ii)   Determine if aerial color, infrared photographs can be used to detect differences in root-knot nematode density.

In 1998, infrared photographs were taken of root-knot nematode infested fields in Lubbock, Hockley, and Terry counties. Ten to 30-acre areas in these three fields were intensively sampled (90-120 samples) for root-knot nematode at midseason.  The photographs were georeferenced and reflectance relationships for the near-infrared red (NIR), red, and green bands at each sampled point were determined.  A number of these samples were also assayed for sand, silt, and clay content.  A correlation analysis was used to indicate relationships between root-knot nematode density and these three bands, or combinations of these bands.  At all three sites there was a significant (P=0.05) correlation between root-knot nematode density and certain band combinations (Table 1), though the relationship was different between each field.  There was a significant relationship between soil texture and band combinations in all three fields (Table 1).  In the Lubbock county and Terry county fields, there were similar relationships between single bands, soil texture, and root-knot nematode density, indicating that it may be soil texture which is being directly measured rather than root-knot nematode affects on plants.

In 1999, color infrared aerial photographs were taken of nine irrigated cotton fields in Dawson (1 field), Gaines (1 field), Hockley (2 fields), Lubbock (2 fields), and Terry (3 fields) counties.  Soil samples have been taken and assayed for root-knot nematode currently in 5 of these fields. .  The photographs were georeferenced and reflectance relationships for the NIR, red, and green bands at each sampled point were determined.  A correlation analysis was conducted at each site to determine if a relationship existed between root-knot nematode density taken in the fall, and infrared photographs taken in July or August.  Soil is being saved for texture analysis during the winter of 1999-2000.  In 3 of the 5 fields that have been sampled, there was a significant correlation between root-knot nematode density and reflectance values (Table 2). In all three of these fields there was a correlation between reflectance of the ratio of near-infrared and red bands to root-knot nematode density.  It appears that infrared photography has potential for aiding in the samples taken for root-knot nematode density.  However, it is necessary to determine what factors are responsible for a significant relationship between root-knot nematode density and reflectance.  Important factors may include soil moisture nonuniformity (slopes for example), soil texture, and rate of nematicide applied at planting or other nematode control measures. 

iii)   Develop a height sensor to measure cover crop differences

Dr. Steve Searcy developed a height sensor based on light beams being passed between two light bars.  The unit was attached to a tool bar behind a tractor.  This apparatus generated a series of 0's or 1's if the beam was broken or reached the second light bar.  The unit was attached to an OmnistarÒ differentially corrected global positioning system so that a computer in the tractor recorded the position as well as height. Dr. Searcy will send a final report on this part of the project once he returns from a trip.

Objective 3.   Determine the economic and physical feasibility of precision agriculture components as they relate to farming systems

Typically producers or consultant take from 1 to 4 soil samples from a 120-acre circle to assay for root-knot nematode.  With the level of aggregation known for this nematode, that number is insufficient to practice precision application of nematicide.  The cost of assaying samples for root-knot nematode ranges from $10-25/sample, plus it takes 2 People a full day to intensively sample and georeference where those samples were located in a field.   This brings the cost of intensively sampling and assaying 120 samples for a 120-acre field to approximately $1300 to $3000 per field.  The cost of a blanket nematicidal rate application for that field with 5 lbs/acre of TemikÒ 15G (aldicarb) is $1962.

A sampling study for root-knot nematode was conducted in the same locations from 1996-1998 in three fields located in Hockley, Lamb, and Lubbock counties.  It was determined that sampling needed to be conducted yearly in one root-knot nematode field, though in a second field, even sampling once in three years was sufficient.  The third field did not require sampling yearly, but could be sampled once every other year intensively.  

The cost of aerial infrared photography was: $125/hour for airplane (the more fields to shoot, the lower the cost per field); $20/roll of film (36 exposures, good only for the day it was loaded into the camera); #13 yellow or orange filter (< $25); film developing costs  (< $10); software to analyze the reflectance values ($50/year).  This technology can cost < $50/field if several fields are shot in a flight.  However, it is still necessary to take some soil samples every year.  The infrared photography can be an adequate guide to taking a minimal number of soil samples (5-10).  However, a better understanding of why there is a relationship between reflectance and root-knot nematode density in some fields, but not others, must be determined.