不同添加剂对土壤中乙草胺吸附／解吸的影响

采用批处理恒温振荡法,利用气相色谱一质谱联用仪研究了人工添加不同吸附物质对土壤中乙草胺的吸附／解吸作用。结果表明,人工添加不同吸附物质对土壤中乙草胺的吸附强度和吸附容量不同,不同的添加剂对土壤中乙草胺的吸附／解吸作用均呈现明显的非线性关系,可用Freundlich模型描述。并且随着土壤中添加量的增大,吸附强度增大、吸附容量增大、所得吸附等温线的非线性也逐步增大;另外,添加剂对乙草胺的解吸迟滞作用也随添加剂含量的增高而更加明显。但是不同添加剂对土壤中乙草胺的吸附能力有明显差异,其中煤粉的吸附能力最大,其次是壳聚糖,沸石最小。     

不同吸附剂对土壤中氟磺胺草醚吸附/解吸的影响

利用高效液相色谱仪结合批处理恒温振荡法,系统研究了人工添加不同吸附物质对土壤中氟磺胺草醚的吸附/解吸作用。试验结果表明:人工添加不同吸附物质对土壤中氟磺胺草醚的吸附强度和吸附容量不同,不同的吸附剂对土壤中氟磺胺草醚的吸附/解吸作用均呈现明显的非线性关系,可用Freundlich模型描述。并且随着土壤中吸附剂的量的增大,吸附强度增大、吸附容量增大、所得吸附等温线的非线性也逐步增大;另外,吸附剂对氟磺胺草醚的解吸迟滞作用也随吸附剂含量的增高而更加明显。但是不同吸附剂对土壤中氟磺胺草醚的吸附能力有明显差异,其中煤粉的吸附能力最大,其次是壳聚糖,沸石最小。     

对硝基氯苯在土壤和腐殖酸上的长期吸附与多步解吸的研究

采用批量平衡实验法研究了对硝基氯苯（p-NCB）在土壤和腐殖酸上的长期吸附和多步解吸,比较了连续的多步解吸与一步解吸的差异。结果表明,随着吸附时间的增加吸附量均会有所增加,随吸附时间增加吸附等温线的非线性增强。p-NCB在液相和固相上的初始浓度对吸附速率有一定影响,低浓度比高浓度时达到平衡的速率要低。对于两种受试土壤,两次解吸得到的等温线均无法与吸附等温线重合,表现出很强的吸附不可逆性。而尽管p-NCB在腐殖酸上表现出明显的非线性吸附（n = 0.794）,但4次解吸后所得到的平衡位点与吸附所得的平衡位点基本落在同一条直线上,对数坐标下进行线性拟合的相关系数（R2）可达0.988,说明吸附过程是完全可逆的。     

阿特拉津对绿麦隆吸附-解吸作用的影响

采用批平衡实验,研究绿麦隆在单一及复合污染体系中的吸附-解吸行为。结果表明,无论是单一体系还是复合体系,吸附等温线均可用Freundlich模型进行良好的拟合。随着阿特拉津浓度的增加,土壤对绿麦隆的吸附作用降低,表明绿麦隆和阿特拉津之间存在竞争吸附,这可能与土壤的有机质类型和绿麦隆、阿特拉津的性质、结构有关。解吸实验表明,随着阿特拉津的浓度增加,绿麦隆的解吸作用增加。吸附过程的拟合指数n值大于解吸过程的对应值,即绿麦隆在不同体系中的解吸作用均存在一定的滞后性。应用Freundlich解吸等温线参数对吸附-解吸等温线的滞后作用进行量化,CT、（CT＋0.5AT）、（CT＋1AT）和（CT＋2AT）处理解吸等温线的滞后系数ω分别为165.200,146.132,94.534和85.945,即随阿特拉津浓度增加,绿麦隆解吸等温线的滞后性降低。     

[A环-U-~(14)C]丙酯草醚在土壤中的吸附与解吸特性研究

丙酯草醚(ZJ0273)是我国拥有自主知识产权的新型高效油菜田除草剂。本文以[A环-U-14C]丙酯草醚为示踪剂,在实验室模拟条件下,采用液体闪烁测量技术对其在7种土壤中的吸附和解吸特性进行了研究。结果表明:(1)丙酯草醚在7种土壤中的吸附等温线均能极显著符合Freundlich、Langmuir和线性模型,相对而言,前两种模型的相关系数R2(0.9883~0.9998)明显高于线性模型(R2=0.9173~0.9593);(2)丙酯草醚在7种土壤中的解吸等温线能被Freundlich模型和线性模型很好地描述;(3)丙酯草醚极易被土壤吸附,不同类型的土壤对其吸附的差异较大,吸附常数KF与土壤有机质含量呈显著正相关,与之对应的解吸率极低。丙酯草醚吸附解吸过程存在明显的滞后现象,应科学合理地在有机质丰富的土壤中使用。     

磷含量和秸秆添加量对褐土锌吸附—解吸的影响

采用室内培养的方法,通过人为添加不同量的玉米秸秆和磷,研究不同含量磷和作物秸秆对土壤锌吸附—解吸的影响,以探讨磷—锌在土壤中的交互作用机制。结果表明:低锌(Zn10:添加Zn2+浓度为10 mg L-1)条件下,土壤对Zn2+的吸附量随土壤速效磷含量的增加而逐渐降低,表明在石灰性土壤中,随磷含量的增加提高了土壤锌的有效性;而Zn2+的解吸量随土壤中磷含量的增加先升高后降低,添加Zn2+浓度为80 mg L-1(Zn80)条件下,土壤对Zn2+的吸附量明显大于Zn10条件下。土壤中添加不同秸秆量对不同浓度Zn2+吸附时,低锌(Zn10)处理下,在相同磷含量情况下,土壤对Zn2+的吸附量随秸秆添加量的增加而减少,而土壤对Zn2+的解吸量随秸秆量的增加而增加。在不同磷水平下,不同秸秆添加量对Zn2+的吸附趋势差异较大。高锌(Zn80)处理下,土壤对Zn2+的吸附量在不同秸秆量处理下趋势大致相同,且Zn2+吸附量随磷含量的提高先升高后降低;在同一磷水平下,土壤对Zn2+的吸附趋势和Zn10时相似。利用KNO3进行解吸Zn2+时,不添加秸秆和低量秸秆处理变化趋势相同,均在添加磷量为360 mg kg-1时解吸量达到最大,分别为363.5 mg kg-1、424 mg kg-1,而高量秸秆处理下,Zn2+解吸量随磷含量的增加先升高后降低。     

不同温度下镉在典型农田土壤中的吸附动力学特征

按土重的3%和5%向采自海南和广西的3种可变电荷土壤中添加由稻草制备的生物质炭,混合培养30 d后用一次平衡法研究了生物质炭对土壤吸附Cd（Ⅱ）的影响及其与土壤表面电化学性质的关系,旨在阐明生物质炭促进可变电荷土壤吸附和固定Cd（Ⅱ）的机制。结果表明,添加稻草炭显著提高了3种土壤的阳离子交换量（CEC）和土壤pH,并使土壤胶体Zeta电位向负值方向位移。因此,添加稻草炭增加了土壤表面的负电荷量,土壤表面对Cd（Ⅱ）的吸附容量增强,使3种可变电荷土壤对Cd（Ⅱ）的吸附量增加,且Cd（Ⅱ）吸附量的增幅随稻草炭添加水平的提高而增加。Freundlich方程和Langmuir方程可以拟合3种土壤对Cd（Ⅱ）的吸附等温线,但Freundlich方程拟合效果更好,该方程表征吸附容量的常数k也随着稻草炭添加水平提高而增大。研究表明在pH3.0~5.0范围内,稻草炭均增加土壤对Cd（Ⅱ）的吸附量。添加稻草炭提高土壤pH,促进Cd（Ⅱ）的吸附,因为Cd（Ⅱ）的吸附量随pH升高而增加。解吸实验表明,添加稻草炭处理Cd（Ⅱ）的解吸量高于对照处理,说明生物质炭提高了土壤对Cd（Ⅱ）的静电吸附量。     

稻草生物质炭对3种可变电荷土壤吸附Cd（Ⅱ）的影响

按土重的3%和5%向采自海南和广西的3种可变电荷土壤中添加由稻草制备的生物质炭,混合培养30 d后用一次平衡法研究了生物质炭对土壤吸附Cd（Ⅱ）的影响及其与土壤表面电化学性质的关系,旨在阐明生物质炭促进可变电荷土壤吸附和固定Cd（Ⅱ）的机制。结果表明,添加稻草炭显著提高了3种土壤的阳离子交换量（CEC）和土壤pH,并使土壤胶体Zeta电位向负值方向位移。因此,添加稻草炭增加了土壤表面的负电荷量,土壤表面对Cd（Ⅱ）的吸附容量增强,使3种可变电荷土壤对Cd（Ⅱ）的吸附量增加,且Cd（Ⅱ）吸附量的增幅随稻草炭添加水平的提高而增加。Freundlich方程和Langmuir方程可以拟合3种土壤对Cd（Ⅱ）的吸附等温线,但Freundlich方程拟合效果更好,该方程表征吸附容量的常数k也随着稻草炭添加水平提高而增大。研究表明在pH3.0~5.0范围内,稻草炭均增加土壤对Cd（Ⅱ）的吸附量。添加稻草炭提高土壤pH,促进Cd（Ⅱ）的吸附,因为Cd（Ⅱ）的吸附量随pH升高而增加。解吸实验表明,添加稻草炭处理Cd（Ⅱ）的解吸量高于对照处理,说明生物质炭提高了土壤对Cd（Ⅱ）的静电吸附量。     

天然土壤中典型多溴联苯醚解吸过程的初步研究

选择5种有机质含量不同的天然土壤,采用批量实验方法考察典型多溴联苯醚8DE47的解吸行为,并尝试利用非线性Freundlich模型和线性模型模拟不同初试浓度条件下BDE47的土壤解吸过程。针对较为显著的器壁吸附影像,所有检测数据均进行器壁吸附定量修正。结果表明,BDE47土壤解吸过程总体分为初始的快解吸和后续的慢解吸两个阶段。在初始阶段,BDE47解吸过程表现为线性行为,但非线性特征随解吸时间延长呈现增强趋势。土壤有机质（用TOC表征）释放的溶解有机质是影响土壤中BDE47解吸行为差异的主要因素之一。     

黑土锌有效度的物理化学研究法

锌是动植物必需微量元素同时亦是污染土壤的重金属元素,研究黑土中锌形态及其有效度对保护黑土农业生态环境具有重要意义。以黑土13年长期定位试验为研究对象,采用物理化学研究法,分析评价黑土Zn形态转化及锌有效度。结果表明,长期不施肥黑土有效锌(DTPA-Zn)含量可达1.96 mg kg-1,长期施肥可显著增加黑土交换态Zn和无定型氧化铁结合态Zn含量,从而显著提高黑土有效Zn含量,可增至3.3 mg kg-1,对土壤全Zn未有明显增加;配施有机肥可显著增加矿物态Zn以外其他各形态Zn含量,土壤有效锌含量随有机肥施用量增加而逐渐增加,最高可达14.5 mg kg-1。长期施肥使土壤酸化从而降低了黑土对Zn2+的吸附强度和容量,且其吸附的Zn2+更易解吸出来,配施一定量有机肥处理虽未能减缓土壤酸化,可在一定程度上增加土壤对Zn2+的吸附强度与容量,但其吸附的Zn2+更难以解吸。总体黑土有效锌含量相对较高,对Zn2+吸附强度和容量均较高,但随着施肥引起土壤酸化而降低其对Zn2+吸附强度和容量。     

Sorption and desorption behaviors of diuron in soils amended with charcoal

Charcoal derived from the partial combustion of vegetation is ubiquitous in soils and sediments and can potentially sequester organic contaminants. To examine the role of charcoal in the sorption and desorption behaviors of diuron pesticide in soil, synthetic charcoals were produced through carbonization of red gum (Eucalyptus spp.) wood chips at 450 and 850 degrees C (referred to as charcoals BC450 and BC850, respectively, in this paper). Pore size distribution analyses revealed that BC850 contained mainly micropores (pores approximately 0.49 nm mean width), whereas BC450 was essentially not a microporous material. Short-term equilibration (< 24 h) tests were conducted to measure sorption and desorption of diuron in a soil amended with various amounts of charcoals of both types. The sorption coefficients, isotherm nonlinearity, and apparent sorption-desorption hysteresis markedly increased with increasing content of charcoal in the soil, more prominently in the case of BC850, presumably due to the presence of micropores and its relatively higher specific surface area. The degree of apparent sorption-desorption hystersis (hysteresis index) showed a good correlation with the micropore volume of the charcoal-amended soils. This study indicates that the presence of small amounts of charcoal produced at high temperatures (e.g., interior of wood logs during a fire) in soil can have a marked effect on the release behavior of organic compounds. Mechanisms of this apparent hysteretic behavior need to be further investigated.     

Biochar Increases Diuron Sorption and Reduces the Potential Contamination of Subsurface Water with Diuron in a Sandy Soil

The herbicide diuron is widely used in agricultural areas in Brazil, whereas it has high potential for subsurface water contamination due to its physicochemical characteristics. Recent studies have demonstrated the potential of biochar as a sorbent and possible pesticide leaching mitigation. The objective of this study was to investigate the long-term effect of biochar application on the kinetics of sorption and desorption of diuron in a Cerrado Haplic Plinthosol. Samples were collected in an experiment conducted in the field in a randomized block design consisting of the combination of two levels of fertilizer application (0 and 300 kg ha^-1 of 5-25-15 formula of NPK fertilizers) and three doses of biochar (0, 16, and 32 Mg ha^-1). The Freundlich isotherm accurately described the sorption of diuron in all treatments. Biochar application increased the sorption and reduced the desorption of diuron. This effect was attributed to the contribution of biochar to total organic carbon (C) and C in the humin fraction and to the increase in the reactivity of the humic acid and humin fractions, which was significantly highly correlated with the sorption coefficient (K_f). A positive correlation between the partition coefficient of organic C and K_f confirmed the importance of the soil organic compartment for the sorption of diuron. The higher diuron sorption and lower diuron desorption capacities of sandy soils after biochar application could reduce the potential risk of diuron leaching and contamination of subsurface water.     

Assessment of three vermicomposts as organic amendments used to enhance diuron sorption in soils with low organic carbon content

Vermicomposts from the wine and distillery industry containing spent grape marc (V1), biosolid vinasse (V2) and alperujo (V3) from the olive‐oil industry were investigated as organic amendments to a sandy and a clay soil with low organic carbon (OC) contents (≤1%). The sorption‐desorption process was studied in batch experiments using diuron as a non‐ionic herbicide model. The effect of soil and vermicompost characteristics, the solution's ionic strength and incubation time of amended soils on the sorption process was studied. The addition of vermicompost changed soil properties and enhanced sorption capacity by two‐ to four‐fold. The K_oc variability showed that exogenous OC composition influenced diuron sorption. Vermicompost V1, which had the largest OC and lignin content, recorded the largest sorption increment. Vermicompost V3, which had the greatest dissolved organic carbon content and a high degree of humification, made the smallest contribution to sorption. Sorption was also dependent on extraneous calcium in the solution. The incubation of amended soils reduced diuron sorption efficiency except with V3. Pyrolysis‐gas chromatography (Py‐GC) analysis was a useful tool to characterize the vermicomposts and to understand the variation of diuron sorption constants after vermicompost incubation. This research encourages the use of vermicompost from agro‐industrial wastes as a sustainable means to minimize the side effects of neutral herbicides.     

Sorption of s-Triazine Herbicides in Organic Matter Amended Soils: Fresh and Incubated Systems

Fresh amendment of soil with sewage sludge and composted sewage sludge resulted in increased sorption of three s-triazine herbicides: atrazine, ametryn and terbuthylazine. The extent of increased sorption (as evaluated by sorption coefficients K_d or K_f) was a function of soil type, such that sorption in amended organic carbon-poor soil (0.4% OC) was more enhanced than in amended organic carbon-rich soil (1.55% OC). Despite significant differences between the organic amendments in terms of humic and fulvic acid content, humin content, soluble organic matter content, total organic matter content, and H/C and O/C atomic ratios, organic matter composition had no discernible effect on either sorption distribution coefficients or on isotherm linearity in amended soils. Soils amended with composted sludge had the same sorption potential as did soils amended with the analogous uncomposted sludge. After incubating soil-sludge mixtures for a year at room temperature, organic matter content decreased to original pre-amendment levels. Sorption coefficients for the three compounds similarly decreased to initial pre-amendment values. Organic carbon normalized sorption coefficients (K_oc) were essentially identical in the soils, amended soils, and incubated amended soils, indicating that sludge and compost derived organic matter does not have a significantly different sorption capacity as compared with the original soils, despite compositional differences.     

菲在土壤/沉积物上的吸附-解吸过程及滞后现象的研究

实验研究了菲在土壤 /沉积物上的吸附 解吸过程。CHL土壤和HFH沉积物中有机质的固相13 CCPMASNMR谱图很相似 ,表明样品中有机质的组成差异不大 ;菲在土壤 /沉积物上的吸附过程表现出明显的非线性 ;线性模型不适合拟合菲的吸附等温线 ,Freundlich模型和双区位反应模型 (DRDM)较好地拟合了菲的吸附等温线 ,其中DRDM模型还清楚地反映菲在低浓度和高浓度下不同的吸附方式 ;另外 ,研究表明菲在土壤 /沉积物上的解吸过程中存在明显的滞后现象 ,这可能和土壤 /沉积物有机质的异质性和土壤胶团微小孔隙的存在有关。     

Fate of diuron and terbuthylazine in soils amended with two-phase olive oil mill waste

The addition of organic amendments to soil increases soil organic matter content and stimulates soil microbial activity. Thus, processes affecting herbicide fate in the soil should be affected. The objective of this work was to investigate the effect of olive oil production industry organic waste (alperujo) on soil sorption-desorption, degradation, and leaching of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and terbuthylazine [N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine], two herbicides widely used in olive crops. The soils used in this study were a sandy soil and a silty clay soil from two different olive groves. The sandy soil was amended in the laboratory with fresh (uncomposted) alperujo at the rate of 10% w/w, and the silty clay soil was amended in the field with fresh alperujo at the rate of 256 kg per tree during 4 years and in the laboratory with fresh or composted alperujo. Sorption of both herbicides increased in laboratory-amended soils as compared to unamended or field-amended soils, and this process was less reversible in laboratory-amended soils, except for diuron in amended sandy soil. Addition of alperujo to soils increased half-lives of the herbicides in most of the soils. Diuron and terbuthylazine leached through unamended sandy soil, but no herbicide was detected in laboratory-amended soil. Diuron did not leach through amended or unamended silty clay soil, whereas small amounts of terbuthylazine were detected in leachates from unamended soil. Despite their higher sorption capacity, greater amounts of terbuthylazine were found in the leachates from amended silty clay soils. The amounts of dissolved organic matter from alperujo and the degree of humification can affect sorption, degradation, and leaching of these two classes of herbicides in soils. It appears that adding alperujo to soil would not have adverse impacts on the behavior of herbicides in olive production.     

Sorption-desorption of aminocyclopyrachlor in selected Brazilian soils

Aminocyclopyrachlor sorption/desorption was investigated in 14 soils from Brazil, representing a range of pH, and organic carbon (OC) and clay contents. The Freundlich equation adequately described behavior of aminocyclopyrachlor in soil. Freundlich sorption coefficient (K(f)) values ranged from 0.06 to 1.64 and 1/n values for ranged from 0.9 to 1.0. Sorption was correlated to OC (K(f,oc) ranged from 11 to 64) and clay contents. The lowest sorption was found for soils with very low OC contents (0.50-0.65%) and loamy-sand to sand textures. The 1/n values for desorption were lower than those observed for sorption, suggesting that aminocyclopyrachlor sorption by soil was not reversible; hysteresis coefficients ranged from 0.13 to 0.74. The results suggest that although aminocyclopyrachlor would be very mobile based on its sorption coefficients, its potential depth of leaching may be overestimated due to the hysteretic desorption.     

萘和p,p′-DDE在典型包气带介质上的吸附动力学及吸附-解吸特征

选取3种典型包气带土壤为吸附剂,萘和p,p′-DDE为吸附质,研究了其吸附动力学特征及吸附解吸规律。实验结果显示,初始浓度越大,吸附到达平衡所需时间就越短。数据拟合结果表明,单一级次的动力学方程难以描述两种吸附质的吸附动力学特征,分析认为土壤对有机污染物的吸附过程不是单一反应,而是有机污染物在无机矿物、无定型有机碳和凝聚型有机碳上同时进行吸附反应的复合结果。萘与p,p′-DDE的吸附、解吸过程均表现出非线性,Freundlich方程的吸附指数n在不同程度上偏离1;两种污染物在土样中的吸附过程不完全可逆,Kow、初始浓度以及土壤有机碳含量（fo）c的差异都影响其在土壤不同组分上的吸附百分比,进而影响解吸率。萘更多地吸附在无机矿物表面及无定型有机碳上,随着初始浓度的增大（37.7~780.9μg.L-1）,解吸率可从10%左右增至近85%;而当初始浓度为37.7μg.L-1时,随foc的增大（0.01%~0.65%）,解吸率由12.39%降至3.90%。p,p′-DDE则更多地吸附在凝聚型有机碳上,解吸率随浓度的变化（11.0~275.1μg.L-1）仅在1%~5%内波动,当初始浓度为11.0μg.L-1时,解吸率随foc的增大由4.49%降至1.06%。两者解吸率都和foc呈负相关关系。     

施入粉煤灰和污泥对酸性淋溶土镉和铅吸附的影响

The safe recycling of fly ash (FA) and sewage sludge (SS) in the agricultural processes comprises an important environmental technology on waste management. Soils amended with FA and SS may change their ability to adsorb heavy metals due to either increase of soil pH or decomposition of sludge-borne organic matter. Thus, Cd and Pb sorption was investigated by 1-month incubation under soil moisture content at field capacity and room temperature with an acidic Typic Haploxeroalf from central Greece amended with varying amounts of FA and SS. Batch experiments were conducted by equilibrating the soil samples with CaCl₂ solutions containing 0-400 mg Pb L^-1 or 0-100 mg Cd L^-1. The results showed that the Freundlich equation described well the Cd and Pb sorption. Distribution coefficient (K_d) values of Pb were higher than those of Cd in all the treatments of this study. Application of FA increased K_d values for Cd and Pb to 8.2 and 2.3 times more than the controls, respectively. Simultaneous applications of FA and SS caused a K_d increase of 3.8 and 2.1 times compared to the treatments that received only SS for Cd and Pb, respectively. Treatment of SS alone did not significantly change Cd and Pb sorption compared to the controls. The sorption reactions seemed to be mainly affected by soil pH, which was revealed by the significant correlations of Cd and Pb sorption with soil pH. These suggested that fly ash was very useful as a low-cost adsorbent for Cd and Pb and could be used as an ameliorant for biosolid-amended acidic soils.     

Effect of coffee husk and cocoa pods biochar on phosphorus fixation and release processes in acid soils from West Cameroon

Acid soil in West Cameroon has limited phosphorus (P) availability which limits plant growth. This is mainly because of low pH, high levels of exchangeable aluminium (Al) and iron (Fe) and fixation of P. In this study, acid soils, sampled in Bafang, were amended with biochar produced from coffee husks (CH) and cocoa pod husks (CP) at two different temperatures (350 and 550 °C) in other to evaluate the effect on the physicochemical properties of the acid soil and the effect on P sorption and desorption. The soil was amended with biochar at a rate of 0, 20, 40 and 80 g/kg and incubated for 7 and 60 days. Physicochemical properties of all soil–biochar samples were determined followed by sorption experiments and data fitted in the Langmuir and Freundlich isotherm models in other to evaluate soil P sorption capacity and its affinity to soil amended with biochar. Moreover, desorption studies were done to evaluate the availability of P in soil amended with biochar after sorption. The outcomes of this study reveal an increase in soil pH, electrical conductivity (EC), available P, soil organic carbon and a drastic decrease in exchangeable Al and Fe. The point of zero charge of biochar-amended soil was higher than the control and increased with amendment rate. The experimental data of the sorption of P on soils and soil–biochar samples fits into Langmuir and Freundlich models (R² > 0.9) suggesting that the P adsorption is controlled by both model mechanisms. Soil–biochar mixture results in a decrease in the sorption capacity as compared with the control and the decrease was predominant with increasing amendment rate. At amendment rates of 20, 40 and 80 g/kg after 7 days of incubation, $Q_{\max }$ for SCH350 were 2267, 2048 and 1823 mg/kg which increased to 2407, 2112 and 1990 mg/kg after 60 days of incubation. This tendency was observed for all biochar inputs with respect to the increase in incubation days. Furthermore, desorption of P from soil–biochar mixtures was enhanced with biochar added at greater rate and produced at higher temperature. The desorption percentage was increased by more than around 10% for all biochar types from 20 mg/kg to 80 mg/kg amendment. Thus, biochar addition to acid soils reduces P fixation to acid soil and improves P desorption to soil solution, thereby providing more available P in the soil solution and better conditions for plant growth.