A Possible Alternative to Nematicides for Soil Sterilization

note: internal links for Tables on this page are disabled. Image links are operational.

INTRODUCTION

The purpose of this document is to describe a non-chemical method of soil preparation. Environmental concerns have reduced the variety of poisons available, driven up the price, and generated a lot of justifiable negative public reaction.

Photonic sterilization is not new, from the barber's tools under UV to microwave cooking. Microwave energy has been attempted to serve the above requirement and has proven impractical. Gamma irradiation has been in common use for foodstuffs for many years but has had poor public acceptance partially due to left-over cold-war fear of radionucleides, especially cobalt-60, the most practical gamma source for this function. The use of X-radiation eliminates this concern.

The eventual goal of this research will be the design and construction of a field-usable, tractor-drawn, PTO powered unit to evaluate commercial feasibility for production equipment.

TECHNICAL DISCUSSION

The initial approach was to run an international patent search to determine prior art, nothing in this field or similar fields was found. Effects of various types of radiation on living material brought up many references, an index is being prepared. The majority of the references are atomic weapon related and are of little value as the actual X-ray component of that type of exposure cannot be separated from the gamma and particle exposure. In addition, the radiation pulses are of such magnitude and speed that it is impossible to extrapolate the effects of lower energy, longer duration exposure on the sample.

The next step was a very large literature search for absorption/transmission characteristics of the compounds in various soils, any data on effects of X-rays on living organisms dating as far back as the early part of this century, and realizing that nothing truly meaningful would come out of this without performing a series of experiments.

As the planned exposures were to be in the several thousand rad range, it was not feasible to use medical equipment. Varian was kind enough to provide us with a 75KV X-ray tube that would take the abuse and an electronics package was designed around it.

click for larger image

After several months of design, construction, and careful calibration, IFAS provided samples that were irradiated at stepped levels and the samples were analyzed by graduate students at the University of Florida at 2 inch intervals. The results were not as expected but were very interesting (Table 1). The experiments were repeated several times with similar results. As the next series of experiments did not require a certified bio lab to do the analysis of the samples, equipment was provided to do rapid evaluation at this site. All subsequent results followed the same profile and it was time to move on to the next stage.

Earlier studies made it interesting to shift to the 100-150 KV region and, as the 75 KV machine had a less than desirable beam profile and required fairly long exposure times, a new machine was constructed, again with Varian's support by providing a 4KW continuous duty, 20 KW peak, 150 KV fan-beam tube.

click for larger image

Control Panel

click for larger image

Irradiator

click for larger image

75 KV Multiplier

This device was much more difficult to implement in continuous mode due to requiring plus and minus balanced supplies with the cathode filament floating at 75 KV. As beam current is controlled by cathode emission, an entirely new control system had to be designed. Note: a completely different, electronically scanned, fan-beam X-ray source has been designed, much less expensive and very hardy.

At these radiation levels, multiple safety interlocks were designed into the device including remote sensors enabling automatic shutdown if scattered radiation levels exceed preset limits.

The next series of experiments will involve testing at various dose levels and wavelengths of radiation with the goal being to discover the optimum level not to kill but to render the parasite population non-viable, or, at least, reduce crop damage. All previous tests were done on measuring quick mortality of the pests, the new series will be done on a time measured population increase of treated, infested soil with host plants (Table 2).

updated 17 March, 2001

______________________________________

Additional specific non-published information may be requested from:

BIT Company

3732 134th Place

Wellborn, Florida 32094

email: [email protected]


A Possible Alternative to Nematicides for Soil Sterilization note: internal links for Tables on this page are disabled. Image links are operational. INTRODUCTION The purpose of this document is to describe a non-chemical method of soil preparation. Environmental concerns have reduced the variety of poisons available, driven up the price, and generated a lot of justifiable negative public reaction. Photonic sterilization is not new, from the barber's tools under UV to microwave cooking. Microwave energy has been attempted to serve the above requirement and has proven impractical. Gamma irradiation has been in common use for foodstuffs for many years but has had poor public acceptance partially due to left-over cold-war fear of radionucleides, especially cobalt-60, the most practical gamma source for this function. The use of X-radiation eliminates this concern. The eventual goal of this research will be the design and construction of a field-usable, tractor-drawn, PTO powered unit to evaluate commercial feasibility for production equipment. TECHNICAL DISCUSSION The initial approach was to run an international patent search to determine prior art, nothing in this field or similar fields was found. Effects of various types of radiation on living material brought up many references, an index is being prepared. The majority of the references are atomic weapon related and are of little value as the actual X-ray component of that type of exposure cannot be separated from the gamma and particle exposure. In addition, the radiation pulses are of such magnitude and speed that it is impossible to extrapolate the effects of lower energy, longer duration exposure on the sample. The next step was a very large literature search for absorption/transmission characteristics of the compounds in various soils, any data on effects of X-rays on living organisms dating as far back as the early part of this century, and realizing that nothing truly meaningful would come out of this without performing a series of experiments. As the planned exposures were to be in the several thousand rad range, it was not feasible to use medical equipment. Varian was kind enough to provide us with a 75KV X-ray tube that would take the abuse and an electronics package was designed around it. click for larger image After several months of design, construction, and careful calibration, IFAS provided samples that were irradiated at stepped levels and the samples were analyzed by graduate students at the University of Florida at 2 inch intervals. The results were not as expected but were very interesting (Table 1). The experiments were repeated several times with similar results. As the next series of experiments did not require a certified bio lab to do the analysis of the samples, equipment was provided to do rapid evaluation at this site. All subsequent results followed the same profile and it was time to move on to the next stage. Earlier studies made it interesting to shift to the 100-150 KV region and, as the 75 KV machine had a less than desirable beam profile and required fairly long exposure times, a new machine was constructed, again with Varian's support by providing a 4KW continuous duty, 20 KW peak, 150 KV fan-beam tube. click for larger image Control Panel click for larger image Irradiator click for larger image 75 KV Multiplier This device was much more difficult to implement in continuous mode due to requiring plus and minus balanced supplies with the cathode filament floating at 75 KV. As beam current is controlled by cathode emission, an entirely new control system had to be designed. Note: a completely different, electronically scanned, fan-beam X-ray source has been designed, much less expensive and very hardy. At these radiation levels, multiple safety interlocks were designed into the device including remote sensors enabling automatic shutdown if scattered radiation levels exceed preset limits. The next series of experiments will involve testing at various dose levels and wavelengths of radiation with the goal being to discover the optimum level not to kill but to render the parasite population non-viable, or, at least, reduce crop damage. All previous tests were done on measuring quick mortality of the pests, the new series will be done on a time measured population increase of treated, infested soil with host plants (Table 2). updated 17 March, 2001 ______________________________________ Additional specific non-published information may be requested from: BIT Company 3732 134th Place Wellborn, Florida 32094 email: [email protected]