From Agronomists of the
Potash & Phosphate Institute
655 Engineering Drive, Suite 110
Norcross, Georgia 30092-2837
Phone (770) 447-0335

Fall 1998, No. 8


For the second consecutive year, moisture stress has slashed crop yields and essentially eliminated profits in many areas. It existed on many farms as either too much water, or not enough water or simply poor distribution during the growing season. Even with irrigation and high crop yields, the steady need for water generated higher production costs and cut deeply into profits. The uncertainty of weather has generated many questions about crop production and the management of inputs such as fertilizer for this fall and the 1999 cropping season. Consider some of the following suggestions.

Rainfall quantity and distribution is usually best during the fall-winter months in the Southeast. Winter vegetables, wheat and canola can generate cash flow next spring. Profit from these crops will require special attention to marketing and the selection of best management practices essential for high yield and quality. Unfortunately, there are no short-cuts or input elimination procedures or magic tonics that cut input costs while generating top profit crop yields. Each plant in the field has a basic set of requirements for nutrients and other essential inputs. They must be provided by the soil and from fertilizer.

Soil sample each field immediately after harvest. It is the best tool to determine how much fertilizer, if any, remains from last year’s crop. Unused phosphorus should show up as a higher soil test level because it does not move in the soil like nitrogen, potassium, sulfur, magnesium, and boron. These five mobile nutrients are subject to leaching from very sandy soils with water under very heavy rainfall conditions. If applied after the heavy spring rains and crop yields were low due to drought, then some of the fertilizer applied for the 1998 crop should be available for the 1999 crop. The old saying still holds, "don’t guess, soil test".

Crop management planning can improve input use effectiveness. Proper timing of each operation increases crop response at no extra cost. Likewise, balancing crop needs for potassium and phosphorus with nitrogen can generate a lower unit cost of production and allow best use of available water. Minimize nutrient loss due to leaching during intense rains by programming fertilizer applications with crop need and growth stages. Get the most out of lime by applying and incorporating into the soil as far ahead of planting as possible.

Irrigation is a capital investment beneficial to all crops in the rotation. Drought is a major problem at some time each year. The cost of an irrigation system deserves serious consideration for several reasons. Moisture stress can be reduced. Fertilizer can be programmed to crop needs. Rapid seed germination and plant regrowth are possible. Crop quality improves. Unexpected insect/weed/disease problems can be treated quickly. High-value, short-season crops can be fit into the rotation with less risk. Profit potential improves as fixed costs are spread over more crops and inputs such as labor and equipment can be in use throughout the year.

A productive soil is always a fertile soil. The reason is simply that healthy plants can best cope with crop stress conditions such as limited moisture, insect-disease-weed pressures, or excessively high or low temperatures. Research documents that fertilizer accounts for at least half of the yield generated by most crops. Healthy, well nourished plants allow for the greatest development of the genetic yield potential of seed, best response from crop protection products, and maximum photosynthesis needed for top yield and profit. Phosphorus and potassium are essential ingredients for profitable cropping systems year after year.


For more information, contact Dr. Noble R. Usherwood, Southeast Director, PPI, 655 Engineering Drive, Suite 110, Norcross, GA 30092-2837. Phone (770) 825-8070. E-mail:
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