Yield monitor sensor being developed at ISU Center for Nondestructive Evaluation

Precision farming requires extensive research in two major areas so the science can mature to a point where it can be adapted into everyday farming operations: (1) the ability to evaluate outcomes of physical and chemical procedures implemented in the field by using databases developed by data acquisition over years; research is beginning to provide a clear picture of what can or can't be done; and (2) development of new machinery, equipment, and sensors to be used in precision farming practices; specifically, development of more advanced sensors for data acquisition will have a lasting impact on the overall precision farming activities.

The overall success of precision farming depends on the proper blend of efforts from researchers in both agricultural and engineering sciences. The project reported here is a joint effort between the Center for Nondestructive Evaluation (CNDE) and National Soil Tilth Laboratory researchers and is supported by Ames Laboratory funds.

The project was carried out by the x-ray group at the CNDE, with a laboratory set up to take measurements. The goal was to investigate the feasibility of using x-ray technology to determine grain flow rates. The grain flow rate measurement is a key parameter in forming crop yield maps. Accurate measurement of flow rate has a lasting impact on forming reliable precision agriculture databases.

X-rays offer a positive alternative

The results obtained prove that x-ray technology offers a very competitive alternative to various measurement techniques.

  • Because x-rays are a noncontact method, the technique offers long-term stability of operation. This stability means that the operator can avoid frequent calibrations and equipment maintenance--a clear advantage over other methods.
  • X-rays are relatively insensitive to grain moisture content and the measured quantity provides weight of the yield irrespective of its moisture content.
  • The technique offers a large dynamic range. By using other techniques, operators must recalibrate equipment as large changes are observed in the flow rates.
  • Perhaps most significant is the accuracy level offered by the x-ray technique. Accuracy has a significant impact on the acceptance of any precision agriculture technology. X-ray displays a high sensitivity to small variations in the grain flow rates.

Figure 1 provides profiles of corn for various flow rates typical of small-size combine harvesters. When these profiles are processed, the technique provides results that can claim 1 percent accuracy levels without any exhaustive data processing. The sensitivity of the technique can be easily seen in Figure 2. As a result, x-ray technology is very competitive and feasible in developing flow rate measurement sensors for precision farming data acquisition applications. The future commercial prospects of the technology are being evaluated with Larson Systems.

Figure 1. Signal intensity profiles at various flow rates.

Signal intensity profiles at various flow rates

Figure 2. Estimated mass flow rate vs. signal intensity.

Estimated mass flow rate vs. signal intensity

This article originally appeared on pages 16-17 of the IC-480 (4c Precision Ag Edition) -- April 9, 1998 issue.

Updated 04/08/1998 - 1:00pm