CORN
Crop Observation and Recommendation Network

October 14 - October 20, 2002
C.O.R.N. 2002-35

In This Issue:

A) Corn Grain Quality: Is Aflatoxin An Issue In Ohio
B) Cost Benefit Analysis of a GPS Guidance System
C) Reconditioning Overly Dry Soybeans

A) Corn Grain Quality: Is Aflatoxin An Issue In Ohio - Pat Lipps CORN Questions

Recent agricultural news releases have reported the occurrence of aflatoxin in corn from Texas, Nebraska, Kansas and some parts Iowa, and Illinois. There have been news articles indicating that the aflatoxin problem extends all across the Corn Belt including Ohio. As of now I have no reports of a single documented case of aflatoxin in Ohio, however much of the corn crop is yet to be harvested.

Aflatoxin is a toxin produced by several species of the fungus Aspergillus. The fungus is known to occur in most locations but it produces aflatoxin under certain environmental conditions. Corn that has suffered through severe drought conditions and high temperatures is generally in risk of aflatoxin contamination. Traditionally, the droughty corn growing areas of southeastern and southwest US have persistent problems with aflatoxin. When these conditions occur farther north, corn grain may become contaminated with the fungus and possibly aflatoxin. Drought is not the only prerequisite for aflatoxin production, but the nighttime and daytime temperatures must be high, at least in the 90 degree F range for an extended period of time. We checked the hourly temperatures for several locations in southern Ohio for the time period between July 1 and September 30 and found that although the day time temperatures may have been in the 90 degree F range, the night time temperatures were usually in the low 70 degree F range or lower. This indicates that if the Aspergillus fungus happened to infect corn, the conditions for accumulation of aflatoxin were minimal. We suspect that if aflatoxin is found in corn in Ohio, the levels will be far below the FDA guideline of 20 ppb.

News reports from other states indicated that grain elevators have rejected loads of grain for aflatoxin based on a black light test. Corn growers should be aware that the black light test does not test for aflatoxin. The black light test has been used to check for a blue-green fluorescence of the Aspergillus fungus in grain. The presence of the fungus does not mean the toxin is present and there is no possible way a black light test can determine the level of aflatoxin. There are a number of different fungi that also fluoresce under a black light. The only way to determine the presence of aflatoxin is through chemical analysis. There are several tests that can be used. The grain elevator or grain buyer should tell you what tests they are using to evaluate the grain. You should get the proper documentation concerning the level of contamination and the tests used to determine the contamination from the elevator if any loads are rejected.

B) Cost Benefit Analysis of a GPS Guidance System - Ehsani and Sullivan CORN Questions

One of the main factors that influence the purchase of new precision agricultural equipment is the upfront cost. Over the few past years, the price of this equipment has gone down, but there still is a significant amount of producers who are concerned about having a return on their investment (ROI) into precision agriculture. One of the quickest ways to have a return on investment is with GPS guidance systems. The monetary returns can be from the reduction in chemical costs along with less acres covered which in turn means less fuel is used and less wear on the application equipment. Other returns on investment may be the reduction in stress, increased application speed and ability to work longer hours at night. These are just a few of the benefits and potential savings that a guidance system can have.

Table 1 shows the cost benefits analysis of a guidance system compared to a foam marker for a 1500 acre field. In this table, only overlap is considered in the calculation because it is very difficult to calculate the cost of crop loss due to skip. Also another assumption here is that the percent of overlap for foam marker is 10% and for guidance is about 2%. If these percentage assumptions change, so will the result of the calculation. The percent of overlap for foam marker is taken from the literature and the percent of overlap for guidance is taken from our recent research at the Ohio State University. We are currently conducting a few field tests to determine the average overlap for commercial applicators with both guidance system and foam marker.

Based on our assumptions and according the analysis given in Table 1, with a GPS benefit of $0.53 savings per acre and driving over 1,500 acres, there is a potential savings of $795.00 per year.

By repeating the same calculation as in Table 1 (with same assumptions) for different acreage, it can be found that at least around 800 acres of spraying per year is needed to justify buying a guidance system.

This cost benefit analysis will enable the producer or custom applicator to make an informed decision on purchasing a guidance system and whether that system will contribute to the cost savings of the farming operation.

If more answers are needed before the purchase of a system, please contact: Dr. Reza Ehsani at ehsani.2@osu.edu or Matt Sullivan at sullivan.64@osu.edu.

C) Reconditioning Overly Dry Soybeans - Maier and Montross - Purdue University CORN Questions

Almost every year during the fall harvest, I receive inquiries from farmers and elevator managers about whether it is possible and worth it to recondition overly dry soybeans. A number of years ago we conducted experimental and computer simulation research to evaluate whether it is technically feasible and economically viable to do so. Those results were published in a journal but never as an extension publication. Given the many requests for information on this subject, we have now developed Grain Quality Fact Sheet 48, which is available online at the Purdue Post Harvest Grain Quality and Stored Product Protection Program website at http://www.grainquality.org/ under 'Extension Publications'.

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