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  4. 1997
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Soil Management Notes

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Comments from a Meeting. The Noble Research Institute Soil Fertility and Crop Specialists recently attended a meeting where folks from university extension and research departments and industry discussed current issues related to agricultural production. I decided to use this space to relay some of the major discussion points.

Precision Ag or Site Specific Management. Most agricultural magazines have articles about global positioning, variable rate fertilizer application, grid sampling, yield monitors, etc. A tremendous amount of technology and "gadgetry" is available to help us divide fields into very small manageable units and treat them accordingly.

In some instances it appears technology has gotten ahead of the science needed to evaluate potential benefits. However, there are many cases where farmers have been able to efficiently monitor and manage variability in the fields. Several speakers commented that soil pH, soil nutrient levels, drainage, topography, and soil type account for most of the variation in fields, but soil nutrient levels have received the most attention.

Many of us do not have access to all the equipment needed to map fields according to the nutrient status of each 2 acres (or some very small unit) or to measure and map yields across the entire field. We can begin to divide fields into smaller units according to soil type, topography, and yield differences that are large enough to observe and then do more detailed evaluation of those areas and change some inputs.

If you have a field containing two major soil types and one has a 50 bushel wheat yield potential and the other 25 bushels it doesn't make good economic sense to fertilize each soil the same. Grid soil sampling and the use of yield monitors has shown high yielding areas of many fields contain lower nutrient levels than adjacent low yielding areas because of nutrient removal. How long can the high yields be maintained without applying extra nutrients?

Nutrient Management Plans. We have mentioned this before but many states have adopted regulations requiring nutrient management plans be prepared and approved before fertilizer or animal wastes can be applied. Good production and nutrient application records will be very important. North Carolina has regulations requiring nutrient management plans for application of animal wastes across the entire state and for the application of any nutrients in some areas. Anyone applying fertilizer on more than 50 acres must attend some training. They expect to train about 7,000 people. It seems to just be a matter of time before all of us will have similar guidelines.

Future Fertilizer Supply. As more countries, such as China, strive to increase food production the demand for fertilizers is expected to increase. The U S currently imports about 25% of the total nutrients and some new nitrogen production is being added in the U S, but many plants are very old and may be shut down in the future. Much of the presently known phosphorus reserves are unstable in countries such as Jordan and Morocco. This causes me to want to encourage you to begin applying a little extra phosphorus to build soil levels.

One speaker predicted fertilizer prices for the next few months and indicated nitrogen should be about steady or maybe decrease slightly then level, phosphorus (18-46-0 and similar materials) should be steady or slightly increase and potassium prices should slightly increase. Remember these are predictions.

Comments. After all of this, I can only recommend that you routinely soil test fields (divide them into the smallest manageable units possible according to production potentials or history), set realistic yield goals, apply fertilizer at the best estimated economic rate and timing, plant adapted varieties, and keep good records.