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Fluid Journal : Fluid Journal 1999-2001
1 Fluid Journal Spring 1999 Dr. Byron Vaughan Summary: Precision agriculture is more than the application of NPK. It requires looking at other factors such as drainage, pH, compaction, soil moisture, and micronutrients. Gathering information through soil testing, tissue analysis, past crop experience, trials, and production levels, enables you to make informed and precise recommendations to help top growers achieve cost-effective increases in yield. The right approach corrects damaging nutrient deficiencies and cultural practices that can hurt your growers. It helps them to focus on more effective ways to use their resources. Table 1. Micronutrient sensitivity of major crops, Vaughan, Harris Laboratories. Most sensitive Soil conditions most Nutrient field crops likely deficient Zinc Corn Soil test <1.5 ppm High pH Cool, wet soil Low organic matter Boron Alfalfa Soil test <1.0 ppm Sugar beets Sandy Low organic matter High pH Copper Wheat Soil test <0.3 ppm Peanuts High organic matter Iron Beans Soil test <4.0 ppm Millet High pH Sorghum High carbonates Manganese Navy beans Soil test <2.0 ppm Oats High pH Soybeans Molybdenum Alfalfa Soil test <0.1 ppm Peas High pH Chloride Cereals Soil test <7.0 ppm Dryland soils testing high in K Nitrogen, phosphorus, and potassium (NPK) are often the first three factors considered when making recommendations to growers. Stopping here, however, can be costly. The benefits of NPK can be diminished if you overlook other critical elements such as soil moisture, drainage, compaction, pH, and micronutrients. To take your recommendations and your growers to the level of true precision agriculture, you need to determine how these factors are impacting the individual grower. While all the elements are essential, focus of this discussion will be on those "micro" elements we call micronutrients: • Zinc (Zn) • Boron (B) • Copper (C) • Iron (Fe) • Manganese (Mn) • Molybdenum (Mo) • Chloride (Cl) Normally, yield responses to micronutrients are in the range of 10 to 15 percent, which can be significant. Any one micronutrient can limit growth and yield when it is present in deficient amounts. Thus, fine-tuning micronutrient recommendations can potentially give your top growers an added yield advantage. First order of business will be to look at wrong and right ways to approach the requisites for making recommendations on micronutrients. Wrong way Shotgun. Using this approach you simply apply them all and forget about it. Fine and dandy if your grower has money to burn! Wait and see. By the time you see signs, it will be too late to save the yield. Yield loss also can occur without symptoms because of hidden hunger. Shortchange. Here you cheat yourself and your grower by limiting yourself to a plant analysis, which by itself won't give you enough information. Head in sand. You write off micronutrients as too expensive. This head-in-the-sand approach only hurts your growers. Right way Inquire. First make a determination of the full range of major, secondary, and micronutrients required for the particular crop being grown. It Takes More Than Just NPK Soil moisture, drainage, compaction, pH, and micronutrients are all factors that, if ignored, can limit the potential of NPK.
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