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| Spatial Regression, an Alternative Statistical Analysis for Landscape Scale on-farm Trials: Case Study of Variable Rate Nitrogen Application in Argentina - 2002 |
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| Which models are most appropriate in the analysis of site-specific management trials is unsettled. Precision of yield response functions based on ordinary least squares (OLS) estimates may be compromised by spatially autocorrelated data (Kessler and Lowenberg-DeBoer, 1998). Consequences of inappropriate OLS use include underestimation of field heterogeneity, bias or inefficiency in estimation of crop response to fertilizer rates, and inaccurate budget analysis (Bongiovanni and Lowenberg-DeBoer, 2000). When spatial structure is neglected variable rate technology (VRT) profit margins appear less reliable. Development of consistent and reliable estimation procedures for spatially correlated data is a key step in making precision farming both profitable and practical. This paper compares corn response to variable rate nitrogen (VRN) applications as estimated by two regression techniques: a geostatistics approach (cf. Cressie, 1993; Stroup et al., 1994; Schabenberger and Pierce, 2002), and a spatial econometric approach (Anselin, 1988, 1992; Bongiovanni and Lowenberg-DeBoer, 2001, 2002). | |
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Paper presented at the 6th International Conference on Precision
Agriculture. Minneapolis, MN, USA, July 14-17, 2002. http://precision.agri.umn.edu/2002/ Autores: Dayton M. Lambert, J. Lowenberg-DeBoer y Rodolfo Bongiovanni |
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| Economics of Nitrogen Response Variability over Space and Time: Results from the 1999-2001 Field Trials in Argentina - 2002 |
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| This paper assesses the contribution of an explicit spatial econometric methodology in the estimation of crop yield functions when data from more than one crop seasons is available. The specific case study was for nitrogen (N) application to corn production in Argentina, where the implementation of variable rate technology (VRT) requires methods that use inexpensive information and that focus on the inputs and variability common to Argentine growing areas. The general principles underlying site-specific management are transferable from place to place, but the adjusting of production systems is necessarily region-specific, because soils, climate and economic conditions vary. In the particular case of Argentine producers and agribusiness companies investigated here, some special problems pertain to the adaptation of precision agriculture to local conditions. While yield monitoring in Argentina has followed a similar adoption path to that in North America, variable rate application of inputs has not been widely used because of the high cost of soil sampling combined with relatively low fertilizer use. | |
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Paper presented at the 6th International Conference on Precision
Agriculture. Minneapolis, MN, USA, July 14-17, 2002. http://precision.agri.umn.edu/2002/ Autores: Rodolfo Bongiovanni y Jess Lowenberg-DeBoer |
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| The Root of All Yields - 2001 |
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A comprehensive five-year FARM JOURNAL project shows that creating and
maintaining uniform soil density can spike corn profits by up to $44/acre. "The benefit from uniform soil density is stronger than we anticipated," says Jess Lowenberg-DeBoer, Purdue University economist, who performed the statistical analysis on FARM JOURNAL'S data. "Depending on the soil type, we saw anywhere from a $1/acre to a $28/acre advantage to uniform density across the corn-soybean rotation. Heavy, silty clay loam soils showed the strongest response and the light silt loam upland fields showed the smallest."... |
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Análisis geoestadístico y económico del ensayo comparativo de sistemas
de traslado (ruedas vs. bandas de goma), publicado en el artículo
"The Root of All Yields", en base a un ensayo de cinco años en
el estado de Illinois, EE.UU. Revista Farm Journal, July/August 2001, páginas 12-16. (http://www.flexharrow.com/content/whatsnew/stlkchpprartcle.html) Autores: Rodolfo Bongiovanni, Jess Lowenberg-DeBoer |
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| Asessing the Value of Precision
Agricultdure Data: On-farm Nitrogen Response Research in Argentina - 2001 |
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| Site-specific agricultural technologies make possible the precision application of fertilizers and other inputs. However, many users of variable rate fertilizer application in the United States are finding that the technology does not generate adequate yield gains and input savings to cover its added costs. A key information gap lies between the precision mapping of soil characteristics and the precision application of inputs. That gap is the fertilizer recommendation. Recommendations are typically based upon large-scale regional research that has been synthesized across many sites. By design, state- or regional-level agronomic recommendations omit local site characteristics, which undermines their suitability for guiding site-specific input applications. This workshop explores the use of spatial regression to estimate maize yield response to nitrogen using on-farm experimental data from Córdoba, Argentina (Bongiovanni and Lowenberg-DeBoer, 2001). | |
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Prepared for the AAEA Spatial Analysis Learning Workshop, August 4, 2001. http://www.aaea.org/meetings/aaea/2001/program/index.cfm Autores: Scott M. Swinton, Rodolfo Bongiovanni, Jess Lowenberg-DeBoer and David S. Bullock |
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| A Spatial Econometric Approach to the Economics of Site-Specific Nitrogen Management in Corn Production - 2001 |
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| Spatial technologies such as GPS and GIS increasingly form the basis for site-specific management in crop production. This paper assesses the contribution of an explicit spatial econometric methodology in the estimation of crop yield functions that are used to optimize fertilizer application. The specific case study is for Nitrogen (N) application to corn production in Argentina, where the implementation of variable rate technology (VRT) requires methods that use inexpensive information and that focus on the inputs and variability common to Argentine growing areas. The objective of the paper is to assess the economic value of the application of spatial regression analysis to yield monitor data as a means to optimize variable rate fertilizer strategies. The data in the case study are from on-farm trials with a uniform N rate along strips and a randomized complete block design to estimate site-specific crop response functions... | |
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Paper submitted to the American Journal of Agricultural Economics,
December 2001. http://www.blackwellpublishers.co.uk/asp/journal.asp?ref=0002-9092&src=sbm Autores: Luc Anselin, Rodolfo Bongiovanni y Jess Lowenberg-DeBoer |
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| Precision Agriculture and Sustainability - 2001 |
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| The concepts of precision agriculture and sustainability are inextricably linked. From the first time a global positioning system was used on agricultural equipment the potential for environmental benefits has been discussed. Intuitively, applying fertilizers and pesticides only where they are needed, when they are needed, should reduce environmental loading. This paper will explore the realities of precision agriculture and sustainability. Exactly how can precision agriculture contribute to sustainability? Have the environmental benefits been measured? The paper will start with definitions of sustainable agriculture and precision farming. The next section will review research on the environmental impacts of precision agriculture. The last section will provide an example of how site-specific information and variable rate application could be used in maintaining profitability while reducing nitrogen applications. | |
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Paper submitted to the Journal of Precision Agriculture, November 2001.
Document under revision for publication. http://www.wkap.nl/prod/j/1385-2256
Autores: Rodolfo Bongiovanni y Jess Lowenberg-DeBoer |
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| Precision Agriculture: Economics of Nitrogen Management in Corn Using Site-specific Crop Response Estimates from a Spatial Regression Model - 2001 |
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| Technologies based on computerized information and global positioning systems (GPS) are transforming large-scale commercial agriculture throughout the world. This technology is often labeled "precision agriculture" and is giving new life to the old idea of site-specific management by reducing the cost of crop information and variable rate input application. The underlying concepts of site-specific management are transferable from place to place, but fine-tuning production systems are necessarily site-specific because soils, climate and economic conditions vary. Argentine producers and agribusiness companies face some special problems in adapting precision agriculture to their conditions. While yield monitoring in Argentina has followed a similar adoption path to that of North America, variable rate application of inputs has not been widely used because of the high cost of soil sampling and relatively low fertilizer use. Furthermore, management induced variability in Argentina is less than in the US or Canada (Lowenberg-DeBoer, 1999). | |
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Selected paper presented at the: American Agricultural Economists
Association Annual Meeting, August 5-8, 2001. http://www.aaea.org/meetings/aaea/2001/program/index.cfm Autores: Rodolfo Bongiovanni y Jess Lowenberg-DeBoer* |
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| Nitrogen Management in Corn Using Site-specific Crop Response Estimates from a Spatial Regression Model- 2000 |
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| Technologies based on computerized information and global positioning systems (GPS) are transforming large-scale commercial agriculture throughout the world. This technology is often labeled "precision agriculture" and is giving new life to the old idea of site-specific management by reducing the cost of crop information and variable rate input application. The underlying concepts of site-specific management are transferable from place to place, but fine-tuning production systems are necessarily site-specific because soils, climate and economic conditions vary. Argentine producers and agribusiness companies face some special problems in adapting precision agriculture to their conditions. While yield monitoring in Argentina has followed a similar adoption path to that of North America, variable rate application of inputs has not been widely used because of the high cost of soil sampling and relatively low fertilizer use. Furthermore, management induced variability in Argentina is less than in the US or Canada (Lowenberg-DeBoer, 1999). | |
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Published in P.C. Robert, R.H. Rust and W.E. Larson, eds., Proceedings of
the Fifth International Conference on Precision Agriculture, St. Paul.,
Minn., 2000, ASA/CSSA/SSSA. . http://precision.agri.umn.edu/2kconf/ Autores: Rodolfo Bongiovanni y Jess Lowenberg-DeBoer |
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