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  • 1
    ISSN: 1432-0789
    Keywords: S mineralization ; Soluble organic S ; Soil S fractions ; Animal effects ; Fertilizer effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Topsoils (0–75 mm) from four soil types with different sulphate retention capacities were collected from stock camp and non-camp (main grazing area) sites of grazed pastures in New Zealand which had been annually fertilized with superphosphate for more than 15 years. These soils were analysed for different S fractions and incubated at 30°C for 10 weeks using an open incubation technique in order to assess the extent of S mineralization and the release of soluble soil organic S from camp and non-camp soils during incubation. The soils were preleached with 0.01 M KCl, followed by 0.04 M Ca(H2PO4)2 before being incubated. Pre-incubation leachates and weekly 0.01 M KCl leachates were analysed for mineralized S (i.e., hydriodic acid-reducible S) and total S. Soluble organic S was estimated as the difference between these two S fractions. Results obtained show higher cumulative amounts of all three S fractions in leachates over a 10-week incubation period in camp than in non-camp soils, suggesting that higher mineralization occurred in camp soils. Cumulative amounts of mineralized S from camp and non-camp soils showed a linear relationship with duration of incubation (R 2≥0.985***), while the cumulative release of soluble organic S followed a quadratic relationship (R 2≥0.975***). A significant proportion (14.6%–40.8%) of total S release in KCl leachates was soluble organic S, indcating that organic S should be taken into account when assessing S mineralization. Mineralized S and soluble organic S were best correlated with 0.01 M CaCl2-extractable soil inorganic S (R 2=0.767***) and 0.04 M Ca(H2PO4)2-extractable soil inorganic S(R 2=0.823***), respectively. Soil sulphate retention capacity was found to influence amounts of mineralized S and soluble organic S, and thus periodic leaching with KCl to remove mineralized S from soils may not adequately reflect the extent of soil S mineralization in high sulphate-retentive soils. In low (〈10%) sulphateretentive soils, increasing the superphosphate applications from 188 to 376 kg ha−1 year−1 increased S mineralization but not amounts of C-bonded and hydriodic acid-reducible soil S fractions.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 25 (1997), S. 372-381 
    ISSN: 1432-0789
    Keywords: Key words Cropping systems ; Biodynamic farms ; Soil organic matter fractions ; Microbial biomass ; Soil quality indicators
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of cropping systems on soil organic matter (SOM) in a pair of conventional and biodynamic mixed cropping farms were investigated. Soil samples (0–75 and 75–150-mm depths) were analysed for total carbon (TC), total nitrogen (TN), microbial biomass C (BC) and microbial biomass N (BN), and sequentially extracted for labile and stable SOM using cold water, hot water, acid mixtures and alkalis. In the biodynamic farm, TC and TN decreased with increasing period of cropping but the reverse occurred under pastures. These were not shown in soils from the conventional farm, probably due to N fertilizer additions. Under pastures, increases in SOM were attributed to greater biological N2 fixation and the return of plant residues and excreta from grazing animals. Overall, sensitive SOM quality indicators found for labile SOM were BN, BN:TN and HC:TC, and for stable SOM were HCl/HFC, HCl/HFC:TC, humin C, humin N, humin C:TC and humin N:TN. The BN and BN:TN were better indicators than BC and BC:TC. The humin fraction was strongly related to both labile and stable SOM fractions suggesting that humin contained non-extractable strongly complexed SOM components with mineral matter and also non-extractable plant and microbial residual components.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0789
    Keywords: Soil organic matter ; Soil S fractions ; Animal effects ; Fertiliser effects ; Excretal S
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Topsoils (0–75 mm) from four different soil types were collected from stock camp and non-camp (main grazing area) areas of grazed pastures in New Zealand, which had been fertilised annually with superphosphate for more than 15 years, in order to assess the effects of grazing animals on the status and distribution of soil S fractions and organic matter. These soils were analysed for organic C, total N, total S, C-bonded S, hydriodic acid-reducible S, 0.01 M CaCl2, and 0.04 M Ca(H2PO4)2-extractable S fractions, and soil pH. Soil inorganic and organic S fractions extracted by NaHCO3 and NaOH extractants were also determined. The results obtained showed that camp soils contain higher soil pH, organic C, total N, total S, organic (C-bonded S and hydriodic acid-reducible S) and inorganic S fractions, NaHCO3-and NaOH-extractable soil S fractions but a lower anion retention capacity than non-camp soils, attributed to a higher return of plant litter and animal excreta to camp soils. In both soils, total S, organic S, C-bonded S, and hydriodic acid-reducible S were significantly correlated with organic C (r≥0.90***, ***P≤0.001) and total N (r≥0.95***), suggesting that C, N, and S are integral components of soil organic matter. However, C: N : S ratios tended to be lower in camp (60: 5.6: 1–103: 7.2: 1) than in non-camp soils (60:6.1:1–117:8.3:1). Most (〉95%) of the total soil S in camp and non-camp soils is present as organic S, while the remainder is readily soluble and adsorbed S (i.e. Ca(H2PO4)2-extractable S). C-bonded S and hydriodic acid-reducible S constituted 55%–74% and 26%–45% of total S, respectively, reflecting a regular return of plant litter and animal excreta to the grazed pastures. NaHCO3, and especially NaOH, extracted significantly higher amounts of total soil S (13%–22% and 49%–75%, respectively) than Ca(H2PO4)2 or CaCl2 (〈5%). In addition, NaHCO3 and NaOH-extractable soil S fractions were significantly rorrelated with soil organic S (r≥0.94***), C-bonded S (r≥0.90***) and hydriodic acid-reducible soil S (r≥0.93***). Differences between soils in either camp or non-camp areas were related to their sulphate retention capacities, as soils with high sulphate retention capacities (〉45%) contain higher levels of C-bonded and hydriodic acid-reducible S fractions than those of low sulphate retention soils (〈10%). Long-term annual superphosphate applications significantly increased the accumulation of soil organic and inorganic S fractions, and organic C and total N in the topsoil, although this accumulation did not occur when the superphosphate application rates were increased from 188 to 376 kg ha-1 year-1.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of soil science 46 (1995), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The reactions of two organic (citrate and fulvate) and two inorganic (chloride and phosphogypsum) calcium compounds were studied during leaching of columns of unsaturated acidic soil. The potential of these compounds to decrease the aluminium concentration in the soil solution and remove exchangeable aluminium, and their effects on soil acidity are described.The calcium citrate solution increased the soil solution pH from 5 to a maximum value of 7 in the upper portion of the column. In contrast, the fulvate, calcium chloride and phosphogypsum solutions had little effect on soil-solution pH. Treatment with calcium citrate, or fulvate solution that contained 51 mm Na, removed most of the exchangeable aluminium from the column. The cation exchange sites in the upper portion of the column were saturated with calcium, and the cation exchange capacity of the soil was increased from 35 to c. 80 mmolc kg−1 in the calcium citrate treatment. Leachate from this treatment contained low (〈 2 mm) calcium concentrations and high aluminium concentrations. In contrast, the above changes were not shown by the calcium chloride and phosphogypsum treatments. In these treatments the calcium concentration in the leachate was equal to that in the inflowing solution, which indicated that calcium was transported through the entire column. These results suggest that calcium alone was ineffective in displacing aluminium from the cation exchange sites and a strong complexing agent such as citrate or fulvate is needed to mobilize the exchangeable aluminium.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-0867
    Keywords: apatite cell dimensions ; chemical characteristics ; chemical solubility ; partial acidulation ; phosphate rock ; residual phosphate rock ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Original phosphate rocks (PR) and water insoluble residues (WIR) from mixtures of reactive PRs and single superphosphate, known commercially as longlife single superphosphate (LLSSP), and from partially acidulated PRs (PAPR), were compared in terms of their elemental content, chemical reactivity as indicated by the apatite unit cell ‘a’ dimension and solubility. Phosphate rock reactivity is known to be inversely related to the ‘a’ dimension. Partial acidulation (20%) with commercial grade phosphoric acid resulted in an increase in aluminium (Al), iron (Fe) and fluoride (F) concentrations in the WIRs. The apatite ‘a’ dimensions of WIRs from LLSSPs were greater than those of the respective original North Carolina (NC), Khouribga (KR), Jordan (JR), Sechura (SE) and Arad (AR) PRs added to single superphosphate (SSP), made from Nauru PR (NR)) to produce the LLSSPs. This was attributed to the presence of the less reactive NR in the WIRs left-over from the SSP. Partial acidulation with phosphoric acid increased the apatite ‘a’ dimensions of NC and ElHassa (EH) PRs. The increase in apatite ‘a’ dimension of NC and EH was probably due to selective dissolution of a more reactive fraction of the PRs during partial acidulation. Changes in the apatite ‘a’ dimension following partial acidulation with phosphoric acid were not significant for the other PRs studied, e.g. Gafsa (GF), KR and AR, although differential X-ray diffractograms (DXRD) indicated that the material dissolved during partial acidulation was more reactive than the WIRs and the original PRs. The apatite ‘a’ dimension of NC PR was not affected by pretreatment with 2% or 4% citric acid (CTA). The contrasting response in ‘a’ of NC PR to acidulation with phosphoric and citric acids may be related to differences in the strength of these acids, and/or to the differing environments under which the reactions took place. The 2% CTA and formic acid (FMA) solubilities of the WIRs from LLSSPs and PAPRs were markedly lower than those of the original PRs. This reduction in solubility of PRs following partial acidulation was probably related to changes in mineralogical and chemical composition of the WIRs as indicated by the increases in apatite ‘a’ dimension of some residual PRs and shifts in peak positions in DXRD, to increases in the concentrations of Fe, Al and F compounds, and to coating effects of PR particles by Fe, Al and F compounds. This, in turn, may reduce the agronomic value of the residual PR component of PAPR and LLSSP fertilizers, particularly over the short-term. The solubility of residual PRs following pretreatment with 2% or 4% CTA was slightly lower than that of the original PRs. The pretreatment caused no significant change in the apatite ‘a’ dimension of NC PR. The complexing effects of CTA and its lack of Fe and Al impurities may have prevented the formation of Fe, Al and F compounds. The effect of citric acid on PR reactivity is thus quite different from that of the mineral acids used to prepare LLSSPs and PAPRs.
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  • 6
    ISSN: 1572-9680
    Keywords: nitrogen fixation ; 15N ; %Ndfa ; ryegrass+clover pasture ; silvopastoral system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the 15N dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha−1 year−1) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83–97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Effects of increasing rates of nitrogen (N) and sulphur (S) fertilizers on the yield, digestibility, and composition of N, S, and amino acid of perennial ryegrass (Lolium perenne L.) was studied in a pot experiment using an under-developed S-responsive (Harvey) and a developed non-S responsive (Gorge) soil. Ryegrass plants responded significantly to both N and S fertilization in Harvey soil, but only to N and not S in Gorge soil. Digestibility of the herbage was increased by N fertilization and S has no effect. Total N and S concentrations in herbage increased with increasing rates of N and S applied respectively, but decreased with each increment of S and N applied respectively. Total N: total S ratios were highest in high N low S treatments and were consistently decreased by S application, while N application shows the opposite effect. In severely S-deficientplants, unassimilated N accumulated mainly as non-protein N (NPN) (〉 40 per cent total N), consisting largely of soluble N compounds (〉 90 per cent NPN) such as asparagine/aspartic acid. Under S-sufficiency condition, high N fertilization resulted dominantly in glutamic acid.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 56 (1980), S. 445-457 
    ISSN: 1573-5036
    Keywords: Apple orchard ; Biogeochemistry ; Ca ; Cl ; K ; Mg ; N ; Na ; Nutrient budget ; P ; S
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Data on the dry matter distribution and nutrient reserves (N, P, S, Cl, K, Ca, Mg and Na) in the standing biomass of a grassed-down 14 year-old apple orchard are presented together with mean estimates of nutrient inputs, returns and losses over a 2 year period. The major inputs of N P K and S were through fertilizer additions. The major inputs of Na and Cl were in bulk precipitation plus irrigation whilst both sources were important for Mg and Ca. Total inputs by precipitation plus irrigation plus fertilizer in kg/ha/yr were: N, 81; P, 20; S, 42; Cl, 58; K, 64; Ca, 35; Mg, 10 and Na, 33. Nutrient returns to the orchard floor were dominated by those from returns of herbage clippings orginating from the mowing of the orchard pasture. Autumn leaf fall also contributed significant quantities to the total nutrient returns. Total nutrient returns to the orchard floor through petal fall, fruit drop, leaf fall, foliar leaching (includes leaf washing) and pasture clippings in kg/ha/yr were: N, 545; P, 33; S, 41; Cl, 107; K, 442; Ca, 147; Mg, 35 and Na, 16. The major loss of Na, Mg, Ca, Cl and S was through leaching (this may include a certain amount of chemical weathering). In contrast, the major loss of P and K was in the harvested fruit crop, while for N, losses were about equally divided between the fruit crop and leaching. Total nutrient losses from the orchard by removal of the fruit crop and pruning wood plus leaching losses were estimated in kg/ha/yr at: N, 58; P, 5; S, 28; Cl, 81; K, 124; Ca, 55; Mg, 39 and Na, 80. Inputs minus losses in kg/ha/yr were positive for N, P and S(+23, +16 and +14 respectively and negative for Cl, K, Ca, Mg and Na (−24, −60, −19, −30 and −47 respectively).
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5036
    Keywords: Ca ; Cation leaching ; Exchangeable bases ; K ; Mg ; Mn ; Na ; Soil management ; Soil pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Observations from a soil management trial conducted on a previously grassed down orchard showed that after 3 years the pH of the surface soil (0–10 cm) whether measured in distilled water or 1N KCl was significantly lowered in herbicided and cultivated treatments in comparison with plots under continued grass sod. The drop in pH was accompanied by a decrease in base saturation and a consequent increase in exchange acidity. This was attributed to the leaching of Ca and also Mg from the surface soil of the non-grassed plots. In a subsequent laboratory leaching study, cubic soil blocks (16 cm3) were leached with distilled water at two weekly intervals for 24 weeks. It was found that over the experimental period, the cumulative quantity of cations leached (in milli-equivalents) per soil block from the herbicided and cultivated treatments was approximately 3.5 times that leached from the grassed treatment.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 46 (1977), S. 287-289 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Evidence is presented from a preliminary study showing that C-13 N.M.R. spectroscopy is a useful new tool for the elucidation of the structure of soil organic matter.
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