AGRONOMIC NEWS ITEMS
From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335
Fall 1999, No. 2
Applying fertilizer to our crops seems like a simple enough proposition. There are three major nutrients…nitrogen, phosphorus and potassium…that are frequently required. In fact, it is this frequency of need by crops combined with a relatively high plant requirement that puts them in the major category. Some argue that sulfur, usually grouped with calcium and magnesium as a secondary nutrient, should become the fourth major nutrient. The trace elements are just as essential as the others, but are needed in smaller amounts.
Nutrient deficiencies and imbalances are relatively common. Any fertilizer dealer can point out such problems within a short distance of his or her facility…and researchers can do the same near their experiment stations.
Upon reflection, perhaps it is not just that we don’t ask the question, but that, also, we do not necessarily listen to the answer. How many more decades of research must we do on nitrogen management for corn, as an example, before growers are convinced to follow university and industry recommendations aimed at optimizing the use of this environmentally sensitive nutrient?
Chloride is a recent example of not asking the right question. For years researchers blamed the potassium soil test as being inaccurate when small grains responded to potassium on high testing soils. Finally someone asked the question, “Could the plants be responding to chloride when muriate of potash is applied?” After all, muriate contains 50 percent chloride, and chlorine is, in fact, a plant essential element. The question hadn’t been asked because deficiency of chlorine had not previously been verified in the field. Now, just 10 or so years later, deficiencies have been documented from western Canada southward through most of the western states into Texas. We’ll never know how much yield was lost simply because we did not ask the right question sooner.
California cotton suffered for decades because mid-season decline was blamed on Verticillium wilt. Once the right question was asked…and answered by talented scientists…then the malady was corrected by potassium fertilization, as it ultimately was in other states of the Cotton Belt. Yes, it turned out to be simply a case of potassium deficiency. It was not appreciated that the cotton boll is a strong sink for potassium and, therefore, high-yielding varieties have a very high mid-season requirement. Current potassium research on nut crops in California is turning up substantial yield and quality improvements.
Who should ask the questions? Growers…processors… fertilizer dealers…researchers? The answer is everybody. After all, we all have a stake in food production. The right answer begins with the right question. We won’t know if we don’t ask!