铅镉高污染土壤的钝化材料筛选及其修复效果初探

本研究以重金属高污染农田土壤(全Pb含量为1 277 mg/kg,全Cd含量为39.0 mg/kg)为研究对象,通过土培试验和玉米苗期盆栽试验,探讨海泡石、石灰、腐植酸、钙镁磷肥、磷矿粉、生物质炭等常用稳定材料不同剂量及复配组合对高污染土壤重金属的钝化修复效应。土培试验结果表明,石灰对Pb和Cd钝化效果最好,其次是海泡石,但两者表现为较高添加量处理间没有显著差异;而低剂量生物质炭和腐植酸显著增加土壤有效态Pb和Cd含量,高剂量生物质炭具有较好的钝化效果。盆栽试验表明,海泡石与石灰配施钝化效果较好,与对照相比,土壤氯化钙提取态Pb、Cd含量分别降低了97.5%、81.4%;玉米根和地上部Cd含量分别降低48.5%、34.0%,Pb含量分别降低35.6%、29.6%;但海泡石与磷材料配施显著增加玉米根Pb含量,对玉米Cd吸收没有显著影响。以上结果表明,重金属高污染农田土壤添加合适的改良剂,可较大幅度降低土壤重金属有效性和植物重金属吸收性。     

Alkaline coal fly ash amendments are recommended for improving rice-peanut crops

Abstract

A field experiment investigating amendments of organic material including farmyard manure, paper factory sludge and crop residues combined with fly ash, lime and chemical fertilizer in a rice-peanut cropping system was conducted during 1997–98 and 1998–99 at the Indian Institute of Technology, Kharagpur, India. The soil was an acid lateritic (Halustaf) sandy loam. For rice, an N:P:K level of 90:26.2:33.3 kg ha^?1 was supplied through the organic materials and chemical fertilizer to all the treatments except control and fly ash alone. The required quantities of organic materials were added to supply 30 kg N ha^?1 and the balance amount of N, P and K was supplied through chemical fertilizer. Amendment materials as per fertilization treatments were incorporated to individual plots 15 days before planting of rice during the rainy season. The residual effects were studied on the following peanut crop with application of N:P:K at 30:26.2:33.3 kg ha^?1 through chemical fertilizer alone in all treatments, apart from the control. An application of fly ash at 10 t ha^?1 in combination with chemical fertilizer and organic materials increased the grain yield of rice by 11% compared to chemical fertilizer alone. The residual effect of both lime and fly ash applications combined with direct application of chemical fertilizer increased peanut yields by 30% and 24%, respectively, compared to chemical fertilizer alone. Treatments with fly ash or lime increased P and K uptake in both the crops and oil content in peanut kernel compared to those without the amendments. Alkaline coal fly ash proved to be a better amendment than lime for improving productivity of an acid lateritic soil and enriching the soil with P and K.     

石灰组配土壤改良剂抑制污染农田水稻镉吸收

为达有效地调控污染稻田水稻糙米对Cd吸收,该研究选取湖南省长株潭地区的湘潭、醴陵和株洲3处不同Cd污染程度田块,研究石灰配施海泡石、钙镁磷肥、有机肥对水稻Cd吸收和累积的影响。结果表明,施用石灰及其组配改良剂均可明显提高土壤pH值,有效降低土壤中酸提取态Cd含量和水稻中Cd含量。与不施用改良剂相比,石灰配施海泡石或有机肥、配施海泡石和有机肥,Cd污染稻田土壤pH值平均升高1.08,0.96和0.93个单位,酸提取态Cd质量分数分别平均降低20.6%,15.6%和21.2%。石灰配施海泡石、有机肥或钙镁磷肥处理下在轻度Cd污染田块中糙米Cd含量较对照分别显著降低了48.3%,46.7%和34.2%,石灰配施有机肥、钙镁磷肥或钙镁磷肥和有机肥处理下在中度Cd污染田块中糙米Cd含量较对照分别显著降低了52.8%,47.8%和37.5%,石灰配施钙镁磷肥和有机肥、有机肥或海泡石处理下在重度Cd污染田块中糙米Cd含量较对照分别显著降低了51.2%,44.6%和42.5%,均低于食品安全国家标准中糙米限量值0.2 mg/kg(GB2762-2017)。相关分析表明,土壤中酸提取态Cd含量与水稻根、茎叶和糙米中Cd含量呈显著正相关关系(P0.05),说明土壤酸提取态Cd含量是影响糙米对Cd吸收的关键因素之一。上述结果说明,石灰配施海泡石、有机肥或钙镁磷肥+有机肥可有效调控污染稻田土壤中Cd进入水稻,实现水稻安全生产。     

不同盐碱地改良剂对土壤理化性质、紫花苜蓿生长及产量的影响

为明确国产化盐碱地改良剂在重度盐碱地的施用效果,采用田间试验和室内分析相结合的方法,以牧草和绿肥兼用型紫花苜蓿为供试作物,研究重度盐碱地施用国产1号(2 250 kg·hm-2)、国产2号(7 960kg·hm-2)和脱硫石膏(22 500 kg·hm-2)3种改良剂对土壤理化性质、紫花苜蓿(Medicago sativa L.)出苗率和鲜草产量的影响,以及施用脱硫石膏对土壤(0~20 cm)和紫花苜蓿茎、叶中重金属含量的影响。结果表明,与对照(不施改良剂)相比,施用改良剂处理的紫花苜蓿出苗率提高18.4%~31.7%,3茬鲜草总产量提高18.9%~43.5%;土壤pH下降0.11~1.46,容重降低0.01~0.06 g·cm-3、孔隙率提高1.15%~10.15%,土壤理化性状得到改善;施用脱硫石膏和含有脱硫石膏的国产2号使土壤和紫花苜蓿中汞、铅和铬含量有显著提高,但土壤重金属含量未超过国家《农业土壤环境质量标准》GB15618—2001规定的二级土壤使用标准,紫花苜蓿中汞、镉、铅和铬的含量检测符合国家饲料卫生指标(GB13078—2001)的规定。本研究表明,3种盐碱地改良剂以国产2号的施用效果最好,可在同类型盐碱地大力推广应用。     

Evaluation of three calcium extractants for coastal plain soils

Abstract

Mehlich 1‐Ca is used as an index to predict the Ca requirement for peanut (Arachis hypogaea L.) fruit development in major peanut growing states. Recently, some concern has been raised about the inadequacy of Mehlich 1 extractable Ca for that purpose. Possible use of alternative extractants for soil Ca has been suggested. In this study, relationships among Mehlich 1, 0.2 M NH₄Cl and 0.01 M NaNO₃ extractable Ca were examined in several Coastal Plain soils to which gypsum or lime had been applied. Variability in extractable Ca was much greater following lime treatment than following gypsum treatment. In Bonifay soil, the quantity of Ca extractable by the three extractants was similar in a gypsum treatment, but in a lime treatment (at an application rate equivalent to the gypsum treatment) Mehlich 1‐Ca was 2 and 5‐fold greater than NH₄Cl‐ and NaNO₃‐Ca, respectively. In Greenville soil, Mehlich 1‐Ca was 3 to 4‐fold greater than NaNO₃‐Ca regardless of gypsum or lime amendment.

For soil samples from a field experiment on Lakeland sand, where lime or gypsum was applied prior to planting, Mehlich 1‐Ca was 7.5 and 2.2‐fold greater than NaNO₃‐Ca for the lime and gypsum treatments, respectively. Greater variability in Mehlich 1‐Ca in lime than in gypsum treatments was due to possible inclusion of undissolved limestone in the soil samples, resulting in overestimation of Ca available for peanut fruits. Mehlich 1‐Ca appears to be an adequate index of soil Ca for prediction of supplemental Ca requirement for peanut if lime has not been applied or has been applied well in advance of planting, thus minimizing the inclusion of undissolved limestone with the soil sample taken from the fruiting zone (0–8 cm depth) 10–14 d after planting.     

The Impact of Wood Ash and Green Liquor Dregs Application on Ca, Cu, Zn and Cd Contents in Bark and Wood of Norway Spruce

To counteract nutrient depletion and acidification of forest soils, recycling of waste products from the forest industry has been suggested. Spreading of these waste products will probably change the concentration and availability of Ca and heavy metals in forest soils and thereby the contents of these metals in trees. This field study aimed at examining the influence of pellets of wood ash (ash) or a mixture of wood ash and green liquor dregs (ash+GLD) on the contents of Ca, Cd, Cu and Zn in wood and bark of Norway spruce [Picea abies (L.) Karst.]. The waste products were spread in an amount of 3000 kg ha^?1 in 1996 at a felling site in Sweden and in 1999 and 2002 young spruce trees, planted in 1995, were collected and wood and bark were analysed for Ca, Cd, Cu and Zn with AAS. Changes in the metal content of wood and bark of young spruce trees were found 3 and 6 years after spreading pellets of ash or ash+GLD compared with the control. The effect of the treatments on the metal contents of bark and wood differed and was larger after 3 years than after 6 years. Treatment with ash+GLD tended to have less effect on the metal contents of bark and wood than treatment with only ash. An increase in the contents of Cu and Zn in bark or wood, compared with the control, was only found for the ash treatment and only 3 years after application. Both the ash and ash+GLD treatment decreased the Cd content of the wood and/or bark after 3 years, and after 6 years it still was, or tended to be, lower than the control.     

土壤改良剂对冷浸田土壤特性和水稻群体质量的影响

以南方典型冷浸田为研究对象, 在明沟排水的基础上, 通过田间定位试验, 以不施土壤改良剂为对照, 研究了施用不同土壤改良剂(自研的脱硫灰改良剂、生物活性炭, 市售的土壤改良剂石灰、硅钙肥、腐植酸)对冷浸田氧化还原电位、土壤呼吸强度、土壤微生物数量、水稻群体构建及产量构成因素的影响。结果表明, 施用改良剂能够改善土壤理化性状, 提升土壤速效养分和pH,但除脱硫灰处理外, 其他改良剂处理对土壤Eh未产生显著影响。施用不同土壤改良剂在水稻各生育期均能有效增强土壤微生物呼吸强度和放线菌数量, 并且放线菌数量达到差异性显著水平(P<0.05), 生物活性炭处理下土壤呼吸强度和放线菌数量分别较对照增加67.6%和127.6%。各土壤改良剂处理与CK相比较均有助于提高叶片SPAD、茎蘖数、水稻干物质积累量、成穗数、穗粒数、产量结实率和根系伤流速率。其中以脱硫灰和生物活性炭处理改良效果最佳, 抽穗后29 d时,根系伤流速率较CK分别提高45.4%和39.1%, 叶片SPAD分别增加27.4%和22.5%; 成熟期水稻成穗数较对照提高12.1%和10.7%,干物质积累量增加68.8%和50.5%,产量分别增加12.8%和10.3%。综上所述, 土壤改良剂可有效改善冷浸田土壤特性及水稻群体质量, 脱硫灰和生物活性炭处理的改良效果最明显, 增产幅度最大。     

Soil Fertility,Sugarcane Yield Affected by Limestone,Silicate, and Gypsum Application

The aim of this study was to verify if the application of silicate or lime, in association with gypsum, on sugarcane residue can lead to amendment of subsurface soil acidity, increasing sugarcane yield and profitability. The treatments were: 1 – control (without application of amendments), 2 – gypsum, 3 – dolomitic limestone, 4 – silicate, 5 – dolomitic limestone + gypsum, and 6 – silicate + gypsum. The surface application of gypsum led to reduction in Al (aluminum) contents and Al saturation, and increase in Mg⁺², Ca⁺², K⁺, S–SO₄^?, and base saturation in deeper soil layers, as well as increased yield of stalks, sugar, trash, bagasse, and energy, and greater profit. The application of limestone and silicate, alone or in association with gypsum, amend soil acidity throughout the soil profile. It likewise leads to an increase in stalk, sugar, trash, bagasse, and energy yield, however, application of silicate in association with gypsum leads to the greatest profitability.     

Remediation of Cadmium Pollution in Soils by Different Amendments: A Column Study

Abstract

A column study was conducted to determine the effect of city compost, lime, gypsum, and phosphate on cadmium (Cd) mobility in three well‐recognized benchmark soils of India [viz., (Islamnagar) Vertisol, (Amarpur) Inceptisol, and (Khala) Alfisol]. Columns made of PVC were filled with soil treated with different treatment doses [viz., 0.5% city compost, 1% city compost, 2% city compost, 2.5 t lime/ha, 5 t lime/ha, 2.5 t lime/ha+0.5% city compost, 2.5 t gypsum/ha, 2.5 t gypsum/ha+0.5% city compost, and 100 kg P₂O₅/ha as potassium phosphate (KH₂PO₄). The columns were leached with 100 mg L^?1 Cd under saturated condition. The amount of water moving through the soils was measured as the pore volume. A delayed breakthrough curve (BTC) of Cd in the presence of lime has been observed in all the studied benchmark soil series. Among the treatments, lime application reduced the movement of Cd from surface soil to lower depth of soil to a large extent resulted in 9, 25, and 45% more retention of Cd in surface soil of the Islamnagar, Amarpur, and Khala series respectively. Explanation for reduced Cd mobility in limed soil can be derived from pH changes of soils. In comparison to control soil, phosphate application caused 6, 21, and 30% more retention of Cd in surface soil in the Islamnagar, Amarpur, and Khala series, respectively. Combined application of lime and city compost reduced the movement of Cd in the soil profile. It appears that organic matter controls the sorption of Cd in soils. The amount of Cd sorbed increased with increasing organic carbon content, but gypsum application may leach Cd beyond the root‐zone depth. A rapid breakthrough curve was observed under gypsum‐treated soils. Retardation factor revealed that a somewhat lower degree of Cd retention occurred in the Khala series, which might possibly be attributed to less clay content and low pH. Overall, the column study indicated that total Cd accumulation occurred up to depths of 5–7.5 cm, 7.5–10 cm, and 10–15 cm in soils of Islamnagar, Amarpur, and Khala series, respectively.     

改良剂对土壤酸碱度和烤烟生长及烟叶中重金属含量的影响

为筛选出高效安全的酸性植烟土壤改良剂,采用盆栽试验研究了不同改良剂(生石灰、白云石粉和熟石灰,用量为0.66 g/kg风干土)对酸性土壤p H、烟株生长和烟叶重金属吸收的影响。结果表明,施用石灰和白云石粉均能提高土壤p H,其中生石灰提高的幅度达到0.52单位;改良剂能够促进根系的生长,增加烟株干物质的积累,生石灰、白云石粉、熟石灰处理旺长期烟株总干重分别增加了13%、9%和17%;白云石粉处理增加了烟叶总糖、还原糖含量和糖碱比,石灰处理则降低了总糖和还原糖含量;白云石粉处理显著增加了烟叶的Cd含量,而石灰处理则降低了烟叶的Cd含量,但各处理烟叶中重金属含量均较低。综合考虑改良剂的效果和烟叶的安全性,石灰是烟区酸性土壤改良、提高烟叶产量和安全性的有效技术措施。     

工业副产品改良土壤酸度和铝毒的潜力

It is imperative to choose some low cost, available and effective ameliorants to correct soil acidity in southern China for sustainable agriculture. The present investigation dealt with the possible role of industrial byproducts, i. e., coal fly ash (CFA), alkaline slag (AS), red mud (RM) and phosphogypsum (PG) in correcting acidity and aluminum (Al) toxicity of soils under tea plantation using an indoor incubation experiment. Results indicated that CFA, AS and RM increased soil pH, while PG decreased the pHs of an Ultisol and an Alfisol. The increment of soil pH followed the order of RM > AS > CFA. All the industrial byproducts invariably decreased exchangeable Al and hence increased exchangeable Ca, Mg, K and Na and effective cation exchange capacity. RM, AS and lime decreased total soluble Al, exchangeable Al and organically bound Al. Formation and retention of hydroxyl-Al polymers were the principal mechanism through which Al phytotoxicity was alleviated by application of these amendments. In addition, the heavy metal contents in the four industrial byproducts constituted a limited environmental hazard in a short time at the rates normally used in agriculture. Therefore, the short-term use of the byproducts, especially AS and RM, as amendments for soil acidity and Al toxicity in acid soils may be a potential alternative to the traditional use of mined gypsum and lime.     

Effects of lime rate on corn root characteristics under enhanced ammonium supply

Plant growth under enhanced ammonium supply (EAS) can benefit from control of root‐media acidification. Corn (B37xB79) was grown in a greenhouse in 18.9‐L pots containing Bloomfield fine sand (coarse‐loamy, mixed, mesic, Psammentic Hapludalf) with an initial pH of 5.4. Soil pH was adjusted using either CaCO₃ or Ca(OH)₂ to provide pH increments up to pH 7.4. Nitrogen (100 mg/kg) was added as (NH₄)₂SO₄. A nitrification inhibitor was added to minimize oxidation of the NH₄. Dry weights and Kjeldahl N were determined on leaves, stalks, tillers, and roots of 38 d plants. Acidity was measured from rhizosphere (pHr) and bulk (pHb) soil samples. Roots were sub‐sampled for length and tissue NH₄ determinations. Corn growth at 38 d was not significantly affected by lime amendments. Liming with either form promoted a longer, finer root system. Root tissue NH₄ concentration decreased as rhizosphere pH increased for both lime forms up to a rhizosphere pH of 6.9. Rhizosphere acidification, the difference between pHr and pHb, decreased with lime rate, especially for the CaCO₃ form. Effects on root parameters were generally associated with pH differences and not with lime form.     

不同改良剂对河套灌区盐渍化土壤性状和葵花生长特性的影响

为了评价不同改良剂对盐渍化土壤的改良效果,以葵花为研究对象,采用大田裂区试验方法,设置生物炭(DC,22.5 t/hm~2)、脱硫石膏(DS,37.5 t/hm~2)、脱硫石膏加有机肥(DSF,各37.5 t/hm~2)、对照(DCK)4种处理。结果表明:施加改良剂均降低了土壤容重,增加了土壤孔隙度,生物炭效果最明显,在耕层(0—20 cm)收获后较播种前土壤容重降低6.11%,是DCK的4倍,孔隙度增加12.89%,是DCK的5倍;脱硫石膏降低土壤pH和电导率效果最优,最大降幅分别为10.09%和28.51%;3种改良剂对盐渍化土壤的肥力效应不同,与对照相比,在收获后生物炭处理显著提高土壤耕层有机质、碱解氮、速效磷含量,脱硫石膏显著提高速效钾含量;各改良剂处理能显著增加葵花株高、茎粗、干物质积累量和百粒重,且生物炭处理的葵花产量最高,为4 539.60 kg/hm~2,较对照增产32.28%。综上所述,在河套灌区盐渍化土壤中施入不同改良剂后,土壤性状得到明显改善,促进葵花的正常生长,提高了产量。其中施入生物炭22.5 t/hm~2对盐渍土壤改良效果最佳,其次是施入脱硫石膏37.5 t/hm~2,能有效地提高土壤肥力和葵花产量。     

Immobilization of Cu and Cd in a contaminated soil: one- and four-year field effects

Purpose

Many amendments have been applied to immobilize heavy metals in soil. However, little information is available on the changes of immobilization efficiencies of heavy metals in contaminated soils over time. This work investigated the immobilization efficiencies of copper (Cu) and cadmium (Cd) in contaminated soils in situ remediated with one-time application of three amendments for 1 year and 4 years.

Materials and methods

Apatite, lime, and charcoal were mixed with the topsoil of each plot with the amounts of 22.3, 4.45, and 66.8 t/ha, respectively. Soil chemical properties and fractions of Cu and Cd were examined after in situ remediation for 1 year and 4 years. Soil sorption and retention capacities and desorption proportions for Cu and Cd were investigated by batch experiments.

Results and discussion

The addition of amendments significantly increased soil pH, but decreased exchange acid and aluminum (Al). The amendments significantly decreased the CaCl₂ extractable Cu and Cd and transformed them from active to inactive fractions. After the application of amendments for 1 year, the maximum sorption capacities ranged from 35.6 to 38.8 mmol/kg for Cu and from 14.4 to 17.0 mmol/kg for Cd, which were markedly higher than those of the application of amendments for 4 years (Cu, 29.6–34.7 mmol/kg; Cd, 10.9–16.4 mmol/kg). Desorption proportions (D) of Cu and Cd using three extractants followed the order of \( {D}_{{\mathrm{NaNO}}_3}<{D}_{{\mathrm{CaCI}}_2}<{D}_{{\mathrm{MgCI}}_2} \) . Moreover, the retention capacities (R) of Cu and Cd both increased and followed the order of R _apatite?>?R _lime?>?R _charcoal, resulting in higher Cu and Cd in the amended soils than the untreated soil.

Conclusions

Apatite, lime, and charcoal increased the soil sorption and retention capacities of Cu and Cd and resulted in higher immobilization efficiencies in the amended soils than the untreated soil. However, the immobilization efficiencies of Cu and Cd decreased with the decrease of sorption capacities after 4 years. It was concluded that apatite had the best effect on the long-term stability of immobilized Cu and Cd and can be applied to immobilize heavy metals in contaminated soils.     

Effects of Biochar and Biosolid on Adsorption of Nitrogen,Phosphorus, and Potassium in Two Soils

Increasing the retention of nutrients by agricultural soils is of great interest to minimize losses of nutrients by leaching and/or surface runoff. Soil amendments play a role in nutrient retention by increasing the surface area and/or other chemical processes. Biochar (BC) is high carbon-containing by-product of pyrolysis of carbon-rich feedstocks to produce bioenergy. Biosolid is a by-product of wastewater treatment plant. Use of these by-products as amendments to agricultural soils is beneficial to improve soil properties, soil quality, and nutrient retention and enhance carbon sequestration. In this study, the adsorption of NH₄-N, P, and K by a sandy soil (Quincy fine sand (QFS)) and a silty clay loam soil (Warden silty loam (WSL)) with BC (0, 22.4, and 44.8 mg ha^?1) and biosolid (0 and 22.4 mg ha^?1) amendments were investigated. Adsorption of NH₄-N by the QFS soil increased with BC application at lower NH₄-N concentrations in equilibrium solution. For the WSL soil, NH₄-N adsorption peaked at 22.4 mg ha^?1 BC rate. Biosolid application increased NH₄-N adsorption by the WSL soil while decreased that in the QFS soil. Adsorption of P was greater by the WSL soil as compared to that by the QFS soil. Biosolid amendment significantly increased P adsorption capacity in both soils, while BC amendment had no significant effects. BC and biosolid amendments decreased K adsorption capacity by the WSL soil but had no effects on that by the QFS soil. Ca release with increasing addition of K was greater by the WSL soil as compared to that by the QFS soil. In both the soils, Ca release was not influenced by BC amendment while it increased with addition of biosolid. The fit of adsorption data for NH₄-N, P, and K across all treatments and in two soils was better with the Freundlich model than that with the Langmuir model. The nutrients retained by BC or biosolid amended soils are easily released, therefore are readily available for the root uptake in cropped soils.     

The use of coal fly ash in sodic soil reclamation

An experiment was conducted for two years in northwest India to explore the feasibility of using coal fly ash for reclamation of waterlogged sodic soils and its resultant effects on plant growth in padi–wheat rotation. The initial pH, electrical conductivity, exchangeable sodium percentage and sodium adsorption ratio of the experimental soil were 9.07, 3.87 dS m⁻¹, 26.0 and 4.77 (me l)^−1/2, respectively. The fly ash obtained from electrostatic precipitators of thermal power plant had a pH of 5.89 and electrical conductivity of 0.88 dS m⁻¹. The treatments comprised of fly ash levels of 0.0, 1.5, 3.0, 4.5, 6.0 and 7.5 per cent, used alone as well as in combination with 100, 80, 60, 40, 20 and 10 per cent gypsum requirement of the soil, respectively. There was a slight reduction in soil pH while electrical conductivity of the soil decreased significantly with fly ash as measured after padi and wheat crops. The sodium adsorption ratio of the soil decreased with increasing fly ash levels, while gypsum treatments considerably added to its favourable effects. Fly ash application increased the available elemental status of N, K, Ca, Mg, S, Fe, Mn, B, Mo, Al, Pb, Ni, Co, but decreased Na, P and Zn in the soil. An application of fly ash to the soil also increased the concentrations of above elements except Na, P and Zn in the seeds and straw of padi and wheat crops. The available as well as elemental concentrations in the plants was maximum in the 0 per cent fly ash + 100 per cent gypsum requirement treatment except Na and heavy elements like Ni, Co, Cr. The treatment effects were greater in the fly ash + gypsum requirement combinations as compared to fly ash alone. Saturated hydraulic conductivity and soil water retention generally improved with the addition of fly ash while bulk density decreased. Application of fly ash up to 4.5 per cent level increased the straw and grain yield of padi and wheat crops significantly in both years. The results indicated that for reclaiming sodic soils of the southwest Punjab, gypsum could possibly be substituted up to 40 per cent of the gypsum requirement with 3.0 per cent acidic fly ash. Copyright © 2003 John Wiley & Sons, Ltd.     

Response of rice to basic slag,lime, and leaching in two saline-acid sulfate soils in pot experiments

Pot experiments were conducted to evaluate the effects of basic slag (6 to 18 t/ha), lime (CaCO₃: 3 to 9 t/ha), lime (3 t/ha) plus MnO₂ (100 mg/kg), and leaching (1.8 L/kg soils) on the growth, yield, and nutrition of rice plants grown on two saline-acid sulfate soils. The Sulfic Fluvaquent (Chakaria series) and Typic Sulfaquent (Badarkhali series) respectively showed low pH (4, 4.3); high electrical conductivity (16.2, 14.2 mS/cm), sodium adsorption ratio (13.6, 12.8), and water soluble SO₄2^? (4.6, 4.9 cmol/kg). The growth and yield response of rice to the treatments were found better in Chakaria than in Badarkhali soil. The leaching treatment was found to be the best to produce the maximum straw, and grain yield (869% increase over the control) and the highest dose of basic slag (18 t/ha) was ranked second (728%) in Badarkhali soil. But in Chakaria soil, the best response (928%) was determined with the highest dose of lime (6 t/ha) followed by the leaching (900%) treatment. The additional application of Mn0₂ (100 mg/kg) with lime (3 t/ha) significantly increased the straw and grain yields of rice by 42–47% compared with the lime 3 t/ha in both the soils. Similar effects were observed for N, P, and K concentrations in plant straw at maturity. Leaching, basic slag, and lime treatments exerted significant decrease of the Fe, Mn, Zn, and S concentrations in plants, increase of soil solution pH and optimization of some element concentrations in the plants and soil solutions.     

Combined amendment of immobilizers and the plant growth-promoting strain Burkholderia phytofirmans PsJN favours plant growth and reduces heavy metal uptake

In the surroundings of a former Pb/Zn smelter in Arnoldstein (Austria) heavy metal concentrations in planted crops exceed thresholds for usage as food and feed. The aim was to study the effects of a plant growth-promoting bacterial strain in combination with immobilizing soil amendments on plant growth, heavy metal uptake and on microbial community structure. Pot experiments were performed whereby two maize cultivars were grown in different contaminated soils and treatments consisted of Burkholderia phytofirmans strain PsJN with and without addition of gravel sludge and siderite bearing material. Inoculation with strain PsJN significantly improved root and shoot biomass of maize independent of immobilizer addition. Analysis of heavy metal content of the rhizosphere and leaves indicated that immobilizing amendments had significant reducing effects on NH₄NO₃ extractable Zn and Pb in soil and in plants grown in treated soils. Microbiomes were analysed by cultivation-independent pyrosequencing analysis of 16S rRNA genes. The results showed clear effects on community composition in response to the immobilizer amendments, whereas inoculation with B. phytofirmans affected microbiome diversity only to a minor extent.     

不同改良剂对滨海盐渍土盐碱指标及作物产量的影响研究

针对江苏滨海盐渍土的特点,采用5种土壤改良剂,通过田间试验分析了不同处理土壤盐碱指标的变化状况,并结合作物产量筛选出适宜的改良剂。结果表明：禾康、康地宝、腐殖酸处理后,土壤盐分含量、pH、总碱度和钠吸附比（(SAR）)较对照都有所降低,其中腐殖酸处理降低量最多,各指标分别为0.53 g/kg、0.16、0.170 cmol/kg和2.61;石膏处理后,土壤盐分含量增加0.16 g/kg,但pH、总碱度和钠吸附比与对照相比分别降低0.08、0.09 cmol/kg、3.33;金满田生物菌剂处理后土壤盐分、pH、总碱度和钠吸附比与对照相比差异不明显。改良剂处理后作物产量都有所提高,其中腐殖酸处理较对照增加最多,油菜和玉米分别增产15.68% 和9.15%。     

Influence of plant species and phosphorus amendments on metal speciation and bioavailability in a smelter impacted soil: a case study of food-chain contamination

Purpose

The present research aimed to assess the influence of two phosphorous (P) amendments on metal speciation in rhizosphere soil and the soil–plant transfer of metals.

Materials and methods

Complementary experiments were performed: field experiments on a contaminated cultivated soil and laboratory experiments on an uncultivated contaminated soil to highlight the mechanisms involved in metal-phosphorous interactions. In laboratory experiment, P amendments were added at 120 mg P/kg of soluble KH₂PO₄ amendment and 9,000 mg P/kg of solid Ca₅(PO₄)₃OH amendment.

Results and discussion

Field-culture results showed the possible food-chain contamination due to Pb, Cd, Cu, and Zn phytoaccumulation by pea and mustard plants from a cultivated agricultural soil. Moreover, P-metal complexes were observed by microscopy in the rhizosphere soil. In laboratory experiments, the application of P amendments significantly increased Pb and Zn level in rhizosphere soil compared to control. Phosphate amendments significantly increased metal-P fraction and decreased “oxides” and “organic matter” fractions of Pb and Zn. Soluble-P amendment was more effective than solid P amendment in changing Pb and Zn speciation. The changes in metal speciation are higher in the rhizosphere soil of pea than tomato. Application of P amendments increased Pb and Zn TF root/soil but decreased TF shoot/root.

Conclusions

The effectiveness of in situ metal immobilization technique varies with the type and quantity of applied P amendment as well as plant and metal type.