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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 28 (1999), S. 259-266 
    ISSN: 1432-0789
    Keywords: Key words Aggregate stability ; Microbial biomass ; Microbial activity ; Soil organic matter ; Microbial quotient
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effects on soil condition of increasing periods under intensive cultivation for vegetable production on a Typic Haplohumult were compared with those of pastoral management using soil biological, physical and chemical indices of soil quality. The majority of the soils studied had reasonably high pH, exchangeable cation and extractable P levels reflecting the high fertilizer rates applied to dairy pasture and more particularly vegetable-producing soils. Soil organic C (Corg) content under long-term pasture (〉60 years) was in the range of 55 g C kg–1 to 65 g C kg–1. With increasing periods under vegetable production soil organic matter declined until a new equilibrium level was attained at about 15–20 g C kg–1 after 60–80 years. The loss of soil organic matter resulted in a linear decline in microbial biomass C (Cmic) and basal respiratory rate. The microbial quotient (Cmic/Corg) decreased from 2.3% to 1.1% as soil organic matter content declined from 65 g C kg–1 to 15 g C kg–1 but the microbial metabolic quotient (basal respiration/Cmic ratio) remained unaffected. With decreasing soil organic matter content, the decline in arginine ammonification rate, fluorescein diacetate hydrolytic activity, earthworm numbers, soil aggregate stability and total clod porosity was curvilinear and little affected until soil organic C content fell below about 45 g C kg–1. Soils with an organic C content above 45 g C kg–1 had been under pasture for at least 30 years. At the same Corg content, soil biological activity and soil physical conditions were markedly improved when soils were under grass rather than vegetables. It was concluded that for soils under continuous vegetable production, practices that add organic residues to the soil should be promoted and that extending routine soil testing procedures to include key physical and biological properties will be an important future step in promoting sustainable management practices in the area.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 30 (1999), S. 210-216 
    ISSN: 1432-0789
    Keywords: Key words Microbial biomass ; Microbial activity ; Soil organic matter ; Metabolic quotient ; Arginine ammonification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The effects of 5 years of continuous grass/clover (Cont grass/clover) or grass (Cont grass) pasture or 5 years of annual grass under conventional (Ann grass CT) or zero tillage (Ann grass ZT) were compared with that of 5 years of continuous barley (LT arable) on a site which had previously been under arable crops for 11 years. For added comparison, a long-term grass/clover pasture site (LT past) nearby was also sampled. Soil organic C (Corg) content followed the order LT arable=Ann grass CT〈Ann grass ZT〈Cont grass=Cont grass/clover〈LTpast. Trends with treatment for microbial biomass C (Cmic), basal respiration, flourescein diacetate (FDA) hydrolytic activity, arginine ammonification rate and the activities of dehydrogenase, protease, histidase, acid phosphatase and arylsulphatase enzymes were broadly similar to those for Corg. For Cmic, FDA hydrolysis, arginine ammonification and the activities of histidase, acid phosphatase and arylsulphatase, the percentage increase caused by 5 years of continuous pasture (in comparison with LT arable) was 100–180%, which was considerably greater than that for organic C (i.e. 60%). The microbial metabolic quotient (qCO2) was higher for the two treatments which were mouldboard ploughed annually (LT arable and Ann grass CT) than for the undisturbed sites. At the undisturbed sites, Corg declined markedly with depth (0–15 cm) and there was a similar stratification in the size and activity of Cmic and enzyme activity. The microbial quotient (Cmic/Corg) declined with depth whilst qCO2 tended to increase, reflecting a decrease in the proportion of readily available substrate with depth.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 28 (1999), S. 253-258 
    ISSN: 1432-0789
    Keywords: Key words Grazing animals ; Enzyme activity ; Microbial biomass ; Pasture ; Soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The size and activity of the soil microbial biomass in grazed pastures was compared on the main grazing area and on stock camp areas where animals congregate. Two sites were on hill country and three on gently sloping border-dyke irrigated land. Due to the transfer of nutrients and organic matter to the camp areas via dung and urine there was an accumulation of soil organic C, organic and inorganic P and S and soluble salts in the camp areas. Soil pH also tended to be higher in camp areas due to transfer of alkalinity by the grazing animals. Water soluble organic C, microbial biomass C and basal respiration were all higher in soils from camp areas but the proportion of organic C present as microbial C and the microbial respiratory quotient were unaffected. Microbial activity as quantified by arginine ammonification rate and fluorescein diacetate (FDA) hydrolysis was higher in camp than non-camp soils but dehydrogenase activity remained unaffected. Activities of protease, histidase, urease, acid phosphatase and aryl-sulphatase were all higher in stock camp soils. The activities of both histidase and aryl-sulphatase were also higher when expressed per unit of microbial biomass C, indicating that the increased activity was the result of increased enzyme production by the microbial community. Prolonged regular applications of dairy shed effluent (diluted dung and urine from cattle) to a field had a similar effect to stock camping in increasing soil organic matter content, nutrient accumulation and soil biological activity. It was concluded that the stock camping activity of grazing animals results in an increase in both the fertility and biological activity in soils from camp areas at the expense of these properties on the main grazing areas.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0789
    Keywords: Biomass N, S and P ; Lime ; Phosphate ; Phosphatase ; Sulphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of adding lime and/or phosphate to an acid, phosphate-deficient soil on microbial activity, enzyme activities and levels of biomass and extractable N, S and P were studied under laboratory conditions. Following rewetting there was, as expected, an initial flush in microbial growth and activity, as shown by large increases in CO2 evolution, in levels of biomass N, S and P and by accumulation of extractable mineral N and sulphate in the soil. Following rewetting, additions of lime and phosphate further stimulated mineralization of C, N and S. In the first 4 weeks of incubation, the mineralized N accumulated in the soil as ammonium N and there was a concomitant rise in soil pH. After this initial period, nitrification increased substantially and soil pH decreased again. Additions of lime generally increased protease and sulphatase activities but decreased phosphatase activity. Additions of phosphate decreased the activities of all three enzymes. The positive effect of liming on protease and sulphatase activities persisted for the duration of the experiment while accumulation of mineral N and sulphate effectively ceased after about 4 weeks. Furthermore, although phosphate additions decreased the activities of protease and sulphatase they increased the accumulation of mineral N and sulphate. Thus, protease and sulphatase activities were not reliable indicators of the relative amounts of mineral N and sulphate accumulated in the soil during incubation. Some uncertainty surrounded the validity of biomass S and P values estimated by the chloroform fumigation technique because differing proportions of the sulphate and phosphate released from the lysed cells may have been extracted from the different treatments.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0789
    Keywords: Earthworms ; Enzyme activity ; Microbial biomass ; Pasture ; Soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated the quantity and distribution of organic C, microbial biomass C, protease, arylsulphatase and arylphosphatase activity, and earthworm numbers and biomass in the soil from a 37-year-old grazed pasture supplied with superphosphate at rates of 0, 188, and 376 kg ha-1 annually. The results were compared with a non-irrigated wilderness site which had not been used for agriculture and an arable site that had been intensively cultivated for 11 consecutive years. In the 0- to 5-cm layer, organic C followed the trend arable〈wilderness = control〈low phosphate = high posphate and soil biological activity generally followed a similar trend. For example, protease and arylsulphatase activity and microbial biomass C followed the order arable〈wilderness〈control〈low phosphate = high phosphate. The greater activity in the control than the wilderness site was attributed to the more regular turnover of organic matter throughout the year in the control due to the activity of the grazing animals. Earthworm numbers increased in the order arable〈wilderness〈control〈low phosphate〈high phosphate. In the improved pasture sites the earthworm population was dominated by Aporrectodea caliginosa (77–89% of total numbers) although Lumbricus rubellus made an increasing contribution to the population with increasing superphosphate rates. In the unirrigated wilderness site the population consisted of 56% A. caliginosa and 44% L. rubellus. While Octolasion cyaneum and A. rosea made up a small proportion of the population in the improved pasture sites, they were not present in the wilderness or arable sites. A. caliginosa was the only species present in the arable site. The mean fresh weight of individuals followed the order arable〈control = low phosphate = high phosphate〈wilderness and the proportion of jeveniles in the population was greatest in the arable and lowest in the wilderness site.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-0789
    Keywords: Key words Grass/clover residues ; Nitrogen 15N ; N mineralization-immobilization ; N recovery ; Particle size fractionation ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The fate of N when 15N-labelled perennial ryegrass/white clover residues were incorporated into field lysimeters (rate equivalent to 150kgNha–1) and two successive crops of winter or spring wheat were grown was investigated. Loss of 15N over the first winter amounted to 23% and 22% respectively for winter and spring wheat and corresponding losses in the 2nd year were 10% and 14%. Both winter- and spring-sown crops recovered about 10% of residue 15N in the first season and about 1.5% in the second. The percentage of total crop N uptake originating from residue 15N was only 14% and 12% respectively for winter and spring wheat in the first season and 2.5% and 1.9% respectively for the second season. The bulk of the 15N recovered was incorporated into the soil organic matter fraction and at harvest of the 2nd year 55% of added 15N was present as soil organic N. In order to investigate the nature of this soil organic 15N, soil was fractionated into different particle size separates. Both 14N and 15N were concentrated in the medium and fine silt and coarse, and to a lesser extent, medium and fine clay fractions. However, in spring of the first season, 15N was preferentially present in the floating organic matter and to a lesser extent sand-sized fractions (i.e. as particles of decomposing residue). Between then and harvest of the second season there was a redistribution of 15N from these fractions and the medium- and fine-sized clay particles toward the coarse and medium silt-sized fractions. This suggested a movement of 15N toward more aromatic humified material in silt-sized fractions and away from decomposing organic material in sand separates and away from labile organic material in the clay-sized fractions. A laboratory incubation experiment showed that the availability (percentage mineralization) of recently immobilized 15N was greater than that of native soil 14N.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 5 (1987), S. 235-240 
    ISSN: 1432-0789
    Keywords: Biomass N, S, P ; Fragaria × ananassa (Duch.) ; Phosphatase ; Protease ; Sulphatase ; Polyethylene mulches
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effects of white, black and clear polyethylene mulches on temporal fluctuations in protease, sulphatase and phosphatase activities and levels of available and biomass N, S and P in raised beds of soil under a strawberry crop were investigated under field conditions. During spring, summer and early autumn, clear and, to a lesser extent black, polyethylene mulch increased both maximum and minimum mean monthly temperatures over those recorded with white mulch or no mulch. During summer and autumn, soil moisture content measured at monthly intervals was higher under mulched than unmulched conditions. Levels of extractable nitrate and sulphate in soils during autumn followed the order: clear mulch = black mulch 〉 white mulch 〉 no mulch. However, there were no significant differences in levels of enzyme activity or concentrations of biomass N, S or P between treatments. There were significant seasonal fluctuations in estimates of biomass N, S and P, but there was no close relationship between fluctuations in any estimate. This discrepancy was attributed to errors in the chloroform fumigation technique. Enzyme activities showed significant temporal fluctuations but the three enzymes did not show similar times of minimum and maximum activity. The complexity of interactions between soil microbial and biochemical properties and nutrient availability was exemplified by the absence of a discernible relationship between seasonal fluctuations in enzyme activities and levels of biomass N, S and P and/or levels of extractable mineral N, S and P in the soil. Strawberry fruit yields and vegetative growth followed the order : clear mulch = black mulch〉white mulch〉no mulch. Clear, and to a lesser extent black mulch increased the percentage of total yields produced in the first 2 months of cropping.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 50 (1995), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A field experiment compared the effects of sheep, deer and cattle dung on pasture growth and soil nutrient status. Sheep and deer dung pellets degraded rapidly within three to eight weeks, while it was 12 months before all visible cattle dung had gone from the soil surface. The cattle dung initially reduced herbage yield owing to smothering. However, after 40 days, herbage around the edges of the dung patch responded positively to the dung and more dry matter was produced in this patch than in the control patch during the first 12 months. There was no measurable herbage response to sheep dung, but deer dung significantly increased herbage production. While the rate of nutrient application per unit area was similar for sheep and deer dung, the latter was more evenly spread within the patch area. Consequently, a greater percentage of pasture plants in the patch received nutrient additions from the deer dung and a measurable response was recorded. Twelve months after dung application, soil nitrate, phosphate and organic C were higher in dung patches than in the control patches. In cattle dung patches, this response was accompanied by higher microbial biomass C levels, arylsulphatase and arylphosphatase activities. Some residual effect on organic C levels was still evident three years after cattle dung application.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Grass and forage science 38 (1983), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Solution culture and greenhouse studies have both clearly demonstrated the ability of legumes to acidify their rooting medium. Furthermore, research workers comparing the pH beneath undisturbed sites versus all-legume pastures or all-grass versus all-legume (or grass-legume) pastures have observed a lower soil pH under the leguminous pastures. The processes leading to legume-induced soil acidification are reviewed and discussed.The growth of legumes which are fixing atmospheric N2 involves the excess uptake of nutrient cations over anions from soil solution. This results in the net efflux of H3O+ ions from plant roots into the rhizosphere.When virgin lands are sown with legumes the accumulation of soil organic matter, with a consequent increase in cation exchange capacity and exchange acidity, is an important contributing factor to the long-term decline in surface soil (0–10 cm) pH. Nonetheless, such a phenomenon does not explain the decrease in pH below 10 cm soil depth nor the lower pH below leguminous than all-grass pastures. The efflux of H3O+ ions from the legume roots may have an important effect on the soil pH under such conditions. The loss of symbiotically fixed N; from the system through leaching of NO3− - N may also contribute to soil acidification under leguminous pastures.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 49 (1998), S. 0 
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The mechanisms responsible for stabilization of earthworm casts were investigated in a laboratory study. Earthworms (Aporrectodea caliginosa) were fed soil or soil amended with either ground wheat straw or lucerne hay. Cast material and uningested soil material were incubated for 56 days, and changes in aggregate stability (measured by wet sieving), soil biological activity and macronutrient availability were measured periodically. In general, aggregate stability and microbial biomass C tended to increase during the incubation for both cast and soil material, whereas hot-water extractable carbohydrate content declined. For amended treatments, basal respiration rate and microbial metabolic quotient were large at the first sampling (7 days) but declined rapidly thereafter. There was a transitory increase in extractable P in fresh casts compared with uningested material, a sustained increase in mineral N concentrations but no change in exchangeable K content. For unamended treatments, the casts were less stable than soil material, but this difference diminished during incubation. Drying aggregates before analysing them did not reverse this trend. The casts contained more microbial biomass C than soil material did, but the basal respiratory rate, respiratory quotient and hot-water extractable carbohydrate content were less. By contrast, for wheat- and lucerne-amended treatments casts were more stable than soil material, and the microbial biomass was less at all sampling times. For wheat treatments, respiratory quotient and hot-water extractable carbohydrate content were larger for cast than soil material, but the opposite was the case for lucerne treatments. We attribute the stability of casts in amended treatments to the intimate mixing of part-decomposed organic fragments with comminuted soil particles, binding by microbial mucilage associated with the organic fragments and linking and binding by fungal hyphae.
    Type of Medium: Electronic Resource
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