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  • fertigation  (3)
  • Enzyme activity  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Influence of stock camping behaviour on the soil microbiological and biochemical properties of grazed pastoral soils (1999)
    Springer
    Biology and fertility of soils 28 (1999), S. 253-258 
    Details
    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
    URL: http://dx.doi.org/10.1007/s003740050490
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Movement and transformations of fertigated nitrogen below trickle emitters and their effects on pH in the wetted soil volume (1990)
    Springer
    Nutrient cycling in agroecosystems 23 (1990), S. 105-112 
    Details
    ISSN: 1573-0867
    Keywords: Ammonium ; fertigation ; nitrate ; nitrogen ; trickle irrigation ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The movement and transformations of ammonium-, urea- and nitrate-N in the wetted volume of soil below the trickle emitter was studied in a field experiment following the fertigation of N as ammonium sulphate, urea and calcium nitrate. Effects on soil pH in the wetted volume were also investigated. During a fertigation cycle (emitter rate 2lh−1) applied ammonium was concentrated in the surface 10 cm of soil immediately below the emitter and little lateral movement occurred. In contrast, because of their greater mobility in the soil, fertigated urea and nitrate were more evenly distributed down the soil profile below the emitter and had moved laterally in the profile to 15 cm radius from the emitter. The conversion of applied N to nitrate-N was more rapid when urea rather than ammonium-N was applied suggesting that the accumulation of large amounts of ammonium below the emitter in the ammonium sulphate treatment probably retarded nitrification. Following their conversion to nitrate-N, both fertigated ammonium sulphate and urea caused acidification in the wetted soil volume. Acidification was confined to the surface 20 cm of soil in the ammonium sulphate treatment, however because of its greater mobility, fertigation with urea (2lh−1) resulted in acidification occurring down to a depth of 40 cm. Such subsoil acidity is likely to be very difficult to ameliorate. Increasing the trickle discharge rate from 2lh−1 to 4lh−1 reduced the downward movement of urea and encouraged its lateral spread in the surface soil. As a consequence, acidification was confined to the surface (0–20 cm) soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01063337
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of pasture improvement and intensive cultivation on microbial biomass, enzyme activities, and composition and size of earthworm populations (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 185-190 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00336320
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of trickle fertigation with three forms of nitrogen on soil pH, levels of extractable nutrients below the emitter and plant growth (1987)
    Springer
    Plant and soil 102 (1987), S. 211-221 
    Details
    ISSN: 1573-5036
    Keywords: Cucurbita pepo L. ; extractable nutrients ; fertigation ; nitrogen fertilizers ; trickle irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of application of nitrogen as calcium nitrate, urea or ammonium sulphate at two rates through the trickle irrigation system on pH and nutrient status of the wetted volume of soil below the emitters and on growth and nutrition of courgette (zucchini) plants (Cucurbita pepo L.) was investigated. Soil acidification, caused by nitrification, occurred to a large extent in the volume of soil immediately below the emitters in the urea and ammonium sulphate treatments. Acidification was greater at the high rate of N addition and more pronounced with ammonium sulphate than urea. A significant amount of applied urea appeared to move through the soil as urea and consequently, at the same rate of N addition, levels of ammonium were lower directly below the emitter and those of nitrate were higher further away from the emitters for the urea than ammonium sulphate treatments. Soil acidification below the emitters resulted in significant decreases in levels of exchangeable Ca, Mg and K and increases in levels of exchangeable Al, EDTA-extractable Fe, Mn, Zn and Cu and bicarbonate-extractable P. Vegetative growth and harvestable yields of courgettes were increased by both irrigation and nitrogen applications. Vegetative growth was generally greater at the low rate of N addition than at the high one and generally followed the order calcium nitrate 〉 urea 〉 ammonium sulphate. However, fruit yields followed the order urea 〉 ammonium sulphate 〉 calcium nitrate and were larger at the high rate of N for urea and ammonium sulphate treatments and unaffected by rate for the calcium nitrate treatments. It is suggested that with fertigation, the form of applied N can have significant physiological effects of plant growth and yields because N may be applied into the root zone on numerous occasions during the growing season.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02370706
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Principles of fertilizer use for trickle irrigated crops (1985)
    Springer
    Nutrient cycling in agroecosystems 6 (1985), S. 235-255 
    Details
    ISSN: 1573-0867
    Keywords: crop response ; fertigation ; fertilizers ; root distribution ; soil moisture ; trickle irrigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Under trickle irrigation only a portion of the soil volume around each plant is usually wetted. Typically this is an eliptically shaped volume directly below the emitter. Crop root growth is essentially restricted to this volume of soil and nutrient reserves within that volume can become depleted by crop uptake and/or leaching below the root zone. If nutrients are applied outside the wetted soil volume they are generally not available for crop use. Fertilizer placement is therefore an important consideration for trickle irrigated crops. Thus, applications banded close to the emitters are preferable to broadcast applications. In general, injection of nutrients into the irrigation water (fertigation) gives a better crop response than either banded or broadcast applications. Fertigation gives a flexibility of fertilization which enables the specific nutritional requirements of the crop to be met at different stages of its growth. In comparison with conventional methods of irrigation and fertilization it appears that trickle fertigation can, under some conditions, produce comparable or higher crop yields with substantial savings (of up to 50 percent) in fertilizer useage. Fertilizer materials used for fertigation must be completely soluble in water and must not react with substances in the irrigation water to form insoluble precipitates. An uneven distribution of nutrients within the crop rooting zone occurs under fertigation since immobile nutrients such as phosphate become concentrated around the emitter while mobile ions such as nitrate and potassium move downward and outward with the wetting front and accumulate at the periphery of the wetted soil volume. Plants, however, appear to have the ability to adapt to spatial variability of available nutrients in soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048798
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    Paper (German National Licenses)
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