major cations and heavy metals varied among elements and plant species. Cadmium, Zn and K were taken up rapidly by all plant species in response to the amount supplied by mass flow. In contrast, the supply of Ni was in excess of its uptake by radish and water spinach. The uptake of all elements was positively correlated (p<0.0001) with mass flow and the transpiration rate in individual plant species. The study suggests that fertilizer cations increased the uptake of metals by improving growth conditions, but the magnitude of increase depended on plant species. This revised version was published online in November 2006 with corrections to the Cover Date.     

Historical role of manure application and its influence on soil nutrients and maize productivity in the semi-arid Ethiopian Rift Valley

Maize yield dynamics generally involve temporal changes, because increasing soil organic matter through manure application influences maize yields over the longer term, while inorganic nutrient application controls shorter term yields. These temporal soil properties and yield changes have been measured with long-term experiments. In sub-Saharan Africa (SSA), long-term experiments (more than 20 years) are rare due mainly to lack of funds. Farmers in the semi-arid northern Ethiopian Rift Valley (NERV) apply manure to maize fields in the long term. The relationships between the manure application levels, nutrient supply, soil nutrient levels, maize grain yields, and above-ground plant nutrient uptake levels were investigated by field measurement, interviews with farmers, laboratory analyses, and 2-years’ yield trials. The farmers applied on average 6.0 Mg ha^?1 yr^?1 of manure over 16.8 years on average. Significant linear or curve-linear correlations were found (1) between the annual nutrient supply and soil nutrient levels and (2) between the soil nutrient levels and maize productivities with minor exceptions. The regression equations determined from the yield trials proved 3.0 and 4.0 Mg ha^?1 of maize yields can be expected when soil available N contents were 3.9 and 5.1 mg kg^?1 in an ordinary rainfall year in NERV. For the farmers who apply 6.0 Mg ha^?1 yr^?1 manure, they are recommended to use 30 kg ha^?1 yr^?1 additional Urea to attain 3.0 Mg ha^?1 maize yields. These types of assessment methods do not require much cost, and yet it can provide long-term scientific information in SSA.     

FeCl_3-柠檬酸复合淋洗剂去除土壤中Pb、Cd机理研究

以FeCl_3-柠檬酸复合淋洗剂为淋洗剂,测定不同浓度淋洗剂作用时土壤pH、Eh值变化,进行FeCl_3-柠檬酸复合淋洗剂对土壤中Pb和Cd的淋洗动力学实验,采用BCR连续提取法对淋洗前后土壤中Pb、Cd赋存形态进行分析。结果表明,随着淋洗剂浓度的增大,土壤pH值下降,Eh值增大,且FeCl_3-柠檬酸复合淋洗剂作用时土壤pH和Eh变化较FeCl_3和柠檬酸单一作用时更明显,0.2 mol/L FeCl_3-柠檬酸为适宜淋洗剂;Pb、Cd的淋洗平衡时间为120 min,过程分为快速淋洗阶段、慢速淋洗阶段和淋洗平衡阶段,Pb、Cd的平衡淋洗量分别为0.109 mg/g和0.015 mg/g,分别占土壤中其含量的95.98%和97.98%;淋洗后,土壤中Pb和Cd各形态含量均有所下降,Pb的酸可提取态、可还原态、可氧化态和残渣态分别降低82.97%,62.04%,55.29%和22.12%,而Cd的4种形态分别降低96.7%,95.03%,29.59%和17.71%。     

FeCl_3-柠檬酸复合淋洗剂去除土壤中Pb、Cd机理研究

以FeCl_3-柠檬酸复合淋洗剂为淋洗剂,测定不同浓度淋洗剂作用时土壤pH、Eh值变化,进行FeCl_3-柠檬酸复合淋洗剂对土壤中Pb和Cd的淋洗动力学实验,采用BCR连续提取法对淋洗前后土壤中Pb、Cd赋存形态进行分析。结果表明,随着淋洗剂浓度的增大,土壤pH值下降,Eh值增大,且FeCl_3-柠檬酸复合淋洗剂作用时土壤pH和Eh变化较FeCl_3和柠檬酸单一作用时更明显,0.2 mol/L FeCl_3-柠檬酸为适宜淋洗剂;Pb、Cd的淋洗平衡时间为120 min,过程分为快速淋洗阶段、慢速淋洗阶段和淋洗平衡阶段,Pb、Cd的平衡淋洗量分别为0.109 mg/g和0.015 mg/g,分别占土壤中其含量的95.98%和97.98%;淋洗后,土壤中Pb和Cd各形态含量均有所下降,Pb的酸可提取态、可还原态、可氧化态和残渣态分别降低82.97%,62.04%,55.29%和22.12%,而Cd的4种形态分别降低96.7%,95.03%,29.59%和17.71%。     

Formation of oxidation compounds in sunflower and olive oils under oxidative stability index conditions

The objective of this work was to study the evolution of oxidation under oxidative stability index (OSI) conditions using the Rancimat apparatus. Sunflower oils with different degrees of unsaturation (conventional high‐linoleic sunflower oil, genetically modified high‐oleic sunflower oil, and a 1 : 1 mixture of both of them) and virgin olive oil were used. The sunflower oils were tested at 100 °C, while the olive oil was assayed at 100, 110 and 120 °C. Samples were analyzed at different time points and conductivity values, until the induction period (IP) was overpassed. A combination of adsorption and size‐exclusion chromatography was used for the quantification of oxidized triacylglycerol (TG) monomers, dimers and polymers. Additionally, peroxide values (PV) and ultraviolet absorption at 270 nm (K₂₇₀), as well as losses of tocopherols, were measured. The results showed that oxidized TG monomers were the only group of oxidation compounds that increased during the early oxidation stage. The end of the IP was marked by the initiation of polymerization after the exhaustion of tocopherols. In comparison with reported results obtained at room temperature, the main difference found was that the amounts of oxidation compounds at the end of the IP were much lower at OSI test temperatures. With the exception of the K₂₇₀ values, the results also showed that the IP endpoints provided by the OSI test were slightly higher than those obtained by quantification of oxidized TG monomers or by PV determination.     

The effect of plant residues on plant uptake and leaching of soil and fertilizer nitrogen in a tropical red earth soil

Two field experiments, in which differing amounts and types of plant residues were incorporated into a red earth soil, were conducted at Katherine, N.T., Australia. The aim of the work was to evaluate the effect of the residues on uptake of soil and fertilizer N by a subsequent sorghum crop, on the accumulation and leaching of nitrate, and on losses of N.Stubble of grain sorghum applied at an exceptionally high rate (~ 18 000 kg ha^–1) reduced uptake of N by sorghum by 13% and depressed the accumulation of nitrate under a crop and particularly under a fallow.Loss of fertilizer N, movement of nitrate down the profile, and uptake by the crop was studied in another experiment after application of N as¹⁵NH₄ ¹⁵NO₃ to field microplots. By four weeks after fertilizer application 14% had been lost from the soil-plant system and by crop maturity 36 per cent had been lost. The pattern of¹⁵N distribution in the profile suggested that losses below 150 cm had occurred during crop growth. The recovery of¹⁵N by the crop alone ranged from 16 to 32 per cent. There was an apparent loss of N from the crop between anthesis and maturity. Residue levels common to sorghum crops in the region (~ 2000 kg ha^–1) did not significantly affect uptake by a subsequent sorghum crop, N losses, or distribution of nitrate in the profile.     

焦化厂土壤中PAHs的热脱附行为及其对土壤性质的影响

采用滚筒式间接加热设备,在50～450℃加热温度和30 min停留时间实验条件下,测试了焦化厂污染场地低含量（S1）和高含量（S2）PAHs污染土壤中16种PAHs的热脱附效率和残留量的变化,并初步分析了热脱附处理对土壤有机碳（TOC）、可溶性有机碳（DOC）、比表面积（SA）和粒径分布的影响,结果表明：加热温度、污染物含量和污染物分子量对PAHs的脱附效率均存在极显著影响（p<0.01）,其中加热温度影响程度最大。S1和S2土壤中各类PAHs在加热温度达到其熔点附近开始有效脱附,LPAHs（低分子量PAHs）与HPAHs（高分子量PAHs）之间的热脱附效率仅在不超过300℃（S1土壤）和400℃（S2土壤）加热条件下存在明显差别。土壤中各类PAHs的脱附与其有效态密切相关,S1和S2土壤中有效态PAHs分别在200～250℃和250～300℃加热条件下几乎全部脱附。450℃加热温度条件下,S1和S2土壤中∑PAHs（总PAHs）脱附效率能够达到91.3%和98.4%,其中8种目标PAHs的含量范围分别为0.07～0.71 mg·kg^-1和0.26～40.20 mg·kg^-1,土壤中部分PAHs仍超过相应的北京市《场地土壤环境风险评价筛选值》住宅用地筛选值;450℃加热温度下,S1和S2土壤中TOC含量分别下降51.4%（p<0.05）和23.1%（p<0.05）,S1和S2土壤中DOC变化趋势相反,SA的下降、较粗颗粒比例略有增加和电镜扫描中土壤颗粒团聚现象相吻合。     

The long-term residual value of rock phosphate and superphosphate fertilizers for various plant species under field conditions

In three, long-term field experiments on different lateritic soils in south-western Australia, the effectiveness of superphosphate and rock phosphate fertilizers applied 10 years (one experiment) or 4 years previously was measured relative to the effectiveness of freshly-applied superphosphate (relative effectiveness or RE) using several different plant species. For the species comparisons, RE values were estimated using the initial slope of the relationship between yield and the level of P applied. In addition, RE values were also determined for different levels of application to test whether RE values for previously-applied fertilizer changed with increasing level of application. Soil samples were collected 3–5 months before sowing for a soil test for phosphate (P) and the soil test values were related to plant yields measured later that year. At each site, the RE value of previously-appliedrock phosphate was calculated using initial slopes and was mostly consistently low and was similar (0.04–0.18) for all plant species. The exceptions were that the RE value about doubled for barley in one experiment and for another experiment the effectiveness of calcined (heated) C-grade ore (Calciphos) was about 2–3 times that of the untreated (i.e. unheated) fertilizer. In most cases, the RE value of previously appliedsuperphosphate at each site was similar (0.23–0.34) regardless of plant species. The exceptions were that the RE value was about double for barley in one experiment and about half for triticale in another. Rock phosphates applied 4 or 10 years previously were between about one twentieth to one quarter as effective as freshly applied superphosphate. Superphosphate applied 4 or 10 years previously was between about a quarter to one third as effective as freshly-applied superphosphate. At each site, the yield of each species was closely related to the P content of plant tissue and the relationship was independent of the fertilizer type or when the fertilizer was applied. At each site and for each plant species, the RE value of the previously-applied rock phosphate was estimated for different levels of application and generally decreased with increasing level of application, whereas the RE value for previously-applied superphosphate mostly remained approximately constant. At each site, the relationship between yield and soil test values (i.e. soil test for P calibrations) differed depending on the fertilizer type and the plant species.     

Influence of pulsed electric field on growths of soil bacteria and pepper plant

DC 20 volt of electricity was charged to the electrodes placed around hot pepper plants to induce electrical redox reaction. Anode and cathode were periodically exchanged at intervals of 30 seconds to develop a pulsed electric field (PEF), by which the ORP of the soil around the pepper plant roots were fluctuated from 17 to −13 volts. Mean viable cell number of the intrinsic bacteria in five different positions was variable from 77,000 to 396,000 around electrodes and 339,000 to 680,000 around plants in the PEF, and 538,000 to 927,000 around plants in the conventional field. The mean viable cell number of the extrinsic bacteria (R. solanacearum) in five different positions was variable from 15,000 to 47,000 around electrode and 152,000 to 374,000 around plant in the PEF, and 294,000 to 607,000 around plants in the conventional field. Mean 3.93 and 5.67 of hot pepper plants were infected with bacterial wilt every two days by passive and active infection, respectively, in the conventional field. Mean 1.25 and 2.5 of hot pepper plants were infected with bacterial wilt every two days by passive and active infection, respectively, in the PEF. Mean sprouting number of seeds in the PEF and conventional field and was 45.0 and 48.2, respectively. Mean dry weight of hot pepper plants was 3.15 g and 2.51 g in the PEF and conventional field, respectively. The TGGE band pattern in the PEF was not very different in comparison with that in the conventional field (B and D) based on the band number, which corresponds to the bacterial diversity. This study suggests that the PEF would be functioning as an environmental factor to inhibit bacterial growth rather than to be a physical agent to destroy bacterial cells.     

The influence of seasonal conditions,plant species and fertilizer type on the prediction of plant yield using the Colwell bicarbonate soil test for phosphate

Testing for soil phosphate (P) using the Colwell procedure is widely used in south-western Australia to estimate fertilizer applications required for crops and pastures. The relationship between plant yield, expressed as a percentage of the maximum yield, and soil test values is assumed to be constant in different years for the same soil type and plant species. Data from 11 long-term field experiments in south-western Australia show that regardless of whether percentage of maximum or absolute yield is used, the relationship between yield and soil test values is different (1)in different years, for the same site and where the same P fertilizer type has been used. This occurred irrespective of whether the same or different plant species were grown in different years; (2)where different types of P fertilizer had been used, for the same site, same year and same plant species; (3)for different plant species, for the same site, same year, and same type of P fertilizer. We conclude that considerable errors in the recommendation of fertilizer rates may result from the assumption that there is a constant relationship between soil test and yield.     

Long-term effect of fertilizer and manure application on soil-carbon sequestration and soil fertility under the wheat–wheat–maize cropping system in northwest China

Maintenance of soil organic carbon (SOC) is important for the long-term productivity of agroecosystems. An investigation was conducted to study the effects of long-term application of inorganic fertilizers and farmyard manure (FYM) on soil organic carbon (SOC), nitrogen, phosphorus, and potassium nutrient content, water-stable aggregate distribution, and aggregate-associated carbon in a field experiment started in 1982 in an arid region of northwest China. Application of inorganic fertilizer alone (N, NP, or NPK treatments) did not increase SOC concentrations compared with no application of fertilizers (CK) and SOC concentration was significantly reduced, by 18% on average, compared with the initial value at the beginning of the experiment. Application of imbalanced inorganic fertilizer (N and NP), especially, resulted in a significant decrease in available phosphorus and potassium nutrients at a depth of 20 cm. This indicates that long-term application of inorganic fertilizers were inadequate to maintain levels of SOC and nutrients under conventional management with no aboveground crop residues returning to the soil. Long-term application of FYM alone or combined with inorganic fertilizers (M (FYM), MN, MNPK, or MNPK treatments), however, improved SOC and total nitrogen concentrations from initial values of 12.1 and 0.76 g kg⁻¹, respectively, to 15.46 and 1.28 g kg⁻¹, on average, and also enhanced available nitrogen, phosphorus, and potassium concentrations by 47, 50, and 68%, respectively, during the 23-year period. Treatment with FYM resulted in a 0.48 mm greater average mean weight diameter (MWD) of aggregates and a higher percentage of macro-aggregates (>2 mm) and small macro-aggregates (2–0.25 mm) than treatment without FYM. The MWD increased with increasing SOC concentration (R ²=0.75). The SOC concentration was highest in small macro-aggregates, intermediate in macro-aggregates, and lowest in micro-aggregates (0.25–0.05 mm). Approximately 54–60% of total SOC was stored in micro-aggregates (0.25–0.05 mm) and sand+silt fractions (<0.05 mm) after treatment without FYM but 57–64% of total SOC was stored in macro-aggregates (>0.25 mm) after treatment with FYM. MNPK treatment had the greatest effect on improving the levels of SOC and NPK nutrients and in enhancing the formation and stability of macro-aggregates.     

Influence of treated sewage sludge applications on temporal variations of plant nutrients and heavy metals in a Typic Xerofluvent soil

The objective of this study is to determine influence of Treated Sewage Sludge (TSS) rates as organic matter and nutrient resource on temporal variations of some macronutrients and micronutrients and heavy metals concentrations in a Typic Xerofluvent soil. The experiment was conducted in Menemen Plain, in the Western Anatolia Region of Turkey in 2003–2005. Moist TSS was added to the soil at the rates of 0, 30, 60 and 90 Mg ha⁻¹ on May 1, 2003. Peanut (Arachis hypogaea) was planted as the first crop. On the other hand, mixture of green barley (Hordeum vulgare) and common vetch (Vicia sativa L.) was planted as the second crop. During the experiment, soil samples were taken five times. Increasing TSS applications to this soil resulted in significantly increased concentrations of total N, Cu, Pb and Ni, and available P, K, Ca, Fe, Cu, Zn, Mn concentrations in soil. However, concentrations of available Mg and Na, total Fe, Zn, Mn, Cd, Co and Cr in soil did not significantly change. Micronutrients and heavy metals concentrations in soil were found under threshold values in all sampling periods in this study. Available nutrient concentrations in the soil decreased particularly in the last sampling periods because of plant uptake of nutrients from the applied TSS. It is recommended that 90 Mg ha⁻¹ moist TSS can be added once in a 2-year period for improving nutrient concentrations in Typic Xerofluvent soil.     

间作制度的土壤养分变化及生态、经济效益

间作是我国普遍使用的一种栽培制度,从土壤养分、生态效益和经济效益3个方面介绍间作的优势及一些不足,旨在为更好地合理安排间作提供参考与指导。     

The effect of polar soil components on the phase inversion temperature and optimum detergency conditions

Previously reported results have shown that optimum removal of a hydrocarbon soil from polyester/cotton fabric occurs above the cloud point at the phase inversion temperature (PIT) of nonionic surfactant/water/soil systems. Through comparison of phase behavior measurements to radiotracer detergency studies using model sebum soils, i.e., cetane/oleyl alcohol and cetane/oleic acid blends, the relevance of the PIT for removal of nonpolar/polar soil mixtures has also been demonstrated. For these soils, the PIT is typically below the cloud point, and the highest level of soil removal is found between the PIT and cloud point rather than only at the PIT. This relatively temperature-insensitive soil removal is attributed to the preferential solubilization of polar soil components which continually changes the composition of the residual soil during the washing cycle. These findings explain the long-observed results that 4- to 5-EO alcohol ethoxylates are preferred for the removal of nonpolar soils while 6- to 9-EO ethoxylates are the more effective surfactants for sebum soils.