Original Papers: Manganese toxicity of melon plants growing on an isolated soil bed after steam sterilization

(Jpn. J. Soil Sci.Plant Nutr., 77, 257–263, 2006)

The symptom of blighted leaves was observed for the melon plants grown on an isolated soil bed after steam sterilization (SS) in a greenhouse in Kochi Prefecture, Japan. To clarify the causes of this symptom, soil and plant analyses were conducted in the first experiment. Manganese concentrations in the leaves with the symptom were higher than 1,000 mg kg?1and exchangeable Mn in the soil was higher than 30 mg kg?1, which indicated the observed symptom was due to Mn excess. In the second experiment, formation of Mn oxide-dissolving substances after SS was examined for several organic amendments, because large amounts of palm chips had been supplied to the soil before SS in the first experiment. As a treatment similar to SS, palm chips, bark compost, and cattle feces manure were autoclaved. The water extracts were collected before and after the autoclave treatment and the Mn oxide-dissolving capacities of the extracts were evaluated. The Mn oxide-dissolving capacity of the water extracts after SS was remarkably higher than before SS, and the value was highest in palm chips, and followed by bark compost, and cattle feces manure. Fractionation and HPLC analysis of the water extracts after SS revealed that the main substance behind Mn oxide reduction in palm tips was arabinose and that in bark manure was malic acid. Further, Mn oxide-dissolving capacities of the water extracts were almost completely explained by the amounts of arabinose or malic acid found in these materials. From these results, it was considered that reducing substances such as arabinose were released by SS from the palm chips which had been applied in large quantity before SS and these reducing substances dissolved the soil Mn oxides and increased the amounts of available Mn, which led to the occurrence of Mn toxicity to the plants.     

长期定位施肥对土壤铁、锰形态及剖面分布的影响

本文采用改进的BCR连续提取法,对沈阳农业大学棕壤肥料长期定位试验地31年不同施肥处理土壤铁和锰含量变化及其剖面变异规律进行研究。结果表明:与试验前相比,耕层土壤两种元素水溶态和弱酸溶态含量都有所增加,而可还原态和残渣态含量则有不同程度的减少;铁和锰都以残渣态和可还原态为主。在空间分布上,两种元素弱酸溶态和可氧化态含量随土层的加深而减少,残渣态则相反。研究表明,有机肥能在一定程度上改变铁和锰在各形态间的分配,并且有机肥能活化残渣态铁和锰。     

Kinetics of Iron and Manganese Release from Contaminated Calcareous Soils

Knowledge of the release of heavy metals (HM) and their chemical speciation is necessary for characterizing HM behavior in soils. The kinetics and characteristics of iron (Fe) and manganese (Mn) release were studied in 10 contaminated calcareous soils using 0.01 M calcium chloride (CaCl₂), 0.01 M ethylenediamine tetraacetic acid (EDTA), and 0.01 M malic acid (malic acid) extractions. Iron and Mn in soil samples were fractionated before and after 2084 h kinetic release using a sequential extraction procedure. The proportion of Fe and Mn released by EDTA was greater than that with CaCl₂ and malic acid. A power model satisfactorily described Fe and Mn release from soils. In general, the mean release rate of Fe was greater than that of Mn, indicating a greater rate of Fe release from contaminated soils. It was shown that Fe and Mn distributions were similar in native soils and they were mainly found in Fe-Mn oxides and organic-matter (OM) fractions. There were changes in the proportional distribution of Fe and Mn in all soils during the 2084 h kinetic study with different extraction solutions. In general, the proportions of Fe and Mn associated with carbonate (CARB) and OM fractions tended to decrease, with corresponding increases in the Fe-Mn oxides for Mn and residual (RES) fractions for Fe during the kinetic study with all extraction solutions. The Fe and Mn solubility at the initial and final stages of release was controlled by siderite (FeCO₃), vivianite [(Fe)₃(PO₄)₂·8H₂O], MnCO₃(am), MnHPO₄, and rhodochrosite (MnCO₃) minerals in all extraction solutions. Based on a risk assessment and percentage of release of metals, there is a high potential for Mn release into the food chain from contaminated soils.     

Trace elements accumulation in soil and rice plants irrigated with the contaminated water

We carried out a study to see the effect of contaminated water of Nullah Dek on fine rice paddy and straw yields and trace elements accumulation in different parts of rice plants and soil. A site was selected near the bank of Nullah Dek at Kot Pindi Das in the District of Sheikhupura, Pakistan. The water of this nullah is contaminated by industrial effluents carrying different micronutrients. This water was employed to grow rice crop. Water samples were collected before transplanting and during the season with 15 days interval for analysis from 20 July to 1 November 2002 from a spot near village Shamke. Three fine rice varieties, viz. Super Basmati, Shaheen Basmati and Basmati 2000 were transplanted. These rice varieties were grown up to maturity. Paddy and straw yields data were recorded. Six composite soil samples from three random spots were collected from the experimental site before the start of the study to see the status of trace elements in soil. After the harvest of rice crop, soil, paddy and straw samples were analysed for Zn, Cu, Fe and Mn. The chemical analysis of Nullah Dek water showed that total salts concentration was greater than the safe limit, i.e. electric conductance (EC) > 1.0 dS m⁻¹. Even sodium adsorption ratio (SAR) was very high, but there was no problem of high residual sodium carbonate (RSC). Zn, Cu, Fe and Mn were present but within safe limits. The water of Nullah Dek remained within permissible limits of irrigation from onset of rainy season till 15 October. There was an increase in EC, SAR and trace elements concentrations after 15 October but within safe limits. Soil analysis revealed its saline nature, devoid of sodicity. Among trace elements, the zinc ranged between deficiency (<0.5 mg kg⁻¹) and adequate limits (>1.0 mg kg⁻¹). Copper, Mn and Fe were present in adequate amounts. After the harvest of rice crop there was a slight decrease in pH, EC_e and SAR at both the depths, while the concentrations of all trace elements were slightly increased with more in upper layer than the lower layer. Shaheen Basmati produced the maximum paddy yield followed by Basmati 2000 and then Super Basmati. The chemical analysis of paddy samples indicated a sufficient accumulation of zinc (1.68–1.78 mg kg⁻¹), copper (1.38–1.45 mg kg⁻¹), iron (6.12–6.37 mg kg⁻¹) and manganese (2.22–2.42 mg kg⁻¹). Analysis of rice straw also showed sufficient accumulation of zinc (27.50–28.50 mg kg⁻¹), copper (20.0–20.50 mg kg⁻¹), iron (270–280 mg kg⁻¹) and manganese (2.38–2.41 mg kg⁻¹).     

Genotypic Difference in Resistance to Internal Bark Necrosis in Apple Trees Is Related to Manganese Uptake,the Distribution of Manganese,and Antioxidant Activity

Field investigations and pot culture experiments were performed to elucidate the genotypic differences of two apple cultivars that vary in resistance to internal bark necrosis (IBN). Factors examined were manganese (Mn) uptake, antioxidant activity, as well as the accumulation and distribution of Mn in apple branches. Lesser Mn concentrations were found in the bark and branches of an IBN‐tolerant cultivar (‘Jonagold’) than in those of the sensitive cultivar (‘Fuji’) from both field investigations and pot culture, which is correlated with a reduction in Mn uptake from soil. Histochemical tests and x‐ray microanalyses indicated that Mn is localized in the bark and coincided with the occurrence of necrosis in ‘Fuji,’ whereas a more homogenous distribution of Mn was found in ‘Jonagold,’ possibly resulting in an alleviation of Mn toxicity. Physiological parameters indicated that the occurrence of IBN in apple was related to oxidative stress. Under field conditions, ascorbic acid concentration in the bark or leaves of ‘Fuji,’ which were severely affected by IBN, was less than that of ‘Jonagold.’ Because of greater Mn uptake from soil, an uneven distribution of Mn among tissues, and less reduction activity in the sensitive apple tree, oxidized Mn precipitation occurred in the bark, which ultimately exhibited IBN.     

The impact of long-term cultivation and management history on the status and dynamics of cobalt in a savanna Alfisol in Nigeria

The status of cobalt (Co) in savanna soils of Nigeria is largely unknown, and a long-term experiment including inorganic fertilizer (NPK) and farmyard manure (FYM) and uncultivated land provided information on the way management affected the dynamics of Co in the soil. Total Co increased with increasing depth, whereas readily extractable Co decreased. The mean concentration of Co (5.6–7.9 mg kg⁻¹) was close to the mean value of 8 mg kg⁻¹ reported for soils worldwide, whereas the concentration of extractable Co was less than that reported in most soils. Regression analysis indicated that total Fe predicted up to 78% of the soil Co. The potentially available Co correlated strongly with pedogenic or reducible Mn oxides extracted with dithionite–citrate–bicarbonate. Mass balance calculations showed that fertilization with either NPK or FYM caused losses of between 0.8 and 1.1 g Co m⁻² after 50 years of cultivation against the uncultivated site as a reference. However, Co increased by 1.8 g m⁻² in the soil receiving FYM + NPK, suggesting that the Co of the soil was best maintained under this management probably because of incidental additions of Co in the manures. Furthermore, the positive Co balance in the FYM + NPK plot was partly enhanced by its larger contents of clay, Fe and pedogenic Mn oxides than in either the FYM or NPK plots. Clay, Fe and pedogenic oxides served as Co sinks in this particular savanna soil.     

Reuse of Stabilized Fowl Manure as Soil Amendment and Its Implication on Organic Agriculture Nutrition Management

A major input in intensive organic agriculture is nutrient-rich liquid fertilizers. Guano and other fowl manure are frequently digested in water extracts, and the supernatant is supplied as fertilizer. The resultant manure biowaste (MBW) is commonly disposed of to the environment, posing potential pollution and health risks. The study aims were to determine two types of fowl MBWs for their chemical properties before and after lime treatment and to test their reuse potential as soil amendment. Guano and layer manure were digested, and the residues?? chemical properties were analyzed before and after lime treatment. MBWs were then air-dried and used as a soil amendment in a parsley-growing experiment. The lime-treated MBW composition met the European standards for high-quality biowaste compost. Both digested and lime-treated MBWs had residual nitrogen, 3% and 1% in guano and layer manure, respectively. Parsley grown in soil amended with layer MBW had 100% survival, high yield, and good crop quality compared with controls. Plants grown with soil amended with guano biowaste exhibited lower yield and only 50% survival. These findings indicate that the current practice of disposing guano biowaste to the environment may pollute soil and water bodies, while the land spread of lime-treated layer MBW is safe and may improve soil fertility.     

施硅对高锰诱发苹果粗皮病的影响

为解决辽宁等地高锰引起苹果生理粗皮病发生的问题,2004年在盆栽脱毒富士幼苗上进行施锰的同时施硅与单施锰的试验,待叶、枝发生粗皮病后再施硅矫正。结果表明,本试验条件下施锰400.mg/kg的同时施硅400mg/kg,可安全有效防治粗皮病的发生;施锰400.mg/kg诱发叶片发病后,施硅400.mg/kg可较好地控制粗皮病的发生。施锰400.mg/kg枝干发病后施硅,对粗皮病的蔓延有一定控制作用,但效果不明显。随着施硅量增加,土壤速效钾含量提高,有效铁、有效锌含量降低,说明粗皮病的发生也与上述养分有关系。     

Distribution of sludge‐borne manganese in field‐grown maize

Abstract

The uptake and distribution of manganese (Mn) in field‐grown maize (Zea mays L.) was studied in a long‐term sewage sludge field trial on an acid sandy soil at Bordeaux. Since 1974, sewage sludge had been applied at levels of 101 dry matter (DM) ha^‐1 year^‐1 (SS 10) and 1001 DM ha^‐1 per 2 years (SS 100) on annually cropped maize plots. Treatment with farmyard manure (FYM) at a rate of 10 t DM ha^‐1 year^‐1 served as unpolluted control. Five replicate plants per treatment were examined at six different growth stages. At each stage, the whole plant was separated into its different organs and the Mn distribution was determined in at least 12 different plant parts. Manganese concentrations were always higher in SS 100 plants compared to FYM and SS 10 treated plants. Significant treatment‐dependent differences occurred almost all in the roots and in the different leaf levels while we found similar Mn concentrations in the stalk and in the reproductive organs. In the different stalk levels and in the ear composites we determined low Mn concentrations with critical deficiency values in FYM and SS 10 plants while Mn concentrations in SS 100 plants were in the normal range. Soil treatment also significantly influenced the initial absorption by the roots. Despite low absolute Mn concentrations in the roots of FYM plants, the Mn transfer coefficient (plant Mn concentration/soil Mn concentration) was highest in FYM plants and lowest in SS 100 plants indicating a relatively low Mn plant availability in the sludge‐treated plots.     

Effect of long‐term swine‐manure application on soil hydraulic properties and heavy metal behaviour

This study evaluated the effect of 13 years of swine‐manure application on the changes in soil hydraulic properties, and as associated physicochemical properties, with a focus on heavy metal mobility. Various soil hydraulic properties were measured, including soil water retention (SWR), saturated field hydraulic conductivity (K_fs) and unsaturated field hydraulic conductivity (K_funsat) using a disc infiltrometer. Heavy metal mobility was evaluated with a sequential extraction procedure. At 0–30 cm soil depth in the heavily manured plot (SMhigh plot), SWR at 0 to ?100 kPa was significantly larger than in plots amended with a standard amount of manure (SMstd plot) or with chemical fertilizer (CF plot). K_fs and K_funsat values in both manure‐amended plots were less than in the CF plot under dry soil conditions but greater than those of the CF plot under wet soil conditions. Furthermore, K_fs and K_funsat did not necessarily increase with manure application rates. On the other hand, high‐mobility metal fractions, such as the exchangeable fraction of Zn, and the CH₃CO₂Na‐extractable fraction of Zn and Mn, and the metal–organic complex fractions of Zn, Cu and Mn, increased with the greater manure application rate. In addition, low‐mobility metal fractions, the organically bound fractions of Zn, Cu and Mn in the high SM plot and the easily reducible metal oxide fraction of Mn in both manure‐amended plots were probably affected and released into high‐mobility fractions. This indicated that manure application changed the soil redox conditions by improving the soil structure, depending on the water content of soil pores. Despite the reduction of K_fs and K_funsat by heavy manure application, the transport of high‐mobility metal fractions with either surface water flow or infiltration water flow could be controlled by soil water content at the beginning of a rain or irrigation event.     

Absorption of Ammonia Released from Poultry Manure to Soil and Bark and the Use of Absorbed Ammonia in Solubilizing Phosphate Rock

Composting systems were designed to utilize ammonia (NH₃) released during composting of poultry manure to solubilize phosphate rock (PR). The NH₃ released from decomposing manure was allowed to pass through columns containing soil or bark materials mixed with North Carolina phosphate rock (NCPR) at a rate of 1 mg P g^?1. After eight weeks of incubation, the columns were dismantled and the forms of P and N in PR/soil or PR/bark mixtures were measured. The dissolution of PR was determined from the increases in the amount of soluble and adsorbed P (resin plus NaOH extractable P) or from the decreases in the residual apatite P (HC1 extractable P).

The amounts of NH₄^+-N in the soil and bark columns increased due to absorption of the NH₃ released from poultry manure. No nitrification of absorbed NH₃ occurred, however, unless the soil or bark were reinoculated with a fresh soil solution and incubated for further six weeks.

In the absence of NH₃ absorption, soil and bark materials dissolved approximately 33 percent and 82 percent of NCPR, respectively. The higher dissolution of NCPR in bark was attributed to its higher exchangeable acidity and Ca sink size. There was no increase in NCPR dissolution during the initial NH₃ absorption phase (36 percent and 85 percent dissolution in soil and bark respectively), which may be due to the absence of nitrification. However, during subsequent reincubation when nitrification occurred, the final dissolution of NCPR in the NH₃ treated soil and bark was slightly higher (41 percent and 100 percent, respectively). Protons (H⁺) are released during the oxidation of NH₄⁺ to NO_3? (nitrification) which promote the dissolution of PR. However, most of the H⁺ released during nitrification was involved with soil and bark pH buffering reactions. Only five to 10 percent was involved in PR solubilization in PR/soil mixtures whereas about 50 percent was involved in PR/bark systems.

Bark covers for poultry manure and poultry manure compost heaps have the potential to reduce NH₃ loss and conserve N and may be useful for other purposes such as PR solubilization.     

蚯蚓生物床工程处理对牛粪性质的影响

利用蚯蚓处理有机固体废弃物比传统技术手段具有更明显的优越性,得到越来越广泛的关注。试验通过蚯蚓生物床工程处理牛粪,采用室内分析的方法研究处理前后性质变化特征。结果表明：牛粪经蚯蚓生物床处理后的通水性和透气性得到明显改善,易干燥,无臭气,含水率和电导率明显下降,pH值趋于中性。蚯蚓生物床工程处理使全氮和有机质含量下降,提高了铵态氮、硝态氮、全钾、全磷、有机磷、无机磷和速效磷的含量,降低了钾的生物有效性,对腐殖酸含量无明显影响。对Cr、Cd和Cu的去除效果较好,对Pb、Mn、Zn和Fe的去除效果不佳。蚯蚓生物床工程处理过程丰富了蚯蚓粪中微生物区系,增加了过氧化氢酶活性,降低了脲酶活性,使牛粪中的碳水化合物发生逐步分解,生成腐殖物质,同时使水溶性有机硅化合物分解为无机硅氧化物。     

Long term crop management effects on soil organic carbon,structure, and water retention in a cropland soil in central Ohio,USA

The objective of this study was to determine 13‐year management effects on soil properties between a corn–soybean (Zea mays–Glycine max) cropping system (CSRS) and vegetable production systems (VPS) on a soil in central Ohio. Three treatments included in the VPS were: (1) addition of wood chips, (2) permanent raised beds (PRB) with black polyethylene film (20 μm thick), and (3) bare soil surface (BSS). Additionally, (4) animal manure was applied in all CSRS and VPS treatments except for the wood chips (WCP) added plot in the VPS. Research data from the study show that relatively more soil organic carbon (SOC) stock in the 0–20 cm soil depth of the BSS treatment (100.6 Mg ha^?1) was primarily due to differences in the type of soil amendments applied. For example, composted poultry manure was applied in the BSS and PRB plots, compared with input of fresh dairy manure mixed with straw being applied in the CSRS. Furthermore, soil management practices that aided in avoiding or reducing soil compaction (i.e., PRB or application of WCP in the surface) resulted in the overall improvement in soil structure and water retention, compared with that under chisel and disc ploughing done in the CSRS. The highest plant available water capacity (1.79 cm) was observed in the CSRS compared with 0.97 cm under BSS and PRB plots. These trends suggest that the type and amount of animal manure is critical to increasing SOC stocks in intensively cultivated VPS and CSRS in central Ohio, while also improving soil structure and water retention.     

The response of soil organic matter to manure amendments in a long-term experiment at Ultuna, Sweden

In a long-term field experiment started in 1956 on a clay loam soil at Uppsala, Sweden, changes of organic carbon in the topsoils receiving various organic amendments at the rate of 200 kg C ha^'1 year^'1 were studied to determine soil organic matter characteristics, variations of δ¹³C in the soil and to estimate a carbon balance. Fallow and mineral fertilizer without N led to a significant decrease of soil organic matter (SOM) in the soil, green manure maintained the SOM content, and animal manure and peat increased the SOM content significantly. The stable portion of the added organic materials after 37 years of continuous input was 12·8, 27·3, and 56·7%, for green manure, animal manure and peat, respectively. This was reflected by half-lives of organic carbon originating from the amendments between 3·0 (green manure) and 14·6 years (peat). The isotopic composition of SOM changed both due to mineralization (continuous fallow) and the addition of amendments is topically different from soil humus (green manure, animal manure). The isotopic effect was used to calculate the percentage of carbon derived from animal manure present for the year 1993. This value (55·4%) was larger than that derived from the carbon balance, which indicated a priming effect of the animal manure on the initial soil humus. Mineralization of microbially available organic substances led to an increase in the degree of humification on plots not receiving organic amendments. Adding peat and animal manure resulted in a decrease of the humification index due to the continuous input of poorly humified material. The extinction ratio (E₄/E₆) and ratio of fulvic acid to humic acid changed considerably in the peat treated plots. Fourier transform infrared (FTIR)-measurements of the extracts showed that peat characteristics can be detected in peat treated soils. The other amendments did not alter the characteristics of the extractable humic substances.     

ALUMINUM SPECIATION OF AMENDED ACID TROPICAL SOIL AND ITS EFFECTS ON PLANT ROOT GROWTH

Exchangeable and soluble soil aluminum (Al) is limiting plant growth in many soils worldwide. This study evaluated the effects of increasing rates of dolomite and magnesium carbonate (MgCO₃) on Al³⁺, pH, dissolved organic carbon, cations, anions, and Al speciation on oil palm Deli dura × AVROS pisifera root growth. Dolomite and MgCO₃ additions significantly raised linearly soil solution pH, magnesium (Mg²⁺), nitrate (NO₃ ^?) and chlorine (Cl^?) concentrations; exponentially decreased the activity of phytotoxic Al species [aluminum (Al³⁺), aluminum sulfate (Al₂SO₄), and aluminum fluoride (AlF₃)]; and reduced manganese (Mn) concentration and activity. High activity of those species exponentially reduced root dry weight. Optimum oil palm growth was achieved at: <50 μM monomeric Al, < 30 μM Mn, and <0.20 unit of the ratio Al+Mn to calcium (Ca)+Mg. High activity of Al species and Mn in acidic soil solution cause significant reduction of the root growth. Soil acidity alleviation either with dolomite or MgCO₃ mitigates the toxic effect of Al and Mn.     

Characterization of water soluble organic matter in soils by size exclusion chromatography and fractionation with polyvinylpyrrolidone

Water extracts were obtained from four types of soils (Brown Lowland soil, Yellow soil with manure application for 6 years, non-allophanic Andosol, and allophanic Andosol), and the organic matter in the water extracts was fractionated according to the solubility in acid and adsorption onto polyvinylpyrrolidone (PVP). For the water extracts and their fractions, the amounts of organic C, total N, and anthrone-reactive C (ARC) were analyzed, and high performance size exclusion chromatography (HPSEC) was carried out. The PVP-non-adsorbed fulvic acid (FA) fraction accounted for the largest proportion of the total water-soluble organic C, ranging from 52% for the Yellow soil to 96% for the allophanic Amdosol, followed by the PVP-adsorbed FA and humic acid (HA) fractions. The water extract of the allophanic Andosol was characterized by the lack of HA fraction and a small proportion of PVP-adsorbed FA fraction. For all the water extract samples, more than 90% of the ARC was recovered in the PVP-non-adsorbed FA fraction. The proportion of ARC in the total organic C in the fraction was also highest in the PVP-non-adsorbed FA fraction. The molecular weight (MW) of the humic substances (HS) at peak maximum was estimated at 1,300 Da for the water extracts and their fractions from the Brown Lowland soil and non-allophanic Andosol samples by HPSEC using polyethylene glycols as MW standards. Manure application increased the MW of HS in the HA and PVP-adsorbed FA fractions. On the other hand, only a small amount of HS was found in the water extract of the allophanic Andosol by HPSEC.     

Influence of Manuring on certain soil physical properties in the middle awash area of ethiopia

Abstract

Irrigated soils in Middle Awash area of Ethiopia have poor aeration and low water infiltration rates. In order to improve these characteristics, green manure (dolicus lab‐lab), farm yard manure, and bagasse were incorporated into the soil. As a result, grain and dry matter yields were statistically significantly improved. However, dry matter and grain yield from the application of bagasse were lower even than the control treatment Infiltration rates and bulk density were also measured before and after application of green manure, farm yard manure, and bagasse. Infiltration intake rates before incorporation of dolicus lab‐lab was slightly increased. In contrast, lighter bulk density and total soil porosity were obtained before incorporation of farm yard manure. Overall green manure may be regarded as one of the most promising organic manures in improving certain degraded soil physical properties.     

Fractions of Manganese in Soil under Long-Term Experiment and Their Contribution to Manganese Availability and Uptake by Maize-Wheat Cropping Sequence

Manganese (Mn) is an essential micronutrient needed for plant growth and development, but it can be toxic to plants in excess amounts. Long-term fertilizer experiment and intensive cropping alter the soil properties and also affect its plant-available Mn contents. To understand the dynamics of Mn under long-term fertilizer experiment the present study was initiated during 1972 at the experimental farm of College of Agriculture, CSK HPKV, Palampur (32° 6′ N latitude and 76° 3′ E longitude) in a randomized block design with 11 treatments replicated three times with a maize-wheat cropping sequence. The soils of the experimental area in the beginning of the experiment were acidic in reaction and taxonomically classified as Typic Hapludalfs. Surface (0.0–20 cm) and subsurface (20–40 cm) soil samples taken after the harvest of maize (kharif, 2008) were analyzed for pools of Mn and chemical indices of soil quality using standard analytical methods. Besides, the pools of Mn were also determined in the composite soil samples drawn from adjacent fallow plots. Results showed that all the pools of Mn were noticeably greater in farmyard manure (FYM)–amended plots compared to zero-fertilized plots. Although the residual fraction was found to be the most dominant fraction, organically bound and exchangeable forms were found to play major roles in the nutrient supply, crop productivity, and nutrient uptake. The greatest productivity of maize (2008) and wheat (2008–09) was recorded under the 100% nitrogen, phosphorus, and potassium (NPK) + FYM treatment. FYM and lime treatments resulted in significantly greater uptake of all the nutrients by both the crops compared to other treatments. The organically bound fraction was found to have the greatest significant and positive correlation with yield and nutrient uptake of maize and wheat crops. Further regression analysis studies revealed that the organic form was the most important pool contributing towards the variation in the parameters. Exchangeable and organically bound forms contributed significantly towards diethylene triamine pentaacetic acid (DTPA)–extractable Mn.     

Anatomy and cell wall polysaccharides of almond (Prunus dulcis D. A. Webb) seeds

The anatomy of Prunus dulcis was analyzed by applying several differential staining techniques and light microscopy. Prunus dulcis seed has a thin and structurally complex seed coat, with lignified cellulosic tissue. The embryo has two voluminous cotyledons. Cotyledon cells have a high number of protein and lipid bodies, some of which have phytin. The provascular tissue, located in the cotyledons, is oriented in small bundles perpendicular to the transverse embryonic axis. Prunus dulcis cell wall material is very rich in arabinose (45 mol %). Glucose (23%), uronic acids (12%), and xylose (12%) are also major sugar components. The polymers obtained from the imidazole and Na(2)CO(3) extracts contain mainly pectic substances rich in arabinose, but the sugar content of these extracts was very low. The majority of the pectic substances (also rich in arabinose) was recovered with the KOH extracts. These extracts, with high sugar content, yielded also xyloglucans and acidic xylans. The 4 M KOH + H(3)BO(3) extracts yielded polysaccharides rich in uronic acids and xylose and very rich in arabinose, accounting for 27% of the cell wall material.     

Changes in hot water soil extracts brought about by nitrogen immobilization and mineralization processes during incubation of amended soils

Summary During incubation of an acid cambisol and an alkaline fluvisol, amended with glucose and nitrate, hot water soil extracts were analysed for N content, ultraviolet absorption, and fluorescence. Humic substances in the hot water extracts and in a neutral sodium pyrophosphate extract were fractionated on polyvinylpyrrolidone and measured spectroscopically. Changes in the hot water and pyrophosphate extract compositions were related to changes in microbial biomass, as estimated by substrate-induced respiration, and the hexosamine content of soil hydrolysates. During the incubation, the microbial population in each type of soil developed quite differently, according to the soil pH. Microbial growth and death in the alkaline soil sample induced a maximum of hot-water-extractable ultraviolet-absorptive non-fluorescent substances. The fluorescence of the hot water soil extract increased steadily with incubation time even after the microbial activity was reduced. A similar increase in fluorescence, in accord with the ultraviolet absorption, was found during incubation of the acid soil samples. After 95 days of incubation, the hot-water-extractable fluorescent and ultraviolet-absorptive substances were reduced. N immobilization induced an increase, and N mineralization a decrease, in dissolved organic N. The relative increase in humic substances in the hot water soil extract was much higher than in the pyrophosphate extract. Therefore, humic material, produced by microbial growth and death, is obviously extractable with hot water.