Something Fooling Your Greenness Sensor?

Something Fooling Your Greenness Sensor?

When crop prices are low, most farmers tend to manage their resources more conservatively; and some may whittle their fertilizer inputs to just one or two major nutrients, writes Cliff Snyder and Tai Maaz in a recent article in Plant Nutrition Today. If recent soil fertility management and nutrient rates have been excellent, then slight fertilizer cutbacks may only modestly short-change plant nutrition. However, if that strong fertilization history is not the case on your farm, cutbacks in nutrient inputs can be costly. Cutting back on nitrogen (N) — the real “horsepower” in crop nutrition — may severely penalize yields, crop quality, and profits.

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Remote sensing by multispectral satellite imagery, crop sensing from airplane or other platforms such as unmanned aerial vehicles (UAVs), and measuring crop greenness using chlorophyll meters or digital cameras — and the calibrated software and geographic information systems that may be linked to each technology — are being increasingly used by skilled farmers and their crop advisers. Some farmers have relied on their own on-farm N rate response trials, while others have trusted their past field-by-field experiences, or state/provincial/regional N rate response trials, to guide N rate management. Perhaps too often, others rely on current season seat-of-the-pants visual evaluation of adequate N nutrition.

Increasingly, more farmers and applicators are split applying and varying the rates of their N inputs for major cereal grain crops (and forages), to better match soil and fertilizer N supply with crop uptake demands, and to hedge against the effects of increasing weather uncertainty. For crop N sensing and greenness tools to work effectively, one must first be certain that other nutrients are not limiting. Even the most sophisticated greenness-sensing tools can be fooled by “hidden hunger” and deficiencies of other essential nutrients like sulfur, zinc, iron, and manganese.

Read more at IPNI.net.