Low-Tech Precision Agriculture

The best tool for precision ag is not the latest GPS samples or satellite image. Observations from the combine seat during harvest tell a far more accurate story. Pay attention! The very best precision ag tool is you!

Cereal crops show the impact of soil conditions sooner than they would show up in corn or soybeans. Watching the patterns of growth in your cereals can give an early warning of problems in the field, and direct you back to certain areas for detective work to determine what is going on.

Pockets of acid soils (low pH) are common in some parts of Ontario, but don't show up in a regular soil test. Oats and wheat, and barley to a lesser extent, are sensitive to acid soil conditions. Areas of poor growth should be targeted for soil testing after harvest to confirm whether low soil pH is the problem. In no-till fields, sample only 2" deep, but use this for soil pH only and not for checking nutrient levels. Conventional fields should sample the normal 6" depth. If parts of the field do need lime, the areas of poor growth can provide a natural application map.

Manganese deficiency is relatively common in cereals, showing up where there is a combination of high pH and either sandy, low organic matter, or muck soils. In severe cases, the crop will die completely in these areas, while less severe deficiency appears as stunting in the crop. Manganese is unlikely to be a problem in corn, but watch those areas of reduced cereal growth for manganese deficiency symptoms when that field is planted to soybeans, edible beans, or other cereals.

Cereals are very responsive to nitrogen. A nitrogen shortage causes stunting, yellowing, poor grain yield, and premature ripening. Too much N is even more striking, with lodging the most obvious sign. If your cereal crop is falling down with normal applications of nitrogen fertilizer, it is a good bet that other crops in the rotation are receiving too much N.

Wheat and barley don't like wet feet, so any areas of poor drainage will show up with reduced growth. Similarly, soil compaction will adversely affect crop growth, often following the patterns of tire tracks. Investigation with a shovel or tile probe can help to identify if compaction is the reason for poor crop growth.

So keep your eyes open at harvest time. It's the low-tech approach to precision ag, and just might lead to better crops in the future!

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