Improving yield-related physiological characteristics of spring rapeseed by integrated fertilizer management under water deficit conditions

Two separate field experiments were conducted in 2018 and 2019 as split-plot based on randomized complete block design with three replications to evaluate physiological responses of rapeseed to fertilization treatments (control, chemical fertilizer, inoculation of seeds with PGPR, vermicompost and combined fertilizers) under different irrigation levels (irrigation after 70,100, 130, and 160 mm evaporation). Water stress increased the activities of catalase, polyphenol oxidase, peroxidase and superoxide dismutase and the contents of proline, soluble sugars and malondialdehyde and also leaf temperature, but decreased membrane stability index, chlorophyll content, leaf water content, stomatal conductance and grain yield. Application of fertilizers particularly combined fertilizers decreased proline content and leaf temperature, but increased the antioxidant enzymes activities, soluble sugars, chlorophyll content, leaf water content, membrane stability index, and stomatal conductance under different irrigation intervals. These superiorities of fertilization treatments were led to considerable improvement in grain yield. The results revealed that the combined fertilizer application improved most of the physiological parameters. It was deducted that the application of combined fertilizers reduced chemical fertilizer by about 67% and alleviated the deleterious effects of water limitation on field performance of rapeseed.     

施污土壤重金属有效态分布及生物有效性

以城市污泥为研究对象,将城市污泥与土壤按照一定的质量比配成污泥混合土壤.采用6种不同性质提取剂(0.05mol/L EDTA、0.1 mol/L CH3 COOH、0.01 mol/L CaC12、1 mol/L CH3COONH4,0.05 mol/L NaHCO3和0.05 mol/L Tris-HCl)分别对污泥混合土壤中重金属(Cd、Pb、Cu和Zn)的螯合态、酸溶态、中性交换态、中性结合态、碱性交换态和蛋白质结合态进行提取,考察污泥的添加对土壤中不同形态重金属的消长规律.通过黑麦草盆栽试验,探究污泥混合土壤中不同形态重金属的植物可利用性.结果表明:污泥混合土壤中重金属螯合态比例较大,占总量的20.3％-40.0％;其次为酸溶态和中性结合态,而中性交换态、碱性交换态和蛋白质结合态的含量较低.污泥的添加促进了黑麦草对Cd、Cu和Zn的吸收,在污泥添加率为44.4％时根部对其吸收量达最大,分别较CK处理增加了0.3、2.3和6.5倍.抑制了对Pb的吸收,在污泥添加率为37.5％时,根部对Pb的吸收较CK处理下降0.4倍.Pearson相关系数分析结果表明:污泥混合土壤中以螯合态、酸溶态和中性结合态存在重金属可被黑麦草吸收利用.     

Phytoextraction of cadmium and zinc by Salix from soil historically amended with sewage sludge

Short rotation coppice (SRC) such as Salix spp. can be grown as an energy crop and offers some potential for economic and practical phytoextraction of marginally contaminated arable soil. This study tested various soil amendments intended to increase soil metal availability to Salix, investigated the distribution of metal between different tree fractions and assessed the viability of phytoextraction using SRC on arable soils. Several Salix genotypes were grown in field trials over 4 years. Cd and Zn concentrations were generally ranked in the order leaves > bark > wood. Metal concentrations in wood increased towards the top of the willow stems, whereas concentrations in leaves showed the opposite trend. None of the amendments significantly increased uptake of Zn by willow. However, in response to a range of soil HCl treatments, mean Cd concentrations in stems and leaves were 112% and 130% of control values. Data from the current experiment, and previous studies, were combined to develop a predictive model of Cd and Zn stem uptake by Salix. The minimum biological concentration factor (BCF) required to achieve a prescribed soil metal target was also calculated based on typical proportions of bioavailable Cd in sludge-amended soils for a 25-year Salix rotation. The best Salix genotypes investigated achieved less than 20% of the uptake rate required to remove one third of the soil Cd content (equivalent to the average isotopically exchangeable Cd fraction in soils at the study site).     

Differences on nitrogen availability in a soil amended with fresh, composted and thermally-dried sewage sludge

Anaerobically-digested sludge called fresh sludge (F), composted sludge (C) and thermally-drying sludge (T), all from the same batch, were applied to the surface of a calcareous Udic Calciustept with loamy texture. Dosage equivalent was 10 t ha(-1) of dry matter. The concentration of mineral nitrogen (ammonium and nitrate) in the soil was measured in order to estimate the effects of the post-treatments to which the different kinds of sewage sludge are subjected in relation to the availability of N in the surface layer of the soil. The most significant differences in NH(4)-N and NO(3)-N concentrations due to the transformation of the organic matter were observed during the first three weeks following soil amendment. Thermally-dried and composted sludge initially displayed higher concentrations of ammonium and nitrate in soil. Five months after the amendment, soil applied with fresh sludge showed the highest concentrations of NH(4)-N and NO(3)-N (6.1 and 36.6 mg kg(-1), respectively). It is clear that the processes of composting and thermal-drying influence the bioavailability of nitrogen from the different types of sewage sludge.     

Phytotoxicity and distribution of copper in tropical soil amended with sewage sludge and copper sulfate

Abstract

A greenhouse experiment was conducted to evaluate phytotoxicity and distribution of Cu in a tropical soil amended with sewage sludge (Sw) and copper sulfate (CuSO₄.5H₂O). Samples of a clay soil from the State of Paraná, Brazil were collected at depth of 0–20; 20–40 and 40–60 cm, and brought to the laboratory to be properly accommodated in experimental units (PVC tubes). The Cu treatments were performed by the application of Sw (10 t ha-¹) amended with Cu (SB-T), and by CuSO₄. H₂O (WB-T). Lettuce plants were cultivated in the amended soil in order to predict the toxicity of the Cu. The experiment was conducted for 70 days, and then the lettuce plants and soil samples were collected for analysis. A sequential method was used to separate soil Cu into following fractions: exchangeable, amorphous iron oxide bound, crystalline iron oxide bound, organic matter bound and residual bound. The experimental results showed that Fe, Zn, K, P, Cu and organic matter amounts of the soil increased with the treatment SB-T. The toxic phyto-available Cu content in the soil for the lettuce plants was 80.00 mg kg^-1. A percolation study showed that the Cu contents were larger for the first 20 cm of depth, indicating that the metal was not transported down the soil profile. The Cu content of different fractions declined in an order residual > amorphous iron oxide > crystalline iron oxide > organic matter > exchangeable, regardless of treatment performed. Additionally, the Cu contents added from treatments were determined mainly in amorphous iron oxide fraction.     

Bioavailability and crop uptake of trace elements in soil columns amended with sewage sludge products

In order to assess the potential impact of long-term sewage sludge application on soil health, the equivalent of about 25 years of agronomic applications of low-metal (`EQ') sewage sludge products were made to greenhouse soil columns. After a 6-year period of `equilibration', during which time successive crops were grown with irrigation by simulated acid rain, the plant-available quantities of trace elements were estimated in the soils by extraction with 0.01 M CaCl₂ at 90 °C, and measured directly by uptake into a crop of red clover (Trifolium pratense L.). Soil pH had a strong influence on the level of extractable and plant-available metals, and because the tested sludge products affected soil pH differently, pH was directly factored into the comparison of different sludge treatments with controls. CaCl₂-extractable levels of several metals (Cu, Zn, Mo), sulfur and phosphorus were found to be higher in the soils amended with organic-rich sludge products than in the control soils. However, extractable Cd and Ni were not significantly elevated by the sludge amendments, presumably because of the low total loading of these metals. Copper, Zn and Mo applied in the form of sludge ash had low soil extractability, suggesting that these trace metals were trapped in high-temperature mineral phases formed during sludge incineration, and resisted subsequent weathering in the soil environment. Extractable soil metals in the alkaline-stabilized sludge treatment were also generally low. Phytotoxicity from the sludge metal loadings (Zn≤125, Cu≤135 kg/ha), was not clearly indicated as long as soil pH was maintained in the 6–7 range by lime amendment. Nevertheless, unexplained depressions in yield were noted with some of the sludge products applied, particularly the dewatered and composted materials. On limed soil columns, the most consistent effect of sludge product amendment on red clover composition was a marked increase in plant Mo.     

Carbon and nitrogen mineralization in soil amended with phenanthrene,anthracene and irradiated sewage sludge

Lactic acid production by Lactobacillus brevis and Lactobacillus pentosus on a hemicellulose hydrolysate (HH) of wet-oxidized wheat straw was evaluated. The potential of 11-12 g/l fermentable sugars was released from the HH through either enzymatic or acidic pretreatment. Fermentation of added xylose in untreated HH after wet-oxidation, showed no inhibition on the lactic acid production by either Lb. pentosus or Lb. brevis. Lb. pentosus produced lactate corresponding to 88% of the theoretical maximum yield regardless of the hydrolysis method, whereas Lb. brevis produced 51% and 61% of the theoretical maximum yield after enzymatic, or acid treatment of HH, respectively. Individually, neither of the two strains were able to fully utilize the relatively broad spectra of sugars released by the acid and enzyme treatments; however, lactic acid production increased to 95% of the theoretical maximum yield by co-inoculation of both strains. Xylulose was the main sugar released after enzymatic treatment of HH with Celluclast. Lb. brevis was able to degrade xylobiose, but was unable to assimilate xylulose, whereas Lb. pentosus was able to assimilate xylulose but unable to degrade xylobiose.     

Leaching of boron through sewage sludge amended soil: the role of clinoptilolite

A laboratory experiment was conducted to determine the release of boron from soil-sewage sludge mixtures by leaching using a clinoptilolite type natural zeolite, before land application of the sewage sludge. Soil columns were filled up with the clinoptilolite soil after mixing with sewage sludge at a rate of 30 tons ha(-1) and with two different particle sizes (0.1-0.25 and 1.0-2.0 mm) of clinoptilolite each at the concentrations of 1% and 2%. The particle size and the application rate of clinoptilolite affected both boron leaching from soil compared to the control treatment (soil and sewage sludge mixture). The total soluble boron leached from a soil column varied from 66-92% depending on the applications of clinoptilolite and reached 96% for the control treatment, following application of 80 cm depth of water in all treatments. In the cases of the 1% application rate of 0.1-0.25 and 1-2 mm sized clinoptilolite 78% and 92% of the total boron leached, respectively. While at 2% application rate of 0.1-0.25 and 1-2 mm zeolite, 66% and 87% of total soluble boron leached, respectively. Boron concentrations in the soil layers increased as application rate increased and particle size of clinoptilolite decreased because of its high adsorption capacity. Adsorption isotherms indicated that clinoptilolite had a high adsorption capacity for boron compared to the sewage sludge and soil.     

Nitrogen mineralisation potential in calcareous soils amended with sewage sludge

Mineralisation of organic N is an important consideration when determining the annual amount of sewage sludge to be applied to agricultural soils. The mineralisation of sludge organic N was studied in two different textured soils (clayey and sandy soil) treated with aerobic and anaerobic sludge at two different rates (30 and 50 g sludge kg(-1) soil). The mineralisation of sludge organic N was determined during 20 weeks incubation period by analysis of inorganic N produced by a non-leached procedure. Sludge organic N mineralisation was influenced by soil type, organic N mineralisation being greater in the sandy soil (from 30% to 41%) than in the clayey soil (from 13% to 24%). Mineralisation rates decreased rapidly the first two weeks, followed by a slower decrease with time. Although total mineralisation increased with sludge addition rate, net mineralisation decreased with sludge addition rate, probably due to denitrificaton losses. The aerobically treated sludge gave higher mineralisation rates than the anaerobically treated one. The values of N0 and k for treated soils varied depending on the type of sludge and soil.     

Heavy-metal accumulation in crops grown on sewage sludge amended with metal salts

Poplar (Populus euramericana Robusta), oats (Avena sativa L. Leander), maize (Zea mays L. Ona 36), English ryegrass (Lolium perenne L.), butter head lettuce (Lactuca sativa L. Reskia), spinach (Spinacia oleracea L. Subito) and French beans (Phaseolus vulgaris Prelude), were grown in pots with pure sewage sludge (pH 6.7), amended with Cd, Cr, Cu, Ni, Pb and Zn acetates, either added singly or in combination, to study metal effects on plant growth and metal uptake. Phytotoxic metal doses varied with metal and plant species, increasing in the order Cd<Ni<Cu<Zn<Cr and Pb. The threshold dose of toxic metals applied in combination was generally lower than that of metals given singly. Addition of Cd, Ni and Zn was clearly reflected in the respective plant concentrations. This was much less so for Cu, whereas Cr and Pb concentrations were not affected in most plant species. Critical plant (leaf) metal concentrations were lower for metals applied in combination than for single metals. Because of such phenomena the use of critical levels as a diagnostic tool for determining potential multiple metal toxicity is limited.     

Bioaccumulation of heavy metals in Dactylis glomerata L. growing in a calcareous soil amended with sewage sludge

The total and DTPA-extractable concentrations of Pb, Ni, Zn, Cu, Cr and Cd were measured in a calcareous soil amended with different doses of sewage sludge under field conditions. The same metals were also measured in the roots and leaves of Dactylis glomerata at the end of the first vegetative period after the sludge was added. The root concentrations of all the metals were unrelated to their concentrations in the soil. Leaf concentrations of Zn and Cr correlated with total (Zn) and DTPA-extractable (Zn and Cr) concentrations in the soil. DTPA extraction did not appear to be very useful for evaluating the bioavailability of metals in this kind of soil as it gave very low correlation coefficients with leaf content (r = 0.684, P = 0.0049 for Zn and r = 0.557, P = 0.0249 for Cr). Concentrations of Pb, Ni, Cu, and Cd in roots and leaves of Dactylis glomerata were unrelated to the total or DTPA-extractable concentrations in the sludge-amended soil.     

培养条件下二氯喹啉酸对土壤微生物群落结构的影响

为探讨除草剂二氯喹啉酸对土壤微生物群落结构的影响,在25℃黑暗培养条件下,采用磷脂脂肪酸法(Phospholipid Fatty Acid,PLFA)分析了二氯喹啉酸(0对照、83.3和166.6μg/kg干土)处理对淹水和不淹水水田土壤微生物群落结构的影响。结果表明,在实验处理的60 d内,不淹水水田土壤在83.3μg/kg二氯喹啉酸处理后对土壤微生物生物总量、细菌生物量及真菌生物量有抑制作用,而166.6μg/kg二氯喹啉酸处理后各生物量指标均显著增加,但是两种浓度处理均使土壤真菌/细菌比值下降,说明二氯喹啉酸处理会使不淹水水田土壤微生物稳定性下降;淹水水田土壤在83.3μg/kg二氯喹啉酸处理下,对土壤微生物生物总量和真菌生物量有促进作用,对细菌生物量有一定的抑制作用,166.6μg/kg二氯喹啉酸处理对土壤微生物生物总量、细菌及真菌生物量均有促进作用,从真菌/细菌比值上看,不同浓度处理与对照无显著差异,说明二氯喹啉酸对淹水生物稳定性无明显干扰。PLFA主成分分析表明,不同浓度处理的两种土壤微生物群落均以含14∶0、15∶0、16∶0和18∶2n6c的微生物为优势种群。     

Effect of sanitized and non-sanitized sewage sludge on soil microbial community and the physiology of pepper plants

A greenhouse experiment was conducted to investigate the impact of sanitized (Autothermal Thermophilic Aerobic Digested, ATAD) and non-sanitized (Anaerobic Mesophile Digested) sewage sludge on the activity and functional diversity of soil microbial community and the physiology of pepper plants (Capsicum annuum L. cv. Piquillo). ATAD and anaerobic mesophile sludges were applied to soils at three rates (3, 6 and 12 g (dry matter) per pot) and unamended soil was included as a control. Results showed that ATAD and mesophile sludge application increased the growth and yield of plants, and accelerated their phenological development as the sludge rate increased. The increased growth was a result of the enhanced capacity of plants to produce more leaves and the greater photosynthetic activity per unit leaf area. Besides nutrient supply, the increased soil microbial activity and biomass in amended soils might have indirectly contributed to the enhanced growth and yield of plants. Sludge application decreased soil functional diversity and caused a shift in the community-level physiological profile. Although ATAD and anaerobic mesophile sludges exerted similar effects on plant development, the type of sludge influenced the activity and functional diversity of soil microbial community. Results are discussed in relation to the environmental benefits associated with the ATAD process for sludge treatment.     

不同土壤水分条件下核桃的生理生态特性研究

采用完全随机设计试验方法对不同土壤水分条件下核桃生理生态特性进行研究.结果表明,土壤贮水量、耗水量、水分盈亏值均与灌水量成正比.轻剪、中剪和重剪可分别提高土壤贮水量0.2％、0.5％和0.9％,耗水量-0.5％、-2.0％和-2.5％以及水分盈亏值的1.5、1.9和2.1倍.灌水、覆草、覆膜、修剪处理下的土壤贮水量分别提高了4.4％、1.2％、1.6％和0.5％.灌水(225 kg,4月1日)、中剪、覆草、覆膜处理对增大小叶夹角、提高叶水势效果明显,重剪处理使叶绿素含量增加幅度最大（0.27 mg·dm^-2）.小叶夹角与叶水势呈正相关关系.以小叶夹角作为评估核桃树体水分状况及其立地土壤水分含量状况指标,具有可靠、直观、及时和简单等特点,并具有较高的应用价值.     

The influence of the Cucurbitaceae on mitigating the phytotoxicity and PCDD/PCDF content of soil amended with sewage sludge

The study evaluates the impact of sewage sludge on OECD - Organization for Economic Cooperation and Development and vegetable soil phytotoxicity, measured using three test species: Lepidium sativum, Sinapis alba and Sorghum saccharatum, and total and TEQ PCDD/PCDF (toxic equivalency polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans) soil concentration, measured using HRGC/HRMS - High Resolution Gas Chromatography/High Resolution Mass Spectrometry. It also evaluates the effect of zucchini and cucumber cultivation during 5-weeks period on mitigating these parameters. The application of 3, 9 and 18 t/ha of sewage sludge gradually increases the phytotoxicity of both OECD and vegetable soil. In the case of OECD soil, the highest roots growth inhibitions were observed for S. alba (73%, 86% and 87%, respectively) and the lowest for S. saccharatum (7%, 59% and 70%), while in vegetable soil inhibitions were averagely 25% lower. Sludge application also led to a 38% (3 t/ha), 169% (9 t/ha) and 506% (18 t/ha) increase in PCDD/PCDF concentration, and the TEQs were augmented by 15%, 159% and 251%. Both soil phytotoxicity and total and TEQ PCDD/PCDF concentrations were diminished as a result of zucchini and cucumber cultivation. The maximum reduction of soil phytotoxicity (83%) was observed as an effect of cucumber cultivation, while zucchini was 11% less effective. Zucchini, in turn, was more efficient in PCDD/PCDF removal (37% reduction), followed by cucumber (24%). Such differences were not observed in the case of TEQ reductions (68% and 66% for zucchini and cucumber cultivation, respectively).     

秸秆生物有机肥的施用对土壤供氮能力的影响

通过盆栽试验研究了秸秆生物有机肥的施用对土壤供氮能力的影响。结果表明,与原始秸秆相比,秸秆生物有以与尿素配合施用能明显提高土壤生物量碳,氮的含量,增幅约为3－4倍;土壤微生物量氮与土壤的供氮能力关系非常密切,前期发生强烈的微生物增殖过程,则中后期必会发生无机氮释放过程,这对作物的生长发育极为重要。同时提高了肥料氮利用率,揭示了秸秆生物有机肥配施无机氮肥改善土壤供氮能力的机理。     

Terrestrial Chironomidae on agricultural soil treated with sewage sludge

Adult Chironomidae were caught in emergence traps for three subsequent years (1988–1990) on agricultural soil. Larvae were extracted from soil samples taken since June 1989. The field was subdivided into 5 plots treated with different amounts of sewage sludge. On some plots the sludge was artificially enriched with heavy metalts. The phenology of Chrinonomidae in the three years and their distribution over the different plots are discussed. The results suggest that the abundance of Chironomidae is increased by sewage sludge and appears to be also increased by heavy metals.     

Effect of soil strength on root growth under different water conditions

The objective of this study was to determine the effects of soil water and soil strength on root growth in situations where the individual effects of both of these factors were important. Three grain legumes were grown from pre-germinated seeds for five days on 50-mm compacted columns of two major soils of Sri Lanka. Four or five levels of bulk density (1.1 to 1.8 Mg.m^–3) and five or six levels of matric potential (–0.02 to–2.0 MPa) were used.Soil strength and matric potential effects on root growth were independently significant for most crop and soil combinations. Under high (wet) matric potential (>–0.77 MPa) soil conditions, the effect of soil water on root growth was evident only in its effect on soil strength. Bulk density had a significant effect on root growth independent of soil strength and matric potential in three cases.For all crops and soils, root penetration was 80% of the maximum or greater when the average soil strength (soil water not limiting) was 0.75 MPa or less, and when the average matric potential (soil strength not limiting) was –0.77 MPa or greater (wetter). Root penetration was 20% of the maximum or less when the soil strength was greater than 3.30 MPa (soil water not limiting), and when matric potential (soil strength not limiting) was less than –3.57 MPa. The use of pre-germinated seeds, which contained imbibed water, combined with a lack of water loss from the closed chambers containing the plants is the probable cause for the very low (–3.57 MPa) matric potential that allowed root growth at 20% of the maximum.     

不同土壤水分条件下焕镛木幼苗的生理生态特性

在不同的土壤水分条件下 (土壤含水量分别为 2 0 1%、14 3%和 13 2 % ) ,比较研究濒危物种焕镛木幼苗的生理生态特性 ;测定了焕镛木叶片的净光合速率 (A)、气孔导度 (gs)、内在水分利用率效率 (WUE)、比叶面积 (SLA)及叶片的光合作用 光响应曲线。结果表明 :随着土壤含水量的增加叶片的净光合速率和气孔导度相应增高 ,生长在最高土壤含水量下的植株 ,日平均光合速率、气孔导度分别为 8 5 5± 4 32 μmol·m-2 ·s-1和 81 5 7± 8 4 1μmol·m-2 ·s-1,分别比生长在最低土壤含水量下的植株高 2 5 6 1%和 17 6 8% ;另一方面 ,水分利用效率、比叶面积随土壤含水量的降低而趋于增加 ,土壤含水量最低时 ,植株的日平均水分利用率、比别增加0 2 8%和 15 87% ,其中 ,水分利用效率的变幅较小 ;光饱和点随着土壤含水量的增加而增高。较高的土壤湿度有利于焕镛木的生长。