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| Kyaw, T.; Ferguson, R.B.; Adamchuk, V.I.; Marx, D.B.; Tarkalson, D.D.; McCallister, D.L.. |
| Iron chlorosis can limit crop yield, especially on calcareous soil. Typical management for iron chlorosis includes the use of iron fertilizers or chlorosis tolerant cultivars. Calcareous and non-calcareous soil can be interspersed within fields. If chlorosis-prone areas within fields can be predicted accurately, site-specific use of iron fertilizers and chlorosis-tolerant cultivars might be more profitable than uniform management. In this study, the use of vegetation indices (VI) derived from aerial imagery, on-the-go measurement of soil pH and apparent soil electrical conductivity (ECa) were evaluated for their potential to delineate chlorosis management zones. The study was conducted at six sites in 2004 and 2005. There was a significant statistical... |
| Tipo: Article |
Palavras-chave: Calcareous soil; Fertilizer. |
| Ano: 2008 |
URL: http://eprints.nwisrl.ars.usda.gov/1275/1/1251.pdf |
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| Dobermann, A.R.; Wortmann, C.S.; Ferguson, R.B.; Hergert, G.W.; Shapiro, C.A.; Tarkalson, D.D.; Walters, D.T.. |
| Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. The mean yield with adequate nutrient availability in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska to evaluate crop response to split-applied N was 14.8 Mg per ha. The mean economically optimal N rates (EONR) for irrigated corn varied with the fertilizer N to grain price ratio. At a fertilizer N:corn price ratio of 7, the EONR was 171, 122, and 93 kg per hectare, respectively, for cropping systems with corn following corn (CC), soybean (Glycine max L.) (CS), and drybean (Phaseolus vulgaris L.) (CD). At this price ratio the present University of Nebraska (UNL) recommendation procedure gave mean N recommendations that were 17.2,... |
| Tipo: Article |
Palavras-chave: Corn / maize; Nitrogen. |
| Ano: 2010 |
URL: http://eprints.nwisrl.ars.usda.gov/1415/1/1385.pdf |
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| Wortmann, C.S.; Tarkalson, D.D.; Shapiro, C.A.; Dobermann, A.R.; Ferguson, R.B.; Hergert, G.W.; Walters, D.T.. |
| Nitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean (Phaseolus vulgaris L.) (CD), or soybean (Glycine max L.) (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha–1 . When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant N uptake (UN). Mean fertilizer N recovery in above-ground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal N rate (EONR), and least with CD. Agronomic efficiency of... |
| Tipo: Article |
Palavras-chave: Corn / maize; Nitrogen. |
| Ano: 2011 |
URL: http://eprints.nwisrl.ars.usda.gov/1414/1/1384.pdf |
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