Data/hora: 05/06/2024 12:07:43

Biblioteca(s): | Embrapa Milho e Sorgo.
Data corrente: | 06/09/2002
Data da última atualização: | 25/07/2018
Autoria: | LUCHIARI JÚNIOR, A.; SHANAHAN, J.; SCHEPERS, J.; FRANCIS, D.; SCHLEMMER, M.; SCHEPERS, A.; INAMASO, R.; FRANCA, G.; MANTOVANI, E.; GOMIDE, R.
Afiliação: | Embrapa Milho e Sorgo; EVANDRO CHARTUNI MANTOVANI, CNPMS; REINALDO LUCIO GOMIDE, CNPMS.
Título: | Crop and soil based approaches for site specific nutrient management.
Ano de publicação: | 2002
Fonte/Imprenta: | In: CONGRESSO NACIONAL DE MILHO E SORGO, 24., 2002, Florianópolis, SC. Meio ambiente e a nova agenda para o agronegócio de milho e sorgo: [palestras]. Sete Lagoas: ABMS: Embrapa Milho e Sorgo; Florianópolis: Epagri, 2002.
Idioma: | Inglês
Conteúdo: | Recent precision agriculture research has focused on use of soil- (management zones) and crop-based (crop canopy reflectance determined with on-the-go sensors) methods for variable application of crop inputs such as N. The goal of our work is to show the advancements and applicability of these procedures in the United States and in Brazil obtained in collaborative research developed by ARS and Embrapa. Remotely sensed bare-soil images, elevation data, yield maps and soil electrical conductivity were used to categorize spatial and temporal field variability into management zones. A geo-referenced sampling scheme was designed to obtain soil chemical information for the zones. Stepwise multiple regression analysis was used to identify which indicators of the terrain were associated with spatial variation in crop yield. Elevation, soil color, slope, and soil electrical conductivity accounted for nearly 60% of the spatial variation in average yields, indicating that these variables could be useful when defining management zones. Since soil brightness was correlated with many of the terrain attributes, aerial photography would seem to be a promising method for developing management zones and obtaining important field information related to soil properties and crop productivity. However, because of wide variations in climate and its effect on spatial yield patterns, the management zone concept alone would appear inadequate for variable application of N inputs. A more successful approach would be to use a combination of soil-derived management zones along with the ability to practically monitor in- season crop N status and apply supplemental N as needed. Crop canopy reflectance sensors that measures reflectance at 550, 632, 600, 680 and 800 nm were used to assess chlorophyll status in corn (Zea mays, L.) growing under 5 N rates (0, 50, 100, 150 kg/ha and as needed defined by chlorophyll readings. The sensors are interfaced with a differential global positioning system (DGPS) to facilitate the generation of field reflectance maps. Results show that reflectance data converted into the green normalized difference vegetation index (GNDVI), utilizing the green and NIR bands was the most sensitive to assess variations in leaf chlorophyll content (assumed to be N status induced by varying levels of N application) and that variation in the sensor readings are highly correlated with ground-based chlorophyll meter readings. In the USA, the sensor was mounted on a high-clearance applicator for geo-referenced-on-the-go measurements in an irrigated cornfield. The mapping capabilities of the sensors indicate the potential to detect N stresses and subsequently direct localized application of variable rate N fertilizer. The sensor is robust in its operation and provides a number of data collection options and can be used under cloud conditions. However, significant efforts are still needed to deal with the soil background reflectance under incomplete ground cover situations and to determine the appropriate algorithms to translate sensor output into meaningful management options.
Thesagro: | Solo.
Categoria do assunto: | --
URL: | http://ainfo.cnptia.embrapa.br/digital/bitstream/item/33872/1/Palestra-Crop-soil.pdf
Registro original: | Embrapa Milho e Sorgo (CNPMS)
Exemplares: | CNPMS - (14047-1) - UMT - PL - DD -  -  -  - DIS