Early nutrient management plays crucial role in crop development

Charles Stichler, Texas Extension agronomist, says with current high costs of energy and other crop inputs, farmers have to understand plant physiology to capitalize on basic production practices: when and how much to irrigate, the type of fertilizer and insecticide to use, and how much and when to use it.

“In crop production, pretty good’s not good enough,” Stichler said during the recent Crop Nutrient Management Workshop at the Texas A & M Research and Extension Center in Weslaco.

“Without water nothing happens,” Stichler said. Water does more than keep a plant from wilting; it is the blood system, moving nutrients around, enabling growth and new cell formation. If a producer takes care of insects and applies fertilizer correctly but does not irrigate properly, his energy and money have been wasted.

“You can’t think of water and fertilizer as two separate things, since they work together,” Stichler said.

A cotton producer using typical furrow irrigation can count on about 40 pounds of lint per inch of water. Because drip irrigation supplies nutrients on a regular basis, 75 to 80 pounds of lint can be expected for the same amount of water. Grain sorghum will produce about 300 pounds of crop per inch of water and corn about 5 bushels. “So the leafier the plant, the more water evaporates through the leaves, the more photosynthesis, the higher nutrient uptake, and the higher the yield potential,” he said.

Stichler noted the importance of not wasting sunlight. Though a producer has no control over the sun, he does control how the sunlight hits his crop. Though he believes in narrow row spacing, Stichler warned not to overplant. With cotton, he recommends a maximum of 50,000 to 55,000 plants per acre. If planted heavier the canopy will be too thick for the sun to penetrate.

With cotton, the first ten fruiting nodes account for about 95 percent of the value of the crop. “Without sun, the bolls set in the first and second positions go down quickly.” Longer season varieties of all crops have a higher yield potential because they grow more leaves and nodes to capture more sunlight and convert it to energy.

In most crops, yield potential is set in the first half of the growing season. At first bloom, 95 percent of the cotton that will be harvested is already on the plant, so farmers must be aware of what is happening in their fields early on. Stichler advises marking a calendar at planting time and again 40 days later, when cotton begins its reproductive stage and requires not only exceptional nutrient management but insect management as well.

“About 40 days before bloom, when the cotton flower is just beginning to form, insects can already be tearing up the future little squares that are going to be in the terminal.” With corn and sorghum, by the time the plant flowers, all the ovules that will become a seed are already on the plant. By marking planting time on a calendar then adding 40 days, the farmer will know that his plants are entering the stage when they are starting to produce reproductive forms.

This rapid growth stage takes place between 40 and 70 days when the sorghum head is developing and the number of seeds on a corn cob is being set. “If you don’t have the water and nutrients there during that time you’ll have reduced yield potential.”

He warned of the danger of charcoal rot on sorghum if it is stressed during this period. By marking his calendar when a corn or sorghum plant blooms, a producer can count 35 days forward and apply the last furrow irrigation. Fifty days after bloom, corn and sorghum crops will have completed their growing cycles and will have reached physiological maturity.

Most important to a successful crop is to see what's happening in the field. “Don't just ride around in your truck. Get out there and examine the soil and the crop,” Stichler said. “Remember, the best thing a farmer can put on his field is his shadow.”

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