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  • 1
    Electronic Resource
    Electronic Resource
    Seasonal responses in microbial biomass carbon, phosphorus and sulphur in soils under pasture (1997)
    Springer
    Biology and fertility of soils 24 (1997), S. 421-428 
    Details
    ISSN: 1432-0789
    Keywords: Key words Seasonal responses ; Microbial biomass C ; Microbial biomass P ; Microbial biomass S ; Nutrient cycling ; Pasture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The response of the soil microbial biomass to seasonal changes was investigated in the field under pastures. These studies showed that over a 9-month period, microbial biomass carbon, phosphorus and sulphur (biomass C, P, S), and their ratios (C:P, C:S, and P:S) responded differently to changes in soil moisture and to the input of fresh organic materials. From October to December (1993), when plant residues were largely incorporated into the soils, biomass C and S increased by 150–210%. Biomass P did not increase over this time, having decreased by 22–64% over the dry summer (July to September). There was no obvious correlation between biomass C, P, and S and air temperature. The largest amounts of biomass C and P (2100–2300μg and 150–190μgg–1 soil, respectively) were found in those soils receiving farmyard manure (FYM or FYM+NPK) and P fertilizer, whereas the use of ammonium sulphate decreased biomass C and P. The C:P, C:S, and P:S ratios of the biomass varied considerably (9–276:1; 50–149:1; and 0.3–14:1, respectively) with season and fertilizer regime. This reflected the potential for the biomass to release (when ratios were narrow) or to immobilize (wide ratios) P and S at different times of the year. Thus, seasonal responses in biomass C, P, and S are important in controlling the cycling of C, P, and S in pasture and ultimately in regulating plant availability of P and S. The uptake of P in the pasture was well correlated with the sum of P in the biomass and soil available pools. Thus, the simultaneous measurement of microbial biomass P and available P provide useful information on the potential plant availability of P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740050267
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  • 2
    Electronic Resource
    Electronic Resource
    Quantifying microbial biomass phosphorus in acid soils (2000)
    Springer
    Biology and fertility of soils 32 (2000), S. 500-507 
    Details
    ISSN: 1432-0789
    Keywords: Keywords Fumigation-extraction techniques ; Microbial biomass P ; Acid soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  This study aimed to validate the fumigation-extraction method for measuring microbial biomass P in acid soils. Extractions with the Olsen (0.5 M NaHCO3, pH 8.5) and Bray-1 (0.03 M NH4F–0.025 M HCl) extractants at two soil:solution ratios (1 : 20 and 1 : 4, w/v) were compared using eight acid soils (pH 3.6–5.9). The data indicated that the flushes (increases following CHCl3-fumigation) of total P (Pt) and inorganic P (Pi) determined by Olsen extraction provided little useful information for estimating the amount of microbial biomass P in the soils. Using the Bray-1 extractant at a soil:solution ratio of 1 : 4, and analysing Pi instead of Pt, improves the reproducibility (statistical significance and CV) of the P flush in these soils. In all the approaches studied, the Pi flush determined using the Bray-1 extractant at 1 : 4 provided the best estimate of soil microbial biomass P. Furthermore, the recovery of cultured bacterial and fungal biomass P added to the soils and extracted using the Bray-1 extractant at 1 : 4 was relatively constant (24.1–36.7% and 15.7–25.7%, respectively) with only one exception, and showed no relationship with soil pH, indicating that it behaved differently from added Pi (recovery decreased from 86% at pH 4.6 to 13% at pH 3.6). Thus, correcting for the incomplete recovery of biomass P using added Pi is inappropriate for acid soils. Although microbial biomass P in soil is generally estimated using the Pi flush and a conversion factor (k P) of 0.4, more reliable estimates require that k P values are best determined independently for each soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003740000284
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  • 3
    Electronic Resource
    Electronic Resource
    Modelling soil organic matter changes in ley–arable rotations in sandy soils of Northeast Thailand (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 49 (1998), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The effects of a 3-year ley-arable rotation (2 years under grass, legume or a grass-legume mixture, followed by 1 year under cassava) on the organic C content of upland sandy soils in Northeast Thailand were evaluated using four field trials (Khon Kaen, Chaiyaphum, Mahasarakham and Udon Thani). At all sites under the existing management system of continuous cassava, soil organic C decreased by 9-20% during the 3-year experiment. The carbon model developed at Rothamsted (RCM-26) predicted that soil organic C would decrease consistently under continuous cassava until it reached very small amounts (0.2–0.3%). This was the case for all sites, except Chaiyaphum, where soil organic C had already declined to 0.1%. Evaluatin the rotations using RCM-26 showed that introducing a ley could increase soil organic C, except at Udon Thani where the organic C exceeded 0.47% before the start of the experiment. The data obtained with the rotations showed that RCM-26 could be used to predict the effects of changes in management on organic C content in the upland sandy soils of Norrtheast Thailand over the 3 years. To compensate for an underestimation of the effects of soil moisture deficit on the decomposition rates of organic matter, we propose that because of the prolonged dry season (from December to the following May) soil moisture deficit and the rate-modifying factor for moisture (Am) should be estimated independently of crop cover. Furthermore, to accommodate the very slow decomposition during this time, (Am) should be allowed to decrease to 0.1. Adopting this simple modification provides a more realistic estimate of the organic C inputs needed to simulate the content of soil organic C measured before trials began.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1998.4930463.x
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  • 4
    Electronic Resource
    Electronic Resource
    Charge relationships of phosphate sorption (1975)
    [s.l.] : Nature Publishing Group
    Nature 255 (1975), S. 51-53 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Study of anion sorption by hydrous metal oxides, as developed by Hingston et #/.6'8 is based primarily on shifts in points of zero charge and on the "adsorption envelope". This approach has been questioned9, and the extrapolation of these concepts, developed using pure components, to soils has not ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/255051a0
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  • 5
    Electronic Resource
    Electronic Resource
    Single superphosphate-reactive phosphate rock mixtures. 1. Factors affecting chemical composition (1987)
    Springer
    Nutrient cycling in agroecosystems 13 (1987), S. 223-239 
    Details
    ISSN: 1573-0867
    Keywords: exchangeable P ; free acid ; partial acidulation ; superphosphate ; reactive phosphate rock ; X-ray diffraction pattern
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of additon of reactive phosphate rock (RPR — North Carolina) on the degree of acidulation of unreactive phosphate rocks (PRs — Nauru and Christmas Island A) during the manufacture of single superphosphate (SSP) was examined using32P in isotopic dilution studies. Acidulation of unreactive PR during SSP manufacture continued through denning, granulation and drying. Even after 3 hours drying, between 20 and 30% of the total P remained as free phosphoric acid in the reaction mixture. The addition of North Carolina phosphate rock (NCPR) to ex-den SSP reaction mixture (3:7 NCPR:SSP reaction mixture) preferentially consumed the free phosphoric acid remaining in the reaction mixture. This resulted in reduced acidulation of the unreactive PR in the reaction mixture and partial acidulation (10–23%) of the RPR. Hence the SSP-RPR mixture contains more residual, unreactive PR than is present in SSP. The extent of partial acidulation of the RPR when mixed with SSP was determined by the nature of free acid remaining in the SSP reaction mixture, which in turn is affected by the type of unreactive PR used for SSP manufacture. The free acid in the Christmas Island A reaction mixture contained approximately 8 and 12 times as much Fe and Al respectively as that in the Nauru reaction mixture, and was only half as effective at converting the P in RPR to soluble P. Unless made with extended denning times and carefully chosen PR, SSP-RPR mixtures can contain (a) undesirable amounts of unreactive PR residues, and (b) low quality partially acidulated RPR, both of which have low agronomic value.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066446
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  • 6
    Electronic Resource
    Electronic Resource
    An evaluation of water extraction as a soil-testing procedure for phosphorus II. Factors affecting the amounts of water-extractable phosphorus in field soils (1988)
    Springer
    Nutrient cycling in agroecosystems 15 (1988), S. 225-236 
    Details
    ISSN: 1573-0867
    Keywords: Soil P test ; water extraction ; seasonal variation ; sampling depth ; fertilizer P addition ; microbial biomass P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of seasonal variation, sampling depth, and fertilizer P addition on water-extractable P values were investigated in two field experiments, involving soils of contrasting P retention capacity (Ramiha and Tokomaru) under permanent pasture over 12 months. The effects of the same parameters on Olsen-extractable P were also evaluated. The amounts of water-extractable P in soil were always lower than those of Olsen-extractable P. Over the 12-month period, the average value of water-extractable P in the unfertilized Ramiha soil (0–7.5 cm depth) was 1.8µg g−1 soil compared to an Olsen-extractable P value of 12.6µg g−1. The variability associated with water-extractable P at each sampling time was comparable with that for Olsen-extractable P. However, the relative seasonal variation over 12 months was larger for water-extractable P than for Olsen-extractable P. The results obtained with both extractants showed a seasonal fluctuation which was closely related to the pattern of pasture P uptake. The amounts of water- and Olsen-extractable P were higher in samples taken from the 0–4.0 cm than the 0–7.5 cm sampling depth. Fertilizer P addition resulted in larger increases in water-extractable P in the 0–4.0 cm sampling depth than in the 0–7.5 cm depth. The relative increase in water-extractable P following fertilizer P addition was larger than that of Olsen-extractable P. Seasonal changes in the soil microbial biomass P were not related to changes in either water-extractable P or plant uptake of P. Microbial biomass P may be a less sensitive index of soil P availability than is commonly thought.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01051344
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  • 7
    Electronic Resource
    Electronic Resource
    Characterizing the dissolution of phosphate rock materials by electro-ultrafiltration (1987)
    Springer
    Nutrient cycling in agroecosystems 14 (1987), S. 161-171 
    Details
    ISSN: 1573-0867
    Keywords: Electro-ultrafiltration ; chemical reactivity ; dissolution rate ; ionic strength ; North Carolina phosphate rock ; Sechura phosphate rock ; Chatham Rise phosphorite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Electro-ultrafiltration (EUF) was evaluated as a potential technique for characterizing the dissolution and assessing the chemical reactivity of contrasting phosphate rock (PR) materials. The types of rock used were: three reactive rocks, Sechura phosphate rock (SPR), North Carolina phosphate rock (NCPR), and Chatham Rise phosphorite (CRP), which contains significant amounts of calcium carbonate; one unreactive rock, Tennessee phosphate rock (TPR); and one iron and aluminium phosphate, calcined Christmas Island “C” grade phosphate rock (Calciphos). Dissolution of SPR increased as the solution:solid ratio increased to 250:1, the voltage was increased from 0 to 400 V, and the ionic strength of the extracting solution was increased. The neutralizing effect of any CaCO3 present in PR materials, which is a major limitation with single chemical extraction procedures, does not appear to be a problem with EUF. A limitation of using de-ionized water as the extracting solution with EUF is the small amounts (1 to 6%) of total of P extracted. Addition of NaCl to the extracting solution increased the dissolution of all PR materials, although this varied with the PR. With both de-ionized water and NaCl as the extracting solution, EUF was inferior to 2% formic acid for assessing agronomic effectiveness of the PR materials. EUF appears to be of limited value in assessing the chemical reactivity of PR materials.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066609
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  • 8
    Electronic Resource
    Electronic Resource
    Lime-aluminium-phosphorus interactions and the growth of Leucaena leucocephala (1990)
    Springer
    Plant and soil 126 (1990), S. 9-17 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; aluminium toxicity ; aluminium-induced P deficiency ; chemical composition ; Leucaena ; lime ; Lolium perenne L ; perennial ryegrass ; phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of lime and P on the chemical composition of the tropical legume Leucaena leucocephala were studied in a controlled climate laboratory experiment using 4 (Koronivia, Nadroloulou, Batiri, and Seqaqa) highly-weathered, acid soils from Fiji. For all soils, changes in the concentration of P in the Leucaena tops followed trends similar to the yield response curve, i.e., the concentration of P was highest at the soil pH at which maximum growth occurred. The concentration of Al in plant tops increased on either side of the pH of maximum growth, but Al uptake by the whole plant (tops plus roots) declined steadily with increasing pH. Although complete major (except P) and minor nutrients were added regularly, there was variation in the uptake of nutrients with pH. Poor growth at low pH values was attributed to an Al-induced P deficiency within the plant and at high pH to a soil P deficiency and, to a smaller extent, to the increased concentration of Al in the plant tops.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041364
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  • 9
    Electronic Resource
    Electronic Resource
    Lime-aluminium-phosphorus interactions and the growth of Leucaena leucocephala (1990)
    Springer
    Plant and soil 126 (1990), S. 1-8 
    Details
    ISSN: 1573-5036
    Keywords: aluminium ; aluminium toxicity ; Leucaena yield ; lime ; phosphorus ; phosphorus uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of lime and P addition on the amounts of soil extractable P and Al, and on the growth of the tropical legume Leucaena leucocephala were investigated in a factorial experiment under controlled climate conditions using 4 (Koronivia, Nadroloulou, Batiri, and Seqaqa) highly-weathered, acid (pH initially 3.9 to 4.9) soils from Fiji. Resin-extractable P increased with lime addition and then decreased above pH 5.5, whereas M KCl-extractable Al decreased to undetectable levels at or above pH 5.2. Plant growth was usually adversely affected at low and high pH, even in the presence of added P. The pH (in M KCl) at which maximum growth occurred in the 4 soils varied from approximately 4.4 to 5.2; values somewhat lower than those reported in the literature. Changes in dry matter yield with increasing soil pH were strongly influenced by P status and a positive lime × P interaction was obtained with 3 of the 4 soils. Above pH 5.2, liming decreased the yield of both tops and roots, for reasons which are discussed in part II. The data obtained for extractable soil P and plant P concentrations indicate that P deficiency is a major problem on these soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00041363
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  • 10
    Electronic Resource
    Electronic Resource
    Contribution of organic carbon and clay to cation exchange capacity in a chronosequence of sandy soils (1970)
    Springer
    Plant and soil 33 (1970), S. 104-112 
    Details
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary CEC and oxidisable carbon content were highly correlated (r=0.96) whereas a lower coefficient was obtained for a correlation of CEC and clay content (r=0.57) in a chronosequence of sandy soils from New Zealand. Partial regression coefficients for oxidisable carbon were highly significant in multiple regression equations for all soil groupings whereas in only one equation was the coefficient for clay significant. The CEC of the organic matter for all soils was 1.4 me/g and this value decreased from 1.64 me/g in the young soils to 1.22 me/g in old soils. Peroxidation of selected surface samples caused a reduction in CEC but the results indicated that the clay fractions had a considerably higher CEC (0.57 me/g) than that inferred from multiple regression equations for untreated samples. Selective dissolution analysis indicated that the clay fractions of these soils contained an appreciable amount of amorphous material. Reduction in the CEC of the clay fraction apparently occurs through a blocking by organic matter of the negative charge of the clay components.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378202
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