A laboratory study of the effect of time and temperature on the decline in Olsen P following phosphate addition to calcareous soils

Abstract. The effects of time and temperature on the changes in Olsen P after phosphate application were studied in 13 calcareous soils from Pakistan, an Oxisol from Colombia and an Inceptisol from England. The phosphate sorption reactions were monitored in two stages. The short-term reaction (30 min shaking with added phosphate in the presence of the Olsen bicarbonate solution) showed that over this time the nature of the sorbing material and number of available sites for P adsorption were important but temperature was not. The extent of the short-term sorption was not related to the amount of calcium carbonate. In the long-term reaction (incubating the soils with phosphate at 10, 25 and 45 °C for one year) the amount of Olsen P decreased with time following a power relationship. Increased temperature increased the rate of reaction, following the Arrhenius principle i.e. Q₁₀⊃ 3 (activation energy 83 kJ mol^–1). The effects of time and temperature were well described by a modified power equation Y = a (1 + f_Tt ) ^-b , where Y is the amount of Olsen P extracted after time t , a is the Olsen P value after the short-term reaction (the initial value), f_T is the ratio of the rate constants at any two temperatures and b is a coefficient which represents the loss in extractability with time. On the basis of the initial Olsen P values and subsequent Olsen P values at different times and temperatures a unified decay curve Y/a = (1 + t )^–0.20 was developed where the initial Olsen P values are normalized to 1. The parameters of this equation allow, with limitations, the prediction of changes in Olsen P in these soils if the initial Olsen P value of the soil is known.     

Residual effects of organic acid-treated phosphate rocks on some soil properties and phosphate availability

The effects of the application of organic acid-treated phosphate rocks on the growth and nutrient uptake of Italian rye grass (Lolium multiflorum Lam. cv. Tachiwase) and some properties of the soil were evaluated in a greenhouse pot experiment. Phosphate rocks (PRs) collected from six countries; China, Florida (USA), Jordan, Sri Lanka, Togo, and Tanzania, were treated with 1 M oxalic or tartaric acid at the ratio of 2.5 mL g^-1 PR. The organic acid-treated PRs, containing 12–31% water soluble P, were applied to a granitic regosol (pH 5.8) at 200 mg P pot^-1 (4 kg soil). Untreated PRs and single superphosphate (SSP) were included in the treatments. Italian ryegrass was grown for 175 dafter planting (DAP) with ample supply of other nutrients and water. Shoots were harvested at 56, 119, and 175 DAP and the soils were analyzed for pH and Olsen-P after the experiment. Application of organic acid-treated PRs consistently increased the dry matter yield and P uptake of the plants compared with the application of untreated PRs at each harvest, but they were less effective than SSP. A larger amount of P (calculated per unit water-soluble P applied) was recovered from the organic acid-treated PRs than from SSP. The amount of residual extractable P in the soils with the organic acid-treated PRs was about the same as or significantly larger than that in the soil treated with SSP. Soil pH was also significantly higher than in the control and SSP soils. The results suggest that organic acids could be used to improve the P availability of PRs to plants with favorable residual effects in terms of available P and soil pH, without exerting any adverse effects on plant growth or nutrient acquisition.     

Plant availability of isotopically exchangeable and isotopically nonexchangeable phosphate in soils

Isotopically exchangeable P (IEP) is usually considered to be completely plant‐available and the major source of P for plant uptake. The aim of the present study is to test whether plants can, besides IEP, also use non‐IEP and if part of the IEP has an equilibrium concentration in soil solution which is below the minimum concentration, C_Lmin, and can therefore not be taken up by plants. A pot experiment was carried out with maize for two years on two soils, an acid sandy and a neutral loamy soil, either without P fertilizer or fertilized with ten P sources of different solubility. Throughout both years of the study, pots were kept moist either without plants or planted twice with maize (Zea mays L., cv. Athletico). At the end of the experiment, plant P uptake, P concentration in the soil solution (C_L), and P accessible to isotopic exchange within 5 d (E_5d) were measured. Plant growth decreased the E_5d which was about equal to P uptake by maize for most treatments in the acid soil. But for some treatments, i.e., five in the acid and eight in the neutral soil, P uptake was up to 50% larger than the decrease of E_5d, indicating that plants had, besides IEP, also used P from non‐IEP sources. At adequate P supply, both soils had an E_5d of about 100 mg P (kg soil)^–1, but about 30 to 40 mg kg^–1 of this IEP had an equilibrium P concentration in the soil solution below C_Lmin of 0.1 μmol L^–1 at which P would actually not be plant‐available. This study shows that plants take up P mainly from IEP, but not the whole IEP is plant‐available. Furthermore, plants may also use P from non‐IEP sources.     

Effect of legume incorporation on solubilization of Ogun phosphate rock on slightly acidic soils in SW Nigeria

Most soils in Nigeria are known to be slightly acidic and very low in plant‐available P. These soils need to be fertilized for optimal crop production but cost and scarcity of mineral P fertilizers shifted attention to making direct application of indigenous phosphate rock viable alternative. Laboratory and greenhouse studies were carried out to monitor the effect of the decomposition of legume biomass on the solubilization of Ogun phosphate rock (OPR) on slightly acidic soils. Surface soil samples collected from three experimental sites in SW Nigeria were used. The fertilizer treatments were four rates of P as OPR (0, 30, 60, and 90 kg ha^–1) and one rate of triple superphosphate (TSP, 40 kg P ha^–1). The legume treatments were cowpea (Vigna unguiculata L Walp) and mucuna (Mucuna puriens L). Rice (Oryza sativa) was used in the greenhouse study as the test crop. Soil samples were analyzed for soluble P and pH after 2, 4, 6, and 10 months of incubation in the laboratory while plant tissues collected from greenhouse study were analyzed for P. In the incubation study, significant increase in water‐soluble P was observed when legume biomass was incorporated with phosphate rock at p < 0.05. Highest value in rice dry‐matter yield was recorded with pots treated with mucuna and TSP, also treatment combination of cowpea and OPR significantly increased rice dry‐matter yield by 16% over pots treated with cowpea biomass alone and 42% over control pot (no legume biomass and OPR in the green house (p < 0.05). Thus incorporation of legume biomass significantly increased rate of OPR solubilization.     

5-氨基酮戊酸对水稻植株中32P吸收与分配的影响

以两系杂交粳稻鄂粳杂1号为材料,应用32P示踪技术比较研究了在始穗期喷施不同浓度(10.mg/L、30.mg/L、50.mg/L)的5-氨基酮戊酸(5-Aminolevulinic.acid,ALA)对水稻植株中32P吸收与分配的影响。结果表明,10～50.mg/L.ALA处理稻株的穗、叶片、茎鞘、根系中的32P比活度和放射性活度均显著高于不喷施ALA的对照处理;10～50mg/L.ALA处理使分配到稻株穗部的32P活度百分比显著高于对照,在开花期、乳熟期和腊熟期分别较对照提高了4.3%～6.0%、4.1%～5.0%和2.0%～2.7%。上述结果表明,10～50.mg/L.ALA处理能显著提高稻株各器官对磷素的吸收,并能明显促进磷素向穗部的运输分配,从而使10～50.mg/L.ALA处理水稻的结实率和产量显著增加,与对照相比,结实率和产量分别提高了4.8%～9.9%和5.4%～14.9%,其中以30.mg/L.ALA处理增产效果最大。     

The effect of humic acids on the availability of phosphorus fertilizers in alkaline soils

Abstract. The effect of humic acids on transformation of phosphorus fertilizer was studied in an alkaline soil. Soil P was fractionated following 4 and 15 days incubation after humic acids were applied with phosphorus fertilizer to the soil. The availability of phosphate in the soil and total phosphorus in plants were determined at earing stage and at maturity in a pot experiment, and wheat yield was examined in a field trial. Addition of humic acids to soil with P fertilizer significantly increased the amount of water soluble phosphate, strongly retarded the formation of occluded phosphate and increased P uptake and yield by 25%.     

滇池富磷区土壤中溶磷真菌的筛选及其对油菜的促生作用

从滇池富磷区的89份土样中筛选出48株溶磷真菌,采用钼蓝法测定这些真菌溶解Ca3(PO4)3的能力。结果表明培养液中可溶性磷含量在14.45～64.87?mg/L,其中菌株SPF46、SPF47和Mo-Po的溶磷能力最强,其培养液中可溶性磷含量分别达到55.44、59.78和64.87?mg/L。结合形态特征及ITS rDNA 系统亲缘关系分析,将PSF46鉴定为黄暗青霉（Penicillium citreonigrum）,PSF47菌株鉴定为黑曲霉（Aspergillus niger）,Mo-Po菌株鉴定为草酸青霉（Penicillium oxalicum）。在Ca3(PO4)3、FePO4.4H2O和AlPO4 3种磷源中,这3种溶磷真菌对Ca3(PO4)2的溶磷效果最好。通过盆栽试验表明这3种溶磷真菌对油菜具有较好的促生效果,单一菌株处理,根系增长率在10.16%～294.7%,株高增长率在32.19%～134.5%;叶片直径增长率在35.53%～170.5%;鲜质量和干质量增长率分别在30.71%～189.5%,56%～224%。3种溶磷真菌混合处理,根系增长129.4%,株高增加60.41%,叶片直径增加170.5%;鲜质量和干质量分别增加246.1%、272.2%。     

A comparison of Mehlich I and Mehlich III extractants as predictors of manganese,copper and zinc availability in four Delaware soils

Abstract

The relative effectiveness of Mehlich I (.025N H₂SO₄ + .05N HCl) and Mehlich III (0.2N CH₃COOH + 0.25N NH₄NO₃ +.015N NH₄F + .013N HNO₃ + .001M EDTA) extractants as predictors of Mn, Cu and Zn uptake was assessed in a greenhouse experiment with four Delaware soils. The soils were adjusted to eight pH levels by addition of Ca(OH)₂ or elemental S, and received comparable amounts of Mn, Cu and Zn as either (1) MnSO₄ + CuSO₄ + ZnSO₄ or (2) Poultry Manure. Mehlich 1 and III extractable Mn and Zn, but not Cu, were well correlated in most instances. Excellent correlations were obtained between Mn uptake and Mehlich I and Mehlich III extractable Mn, for all soils and sources. In general, however, neither Zn nor Cu was found to correlate well with plant uptake. Based on this study, conversion to Mehlich III, as a routine soil test extractant for micronutrients, would not result in a significant improvement over the currently used Mehlich I extractant.     

根区温度对黄瓜生长和土壤养分利用的影响

采用盆栽试验,研究了不同土壤温度（对照不加温10?2℃、加温到18?2℃、加温到26?2℃）和不同盐分含量土壤（1#>2#>3#）对黄瓜干物质积累、矿质元素吸收与分配特征的影响,并对土壤性状、酶活性的影响进行了研究。结果表明：与对照不加温10℃相比,加温到18℃和26℃可以克服冬季土壤低温对黄瓜生长的限制作用,促进黄瓜苗的正常生长,为黄瓜开花结果提供保障。随着土壤温度升高,黄瓜果实干物重增加;加温到26℃与加温到18℃相比,三种盐分含量土壤1#、2#、3#黄瓜果实干物重分别增加了41.84%、15.49%、3.59%,同时反映了盐分含量高的土壤加温对提高黄瓜产量更明显。与对照不加温相比,土壤加温使黄瓜单株N、P、K的总摄取量增加,促进黄瓜根系吸收的养分向地上部转移,使土壤中速效养分（碱解氮、速效磷、速效钾）含量降低。土壤加温使土壤脲酶活性明显升高,对磷酸酶和过氧化氢酶影响不大。因此,冬季升高土壤温度可增加黄瓜产量,促进土壤养分转化,提高土壤养分利用率。     

Assessing the fixation and availability of sorbed phosphate in soil using an isotopic exchange method

An isotopic exchange method was used to characterize quantitatively the fixation and plant availability of phosphate previously sorbed by soils. In general, the exchangeability of the sorbed phosphate was much higher than its desorbability for both soils and clay minerals. Isotopic exchangeability of the sorbed phosphate increased with sorption saturation during the initial stage (15–60% saturation), but the increase was less with increasing saturation from 60–90% for all soils tested. Therefore a sorption saturation of 60% was recommended as the upper limit of P fertilization in terms of economical efficiency. For clay minerals, with increasing sorption saturation, the isotopic exchangeability of the sorbed P increased significantly for kaolinite and sesquioxides, but decreased for montmorillonite. Most of the phosphate sorbed by montmorillonite and kaolinite was found to be isotopically exchangeable, but only a small amount of the P sorbed by goethite could be exchanged. The P sorbed by Al oxide exhibited isotopic exchangeability between that of kaolinite and Fe oxide. The isotopically exchangeable phosphate pool could readily account for the P uptake of plants and the available P determined by some commonly used chemical methods, such as Olsen-P and Bray-P.     

The influence of parent material and livestock intensification on plant-available phosphorus values by the Olsen method in Northern Ireland

Abstract. Leaching of phosphorus (P) from agricultural land is the major cause of eutrophication of surface waters in Northern Ireland. However, soil testing using the Olsen method has shown that while soil P in some catchment areas of the Province is low, surface waters within these catchments are, nonetheless, every bit as eutrophic as other local catchments where soil P is high. Soil P measurements on over 6000 samples from Northern Ireland soils (A horizon only) have indicated that Olsen-P values of improved grassland on most parent materials are linearly related to animal intensification. Exceptions are soils derived from peat, marl and basalt. For each of the latter soils, the measured Olsen-P was shown to be around 10 mg L^–1 lower than expected for farms with similar intensification on other parent materials. In particular, the mean Olsen-P values of samples from basaltic soils under grass with total Fe above 62 g kg^–1 and total Mg above 16 g kg^–1 were significantly lower than those from basaltic soils with low total Fe (<37 g kg^–1) and total Mg (<8 g kg^–1). As a result of the depressed Olsen-P value, excessive quantities of P may be applied to these soils to maintain a recommended soil P index thereby enhancing the potential for nutrient enrichment of adjacent surface waters. In such cases, coworkers have shown that acid ammonium oxalate may be a better extractant than bicarbonate as an indicator of plant-available P.     

Influence of residual phosphate fertilizer on labile and extractable zinc in hawaii soils

Abstract

Zinc availability was studied using five soils from Hawaii which had histories of massive phosphorus applications. Heavy phosphate fertilization usually increased extractable Zn, irrespective of the extractant used. The extra extractable Zn associated with the added P probably came from Zn as an accessory element in the fertilizer. Treble superphosphate commonly used in Hawaii contains about 1400 ppm Zn. The Zn content of phosphate fertilizers must be considered before making statements about the effect of fertilizer P on Zn solubility and availability in soils.

Two solutions (0.1N HCl and 0.005M DTPA) were compared as Zn extractants for Hawaii soils. DTPA extracted less Zn than 0.1N HCl. Zinc extracted by repeated HCl treatment was more closely related to the labile Zn pool (E‐values and L‐values) than was DTPA‐extractable Zn. The results suggest that 0.1N HCl extractable Zn, Zn E‐value and Zn L‐value measured the quantity of a single fraction of soil Zn.

Repeated extraction of soil with 0.1N HCl seems to be a suitable procedure for evaluating the Zn status of acid, highly weathered soils of Hawaii.     

Origin of the effect of earthworms on the availability of phosphorus in a phosphate rock

A series of trials was undertaken to evaluate the mechanisms by which earthworms increase the availability of phosphorus (P) in a phosphate rock (PR). In the 6 days that PR pellets were visible on the soil surface, there was no downward movement from the site of application in the presence of earthworms. Results from the glasshouse study with tillage treatments also suggest that earthworms play no direct role in the incorporation of the surface-applied PR. Addition of earthworms (Lumbricus rubellus (Hoff.)) to the soil incubating with SPR resulted in a 32% increase in Bray-extractable soil P after 70 days and increases ranging from 30 to 44% in bicarbonate-extractable soil P over the same period. Dissolution of PR, measured by extraction with 0.5 m NaOH, also increased in the presence of earthworms after 70 days from 24% (120 μg P) to 32% (160 μgP) of added P. These increases in dissolution of the PR in the incubating soil in the presence of earthworms appear to result largely from an increase in the degree of intimate contact of the PR particles with soil surfaces. This was confirmed by optical microscopy. Whereas estimates of ingestion rates, obtained by two traditional methods, indicated that L. rubellus ingested less than 5% of the incubating soil over 70 days, measurement of the proportion of soil affected by earthworms on an area basis using a frame technique ranged from 66% for Allolobophora caliginosa (Savigny) and 89% for L. rubellus, to 100% for the two species combined after 19 days. Results obtained with the frame technique explain more fully the effect of earthworms on the dissolution of the PR during incubation.     

The influence of temperature on the growth and sulfur uptake of oats (Avena sativa L.)

Abstract

Oats were grown in perlite and nutrient solution at temperatures varying from 10/5°C (day/night) to 36/31°C. The optimum temperature for growth of tops was found to be 27°C day/22°C night over an eight week period. Plant S content showed an inverse relationship with yield.

Uptake of S was low at low temperature (10/5, 15/10°C), but was balanced by retarded growth at this temperature. Hence, uptake did not restrict growth at low temperature.     

冷链物流环境下时间温度指示器的制备与应用

为可视化冷链储运过程中桑葚品质和剩余货架期,该研究通过单因素和正交试验调节木糖、甘氨酸、磷酸氢二钾（K₂HPO₄）浓度配比,实时记录不同配比时间温度指示器（time temperature indicator, TTI）的颜色及吸光度变化规律,寻求最佳浓度配比的TTI,利用傅里叶红外光谱和紫外-可见吸收光谱探究TTI内在机理,并用动力学验证TTI恒温和断链情况下的适用性。结果表明,当木糖浓度为1.00 mol/L,甘氨酸浓度为2.00 mol/L,K₂HPO₄浓度为1.00 mol/L时TTI的吸光度更高,颜色变化更为均匀,通过阿仑尼乌斯方程得到TTI活化能为40.13 kJ/mol。桑葚在25、15、10、4、-1 ℃下的失重率、花青素、硬度、可溶性固形物、可滴定酸和维生素C的活化能分别为36.08、40.42、43.35、38.28、43.72、40.41 kJ/mol,与TTI活化能接近,说明TTI可以很好地监测桑葚的剩余货架期。此外,断链模拟结果显示,桑葚开始腐败时,TTI的颜色到达指示终点,桑葚品质变化与TTI颜色变化一致,且在不同温度波动试验下桑葚各指标和TTI的等效温度小于1 ℃,由此说明,在温度波动情况下TTI可以很好地监测桑葚的品质以及剩余货架期。研究结果可为桑葚在储运过程中提供有效的剩余货架期监测,通过调节TTI的制备参数可改变其使用寿命和适用范围,以匹配不同货架期的食品。     

炭化温度和时间与棉杆炭特性及元素组成的相关关系

为了揭示炭化温度和时间对生物质炭特性及元素组成的影响,以棉花秸秆为生物质炭制作原料,对比研究不同炭化温度（300、450、600℃）和时间（0.5、1、2、4、6 h）制备的棉秆炭的pH值、阳离子交换量（CEC）、电导率等特性及有机碳、氮和矿质元素含量及其间的相互关系。结果表明：棉秆炭化出炭率、棉秆炭有机碳含量随炭化温度的升高和时间的延长而降低（出炭率： 48.66%（300℃）>35.39%（450℃）>31.06%（600℃）,有机碳：564.02 g/kg（300℃）>405.94 g/kg（450℃）>259.36 g/kg（600℃）;在300℃下,pH值随着时间的延长而增大,450℃和600℃下基本保持在10.5左右;电导率随炭化温度的升高而增加,在炭化时间内变化不明显,且炭化温度300～450℃对棉秆炭的电导率影响相对较小,600℃影响较大;CEC随炭化温度的升高而降低,在300℃下随炭化时间的延长而增大,450和600℃下则降低。棉秆炭中全磷,全钾,速效钾,钙,镁含量随着温度的升高和时间的延长逐渐增加,全氮和碱解氮则相反,速效磷含量则表现出90.07 mg/kg（450℃）>60.72 mg/kg（600℃）>20.18 mg/kg（300℃）的变化趋势。炭化温度和时间与棉秆炭指标间相关分析表明,炭化温度和时间与出炭率、CEC、有机碳、全氮和碱解氮间呈负相关,与pH值、全磷、全钾、速效磷、速效钾、钙和镁含量呈正相关。综合分析,低温短时间（300℃,1～2h）制备的棉秆炭对农业利用预期效应较好,该研究结论为新疆棉秆炭的制备和农业利用提供理论依据和数据支撑。     

水热炭化温度和时间对鸡粪生物质炭性质的影响

水热炭化被认为是极具潜力的安全处置与资源化利用鸡粪的技术措施之一。该研究将鸡粪在190和260℃水热炭化处理不同时间(1、6和12 h),收集并测定固体产物生物质炭特性,目的在于了解水热炭化反应温度和时间对鸡粪生物质炭特性的影响。结果表明,鸡粪经过水热炭化处理后,46%~56%的干物质转化为生物质炭,C、P质量分数分别增加了5%和59%以上,而H、O、N、K质量分数则分别降低了9%~18%、26%~65%、19%~37%和92%~97%。表面电荷量降低,p H值依变性也减弱,其中有效阳离子交换量降低了50%~90%。生物质炭中1~5μm孔隙显著减少,主要形成1和100μm左右的孔隙。总体来看,水热炭化反应温度越高,反应时间越长,这些指标提高或降低的幅度越大,生物质炭的炭化程度越高;比起反应时间,反应温度对生物质炭性质的影响更大。该文还讨论了鸡粪生物质炭作为土壤调理剂的应用价值与潜力,研究结果可为鸡粪生物质炭在土壤改良等方面的应用提供基础数据。     

Effects of pyrolysis temperature and residence time on physicochemical properties of different biochar types

Here we selected eight types of feedstocks to assess the effects of pyrolysis temperature (300°C, 400°C, 500°C and 600°C) and residence time (0.5, 1, 2, 4, 8 and 24 h), respectively, on the physicochemical properties. The fixed-carbon content, pH value and amount of basic functional groups in biochars increased as the pyrolysis temperature increased from 300°C to 600°C; the opposite trend was found in the biochar yield, adsorption capacity and amount of acidic functional groups. Increasing the residence time at low pyrolysis temperature (300°C) resulted in a gradual reduction in the biochar yield and progressive increase in the pH and iodine adsorption number of biochars. However, increasing the residence time at high pyrolysis temperature (600°C) had little effect on the biochar yield or pH, while it decreased the iodine adsorption number of biochars. Given the effects of pyrolysis conditions on the pH and iodine adsorption number of biochars, low-ash agricultural wastes (e.g. wheat straw) can be pyrolysed at 300°C, 2 h to produce biochar for improving alkaline soils; high-ash agricultural wastes (e.g. sweet potato vine) and forest litter (e.g. fresh leaves of apricot tree) are preferably pyrolysed at 300°C, 4 h to produce biochar for use in acidic soils.     

活化磷矿粉对重金属污染土壤上莴苣生长与品质的影响

用0.5 mol/L草酸与南漳和保康两地的两种低品位磷矿粉在一定条件下混合培养后,施于重金属污染的土壤,通过盆栽试验,研究草酸活化磷矿粉对重金属污染土壤上莴苣生长和品质的影响。结果表明,盆栽试验中,与对照相比,施加磷矿粉和活化磷矿粉后,莴苣的株高、 叶片叶绿素SPAD值、 叶片和茎的维生素C含量都有不同程度的提高,其效果为活化磷矿粉＞磷矿粉＞对照,而叶和茎的硝酸盐含量则降低。同时,施加磷矿粉和活化磷矿粉可以提高土壤有效磷、 交换性钙、 镁含量,降低交换态重金属含量,进而降低莴苣各部分对重金属元素的吸收,如施加活化磷矿粉后莴苣根中Cd、 Cu的含量比对照最高可降低55.1%、 55.24%,地上部分中Cd、 Cu的含量比对照最高可降低59.3%、 53.4%,降低重金属含量的效果依次为活化磷矿粉＞磷矿粉＞对照。