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  • Articles: DFG German National Licenses  (4)
  • corn  (2)
  • soil pH  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Influence of pH, time and rate of application on phosphate rock dissolution and availability to pastures (1991)
    Springer
    Nutrient cycling in agroecosystems 28 (1991), S. 95-101 
    Details
    ISSN: 1573-0867
    Keywords: Phosphate rock dissolution ; soil pH ; solution phosphorus ; phosphorus fractionation ; monocalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Soil Samples were collected from a field experiment conducted to evaluate the agronomic effectiveness of a reactive phosphate rock (PR), Sechura sand, relative to that of monocalcium phosphate (MCP) at different soil pHs and rates of application. The samples were analysed for P soluble in the soil solution and bicarbonate extractable P. The rate of dissolution of PR was calculated from the data on the fractionation of inorganic P. In MCP plots P in the soil solution decreased sharply with time especially at low pHs and high rates of fertiliser application. In PR plots the concentration remained with time at the same as or a slightly higher level than that was found one month after application. Solution concentration of P was lower at very high rates of PR application than at intermediate rates. In both MCP and PR plots bicarbonate extractable P decreased with increasing pH. Bicarbonate extractable P was linearly related to MCP but not to PR applied. The rate of dissolution and the proportion of PR dissolved decreased with increasing rates of PR application but the amount dissolved increased. Phosphate dissolved at high level of PR application did not seem to enhance proportionately either the concentration of P in soil solution or bicarbonate extractable P.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048860
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Tillage effect on seasonal nitrogen availability in corn supplied with legume green manures (1994)
    Springer
    Plant and soil 162 (1994), S. 203-210 
    Details
    ISSN: 1573-5036
    Keywords: corn ; hairy vetch ; red clover ; nitrogen availability ; tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It has been shown that legume green manures have great potential for replacing a substantial amount of the N fertilizer required for corn (Zea mays L.) production. An experiment was conducted in central Pennsylvania (USA) to study seasonal fluctuation of nitrogen (N) availability in corn with conventional tillage (CT) and no-till (NT) following red clover (Trifolium pratense L.) and hairy vetch (Vicia villosa Roth) green manures double-cropped with winter wheat (Triticum aestivum L.). Samples of corn, weeds, and soil were taken periodically and analyzed for total N content in plant tissue and soil nitrate-N content. The sum of plant N (corn plus weed) and soil nitrate-N in the upper 45 cm profile was used as an indicator of total available N. Under CT, total available N increased rapidly upon legume incorporation and reached 80% of the maximum within 4 weeks. Under NT, total available N increased steadily after the legumes were killed with herbicides and reached a maximum within 7 to 8 weeks. Seasonal corn N accumulations with the legume N source were similar to those where corn followed fallow with 200 kg N ha−1 fertilizer with CT, but were less than those in the same fallow 200 kg N ha−1 treatment with no-till. Dry weather conditions together with weed competition reduced N availability to the no-till corn compared to the CT treatments. The seasonal fluctuations of total available N and corn N uptake suggest good synchronization between N availability from the legume green manures and N accumulation by corn plants in both tillage systems under the conditions of this study.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01347707
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Using NCSWAP to simulate seasonal nitrogen dynamics in soil and corn (1995)
    Springer
    Plant and soil 177 (1995), S. 235-247 
    Details
    ISSN: 1573-5036
    Keywords: corn ; nitrogen availability ; N simulation ; soil ; tillage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of this study was to determine if a re-calibrated version of the computer model NCSWAP (version 36) could accurately predict corn growth and soil N dynamics in conventionally tilled (CT) and no-till (NT) corn supplied with legume green manure or ammonium nitrate as N sources. We also attempted to ascertain the reasons for limitations in the model's ability to simulate corn growth and soil N dynamics found by our colleagues in a previous study and to propose potential improvements. The model was calibrated to accurately simulate total available N (N in plant above-ground biomass plus soil nitrate in the 0 to 45 cm profile) for a control and a fertilizer CT treatment in the 1992 growing season. To do so, input values defining the quantities of active soil organic N had to be reduced to 19% of the values proposed by the model developers and a solute transport factor defining the mobile vs. immobile fractions of soil nitrate adjusted from 0.8 to 0.2. The discrepancies between the proposed values and the lower values employed in this study might be due to the uncertainties in quantitatively describing soil N mineralization processes and the way they are handled in the model, as well as the lack of a component simulating macroporous-influenced water flow and solute transport in the model. With the current version, until one knows how to predict what these values are, the model needs to be re-calibrated for each experimental site and condition and thus is of limited value as a general model. With no further adjustment of input values, model validation success was mixed. The model accurately predicted total available N for treatments in the second year of the experiment that had the same N source and tillage as the treatments used for the calibration year but with the different weather and growing conditions. However, total available N was underpredicted where legume green manure was the N source and overpredicted with no-till cultivation. The model was accurate in simulating seasonal corn growth for nearly all the treatments, judged by nonsignificant mean difference (MD) values and highly significant correlation coefficients (r). Prediction of seasonal soil nitrate concentration was less accurate compared to total available N and corn growth variables. Potential improvements in the model's simulation of a no-till system as well as for predicting corn harvest yield and seasonal soil nitrate concentration where N deficiency occurs were discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010130
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Influence of pH, time and rate of application on phosphate rock dissolution and availability to pastures (1991)
    Springer
    Nutrient cycling in agroecosystems 28 (1991), S. 85-93 
    Details
    ISSN: 1573-0867
    Keywords: Phosphate rock ; soil pH ; andepts ; white clover ; ryegrass ; soil phosphorus ; monocalcium phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The agronomic effectiveness of an unground reactive phosphate rock from Sechura, Peru, was compared with that of monocalcium phosphate in a severely P deficient and highly P retentive soil (vitrandept) over a period of three years. Soil pHs were adjusted to pH 5.1, 5.3, 5.6 and 6.4. The sward consisted mostly of ryegrass (Lolium perenne) and white clover (Trifolium repens). Fertilisers were applied at six rates at pH 5.3 and three rates at other pHs in the first year. For two of the rates fertilisers were reapplied in the second year. Dry matter yields, P uptake and ground cover of clover were determined during the experimental period. In phosphate rock treated plots a negative linear relationship was obtained between soil pH and the logarithm of yield. The agronomic effectiveness of phosphate rock relative to monocalcium phosphate increased with time at all pHs. Calculated at fertiliser rates which produced near maximum yields, relative agronomic effectiveness at soil pHs 5.1, 5.3, 5.6 and 6.4 were respectively 58, 60, 18, and 5 in year one; 118, 125, 77 and 38 in year three. At pH 5.3, as the rate of application increased the relative agronomic effectiveness of the phosphate rock generally decreased in year one but was enhanced in the intermediate rates in years two and three. The data for ground cover of clover gave a similar trend to that for herbage yield and P uptake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048859
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    Paper (German National Licenses)
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