Soil nutrient concentrations and stoichiometry under different tree-cropping systems in a purple hillslope in southwestern China

Agroforestry systems strongly impact soil properties, yet their effects on the stoichiometry of soil nutrients remain unclear. This study aimed to determine the tree-cropping systems effects on soil C, N, P and K concentrations and their stoichiometry in 0–10 and 10–20 cm soil depths in a purple hillslope of southwestern China. Five typical agroforestry systems, including Citrus sinensis (L.) Osbeck system (CO), CO and Ipomoea batatas (L.) system (CI), CO and Arachis hypogaea (L.) system (CA), CO and Zea mays (L.) system (CZ), and CO and Solanum melongena (L.) system (CS), were investigated. Tree-cropping systems (i.e. CI, CA, CZ and CS) showed significantly higher soil C, N, P and K concentrations and clay percentage, and lower bulk density than CO system. Nutrient ratios altered inconsistently among five agroforestry systems. Soil depth differed N concentration, N:K ratio, bulk density and total porosity. Soil nutrient concentrations and stoichiometry showed significant correlations with physical properties. N:P ratio was 69.78 and 78.55% lower than the Chinese and World averages in the 0–10 cm soil depth, indicating that severe N limitation occurred in the agroforestry systems. Rational N fertilization and allocation of tree-cropping systems are urgently needed for sustainable development of agroforestry.     

Correlations between element concentrations in spruce foliage and forest soils

Abstract

The relationships between foliage element concentrations in red spruce and soil chemical properties were studied to determine if standard soil measurements of individual elements in soils were well correlated with the concentrations of these elements in foliage. Significant positive correlations between O horizon and foliage concentrations existed only for K, Mn and P. Significant negative correlations between the concentrations of the major divalent cations (i.e. Ca, Mg, Mn) and K in the foliage were found suggesting a possible antagonism between the mono‐ and divalent cations for uptake from the soil. Trees with the highest foliage concentrations of Ca also were determined to be growing on soils which were producing the best growth rates. Foliage concentrations of P, and to a lesser extent K and Mg, were below values considered to be adequate for optimum growth in red spruce.     

Silicon concentrations in soil and bark in Irish Sitka spruce forests

The relationship between plant‐available silicon (Si) soil concentrations and bark Si concentrations in coniferous species is poorly understood. The objectives of this research were to generate baseline data on Si concentrations in soils and bark of Sitka spruce (Picea sitchensis) seedlings in Ireland and to understand better the relationship between soil and bark Si concentrations. Seedlings were harvested from eight plantation forestry sites and two tree nurseries, and Si concentrations in the bark tissue as well as plant‐available Si concentrations in soils (CaCl₂ extractant) were measured. Bark Si concentrations varied significantly between sites and were lowest [mean 790 (± 242 SD) mg kg^?1 dry plant tissue] on acidic, organic rich peat soils, while the highest Si concentrations occurred in seedlings [mean 3688 (± 633 SD) mg kg^?1 dry plant tissue] grown on soils with low C concentration and higher pH values (≈ 4.5 to 5.5 in H₂O). Plant‐available Si soil concentrations were not related to soil C concentrations. There was a negative (but statistically not significant) relationship between plant–soil concentrations and soil pH. A significant negative relationship was observed between plant‐available soil Si concentrations and bark Si concentrations, which may be related to the presence of soil from mixed soil horizons forming the mounds that seedlings were planted on. Uptake and sequestration of Si by seedlings may have been related to the rate of growth of the seedlings, as bark Si concentrations were highest on sites that were expected to have greater seedling growth rates. The negative relationship between bark and plant‐available Si soil concentrations suggest that uptake of Si by Sitka spruce is rejective at higher concentrations.     

不同浓度铜污染对水稻土甲烷氧化菌群落结构的影响

近年来,随着含铜矿产的开采、冶炼和制造等工业“三废”的排放、含铜农药与杀菌剂的长期大量施用以及城市污泥的堆肥利用,农田土壤铜污染日趋严重。土壤含铜量一旦超出其环境承载力,就会对植物、动物和土壤微生物产生危害,严重威胁到生态系统的稳定和人类的健康[1]。我国是水稻生产大国,其种植面积达全国粮食作物栽培面积的1/4,因此,水稻土在我国粮食生产中占有及其重要的地位,是具有重大经济意义的土壤资源[2]。研究表明,过量铜会对水稻根系产生毒害,进而推迟抽穗期,降低产量[3]。铜污染不仅会危害作物地上部分的生长发育,同时也会导致土壤微生物数量、呼吸强度、微生物商、代谢商等的变化,并对微生物的活性和功能产生影     

The relationship between phosphorus and copper concentrations in wheat

Abstract

Poorly managed kaolinitic soils are often too low in P and K for optimum agronomic crop production. Even though many of these soils have relatively high phosphate fixing capacities, P applied at sufficient rates to increase soil P to acceptable levels may induce micronutrient deficiencies. The purpose of this study was to evaluate the effects of applied and residual P on Mn, Zn, and Cu uptake by field grown wheat (Triticum aestivum). Treatments were a one‐time application of P (0, 64, 128, 256, and 384 kg/ha P) and K (0, 110, 220, 440, and 660 kg/ha K) rates arranged in a 5×5 complete factorial. The treatments were applied in October, 1977 and the study was continued through June, 1979. Potassium and P × K interactions did not have a significant effect on Mn, Zn, or Cu uptake. Phosphorus did not affect Mn concentration in the wheat tissue but Zn and Cu concentrations generally decreased as applied and residual soil P levels increased. The tissue Zn concentration at the various plant growth stages did not decrease below defined critical levels. The Cu concentration decreased linearly with applied P and curvilinearly with residual P. The tissue Cu levels often decreased below suggested critical levels. Total Cu in the wheat tissue indicated that the decrease in Cu concentration as P levels increased was not a simple dilution effect resulting from increased plant growth as applied and residual soil P increased.     

Barley responses to copper foliar spray concentrations when grown in a calcareous soil

This study was designed to determine the adequate copper (Cu) foliar spray concentration to correct Cu deficiency on barley (Hordeum vulgare L.) when grown in a calcareous soil. Five Cu foliar spray solution levels were tested (0% or control; 0.03%, 0.06%, 0.13%, and 0.33%). Copper was applied in the sulfate form at the early boot stage. The results showed that Cu flag leaf concentration was increased with the highest Cu application (0.33%), while Cu concentration in the grain was increased with a spray of 0.03%. An antagonism between Cu, Zn, and Fe leaf concentration was observed. Grain yield and harvest index showed a linear positive response to Cu foliar spray concentrations. A significant increase of 19.6% on grain yield was recorded with a foliar spray 0.33% of Cu.     

Water extractable concentrations of Fe,Mn, Ni,Co, Mo,Pb and Cd under different land uses of Danube basin in Croatia

Abstract

Water extraction of trace elements can simulate the concentration of elements in the soil solution from where the plant takes up the elements. The objective of this investigation was to determine the water extractable concentration of seven trace elements (Fe, Mn, Ni, Co, Mo, Pb and Cd) and to assess their relationship with soil properties of the Danube basin in Croatia. Soil samples from the surface layer (0–25 cm) of 74 sites, having different land uses (forest and agricultural land), were collected. Samples were analysed for total and water extractable trace elements as well as for pH, DOC, SOC and CEC. The concentrations of water extractable fraction of trace elements were on average: 20.14 mg kg^?1 for Fe, 3.61 mg kg^?1 for Mn, 0.07 mg kg^?1 for Ni, 0.016 mg kg^?1 for Co, 0.01 mg kg^?1 for Mo, 0.01 mg kg^?1 for Pb and 0.0009 mg kg^?1 for Cd. Soil properties were in the following range: pH 4.3–8 (Avg: 6.35), DOC 6.1–73 mg l^?1 (Avg: 26 mg l^?1), CEC 1.3–24 cmol kg^?1 (Avg: 9 cmol kg^?1) and SOC 0.5–5% (Avg: 1.7%). The concentration of water extractable fraction of trace elements was significantly correlated with pH (p <0.001), DOC (p <0.001 – p <0.05) and CEC (p <0.001) but their relationship with total content of trace element and SOC was rather weak, suggesting that total metal alone cannot be an indicator of toxicity or deficiency. Results show that pH, DOC and CEC are important soil quality parameters taking part in the solubility control of trace metals in the soil rather than their total concentration. The difference between land uses has been observed as well, suggesting that a change in land use can cause a change in trace element solubility.     

Changes in nitrogen and phosphorus concentrations in soil, soil water and surface run-off following grading of irrigation bays used for intensive grazing

Soil tests are often used to identify areas at risk of excessive phosphorus (P) exports. We investigated the changes in soil P (0–20 mm) in four recently laser‐graded (<1 year) and four established (>10 years) irrigated pastures in south‐eastern Australia before and after 3 years of irrigated dairy production. At the second sampling, soil water P and nitrogen (N), and P and N in surface run‐off (overland flow) were also measured enabling comparison of P in surface run‐off with measures of soil P. In surface soil (0–20 mm), grading reduced measures of soil P, while P sorption increased. Over 3 years, in the graded bays, Olsen P, Colwell P and P sorption decreased and water extractable P and P sorption saturation increased, while Olsen P and Colwell P decreased in the established bays. After 3 years, total dissolved P (TDP) concentrations in soil water were greater in the established bays, but dissolved reactive P (DRP) concentrations were unaffected. Organic P in soil water comprised 70 and 32% of TDP in the established and graded bays, respectively. The soil water analyses were reflected in surface run‐off. After 3 years, laser grading decreased TDP, TDN, TP and TN exports in wetting front run‐off by 40, 29, 41 and 36%, respectively, compared with established bays. This is an important result for the management of dairy systems as it suggests that the regular cultivation used to renovate pasture on more intensive dairy farms decreases the exports of P and N.     

Methane production in a flooded soil in response to elevated atmospheric carbon dioxide concentrations

 CH₄ production in a flooded soil as affected by elevated atmospheric CO₂ was quantified in a laboratory incubation study. CH₄ production in the flooded soil increased by 19.6%, 28.2%, and 33.4% after a 2-week incubation and by 38.2%, 62.4%, and 43.0% after a 3-week incubation under atmospheres of 498, 820, and 1050 μl l^–1 CO₂, respectively, over that in soil under the ambient CO₂ concentration. CH₄ production in slurry under 690, 920, and 1150 μl l^–1 CO₂ increased by 2.7%, 5.5%, and 5.0%, respectively, after a 3-day incubation, and by 6.7%, 12.8%, and 5.4%, respectively, after a 6-day incubation over that in slurry under the ambient CO₂ concentration. The increase in CH₄ production in the soil slurry under elevated CO₂ concentrations in a N₂ atmosphere was more pronounced than that under elevated CO₂ concentrations in air. These data suggested that elevated atmospheric CO₂ concentrations could promote methanogenic activity in flooded soil. Received: 2 March 1998     

Twelve-year investigation of copper soil concentrations shows that vineyards are at risk

During the period 2004–2015, the upper soil layer (0–20?cm) was sampled in eight agricultural production areas in Slovenia. Overall, 53, 249, 169, 139, and 413 samples were respectively taken from vegetable fields, arable cropland, hop fields, orchards, and vineyards. Copper was measured in the aqua-regia extracts of these samples using flame atomic absorption spectrometry. The minimum, maximum, average, and median concentrations were calculated for five land uses and for all eight production areas in Slovenia. Sample portions below and/or above the limit, warning, and critical concentrations of 60, 100, and 300?mg/kg, respectively, were calculated as well. The results were compared for different land uses and production areas and showed that the copper concentrations in the vegetable, arable crop, and hop fields and orchards did not exceed the critical concentration. In addition, the copper concentrations in the vineyards exceeded the critical concentration but the maximum copper concentration (508?mg/kg) was still lower than the concentrations reported from other vine-growing Mediterranean countries. Also, the copper concentrations in hop fields exhibited an increasing trend in the Celje (and Maribor) area(s).     

A novel automated method for the adjustment of ionic metal concentrations in soil extracts

A novel method is proposed for correcting metal fraction concentrations remaining within the sediment containing the solid residue of the sequentially extracted fraction. An easy‐to‐use Excel spreadsheet was prepared to assist adjustment of concentration in each fraction and demonstrate the difference between adjusted and non‐adjusted metal concentration of the fraction. The demonstration of a calculation of the modified BCR protocol data showed that this difference may reach 10–15% of the result value. The spreadsheet is available to download at: http://departments.agri.huji.ac.il/zabam/Rosen_Chen_Fraction_Adjustment_Formulae.xls     

Comparison of N2O and CO2 concentrations and fluxes in the soil profile between a Gray Lowland soil and an Andosol

Abstract

We measured nitrous oxide (N₂O) and carbon dioxide (CO₂) fluxes from the soil surface and in the soil through to a depth of 0.3?m, and their concentration profiles through to a depth of 0.6?m in both a Gray Lowland soil with macropores and cracks and an Andosol with undeveloped soil structure in central Hokkaido, Japan. The objective of the present study was to elucidate any differences in N₂O production and flux in the soil profile between these two soil types. In the Gray Lowland soil, the N₂O concentration above 0.4?m increased with an increase in soil depth. In the Andosol, there were no distinctive N₂O concentration gradients in the topsoil when the N₂O flux did not increase. However, the N₂O concentration at a depth of 0.1?m significantly increased and this concentration was higher than the concentration below 0.2?m when the N₂O flux greatly increased. Thus, the N₂O concentration profiles were different between these two soils. The contribution ratios of the N₂O produced in the top soil (0–0.3?m depth) to the total N₂O emitted from the soil to the atmosphere in the Gray Lowland soil and the Andosol were 0.86 and 1.00, respectively, indicating that the N₂O emitted from the soil to the atmosphere was mainly produced in the top soil. However, the contribution ratio of the subsoil to the N₂O emitted from the Gray Lowland soil was higher than that of the Andosol. There was a significant positive correlation between the N₂O flux through to a 0.3?m depth and the flux from the soil to the atmosphere in the Gray Lowland soil only. These results suggest that N₂O production in the subsoil of the Gray Lowland soil could have been activated by NO₃ ^? leaching through macropores and cracks, and subsequently the N₂O produced in the subsoil could have been rapidly emitted to the atmosphere through the macropores and cracks.     

冻融交替对不同施肥水平的黑土中氮磷元素含量的影响

为探究冻融交替对不同施肥水平的黑土中氮磷元素含量变化的影响,对东北地区的黑土进行了模拟冻融处理,并分析其氮磷指标（总氮磷、有效氮磷）的变化。结果表明,冻融交替处理后黑土中全氮的含量会降低,而有效氮和有效磷的含量会提高。单独施加无机肥会加剧冻融交替造成的土壤全氮流失（P<0.05）,5次冻融交替后有效氮含量的增长率降低,有效磷含量的增长率升高。5次冻融交替后,施加有机肥的土壤全氮和全磷含量无显著变化,有效氮和有效磷含量增长率均显著提高（P<0.05）。在寒冷地区冻融条件下的农业生产实践过程中,应适当提高有机肥的施用量,以抑制黑土中氮元素的流失,增强氮磷元素的可用性,保持土壤肥力并降低水体富营养化的风险。     

Assessment of co‐blending water treatment residual with dairy manure to reduce phosphorus concentrations in run‐off in Northern Ireland

Losses of phosphorus (P) to water that follow manure applications can be high while water treatment residuals (WTR) have an appreciable capacity to sorb soluble P which is an important risk factor in determining the susceptibility of manure P to run‐off losses. The objective of this study was to assess whether co‐blending WTR with dairy cow manure prior to surface application would reduce P concentrations in run‐off from grassland. An alum‐derived WTR was collected from a water treatment works (WTW), dried and characterized for its phosphorus sorption capacity (PSC) based on oxalate‐extractable Al and Fe. Multipoint P sorption isotherms were used to calculate the Langmuir P sorption maximum (P_max) and equilibrium P concentration (EPC₀). The WTR contained 170 g Al_ox/kg and 2.2 g Fe_ox/kg with a nominal long‐term PSC of 118 g/kg. Following a 6 day incubation of WTR, the Langmuir P_max was 82.6 g/kg and the EPC₀ of 0.13 mg P/L. Laboratory incubations of manure co‐blended with WTR indicated that 144 g WTR/kg dry matter (DM) manure significantly lowered (P < 0.001) manure WSP by 71.5 ± 16.6% after 108 h, but lower WTR mixing rates of 72 and 36 g WTR/kg had no statistical effect on manure WSP. Results from a field experiment using simulated rain on 0.5‐m² grassland plots showed no significant effect on run‐off P 2 days after applying 50 m³/ha of 6% DM manure co‐blended WTR at rates of 150 and 250 g WTR/kg.     

Effect of increasing pentachlorophenol (PCP) concentrations on bacterial populations in glycine-percolated soils

Summary Population changes of several bacterial groups were compared between soils percolated with glycine and amended with different amounts of pentachlorophenol (PCP). PCP retarded the increase in total viable bacteria with increasing doses of PCP. The increase was followed by a gradual decrease, but the numbers in the soil remained at the maximum level for a short time in the presence of large amounts of PCP. The numbers of Gram-negative bacteria and PCP-tolerant bacterial cells increased dramatically, being followed by a comparable decrease, although the former was always slightly larger than the latter. PCP reduced spore counts. PCP and glycine in the percolation fluid dissipated during the percolation, but the dissipation of glycine was slowed by the presence of increased amounts of PCP. Large portions of PCP were detected in the liquid at the late stage of percolation. Changes in pH suggested biochemical reactions in the percolated soil. The changes differed according to the amount of PCP.     

Metal concentrations in soil and invertebrates in the vicinity of a metallurgical factory near Tula (Russia)

To investigate the effects of emissions from a large metal works near Tula in the Russian Federation, we measured concentrations of iron, manganese, zinc, copper, nickel, lead and cadmium in soil, litter and invertebrates at four sampling sites at different distances from the factory. The sites were located in woodlands in the bed of the Voronka river, near the town of Kosaya Gora in the district of Tula. Additional soil properties (organic matter content, clay content, water holding capacity, Ca, Mg, N, P, and pH) were measured that could explain differences in the bioavailability of the metal burdens. It appeared that the factory is a source of Fe, Mn, Zn, Cu, Ni and Pb. One of the sampling sites had a high nitrogen content in the litter due to emissions from a fertilizer plant in the area. Most of the metal contamination was limited to the immediate surroundings and did not extend beyond a distance of 5 km. Only the site close to the factory can be considered as polluted, however, background concentrations of metals in the Tula area seem to be significantly lower than in present Western European soils and a reference system still has to be developed. Exchangeable metal concentrations (0.01 M CaCl₂ extracts from soil) were very low and were not correlated with the total concentrations, indicating low bioavailability of the pollution. At the most polluted site, concentrations of all metals were positively correlated with each other; correlations decreased with increasing distance. Metal concentrations in soil were often negatively correlated with organic matter content, especially so for nickel. Metal concentrations in invertebrates showed considerable variation between individual species, however, some general patterns were obvious. Concentrations were high in earthworms, oribatid mites and carabid beetles, and low in springtails, centipedes and spiders. There was no relationship between the trophic position of a species and its metal accumulating ability. Iron concentrations in invertebrates at the polluted site were a factor of 2 to 4 higher than at the most remote (reference) site; for zinc and copper the internal concentrations were also elevated, but to a lesser extent than the soil concentrations. The data illustrate the extremely complicated relationship between metal residues in invertebrates and metal concentrations in soil. For most of the saprophageous and predatory arthropods studied total concentrations nor exchangeable concentrations in soil are good predictors; species-specific feeding mechanisms and metal physiologies seem to be the main determinants.     

Changes in the carbon concentrations and other soil properties of some Scottish agricultural soils: Evidence from a resampling campaign

The change in soil carbon (C) concentration, soil pH and major nutrients for approximately 1,000 topsoil sampled from on-farm experimental sites over a thirty-year period from 1950 to 1980 in north-east Scotland are summarized. This period coincided with increased agricultural intensification, which included regular liming and fertilizer additions. During 2017, 37 of these sites were resampled and reanlaysed. While pH and extractable phosphorus (P) and potassium (K) increased over this period, there was no detectable change in the percentage loss on ignition. Composite soil samples were taken by auger from a depth of 0–15 cm and compared with the corresponding archived samples collected at the initiation of each experiment. Analysis of these resampled soils indicated no significant change in soil carbon (C), although soil pH, extractable magnesium (Mg) and K and Nitrogen (N) concentrations were significantly greater (p < .001) but extractable soil P concentration was significantly less (p = .015) compared with the original samples. Even though measuring C concentration alone is a poor indicator of overall changes in soil C stocks, it does provide a relative quick “early warning” of C losses that would justify a more comprehensive measure of stocks.