牛蒡菊糖脱色工艺的研究

研究了6种离子交换树脂和吸附树脂对牛蒡菊糖溶液中色素脱除的影响,筛选出3种树脂：非极性大孔吸附树脂DA201-B和DA201-C、大孔弱碱性的阴离子交换树脂D301-G,通过正交试验对脱色条件进行优化。结果表明：采用树脂D301-G,在pH 6.5,35℃下,牛蒡菊糖溶液的脱色率可达到95%,多糖保留率为75%,蛋白质去除率87%,牛蒡中的色素可能主要以阴离子色素、非极性小分子色素为主。     

Horizontal matter fluxes and leaching losses in urban and peri‐urban agriculture of Kabul,Afghanistan

Little is known about nutrient fluxes and nutrient‐use efficiencies in urban and peri‐urban agriculture (UPA) of rapidly expanding cities in developing countries. Therefore, horizontal flows of carbon (C), nitrogen (N), phosphorus (P), and potassium (K) as well as leaching losses of mineral N and P were measured over 2 years in three representative agricultural production systems of Kabul. These comprised 21 gardens and 18 fields dedicated to vegetable farming, cereal farming, and table‐grape production (vineyards). Across sites (fields and gardens) biennial inputs averaged 375 kg N ha^–1, 155 kg P ha^–1, 145 kg K ha^–1, and 15 kg C ha^–1 while with harvests 305 kg N ha^–1, 40 kg P ha^–1, 330 kg K ha^–1, and 7 kg C ha^–1 were removed. In vegetable gardens, biennial net balances were 80 kg N ha^–1, 75 kg P ha^–1, –205 kg K ha^–1, and 4 kg C ha^–1, whereas in cereal farming biennial horizontal balances amounted to –155 kg N ha^–1, 20 kg P ha^–1, –355 kg K ha^–1, and 5 kg C ha^–1. In vineyards, corresponding values were 295 kg N ha^–1, 235 kg P ha^–1, 5 kg K ha^–1, and 3 kg C ha^–1. Annual leaching losses in two selected vegetable gardens varied from 70 to 205 kg N ha^–1 and from 5 to 10 kg P ha^–1. Night soil and irrigation water were the major sources among the applied nutrient inputs in all studied farming systems, contributing on average 12% and 25% to total N, 22% and 12% to total P, 41% and 53% to total K, and 79% and 10% to total C, respectively. The results suggest that soils in extensive cereal fields are at risk of N and K depletion and in vegetable gardens of K depletion, while vineyards may be oversupplied with nutrients possibly contributing to groundwater contamination. This merits verification.     

离子交换树脂在土壤养分测试中的研究进展

概述了在农业领域中应用离子交换树脂获取土壤养分含量的研究进展,探讨了树脂的预处理方法、使用形式以及提取土壤养分的基本操作和影响因素,同时提出该技术在提取土壤养分中的应用前景及需要解决的问题。     

离子交换树脂膜测定肥料养分在土壤中的变化

在25℃恒温培养条件下,采用离子交换树脂膜(IERM)连续提取法研究了不同肥料(尿素、氯化钾、磷酸二氢钙、缓释复合肥)养分(氮、磷、钾)在土壤中的变化。结果表明,几种肥料养分释放速率各异,缓释复合肥氮、磷养分释放在前期(28 d)释放较慢。用该方法提取肥料养分(N、P、K)在土壤中的释放累积量随时间的增加而增大,用Elovich、双常数、一级扩散、抛物线扩散4种动力学方程来描述二者的关系,拟合度都达到了极显著水平(r=0.863^**～0.999^**)。用该法测定肥料在土壤中释放养分的变化特性与用其测定的土壤本身养分的变化特性相似。从而提出了离子交换树脂膜法作为一种评价肥料养分在土壤中的变化特性的较理想方法的可能性。     

Modified Labile Phosphorus Estimation Method for Arid Ecosystem

A new method for estimation of resin phosphorus (P) in arid soils was developed. Four extractants [hydrochloric acid (HCl), sulfuric acid, nitric acid, and sodium bicarbonate] at various concentrations were used by different ion exchange resins. The results clearly showed HCl was the best extractant at 1.0 N concentration and that 6 h was the optimum time for more adsorption. The optimum adsorption and extraction occurred at 200 rpm and 75 rpm, respectively. Basic anion exchange resin in chloride form was the best resin for P mobilization. A strong correlation (P < 0.001) with the P uptake by different arid crops (pearl millet, clusterbean) was observed. Resin P showed correlation with soil total P (P < 0.001), available and mineral P (P < 0.01), and soil organic P (P < 0.05). The present method for resin-P estimation is found to be an important tool to determine plant P availability and available soil P status under arid environments.     

Water-soluble organic materials in paddy soil ecosystem

Abstract

A column experiment was conducted to analyse the composition of organic materials in the leachate from the plow layer and their fate in the subsoil. Water-soluble organic materials in the leachate were fractionated by insoluble polyvinylpyrrolidone (PVP) and ion exchange resins. The content of total organic carbon (TOC) in the leachate increased by the addition of rice straw (RS) to the plow layer soil sample. The leachate contained a constant amount of PVP-adsorbed Fraction, while that of the PVP-non-adsorbed Fraction changed during the 45 day incubation period. In the fractionation using ion exchange resins, the fraction adsorbed onto the anion exchange resin was the major one.

By the connection of a subsoil column to the plow layer soil column with RS, the TOC content in the leachate decreased by percolation into the subsoil sample. In the Anjo soil sample (Yellow Soil), the decrease occurred throughout the incubation period, and about 90% of the PVP-adsorbed Fraction in the leachate decreased by percolation into the subsoil sample. In the Fukushima soil sample (Gray Lowland Soil), the TOC content decreased in the early and middle periods of incubation, while in the late period the decrease was negligible. This decrease of the TOC content by percolation into the subsoil sample was mainly due to retention in the subsoil sample of the Anjo soil, while in the Fukushima soil sample it was due to decomposition and retention. It was considered that easily decomposable organic materials like organic acids were decomposed in the early to middle periods of incubation, while in the late period the contents of such substances in the leachate from the plow layer soil sample with RS were small and the decrease of TOC was negligible.     

Phosphorus Determination after Mehlich 3 Extraction and Anion Exchange Resin in an Agricultural Soil of Northwestern Spain

Differences in soil phosphorus (P) contents measured by various techniques may have implications for agronomic and environmental testing. Reduced-tillage systems combined with surface manure application increase the potential risk of nutrient losses by surface runoff. A field trial was conducted to evaluate the effect of livestock slurry on nutrient accumulation at the surface layer of an acidic soil rich in organic matter with excess P levels and loamy texture. Two reduced-tillage systems, no tillage (NT) and minimum tillage (MT), and four different fertilizer treatments were assessed. The amounts of P extracted by anion-exchange resin (AER) and by Mehlich 3 (M3) were compared; in addition, differences between two determination methods of P contents extracted by Mehlich 3, namely molybdic acid colorimetric standard procedure (M3-COL) and inductively coupled plasma–mass spectroscopy (M3-ICP), were evaluated. Ninety-six soil samples were taken from the 0- to 5-cm surface layer in three successive dates after increasing manure addition. Colorimetric Mehlich 3 P ranged from 49 to 431 mg dm^–3. The ranks of mean extractable soil P concentrations were AER < M3-COL < M3-ICP. The linear correlation coefficient between M3-COL and M3-ICP was highly significant (R² = 0.89; P < 0.01), but a two-straight-lines model or a quadratic relationship were more adequate for describing the dependence between the two determination procedures after M3 extraction. Relative and absolute differences between M3-COL and M3-ICP showed a tendency to increase as organic carbon content increased. Phosphorus content extracted by AER and M3-COL or M3-ICP reported a significant but much less predictable relationship with R² values of 0.27 and 0.21 (n = 96), respectively. The P in the surface layer accumulated more under NT than under MT.     

应用离子交换树脂膜法评价缓释复合肥料供肥特性的研究

在25℃连续恒温培养条件下,采用离子交换树脂膜(IERM)提取,测定了不同缓释复合肥料(SRCF)在土壤中的氮、磷、钾养分的供肥特性,并与盆栽水稻的养分吸收进行比较。结果表明:56.d内2种SRCF在土壤中NO3--N和NH4+-N养分的日均供应量占普通复合肥(NCF)的3.3%～58.1%,并以NH4+-NNO3--N;2种SRCF的H2PO4-和K+的日均供应量占磷、钾施用量分别为NCF的14.9%、23.2%和92.7%、64.5%。与NCF相比,SRCF氮素和磷素养分在土壤中释放具有明显的缓释作用。Elovich和抛物线扩散方程的b值可分别用来表征SRCF的NO3--N、H2PO4-和NH4+-N、K+养分在土壤中释放后被吸收的日均供肥量。用离子交换树脂膜法提取测定的SRCF养分在土壤中的供肥特性与该法测定的土壤本身养分的供肥特性相似。SRCF氮、磷、钾养分累积释放量与盆栽水稻氮、磷、钾养分吸收量呈显著或极显著的正相关(r=0.869～*0.994**)。用离子交换树脂膜提取测定和评价缓释复合肥料在土壤中养分的供肥特性是一种比较理想的方法。     

Gaseous emissions of nitrogen and carbon from urban vegetable gardens in Bobo‐Dioulasso,Burkina Faso

Urban and peri‐urban agriculture (UPA) is an important livelihood strategy for the urban poor in sub‐Saharan Africa and contributes to meeting increasing food demands in the rapidly growing cities. Although in recent years many research activities have been geared towards enhancing the productivity of this land‐use system, little is known about turnover processes and nutrient efficiency of UPA. The aim of our study therefore was to determine horizontal fluxes of N, P, K, and C as well as gaseous N and C emissions in urban vegetable gardens of Bobo‐Dioulasso, Burkina Faso. Two gardens referred to as “Kodéni” and “Kuinima” were selected as representative for urban and peri‐urban systems classified as: (1) “commercial gardening + field crops and livestock system” and (2) “commercial gardening and semicommercial field crop system”, respectively. A nutrient‐balance approach was used to monitor matter fluxes from March 2008 to March 2009 in both gardens. Ammonia (NH₃), nitrous oxide (N₂O) and carbon dioxide (CO₂) emissions from the respective soils were measured during the coolest and the hottest period of the day using a closed‐chamber system. Annual partial balances amounted to 2056 kg N ha^–1, 615 kg P ha^–1, 1864 kg K ha^–1, and 33 893 kg C ha^–1 at Kodéni and to 1752 kg N ha^–1, 446 kg P ha^–1, 1643 kg K ha^–1, and 21 021 kg C ha^–1 at Kuinima. Emission rates were highest during the hot midday hours with peaks after fertilizer applications when fluxes of up to 1140 g NH₃‐N ha^–1 h^–1, 154 g N₂O‐N ha^–1 h^–1, 12 993 g CO₂‐C ha^–1 h^–1 were recorded for Kodéni and Kuinima. Estimated annual gaseous N (NH₃‐N + N₂O‐N) and C (CO₂‐C + CH₄‐C) losses reached 419 kg N ha^–1 and 35 862 kg C ha^–1 at Kodéni and 347 kg N ha^–1 and 22 364 kg C ha^–1 at Kuinima. For both gardens, this represented 20% and 106% of the N and C surpluses, respectively. Emissions of NH₃, largely emitted after surface application of manure and mineral fertilizers, accounted for 73% and 77% of total estimated N losses for Kodéni and Kuinima. To mitigate N losses nutrient‐management practices in UPA vegetable production of Bobo‐Dioulasso would greatly benefit from better synchronizing nutrient‐input rates with crop demands.     

Extraction Methods for Phosphorus and Their Relationship with Soils Phosphorus‐Buffer Capacity Estimated by the Remaining‐Phosphorus Methodology‐A Pot Study with Maize

Abstract

This work aimed to calibrate Mehlich 1, Mehlich 3, Bray 1, Olsen, and ion‐exchange resin extraction methods with maize phosphorus (P) responses in a pot study with lowland and upland soils with different P‐buffer capacities and to evaluate whether the calibration can be enhanced through the knowledge of remaining P. The experimental design was completely randomized with four replications in a factorial arrangement involving five P concentrations and four lowland or seven upland soils. The remaining P for each soil was determined, P‐buffer capacity was estimated, and the soils were grouped according to the results. Correlation coefficients showed that the remaining P is strongly dependent on clay and soil organic‐matter content, and its determination was useful to the evaluation of the extractants. The classification and grouping of soils according to their P‐buffer capacity improved the correlations between extracted P and plant response for Mehlich 1 and Bray 1 extractants. The Mehlich 3, Olsen, and resin methods presented better performances, independent of soil grouping.     

Chemical Characterization of Inorganic Phosphorus Desorbed by Ion Exchange Membranes in Short‐ and Long‐Term Extraction Periods

Abstract

The chemical characterization of soil phosphorus (P) desorbed by anion and cation exchange membranes is of major importance to better understand which P forms are available to plants in short‐ and long‐term time periods. Two distinct soils, one acidic and one calcareous, were analyzed for P using two extraction procedures with mixed anion and cation exchange membranes. The short‐term (ST) experiment evaluated the effect of increasing the extraction periods up to 24 h, whereas the long‐term (LT) experiment consisted of a sequential extraction procedure using up to seven successive 24‐h extractions. In both experiments, the Chang and Jackson inorganic P fractionation methodology was carried out after each extraction treatment, and each treatment consisted of three replicates. Data were statistically analyzed by ANOVA and nonlinear regressions. In the ST experiment, increasing the extraction time increased the extracted P according to an asymptotic relationship (y=c?ab ^x ). Extracted P proceeded from the most labile fractions in the acidic soil. In calcareous soils, calcium phosphates may also contribute for extractable P. The LT experiment revealed that a single extraction, regardless of that extraction method, cannot predict the long‐term capacity of soils to supply P to the plants. An exponential relationship (P=a×n ^b ) was found between extracted P and the extraction number. Desorbed P proceeded from the most labile fractions in the acidic soil. However, in calcareous soils, some precaution is needed when considering the biological meaning of the results, because the occluded Fe phosphates also revealed significant decreases, probably due to the redox conditions in which these long extractions are performed.     

Using Commercially Available Ion‐Exchange Membranes to Monitor Plant‐Available Nutrients in Cranberry

Abstract

Monitoring in‐season nutrient availability in cranberry (Vaccinium macrocarpon Ait.) is hampered by tissue sampling being limited to a short, late‐summer period, and a low‐pH, high‐iron (Fe) soil environment limits soil‐test result interpretation. To evaluate monitoring available in‐season nitrogen (N), phosphorus (P), and potassium (K), commercially available ion‐exchange membranes (PRS?) were placed in plots where standard fertilizer practices were supplemented with the controlled‐release fertilizer (CRF) Osmocote? 14–14–14 at 0, 112, 224 or 336 kg/ha rates. PRS? nitrate (NO₃)‐N was related only to CRF fertilizer, whereas PRS? ammonium (NH₄)‐N reflected both the CRF and in‐season fertilizer applications. Large increases in PRS? NH₄‐N with increasing CRF rates suggested a synergistic effect of CRF on fertilizer NH₄‐N availability. PRS? P was positively correlated with CRF P but negatively to in‐season P applications, whereas PRS? K was related to in‐season fertilizer applications but not to CRF, suggesting poor plant P availability in the soil environment and relatively little K contribution from CRF, respectively. These results show promise for using PRS? in cranberry.     

高吸水性树脂用于水土保持和节水农业的新思路

水土流失成为头号环境问题,是造成“荒漠化”和生态破坏的主要原因;水资源的日益匮乏又是农业的心腹大患。文章针对各种综合治理办法的特点,介绍能够快速见效的高吸水性树脂新方法的研究现状,探讨用于水土保持和节水农业的高吸水性树脂研究和应用方面值得注意的问题,分析其作用原理,指出了使用高吸水性树脂在防治水土肥的流失、促进节水农业发展的应用前景,并提出了如何做到“保水、保土、保肥、助长和安全”的新思路。