Adding value to spatially managed inputs by understanding site-specific yield response

Abstract

Many mechanized crop producers and agribusinesses are fascinated with precision agriculture technology, but adoption has lagged behind the expectations. Among the reasons for slow adoption of precision agriculture technology is that initial users focused excessively on in-field benefits from variable-rate fertilizer application using regional average fertilizer recommendations. This article illustrates how greater use of site-specific crop response information can improve variable rate input application recommendations.Precision agriculture is spatial information technology applied to agriculture. The technologies include global position systems (GPS), geographic information systems (GIS), yield monitoring sensors, and computer controlled within-field variable rate application (VRA) equipment. Experimentation with these technologies is occurring everywhere there is large scale mechanized agriculture. Commercial use has been greatest in the US, where 43% of farm retailers offered VRA services in 2001. Except for certain high-value crops like sugar beet, farmer adoption of VRA has been mddest. The farm level profitability of VRA continues to be questionable for bulk commodity crops.The theoretical model and illustration presented here suggest that VRA fertilization has not yet reached its profitability potential. Most VKA field trials to date have relied upon existing state-wide or regional input rate recommendations. Unobserved soil characteristics can potentially interact with an. input to make its effect on yield vary site-specifically within fields. Failure to use site-specific response functions for VRA applications may lead to a misallocation of inputs just as great as that which results from using uniform applications instead of VRA.Agricultural economists have a long history of estimating output response to input applications. Several have started to develop tools to estimate site-specific responses from yield monitor and other precision agriculture data. Likewise, agricultural economists have developed an important body of research results on information value based on managing variabilitytypically in temporal settings. With these tools, a major potential exists to develop further benefits from precision agriculture technologies that permit truly spatially tailored input applications. 0 2002 Elsevier Science B.V. All rights reserved. JEL classiJication: Q12; Q16 (D.S. Bullock). 0169-5150/02/$see front matter 0 2002 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 9 -5 1 5 0 ( 0 2) 0 0 0 7 8 -6

Site-specific production functions for variable rate corn nitrogen fertilization

“…The potential environmental benefits consist primarily of a reduction in the soil residual NO3-N concentration at the end of the growing season and consequently in reductions in leaching of NO3-N (Dinnes et al 2002). It should be noted that the EONR for a whole field is not necessarily equivalent to the mean of the EONR for subsections of fields (Bullock et al 2002). Thus, at times VRN affords the opportunity to reduce the total amount of NF applied while increasing crop yield.…”

“…Compared to variable rate application of phosphorus or potassium fertilizers, the adoption of VRN has been extremely limited (Bullock et al 2002;Robert 2002). There are agronomic and economic reasons for this limited adoption of VRN.…”

“…Response models specifically developed for VRN management must consider the processes controlling crop response to NF within fields (Bullock et al 2002;Ferguson et al 2002). Bullock and Bullock (2000) proposed a theoretical framework to analyze site-specific production functions.…”

A Comparison of Four Spatial Regression Models for Yield Monitor Data: A Case Study from Argentina

“…Variable-rate seeding and pesticide application were used on 1%-3% of area depending on the crop. Bullock et al (2002) identified the lack of site-specific crop response information as a constraint to adoption of spatial crop management practices. Most variable rate input application is still based on whole field (WF) crop response information.…”

Mapping Economic Returns to Agriculture for Informing Environmental Policy in the Murray–Darling Basin, Australia

“…Most research into the mapping of agricultural returns has been focused at paddock and farm property scales within the field of precision agriculture. Numerous studies have undertaken paddock scale economic modelling to quantify the economic benefits of remedial measures such as more targeted soil treatments [13]. However, there have been few attempts to apply these models over large regions.…”