三种水稻土对磷的吸附解吸特性

实验研究了三种不同水稻土磷等温吸附及解吸的情况,并对影响等温吸附特性的因素做了相关探讨。结果表明:三种水稻土磷吸附曲线与简单的Langmuir等温吸附方程极为吻合,磷的解吸曲线与Langmuir等温方程也具备较好的吻合性。供试样品的相关系数均达到显著水平。土壤物理性粘粒含量显著影响土壤最大吸磷量,但对土壤磷的解吸量没有显著影响。     

三种铁氧化物的磷吸附解吸特性以及与磷吸附饱和度的关系

采用三种人工合成铁氧化物(针铁矿、赤铁矿和水铁矿)比较了结晶态和无定形铁氧化物对磷的吸附—解吸特性以及与磷吸附饱和度的关系。结果表明,三种铁氧化物的磷吸附特性均可用Langumir方程来描述,相关系数均大于0.9,达到极显著水平。从磷最大吸附量(Qm)、吸附反应常数(K)和最大缓冲容量(MBC)三项吸附参数综合考虑,水铁矿(无定形)对磷的吸附无论在容量还是强度方面均比结晶态铁氧化物针铁矿和赤铁矿大得多。水铁矿吸附的磷比针铁矿和赤铁矿所吸附的磷更难解吸;水铁矿的大量活性表面并没有表现出增加磷释放的作用。磷吸附饱和度有望作为评价土壤或铁氧化物磷吸附—解吸的强度和容量因子的一个综合指标。     

干湿交替过程中石灰性土壤磷吸附和解吸的变化

培养试验表明：淹水便石灰性土壤磷吸附量增加，沙土尤为显著，被吸附的磷容易解吸，对作物仍然有效；回旱后土壤对磷的吸附量减少，但解吸量也小，施用稻草能降低石灰性土壤对磷的最大吸附量（Ｘｍ）和结合能常数（ｋ），淹水后作用更明显。     

施磷对水稻土硅素吸附与解吸特性的影响

研究了水稻土中施磷 (P)对硅 (Si)吸附与解吸特性的影响。结果表明 ,由于土壤中Si、P元素化学性质和结构相似 ,存在着竞争性吸附 ,施P降低了土壤中Si的吸附量 ,同时增加了土壤Si的解吸量 ,提高土壤Si的解吸率。表明P在降低土壤Si吸附量的同时 ,也由于降低了土壤对Si的吸附结合能 ,从而增加了Si的解吸量。P的存在对Si的吸咐具有一种外推作用。连续解吸试验进一步证实了上述的观点。     

铜尾矿对水溶液中磷的吸附与解吸

为研究铜尾矿作为吸附剂对水溶液中磷的吸附与解吸,从铜陵尾矿库采取尾矿样本,以其作为吸附材料对KH2PO4配制的水溶液进行吸附,用比色法测定磷的平衡浓度,然后计算平衡吸附量和解吸量。结果表明,Langmuir和Freundlich等温吸附方程能够较好地描述铜尾矿对水溶液中磷的吸附过程;尾矿废弃物对水溶液中磷酸根的吸附量与尾矿样本中游离氧化铁、晶质氧化铁、有机络合铁含量以及烧失量呈极显著正相关,而与pH呈极显著负相关;各种植物群落下A层尾矿对磷的吸附量低于C层,尾矿对水溶液中磷的平均最大吸附量超过0.85 mg.g-1,铜官山老尾矿库白茅群落下硬盘层对水溶液中磷的平均最大吸附量达到8.66 mg.g-1,被铜尾矿吸附的磷的平均解吸率低于5%。     

施硅对水稻土磷素吸附与解吸特性的影响研究

研究了水稻土中施Si对P吸附与解吸特性的影响。结果表明 ,由于土壤中Si、P存在着竞争性吸附 ,当Si施入土壤时 ,它必然占据一部分Si、P共用的吸附点位 ,降低了土壤中P的吸附量。施Si对P解吸量的影响比较复杂 ,在低P浓度 (10、20、30mg/kg)时 ,施Si增加了P的解吸量 ;在高磷浓度 (40mg/kg)时 ,施Si后P的解吸量变化不大 ,而P浓度为 50mg/kg时 ,P的解吸量随Si的施加呈下降趋势。表明Si减少P吸附量的同时 ,也由于降低了土壤对P的吸附结合能 ,而增加了易解吸P的含量。施Si明显的提高了土壤P的解吸率     

有机肥对土壤磷吸附一解吸的直接影响

本文采用自行设计的一种扣除来自有机肥中磷的方法,对有机肥影响土壤磷吸附与解吸的直接作用进行了研究。结果表明,猪粪和牛粪均能明显降低两种水稻土对磷的吸附,增加磷解吸;而纤维素只有在土壤磷水平较高时才起作用。上述作用在红壤性水稻土中优于青紫泥;在同一土壤上,对磷水平高的土壤的作用明显大于磷水平低的土壤。在有机肥对土壤磷吸附—解吸的直接影响中,其中的可溶性有机机物起主要作用。     

有机肥对土壤磷吸附一解吸的直接影响

本文采用自行设计的一种扣除来自有机肥中磷的方法,对有机肥影响土壤磷吸附与解吸的直接作用进行了研究。结果表明,猪粪和牛粪均能明显降低两种水稻土对磷的吸附,增加磷解吸;而纤维素只有在土壤磷水平较高时才起作用。上述作用在红壤性水稻土中优于青紫泥;在同一土壤上,对磷水平高的土壤的作用明显大于磷水平低的土壤。在有机肥对土壤磷吸附解吸的直接影响中,其中的可溶性有机机物起主要作用。     

四川盆地丘陵区农田土壤对磷的吸附与解吸特征

研究了四川盆地丘陵区典型水田和旱地土壤对磷的吸附与解吸特征,并讨论了吸附-解吸参数与土壤基本理化性质的关系。结果表明,不同pH的农田土壤对磷的吸附和解吸均存在显著差异,土壤对磷的吸持能力表现为中性土壤〉酸性土壤〉石灰性土壤,中性有利于土壤吸附磷;水稻土对磷的最大吸附容量（Qm）和最大缓冲容量（MBC）高于紫色土,而临界平衡磷浓度（EPC0）和解吸率（b）低于紫色土。农田土壤对磷的吸附与解吸参数还受土壤理化性质的影响,Qm和MBC与有机质含量、无定形铁（Fe-ox）含量呈极显著正相关（P〈0.01,n=6）;吸附常数（K）与有机磷含量呈显著负相关（P〈0.05,n=6）;EPC0与土壤pH、CaCO3含量呈显著负相关,与有机磷含量呈显著正相关（P〈0.05,n=6）;b与Fe-ox含量呈显著负相关（P〈0.05,n=6）。     

江西省典型水稻土对镉的吸附解吸特性研究

以江西省2种典型水稻土(潜育型、潴育型)为试材,采用振荡平衡法研究了镉在水稻土中的吸附-解吸行为,并利用保留因子对镉在水稻土中的环境风险进行了评估。结果表明:潴育型水稻土的吸附能力较强,明显大于潜育型水稻土,但潴育型水稻土的解吸能力小于潜育型水稻土;2种水稻土对镉的吸附均可用Freundlich方程较好的拟合;镉的环境风险随镉含量的升高先减小后增大,且潜育型水稻土大于潴育型水稻土,但镉在2种水稻土中潜在环境风险均较大。     

植稻年限对土壤铁锰氧化物的影响

以浙江不同耕作年限水田和旱地为研究对象,探讨了植稻年限对土壤铁锰氧化物的影响,并揭示了水稻土发育过程中铁锰氧化物的剖面运移规律和诊断意义。结果表明:①土壤剖面中,全Fe、游离Fe及全Mn的变异随着种稻时间的延长而增大。种植达到一定年限时,全Fe、全Mn以及游离Fe在土壤剖面下层出现淀积。在各种铁锰氧化物中,对水稻土最具诊断意义的是游离Fe和全Fe。②无定形Fe以及络合态Fe、Mn与有机质呈显著正相关。植稻年限对它们的影响是通过对有机质的影响达到的。     

石灰性水稻土中磷酸铁对水稻磷营养的贡献

A study was carried out on contribution of iron phosphate to phosphorus nutrition of rice plant under waterlogged and moist conditions,respectively,by use of synthetic Fe^32 PO4.nH2O,tagging directly the iron phophate in calcareous paddy soils.Results showed that under waterlogged condition,similar to iron phosphate in acidic paddy soils.that in clacareous paddy soils was an important source of phosphorus to rice plant ,and the amount of phosphorus originated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.     

Changes of redox and pH conditions in a flooded soil amended with glucose and manganese oxide or iron oxide under laboratory conditions

The changes of Eh and pH in soil suspension (Ah-horizon of a Mollic Gleysol) and Mn²⁺ or Fe²⁺ concentrations in the equilibrium soil solution at different levels of glucose (0%, 0.5% and 1%) and MnO₂ (0%, 0.025%, 0.05% and 0.1%) or Fe₂O₃ (0%, 0.025%, 0.05% and 0.1%) were examined. It was found that the degree of Mn- and Fe-reduction in soil depends mainly on the presence and the amount of an easily decomposable carbon source and to a minor degree on the content of native or added forms of MnO_O2 or Fe₂O₃ in the soil. Theoretical relationships between the water soluble manganese and iron and the Eh and pH values have been verified, when the observed initial drop of Eh was eliminated. It was found that the water soluble manganese content was described best by the Mn₂O₃/Mn²⁺ redox system, and that of iron by the Fe₃ (OH)₃/Fe²⁺ system.     

不同施磷量下稻田土壤磷素平衡及其潜在环境风险评估

【目的】对南方赤红壤区不同施磷量下稻田土壤的磷素平衡及其潜在环境风险进行评估,为该地区合理施磷、 减轻农业面源污染提供依据。【方法】采用大田定位监测试验,3个不同年份(2011~2013年)早、 晚稻分别设置4个施磷水平(施磷范围为P2O5 0、 63~81、 126~162、 252~324 kg/hm2,分别用P0、 P1、P2、P3表示),连续3年测定早、 晚稻的稻谷和稻秆产量,分析其磷养分含量,以施磷水平与水稻地上部磷素累积量间的差值表示土壤磷素表观盈余量。同时,采集施基肥和穗肥后1、 2、 3、 5、 7和9 d的田面水,测定总磷含量,利用Split-line模型对2011~2012年每造水稻收获后小区耕层土壤Olsen-P含量和所有监测时间点的田面水总磷平均浓度进行分段回归,并对二者之间的相关关系进行分段回归拟合。【结果】 施磷量P2O5 63~81 kg/hm2的处理稻谷产量显著提高,但磷肥施用量增至2倍时,稻谷产量无明显增加,继续增至4倍时,前3造水稻稻谷的产量增加也不明显。施磷可不同程度地提高水稻地上部的磷素累积量、 土壤表观磷素盈余量和Olsen-P含量,且三者均随施磷量的增加而增加。在施肥后1~3 d内无磷处理田面水总磷浓度较高,是磷素流失的高危险期; 施磷量P2O5 63~81 kg/hm2的处理显著提高了施肥后2 d内田面水的总磷浓度,而P2O5 252~324 kg/hm2的处理在监测期间田面水总磷浓度均显著高于无磷处理。 Split-line模型模拟土壤Olsen-P与田面水总磷的关系,得出在本试验区土壤环境条件下,可能导致田面水中磷激增的土壤Olsen-P临界含量为19.0 mg/kg,对应的施磷量为P2O5 63 kg/hm2,与土壤磷素持平的施磷量一致。【结论】综合考虑水稻产量效应、 土壤磷素表观平衡和磷素环境风险,在本研究区域目前的土壤环境条件下,P2O5 63 kg/hm2为水稻产量较高、 环境风险较小的推荐施磷量。     

除草剂二氯喹啉酸对水稻田土壤酶活性短期影响

Birnessite occurs in a wide variety of natural environments, and plays an important role in soil chemistry. A modified Stāhli procedure was used to synthesize sodium birnessite in an alkali medium by O2 oxidation. The effects of preparative parameters on the synthesis of birnessite, such as pretreatment on solutions with N2, reaction temperature, O2 flow rate, fluxion velocity of the reaction suspension, and dehydration conditions were investigated. The fluxion velocity of the reactive suspension and O2 flow rate significantly influenced the synthesis of birnessite. Vigorous stirring raised the fluxion velocity of the reaction suspension and easily allowed synthesis of pure crystalline birnessite. However pretreatment of the reacting solutions with N2 and the reaction temperature had little effect on the synthesis. Diffusion of O2 was the controlling step during the course of oxidation. The optimum synthetic conditions for pure birnessite were: a NaOH to Mn molar ratio of 13.7, an O2 flow rate of 2 L rain^-1, and oxidation for 5 hours with vigorous stirring at normal temperatures. The chemical composition of the synthesized pure birnessite was Na0.25MnO2.07-0.66H2O.     

铁氧化物对厌氧水稻土中乙酸的矿化、转化及其激发效应的影响

乙酸是甲烷产生过程的重要底物,其在水稻土中的矿化和转化过程对水稻土碳循环和固碳减排具有重要意义。在长期淹水的水稻土中,铁作为重要的变价金属元素,对乙酸的矿化和转化可能具有重要影响。因此,本研究向水稻土中添加13C-乙酸、水铁矿和针铁矿,动态监测厌氧培养（100 d）期间CO2和CH4排放规律和土壤环境因子的变化规律,同时分析乙酸的矿化和转化特征以及CO2和CH4的激发效应,并解析不同铁氧化物在其中的作用效应。结果表明,培养结束后,只添加乙酸的处理中33%和36%的乙酸分别矿化为CH4和CO2,另外0.12%、2%和28%的乙酸分别形成了可溶性有机碳（DOC）、微生物量碳（MBC）和土壤有机碳（SOC）。乙酸添加引起了CO2负激发效应和CH4正激发效应。土壤产生CO2和CH4比例因乙酸的添加由3.46:1变为1.83:1。针铁矿的添加显著增加了乙酸来源的CO2累积排放量,但水铁矿对乙酸来源的CO2累积排放量却无显著影响。水铁矿和针铁矿均显著降低了SOC来源的CO2累积排放量,加剧了乙酸引起的CO2负激发效应。水铁矿和针铁矿均显著降低了乙酸来源的CH4累积排放量,对SOC来源的CH4累积排放量无显著影响。水铁矿和针铁矿显著增加了乙酸转化为MBC和SOC的比例。因此,乙酸在土壤中的矿化和转化行为会影响土壤原有有机碳产生CO2和CH4;水铁矿和针铁矿结晶程度不同,对乙酸的矿化、转化及其激发效应的影响也不同。研究结果可为稻田的固碳减排提供一定的理论依据和技术支撑。     

有机肥对磷的吸附-解吸的影响及在红壤发育成的水稻土上的有效性

A field test with the traditional rotation of paddy rice/upland crop (wheat) was carried out on a paddy soil derived from red earth to elucidate the effect of organic manure on the phosphorus adsorption-desorption by soil and its P availability. Soil samples were taken from different treatments at rice harvesting stage and analysed. The isothermal adsorption of P by the samples fitted very well with Langmuir equation, and hence, the parameters in the equation, i.e., maximum adsorption (qm), constant related to bonding energy (k) and their product (k × qm) could be used as a comprehensive index to characterize the potential P adsorptivity of the soil. Organo-inorganic fertilization and organic manuring could decrease qm and k, while mineral P application had little effect on them. The isothermal desorption of P was significantly correlated with initially added and isothermally adsorbed P. Part of P added was fixed, which represented the P fixation capacity of soil, and organic manuring could obviously lower the P fixation. The content of soil available P had a significant negative correlation with qm, k and fixed P. It is concluded that organic manure could increase the P availability of paddy soil derived from red earth by decreasing qm, k, maximum buffering capacity (MBC=k × qm) and fixation capacity.     

磷细菌在复垦土壤上生长规律及对磷解析特性的影响

为了解磷细菌在山西采煤塌陷复垦土壤上的应用效果,以采煤塌陷复垦土壤为研究对象,通过室内培养方法,设空白对照,探索了施有机肥(M)、磷细菌(B)、磷细菌+葡萄糖(BG)、磷细菌+尿素(BU)、磷细菌+葡萄糖+尿素(BGU)、磷细菌+葡萄糖+尿素+有机肥(BGUM)对磷细菌生长和土壤养分、磷吸附解吸的影响,其中磷细菌菌液浓度为1.2×108 CFU·m L?1,接种量为5 m L·盆?1。结果表明:在培养周期内各处理磷细菌数量呈先增加后减少的趋势,BGUM处理磷细菌数量远高于其他处理;培养的60 d内BGUM处理土壤磷细菌数量由最初的1.0×106 CFU·g?1降到3.3×104 CFU·g?1,60 d后,BGUM处理磷细菌数量分别是BGU、BG、BU、B处理的300倍、367倍、1 650倍、3 300倍。M、B和BGUM处理复垦土壤有效磷含量分别比CK处理增加172.27 mg·kg?1、3.00 mg·kg?1和188.9 mg·kg?1,施用有机肥或者接种磷细菌可以显著增加土壤有效磷含量,葡萄糖、尿素、有机肥与磷细菌配合施用对复垦土壤有效磷增加的效果更显著。随着外加磷源浓度的增加,各处理复垦土壤吸磷量和解吸磷量都呈现增加的趋势,Langmuir等温吸附方程是描述各处理等温吸附特征的最佳方法;与CK相比,BGUM处理土壤最大吸磷量降低幅度最大,减少119.05 mg·kg?1,吸附常数也显著降低,BGUM处理复垦土壤磷的平均解吸率为33.20%,显著高于其他处理(P0.05)。因此,在各处理中,BGUM处理土壤磷细菌数量最多,对复垦土壤有效磷的增加效果最显著,对土壤最大缓冲容量和平均解吸率影响最大。BGUM处理是磷细菌在复垦土壤上应用的最佳选择,即在复垦土壤上施用磷细菌时,应该与合适的碳源、氮源及有机肥共同配合施用。     

中国水稻土磷储量及其空间分异

Due to the growing concern about the agricultural phosphorus (P) losses pollution, an in-depth understanding of P in paddy soils of China would be helpful in providing a national perspective of the environmental impact of P cycling and fertility on China’s farms. In this study, we evaluated the P storage and the P density of paddy soils in China, characterized the spatial variations of P among the subgroups of paddy soils and soil regions in China, and evaluated the P data using GIS-based analysis, which included a newly compiled 1:1 M digital soil map of China, and using 1 490 soil profiles. The available and total P densities of paddy soils were 6.7 and 698.5 g m-3, respectively. Overall in China, the total P storage within 1 m of paddy soils was estimated to be 330.1 Tg. The P density of paddy soils varied substantially with subgroups due to the different soil water regimes such as groundwater table and soil drainage. The P availability in paddy soils, especially in surface layer, was higher in high temperature and precipitation areas. Further research is needed to examine more anthropogenic impact factors, such as increasing use of chemical fertilizer.     

Chronosequence of paddy soils and phosphorus sorption–desorption properties

Purpose  

Accumulated soil phosphorus (P) in agricultural lands due to long-term organic manure and mineral phosphate fertilizer input is considered one of the main non-point pollution sources to surrounding surface water bodies. A chronosequence of soils is a potent instrument for pedological investigation and allows assessment of the effect of duration of agricultural cultivation on the environmental risk to water bodies of P loss from soil.