Researchers at the University of California – Davis have developed optimal vegetative indices to estimate cotton yield at the pre-harvest stage using remotely sensed imagery and have submitted a manuscript for publication from this work. They found, for example, that the relationships between water and chlorophyll were not identical across the field and that crop stressors are changing throughout the growing season.

From their work on this project they have published papers on variable soil moisture, imagery and mapping mineral content using hyperspectral images. They also have made significant progress on comparing the crop water content to irrigation demand, including finding a statistically significant relationship between image based estimates of canopy water content and the length of the period since the last irrigation.

The goal of 2004 work is to refine current results to improve the accuracy in which water demand can be predicted. The overall aim is providing the grower with accurate water content maps to allow integration of this information into farm management practices.

A variable rate irrigation project in Georgia includes a research pivot that covers 6.75 acres on a field with several soil types.

Work by University of Georgia researchers has led to the development of a variable rate irrigation (VRI) system that retrofits on existing systems, saving water while maintaining production and profitability for the farmer and rural community. In 2002 and 2003, detailed information was collected on five VRI pivots located in different areas of Georgia. Along with millions of gallons of water savings, yield increased due largely to not over watering the boggy parts of the field and being able to apply more water to the very sandy spots.

Best use of VRI relies on good methods to help define a field’s non-uniformity. Developing soil moisture sensing systems is also critical to providing feedback to the system and monitoring its effective use. Researchers believe that remotely sensed imagery coupled with wireless local sensing systems will enhance the economic and environmental benefits associated with efficient irrigation management.

Their 2004 objectives are to: 1) develop and field test a rapid, cost effective system that can give growers a reliable estimate of VRI system’s impact on a field and 2) couple the VRI system to a wireless soil moisture sensing system that will monitor water needs for each part of the field.

Jackson State Community College scientists work thus far indicates that variable rate cotton production systems which utilize multispectral image analysis for crop production zone creation are profitable and likely to have wide success in commercial cotton production in the Mid-South.

Their investigation showed a cost savings of more than $60 per acre in 2002 and 2003 for crop inputs with a yield increase of 63 lbs. per acre in 2002 and 163 lbs per acre in 2003. Total returns to the grower of $90 plus in 2002 and $150 per acre in 2003 resulted from the use of image technologies and variable rate application.

In 2004 they continued to develop a combined image/sensor based variable rate application system for cotton producers.

Their work is based on the Oklahoma State University- developed sensor control system. The overall aim is to allow a $60-$150 per acre decrease in production costs along with a potential yield improvement.

Texas Tech University engineers are developing procedures for applying airborne remote sensing to site-specific cotton management in the Texas High Plains.

Texas Tech University engineers are developing procedures for applying airborne remote sensing to site-specific cotton management, including the application of agrochemicals and irrigation, in the Texas High Plains. Information collected in this study will be used to evaluate differences in net income (gross income from the crop minus production costs, including costs of data acquisition) between precision agriculture and conventional crop management.

In 2004, remote sensing image data collected during the growing season will be used to delineate management zones within fields for variable-rate Pix and defoliant application. Yield mapping data will be analyzed for the variable-rate and uniform treatments using GIS software to determine significant differences and to evaluate the potential benefits of variable-rate versus uniform application. Fiber quality will be mapped for several fields from samples taken during harvest and analyzed by the International Textile Center.

Results of these experiments will be used to formulate a method for site-specific management to manipulate boll maturity and improve fiber quality in parts of fields that are prone to discounts.

From research in 2002 and 2003, researchers at the University of Arkansas have determined that it is possible to identify compacted areas with soil electrical conductivity measures made by VERIS.

They are now evaluating VERIS and remote sensing technology for identifying and mapping soil compaction levels in the field. That information will be used to develop subsoiling guidelines for Arkansas cotton production based on the VERIS and/or Landsat data. Selective subsoiling of only compacted fields or compacted areas in a field could save up to $15 per acre on production costs.

Variable rate technology based on remote sensing has been demonstrated in Louisiana with applications of plant growth regulators and defoliants.

Louisiana State University researchers now are conducting demonstrations – aimed at producers, agricultural consultants and commercial pesticide applicators - of spatially variable insecticide use based on historical yields/profitability.

Researchers also want to: 1) develop a better understanding of the economics of spatially variable inputs; 2) adapt the current prototype application system and evaluate performance on a commercial aircraft; and 3) validate the use of these technologies on multiple farms using various production strategies.