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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 1103-1108 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Zea mays L.) and N leaching were determined with alternate-furrow and every-furrow irrigation water applications, each with fertilizer bands of 15N-enriched (NH4)2SO4 placed either in the row or in the furrow. In 1994 fertilizer N leached to ≈1 m for the every-furrow irrigation with fertilizer placed in the irrigated furrow, but to 0.5 m or less for the other treatments. In 1995 the fertilizer leaching was similar among the treatments because of less irrigation and more rainfall during the growing season. There were no statistically significant differences for irrigation water placement effects on plant biomass or total N uptake, indicating that alternate-furrow irrigation is not detrimental to crop production compared with every-furrow irrigation for similar applications of water. This study showed that placing fertilizer in the nonirrigated furrow of an alternate-furrow irrigation system or placing fertilizer in the row with either alternate- or every-furrow irrigation has the potential to decrease fertilizer leaching without reducing crop productivity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 984-991 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: –1 . Systems included a 2-yr. winter wheat (Triticum aestivum L.)-fallow (WF) and more intense 3-yr winter wheat-corn (Zea mays L.)-fallow and winter wheat-sorghum [Sorghum bicolor(L.) Moench]-fallow and 4-yr rotations. To quantify the effectiveness of the intensified systems at utilizing precipitation, we introduce the System-Precipitation-Storage Index (SPSI) and System-Precipitation-Use Index (SPUI). Mean SPSI values were 0.19 and 0.28 for 2- and 3-yr systems, respectively, meaning that the fallow periods in the 3-yr rotation were collectively 47% more efficient at storing precipitation than fallow in WF. Inclusion of a summer crop, such as corn or sorghum, increased the fraction of precipitation allocated to growing-season crop production (i.e., SPUI) from 0.43 in WF to 0.56 (i.e., an increase of 30%) in 3-yr systems. The gains in efficient use of precipitation with intensification resulted from (i) reducing the frequency of the inefficient fallow preceding wheat, and (ii) using water for transpiration that would otherwise be lost during fallow through soil evaporation, runoff, and deep percolation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 1006-1017 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: 3 response to beef-manure application on a corn (Zea mays L.) field and tested the Root Zone Water Quality Model (RZWQM) for manure management. The experiment site was located in Northeastern Colorado on a silage-corn field with a history of fertilization with beef manure every fall after corn harvest. To study the residual effect of long-term manure application, 582 kg ha–1 of manure-N was applied to the east side of the field in the fall of 1993, 1994, and 1995, while the west side received manure in 1993 only. Average silage-corn yields from the west site were 25.4, 31.9, and 22.5 Mg ha–1 for 1994, 1995, and 1996, respectively, which were not significantly different from that harvested from the east site (25.1, 30.9, and 24.3 Mg ha–1, respectively). Average soil NO3 concentrations decreased significantly from 14.9 to 8.5 mg N kg–1 in the top 30 cm of soil, and from 5.4 to 3.7 mg N kg–1 in the 30- to 60-cm soil profile after stopping manure application. No significant difference in soil NO3 concentrations between the manured and not-manured sites was found below 60 cm. Average plant N uptake ranged from 140 to 362 kg N ha–1 and was not significantly different between the two sites. The RZWQM was calibrated on the basis of the measured silage-corn yield and plant N uptake, and was then used to predict soil NO3 concentration and total water storage in the soil profile. Generally, the calibrated model provided adequate predictions for both NO3 and soil water content with r 2 〉 0.83. The model was further used to evaluate alternative scenarios of manure and water management.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Soil Science Society of America journal 62 (1998), S. 1228-1233 
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-0661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: K s) using a modified Kozeny-Carman equation. This equation is of the form of a coefficient (B) multiplied by effective porosity raised to a power (n). The purpose of this study was to improve the predictive capability of the modified Kozeny-Carman equation by including information from moisture release curves (soil water content vs. matric potential relation). We fitted the Brooks-Corey (B-C) equation parameters (pore size distribution index and air entry potential) to moisture release data from a large database (〉500 samples). Values of K s were also available from the same source. Inclusion of the pore size distribution index into the Kozeny-Carman equation improved the K s estimation over using only effective porosity, but only slightly. The improvement came through a better estimation of large values of K s. We also fit a relationship for the coefficient (B) of the Kozeny-Carman equation as a function of the two B-C parameters with a constant value of n = 2.5 for the exponent. Overall the use of Brooks-Corey parameters from moisture retention data improved estimates of K s over using effective porosity (φe) alone. There is still considerable error in predicting individual K s values, however. The best forms of the equation was when λ was included in the term for the coefficient for the modified Kozeny-Carman equation. The next best form was when λ was included in the exponent for φe The two best models appeared to better preserve the mean, standard deviation and range of the original data.
    Type of Medium: Electronic Resource
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