PRECISION AGRICULTURE INITIATIVE FOR THE TEXAS HIGH PLAINS

2001 ANNUAL COMPREHENSIVE REPORT

Texas Agricultural Experiment Station and Texas Agricultural Extension Service

Reporting Period:      January 1, 2001 to December 31, 2001

Objective 1:

A.     Summary of Progress:

      Introduction and Background:

      Most Texas High Plains producers are dubious of the practical application of precision agriculture techniques.  This is in part due to the conflicting information among consultants, researchers, fertilizer dealers, etc.  This project seeks to build a partnership among producers, consultants, extension, and research personnel to examine precision agriculture techniques in producer fields.  In 2000, by working with a local consultant, a producer’s field was identified that had been yield mapped for the last three years.  Yield maps consisted of 2 wheat crops and 1 corn crop. After studying the yield maps it was determined that the field had enough soil variability to be a good candidate for variable rate fertilizer application (VRT).  In the spring of 2000 the 70 acre field (½ circle) was soil sampled using a 0.5 acre grid size.  Prior to corn planting, recommendations for VRT application were made with the assistance of the local consultant and private applicator. Fertilizer application to compare variable rate vs. blanket rate applications conducted in replicated strips (irrigation spans) intermingled across the field were made. Nutrients examined were phosphorus and potassium.  Nitrogen was applied uniformly across the field.  To gain additional information during the growing season the site was examined by both satellite and airplane multi-spectral imagery.  The purpose of the remote sensing was to determine if the imagery could pick up stress in the field early enough to allow for the addition or change of a cultural practice to favorably impact yield.  At the end of the season corn yield from the two fertilizer application methods were compared by yield mapping the field.

Results suggested variable rate fertilizer application was not economical. Yield from both application methods were essentially the same.  However, because of the additional cost of the intensive grid soil sampling required for VRT, the traditional blanket application of fertilizer was more economical. It also appears that increasing soil sampling grids to 2.5 acres would have produced a similar variable rate fertilizer map as that produced from our 0.5-acre grid. This would make the VRT application much more economical.  Also, using multi-spectral imagery from airplane flyovers appears to have better potential for identifying potential problems in a field than using satellite imagery. Airplane flyovers allowed for sharper images and more control over when the image was taken (date).

      2001 Results:

A fall wheat crop immediately followed the corn crop harvested in 2000.  The wheat was yield mapped in the summer of 2001.  The yield map was somewhat similar to the one obtained in 1999, showing large areas of variability in yield.  However, at the site in the field where both K and P were applied by VRT application yield appeared to be higher than what was observed in 1999 under a blanket treatment of P.  This site had a higher wheat yield than in adjacent sites where the P was applied in a traditional blanket application.

A second field was identified in 2001 for soil characteristics and nutrient mapping.  The site was identified by examining corn yield maps from previous years.  The field site was soil sampled using a 0.5-acre grid size.  Mapping of the soil characteristics and nutrient content revealed significant areas of variability.  The producer applied a blanket application of N and P to the field site.  After corn harvest the yield map was compared to the soil map.  From visual observation of the maps, K variability appeared to have the greatest impact on yield.  Maps will be analyzed using statistical correlation to verify the visual observation.  Potassium (K) is a nutrient that is not normally applied to Texas High Plains soils.  It would be interesting to apply a variable rate application of K to the field in 2002 to see if we can get a positive yield response in those areas that are low in K. 

B.     Education/transfer:          Data was shared with consultants, producers, and agri-business personnel involved in the study.            

C.     Milestones achieved:      N/A                                                                

D.     Publications:                     None

E.     Precision agriculture proposals:                         Texas Corn Board (2001).  Not funded.          

F.      Precision agriculture meetings attended/papers (posters) presented:         None       

G.     Other Developments:      This objective was not funded for the 2001 - 2003 biennium.  An attempt will be made to fund a portion of this project on other funds in 2002.

Objective 2:

A.  Summary of Progress:

The automatic spot sprayer being used is manufactured by Patchen and goes by the trade name WeedSeeker sprayer.  The sprayer incorporates new technology that only applies herbicide to weeds that are present in-between crop rows.  The sprayer uses advanced optics to sense the presence of weeds.  When a weed enters the sight of its sensor unit, it signals a spray nozzle to deliver a precise amount of herbicide.  Data generated from 2000 indicated that a significant reduction in the total amount of herbicide applied could be achieved by using the WeedSeeker sprayer in sorghum.  However, weed control was not acceptable when the WeedSeeker sprayer was used alone due to weeds that emerged in the crop row.  A combination of a banded pre-emergence application over the sorghum row followed by a post application with the WeedSeeker sprayer to control weeds in between the rows resulted in good weed control while reducing the overall amount of herbicide applied compared to a broadcast application. 

In 2001, a producer was identified who had a field for which we could demonstrate the WeedSeeker sprayer on a larger scale.  Pre-emergence banded and broadcast treatments were made to the sorghum crop.  Following crop emergence we planned to follow the banded application with a post treatment using the WeedSeeker sprayer.  Unfortunately no rainfall was received for 6 weeks following the dry sowing of the sorghum crop.  As a result, the  sorghum stand was very erratic to non-existent forcing the abandonment of the demonstration. 

B. Education/transfer:          Data from 2000 was share at several extension production meetings in 2001.                

C.  Milestones achieved:       N/A                                                                

D.  Publications:                     None

E.  Precision agriculture

      proposals:                         None       

F.  Precision agriculture

      meetings attended/papers

      (posters) presented:         None       

G.  Other Developments:      This objective was funded for the 2001 - 2003 biennium.