|
|
|
|
|
| Garcia, J.P.; Wortmann, C.S.; Mamo, M.; Drijber, R.; Tarkalson, D.. |
| Stratification of nutrient availability, especially of P, that develops with continuous no-till (NT) can affect runoff nutrient concentration and possibly nutrient uptake. The effects of composted manure application and one-time tillage of NT on the distribution of soil chemical properties, root colonization by arbuscular mycorrhizae (AM), and plant P uptake were determined. Research was conducted on Typic Argiudoll and Moffic Hapludaff soils under rainfed corn (Zea mays L.) or sorghum [Sorghum bicolor (L.) Moench.] rotated with soybean [Glycine max (L.) Men.] in eastern Nebraska. Tillage treatments included NT, disk, chisel, moldboard plow (MP), and mini-moldboard plow (MMP). Subplots had either 0 or 87.4 kg P ha -I- applied in compost before... |
| Tipo: Article |
Palavras-chave: Tillage; Mass Import - autoclassified (may be erroneous). |
| Ano: 2007 |
URL: http://eprints.nwisrl.ars.usda.gov/57/1/1219.pdf |
| |
|
|
| Tarkalson, D.D.; Kachman, S.D.; Knops, J.M.N.; Thies, J.E.; Wortmann, C.S.. |
| Results of a previous laboratory study indicated that six transgenic crops expressing the Cry1Ab insecticidal protein from Bacillus thuringiensis (Bt) decomposed at a slower rate than their respective non-Bt isolines. Consequently, litter decomposition rates, nitrogen cycling, and carbon pools may change in agricultural systems as the result of the widespread use of Bt crops. In this study, we assessed the decomposition rates and chemical composition of commonly grown hybrids of Bt and non-Bt isolines of corn (Zea mays L.) in the field. Leaves, stalks, and cobs from two Bt corn hybrids (Pioneer 34N44 Bt and NC+ 4990 Bt) and their non-Bt isolines (Pioneer 34N43 and NC+ 4880) were analyzed for biomass fractions (soluble, hemicellulose, cellulose, and lignin)... |
| Tipo: Article |
Palavras-chave: Nitrogen. |
| Ano: 2008 |
URL: http://eprints.nwisrl.ars.usda.gov/1273/1/1250.pdf |
| |
|
| |
|
|
| 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 |
| |
|
|
| 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 |
| |
|
|
|
