腐殖酸物质对磷在褐土中迁移的影响

采用室内土柱实验研究了腐殖酸和腐殖酸钠在与磷肥共施时对磷在褐土中迁移的影响。结果表明,与单施磷酸二氢钙相比,共施腐殖酸钠缩短了磷在土壤中的迁移距离,明显降低了施肥点附近微域中的水溶性磷和酸溶性磷含量,磷向土体中的迁移量也显著下降;相比之下,共施腐殖酸则明显增加了磷的迁移距离和迁移量,对肥际微域中不同形态磷的含量均有显著提高作用。因此,腐殖酸促进了磷在褐土中的迁移,适宜与磷肥配合施用,而腐殖酸钠不适合与磷肥共施。     

施用堆肥对葡萄园土壤中敌草隆残留与迁移的影响

Diuron is frequently detected in surface- and groundwater under the vineyards, where organic amendments are often used, in Burgundy of France. Undisturbed column experiments were conducted to study the influence of three composted organic amendments on diuron leaching through columns of two vineyard soils from Vosne-Roman′ee(VR, calcareous Cambisol) and Beaujolais(Bj, sandy Leptosol), France. Bromide(used as non-reactive tracer) and diuron breakthrough curves(BTCs) were analyzed using convectivedispersive equation(CDE), two-region(mobile-immobile, MIM) and two-site models. No influence of the composts was observed on the bromide recovery rates. The CDE model described well the bromide BTCs for all columns of the Bj soil and seven of the VR soil, suggesting a homogeneous water flow. However, for five VR soil columns, the MIM model fitted better, suggesting a partition of the water flow(15%–50% of matrix flow). The texture, the coarse material content and the tillage of the VR soil could explain this heterogeneity. However, for all columns, diuron leaching was greater through the Bj soil(46%–68%) than the VR soil(28%–39%). The compost addition resulted in a contrasting effect on diuron leaching: no difference or a decrease was observed for the VR soil, probably due to an increase of adsorption sites, whereas no difference or an increase was observed for the Bj soil possibly because of interactions and/or competition of diuron with the compost water-extractable organic matter which could facilitate its transport. All the diuron BTCs were best described using the two-site model, suggesting a large proportion of time-dependent sorption sites(30%–50%). The soil type and the nature of the amendments had contrasting influences on diuron transport. Composts with a high water-soluble fraction must be avoided in sandy soils to reduce the risk of groundwater contamination.     

夏玉米和冬小麦秸秆对石灰性土壤磷吸附特性及磷素形态的影响

本文对夏玉米秸秆(MR)和冬小麦秸秆(WR)单施或者与P肥混施(在等P量条件下)对石灰性土壤P的吸附特性及其形态转化进行了为期15周的室内模拟培养研究,结果表明,无论是MR和WR单施,还是秸秆与P肥混施,都可以减少土壤对P的吸附量,提高土壤P的活性,其中秸秆单施处理的活性无机磷(Pi)和有机磷(Po)(NaHCO3-P或者NaOH-P)提高较大,夏玉米秸秆单施时,比对照(CK)增加Pi、Po的量分别达6.0、5.6mgkg-1(NaHCO3-P),增加NaOH-Po为12.7mgkg-1。并通过Langmuir方程求得P的最大吸附量(b)、P吸附结合能常数(k)、P素最大缓冲量(MPBC)、标准需P量(SPR)的值,进一步说明了两种秸秆均可使土壤对P的吸附能力降低,增加土壤中P的活性。     

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.     

有机肥对石灰性土壤无机磷组分的影响

研究了３种有机肥料对土壤无机磷组分的影响，其中猪粪能显著提高土壤中Ｃａ２－Ｐ、Ｃａ８－Ｐ、Ａｌ－Ｐ和Ｆｅ－Ｐ的含量，紫云英及稻草的作用明显低于猪粪，３种有机肥料对Ｃａ１０－Ｐ的影响都很小。     

过磷酸钙对石灰性土壤有效磷及无机磷组分的影响

为研究水溶性磷肥在石灰性土壤中的转化,采用室内土壤培养的方法,在土壤中分别添加过磷酸钙0、6.25、12.5、25、50和100 mg/kg干土(即P0、P6.25、P12.5、P25、P50和P100处理),保持土壤湿度为田间持水量的70%～80%,在25℃恒温培养箱中培养120 d。培养期间在第1、3、7、15、30、60和120 d连续采样,测定土壤Olsen-P、CaCl2-P和各无机磷组分的含量。结果表明,在石灰性土壤中施用过磷酸钙能显著增加土壤Olsen-P和CaCl2-P含量,在一定的培养时间内,过磷酸钙转化为土壤Olsen-P和CaCl2-P的比例不随施肥量的变化而变化。随着培养时间的延长,土壤有效磷含量逐渐下降,尤其是培养前期(前7 d)土壤有效磷含量显著下降,之后下降速率减缓。施入土壤中的过磷酸钙主要转化为Ca2-P和Ca8-P(两者之和约占90%),其次是Al-P和Fe-P(两者之和约占10%),在短期内O-P和Ca10-P相对较为稳定。随着培养时间延长,Ca2-P逐渐向Ca8-P转化,在培养的前30 d转化速率较快,之后速率减缓。随着磷肥施用量的增加,Ca2-P转化为Ca8-P所需的时间逐渐延长。Olsen-P和CaCl2-P含量均与土壤无机磷组分中的Ca2-P、Ca8-P和Al-P含量呈显著正相关,通过逐步回归分析表明,其中Ca2-P是土壤Olsen-P和CaCl2-P的主要来源。     

淹水对石灰性土壤无机磷形态转化的影响

  【目的】  磷肥施入土壤后大部分转化为与铁氧化物关系密切的Fe-P和O-P,而淹水后土壤中铁的氧化还原过程可能影响与铁氧化物结合的磷的形态及有效性的变化。研究不同施磷处理下淹水土壤Fe (II) 、无机磷组分等的变化,以期明确淹水后土壤无机磷形态及磷有效性变化及其与铁氧化还原过程的关系。  【方法】  用不施磷土壤 (P0) 和连续6年施用P 180 kg/hm2的土壤 (P180) 进行室内模拟培养试验。将土壤装于西林瓶内,加水模拟淹水条件,西林瓶密封后,分别在避光或者光照条件下,于 (30 ± 1)℃恒温培养40天。测定供试土壤以及淹水培养土壤中的速效磷、无机磷以及不同形态无机磷组分含量,测定培养过程Fe (II) 的动态变化,以探讨磷形态转化与铁氧化还原过程的关系。  【结果】  施用磷肥显著增加土壤中的速效磷含量和无机磷总量,P0处理土壤速效磷含量为 (7.65 ± 1.65) mg/kg,P180处理土壤速效磷含量高达 (33.5 ± 2.01) mg/kg。施入土壤中的磷只有很小部分以Ca₂-P存在,主要以Ca₁₀-P、Ca₈-P、Al-P和Fe-P形态存在。避光淹水培养后,土壤速效磷含量增加,P0和P180处理土壤速效磷含量的增量分别为8.44、2.95 mg/kg。淹水培养降低了土壤Ca₈-P含量,提升了Fe-P、O-P、Al-P含量。光照和避光条件下P180处理土壤中Ca₈-P含量分别降低106.8、156.2 mg/kg,Fe-P含量分别增加23.4、47.0 mg/kg,O-P含量分别增加64.1、92.9 mg/kg,Al-P含量分别增加38.8、34.7 mg/kg,避光时Ca₈-P降幅以及Fe-P和O-P的增量均大于光照条件下。避光条件下,铁还原量和还原最大速率与Ca₈-P变化量之间存在显著负相关关系,与Fe-P、O-P增量之间存在显著正相关关系。  【结论】  淹水条件下,石灰性土壤中的Fe (Ⅲ) 还原形成Fe (Ⅱ) 和Fe (Ⅲ) 混合物,增加了铁氧化物的比表面积和磷吸附点,可促进Ca₈-P向O-P、Fe-P和Al-P转化。光照降低了Fe (Ⅲ) 的还原量,可能是Ca₈-P向O-P、Fe-P和Al-P转化率低的原因之一。     

石灰性土壤中磷的固定Ⅰ.土壤中有机质对磷酸固定的影响

1.土壤质地对磷的固定有直接关系,质地愈粘、小于0.01毫米颗粒愈多,磷的固定也愈强。2.有机质可以减少磷的固定。质地相同的土壤,有机质含量高者磷酸固定量较小。3.石灰性土壤经磷饱和处理后,钙结合态磷的含量至少占全磷量的60%以上。     

腐殖酸对钾在褐土中迁移和转化的影响

采用室内土柱实验研究了腐殖酸与钾共施时腐殖酸对钾在褐土施肥点附件微域中迁移和形态转化的影响。研究结果表明,与单施KCl处理相比,共施腐殖酸没有明显改变肥料钾在褐土中的迁移距离,在培养7天时增加了肥际微域中的水溶性钾含量,而在培养28天时则降低了其含量;共施腐殖酸明显增加了交换性钾含量以及在土壤中的迁移量,但减少了非交换性钾的含量和迁移量。说明共施腐殖酸减少了土壤晶格对钾离子的固定,提高了外源钾在褐土中的有效性。     

Recovery of phosphorus fertilizer in potato as affected by application strategy and soil type

Phosphorus (P) fertilizers are usually supplied prior to or at planting of potato even though most P is taken up 40 to 80 d after emergence. This may lead to inefficient P use as a result of P leaching or fixation in the soil. This study evaluates the effects of split P application at multiple times during the growth period according to the plant's need for P. Potato (Solanum tuberosum L. cv. Ditta) was grown in pots in climate chambers, and radioactive ³²P isotope was used to distinguish between the fertilizer and soil‐derived P sources. Two soils were tested in combination with five application rates of P, and the plants were harvested at four dates. The results show that the recovery of P fertilizer can be significantly enhanced if the P supply is split. The result also showed that the proportion of soil‐derived P, accumulated in the plant, was significantly reduced both when more fertilizer P was applied to the soil and when P supply was split into several applications. The positive effects of multiple P applications on the P recovery were greatest in the soil with low P status and low buffer capacity.     

Phosphate fertilizer form and application strategy affect phosphorus mobility and transformation in a drip‐irrigated calcareous soil

The objective was to increase understanding about how P fertilizer form and application strategy affect P mobility and use efficiency in a drip‐irrigated calcareous soil. The study used two P forms (granular or liquid P) and two application methods (single or repeated application). Phosphorus uptake by roots was simulated by using diffusive gradients in thin films (DGT). Six fractions of inorganic P were obtained using the Jiang‐Gu sequential fractionation scheme. Mobility of P was greater when the fertilizer was applied in liquid rather than granular form. Depending on the fertilizer application rate, Olsen P concentrations 13.5–43 mm from the application point were larger by 22–96% in the liquid P treatment than in the granular P treatment. Liquid P increased DGT‐absorbed P by 29% and Ca₂‐P by 17% compared with granular P averagely. The P uptake and PUE were averagely larger by 32 and 121%, respectively, in the liquid P treatment than in the granular P treatment. In conclusion, liquid P fertilization reduces P fixation and increases P diffusion, availability, and bioavailability in calcareous soil. Phosphorus mobility is greater when the fertilizer is applied in a single rather than repeated application.     

Nutrients in a calcareous soil affected by Cadmium

A calcareous soil (Haploxeroll calcic) was amended in two different forms according with the standard nutritional requirements of tomato plant. The treatments applied were: i) an organic fertilization applying sewage sludge (SS), ii) an inorganic fertilization (IN) using mineral fertilizers (NPK), and iii) a treatment called W where no fertilizer was applied. For each treatment, cadmium (Cd) pollution was added to the soil establishing different concentrations (0, 3, 30 and 100 mg kg^‐1 d.w.). The availability of macronutrients and micronutrients were analyzed in the soil. Phosphorus (P), iron (Fe), and copper (Cu) were the nutrients more affected by Cd. In general, sewage sludge favored the availability of nutrients in the same degree of the inorganic fertilization.     

Insights into sorption and leaching behavior of sulfadiazine in soil as affected by humic acid

Journal of Soils and Sediments - Sulfonamides with high mobility in the soil pose a significant threat to environmental ecology and human health. Organic matter is known to affect the sorption and...     

Legacy phosphorus in calcareous soil under 33 years of P fertilizer application: Implications for efficient P management in agriculture

Phosphorus (P) fertilizers have long been applied in agriculture. However, the influence of long-term P addition on the evolution of soil P fertility and legacy P characteristics have not been well-documented. Herein, literature data were collected from the Chinese National Knowledge Infrastructure Database (CNKI) to explore the evolution of soil P fertility after 33 years of application of P fertilizer; different soil samples were collected from cropland and adjacent uncultivated land to analyse the distribution of P fractions at different soil depths (0–0.8 m) using Guppy's sequential P extraction method. We found that soil Olsen-P significantly increased by 3.6-fold (from 7.2 mg kg⁻¹ in 1981 to 25.9 mg kg⁻¹ in 2013) after 33 years of P application, while total P increased slightly. The ratios of inorganic P fractions in cropland to those uncultivated land followed NaHCO₃-P (1.47) > NaOH-P (1.38) > resin-P (1.37) > residue-P (1.17) > HCl-P (1.11), suggesting that long-term P addition contributed more to labile and moderately labile P rather than non-labile P. Moreover, a principal component analysis could distinguish between cropland and uncultivated land, indicating that long-term application of P fertilizer changed soil P characteristics. Compared to uncultivated land, soil NaHCO₃-P in cropland was closely associated with soil organic C, total nitrogen and carbonate. Collectively, our findings highlight that soil legacy P was notably increased after long-term of P application, and a large portion of the applied P remained in labile and moderately labile forms. Therefore, soil legacy P can be recommended as a useful P management tool.     

Changes in recovery of native and applied phosphorus with time as affected by soil properties in some calcareous soils

In an attempt to investigate variations in availability of native and applied phosphorus (P) with time, twenty five calcareous soil samples were treated with 0, 50 and 500 mg P kg^?1 soil and incubated at 80–90% of field capacity moisture content in an open door glasshouse for a period of one year. Soil samples were taken out at certain intervals for P extraction with Olsen extractant under moist condition. Results indicated that following wetting the mean value of native Olsen-P decreased initially and then increased gradually with time of incubation. Generally, the short term (24 h) recoveries were not correlated with long term ones. The recovery of added P with time was described properly by the following new proposed model: R = 100/(1 + kt^b), where R is percent recovery at time t, and k and b are empirical parameters. The values of k constant at 50 and 500 mg P kg^?1 were in the ranges of 0.40 to 1.22 (0.84 ± 0.25, on average) and 0.04 to 0.52 (0.23 ± 0.14, on average), respectively. The corresponding respective values of b constant also ranged from 0.05 to 0.32 (0.15 ± 0.06, on average) and 0.12 to 0.92 (0.46 ± 0.23, on average).     

Adsorption kinetics of zinc in a calcareous soil as affected by pH and temperature

Abstract

Sorption of zinc (Zn) in a calcareous soil was studied using a miscible displacement procedure. Sorption of Zn in soil can be described by a second‐order equation and by a diffusion equation based on the overall higher value of correlation coefficient and the lower value of standard error. The results show that the sorption of Zn in soil was increased by elevated temperature and pH. The maximum of Zn sorbed in soil increased, but the rate coefficient decreased with increasing pH. The maximum of sorbed Zn and rate coefficient tended to increase with elevated temperature. The value of activation energy (E_a) estimated with different kinetic equations was found to be variable and in the range of 5.0–17 kJ.mol^‐1. The relative diffusion rate coefficient (D/r²), estimated using a diffusion equation, was found to be in the order of 10^‐6 sec^‐1. The intra‐aggregate diffusion and/or film diffusion of Zn may be a rate‐limiting process in the sorption of Zn in soils.     

Yield and phosphorus uptake of a processing tomato crop grown at different phosphorus levels in a calcareous soil as affected by mycorrhizal inoculation under field conditions

We have evaluated the effectiveness of arbuscular mycorrhizal fungi (AMF) inoculation (+M and ?M) at 0, 60, and 120 kg ?ha^?1 of P fertilizer on crop growth (IE_g), plant P nutrition and yield (IE_y), and on mycorrhization occurrence in a processing tomato crop. Two experiments were carried out in calcareous soil under field conditions. Phosphorus fertilization had no effect on crop growth and yield. At harvests, +M plants showed higher aerial dry weight, fruit fresh weight, and P concentration. Inoculated plants produced larger inflorescences, higher flower number, and total and marketable fruit number compared with ?M plants. At P₀ and P₆₀, plants associated with exogenous AMF were able to enhance P recovery, nevertheless factors other than the P uptake improvement concurred to make the inoculation effective. In both years, P fertilization enhanced IE_g and IE_y, and the application of 60 kg ?ha^?1 of P in inoculated soil was enough to reach high production level (134 Mg ?ha^?1). In the first trial, due to earlier root mycorrhization in inoculated and P fertilized soil, higher IE_g and IE_y were obtained compared with the second experiment. In the latter, during the initial phase, plant growth was more affected by P fertilization than by soil arbuscular mycorrhizal (AM) inoculation. Root mycorrhization by native AM fungi indicates that the intensive management of the investigated agro-system did not depress fungi infectivity; however, it caused the selection of less effective AMF. The application of selected AMF as a biofertilizer may represent an innovative ecosustainable practice for improving the crop profitability for growers while reducing the need for P fertilization.