D6—Uncaster farming, Saturday ,iuiy 2,1983, LANCASTER - Post emergence applications of nitrogen are expected to become more popular as com growers seek ' to improve fertilizer efficiency and maximize per-acre profits. Extensive research by university and private soil specialists has fueled this trend. Split applications improve nutrient recovery by making more N available to the crop during its peak demand period. They also provide good insurance against fertilizer losses. “The question today is not whether you should apply some N after planting, but how much you should apply and when,” insists Don Johnson, an agronomist with Allied Chemical. “The answer hinges on your soil type, yield goals, cultural practices, and the type of application and tillage equipment you have available. ’' Weather is another factor. In wet seasons, com growers who applied as much as 200 pounds N per acre before planting still find it pays to make a post-emergence ap plication. It depends on how much N was lost to leaching and denitrification. Practical Program Because a corn crop's peak demand period for N is six to 12 weeks after planting, “spoon feeding” the mobil nutrient in small increments throughout the growing season maximizes its utilization. Such a program is not always practical, however. “Unless you have sprinkler irrigation and can fertigate N whenever you water, there is no way you can apply N four to eight tunes after crop emergence,” Johnson says. “You’ll have to find a compromise.” But a compromise is still at tractive. According to Johnson, making one post-emergence ap plication of N is usually enough to boost crop yields 10-15 percent - even on higb-fertility soils. A post emergence application also lets farmers adjust their N rate to the quality of their stand. In a good year, it may pay to apply more N than was originally planned. Other nutrients, such as sulfur or zinc, also may be needed. What’s the best time for post emergence applications of N? Rescue treatment Farmers making rescue treatments will have to get into the fields as soon as possible to correct the N deficiency and prevent further yield loss. However, far- n Roskamp Low-Pro Feed ing er Low-Pro Feed Processing Center The Grappler Feed Processing Center makes feeding less of a chore its design allows easy installation in almost any location With the electronic control panel Vibra-Meters and weigher/durnper you have a complete teed processing center at your tmger tips Forget standing in the cold Or starting those fuel guzzling tractors for portable mixers Simply push a button and let a small shpor 7' hp motor do the work Instead of you ROLLER MILLS FOR ANY PURPOSE See Page A-27 Does corn need post-emergence N? mers who plan on making a post emergence application can usually be more flexible. They can also do the job for less money. To save a tnp across the field, most com growers will band N when they cultivate or apply a post-emergence herbicide. Other farmers will make a special trip because the economic returns of a split application make it wor thwhile. “If you have a choice, and if you're only going to be making one post-emergence application, the ideal tune to do it would be at the eight- to 10-leaf stage of crop development,” Johnson says. “That’s when the crop is on the threshold of its peak demand period for N.” How Much and When? How much N should com growers save for post-emergence application? Making a 70/30 or 60/40 split of preplant and post-emergence N is the most practical program for farmers with medium-textured soils, Johnson says. “This way, if ram or .something else prevents you from getting into your fields on schedule, you’ll still have enough N in the soil to support the crop for awhile,” he explains. But the groundrules change on soils that are prone to N deficiency. These mclude coarse textured sandy soils, where N can be leached, and fine-textured heavy soils with poor drainage, l&T Vanco GIVE US A CALL. WE DELIVER & INSTALL! 12 SIZES AVAILABLE • BIG BEN STURDY • DEPENDABLE FREE STALLS & HEIFER STALLS • PICKUP TRUCK BED MATS ONE PC. CONSTR. FITS MOST TRUCKS where N can be lost to denitrification. “On these high-risk soils, you’re better off reversing the formula and applying 60-70 percent of your N after crop emergence,” Johnson says. Develop contigency Knowing that ram could prevent them from making that second application on time, most com growers are reluctant to save that much N for post-emergence ap plication. But Johnson discounts this concern. "If it’s too wet to get into the field to apply N, then it’s also probably too wet for your preplant N to be very effective,” he says. "Most of it probably left the soil. So either way, your crop could run short of nitrogen.” To make sure the crop gets enough N, Johnson suggests developing two or three con tingency plans. "If the crop is hurting, then you may have to fly on a little N to nurse the crop through the stress period,” he says. He recommends using a high quality N solution with low free ammonia to minimize fertilizer bum. Farmers should consult their fertilizer dealer or extension specialist about application rates and precautions. Using a nitrogen based foliar fertilizer, such as NZN (15-fWWZn), NMG (14-0-0-4 Mg) or NFE (MMMMFej, is still another alternative. These materials were Kraiburg Happy Moo Mats MORE UDDER ON THE RUBBER * * ALSO AVAILABLE * * designed for foliar application. Farmers saving the bulk of their N for post-emergence application should also have access to a high clearance sprayer, Johnson says. “If ram sets you back, the crop may be too tall to put on the N with a cultivator,” he says. “Using a high-clearance sprayer doesn’t present any problems, but you should know ahead of tune where you can rent or borrow one. Don’t wait until the last minute.” Post-emergence applications of nitrogen can be made as late as tasselmg time and still produce a good return on investment, Johnson says. Replenish losses As mentioned earlier, not all post-emergence applications of N are planned in advance. In wet seasons, many corn growers are forced to make rescue treatments to replenish N lost to leaching or denitrification. How much N should these far mers apply V In states where N losses have been a recurring problem, a few extension services have developed soil maps that indicate potential N losses with respect to amount and frequency of rainfall. _ The University of Illinois is one example. Farmers in most other states, however, have to rely on guesswork. In these situations, a good benchmark would be 50 pounds N per acre, Johnson says. the rubber mat specialist 10 YEAR WRITTEN WARRANTY "A 50-pound shofof N will nice effect on the crop and get it’ back on track,” Johnson explains. •‘Your crop may only need 40 pounds, or it may need 60. But a 50- pound rate is a good ballpark figure to use. If you find you need more, you can always maim another application or rely on a foliar fertilizer to fill the gap." Spot Treatments Spot treating problem areas is another option, though it will usually pay to apply additional N to the entire field, John says, "Generally, if one section of a field is short on nitrogen, the entire field could probably benefit from ad ditional N fertilizer,” he says. "You might get a 30-bushel in crease here and only a 10-bushel response there, but overall it should be a good investment. A compromise would be to adjust your N rate as you go along,” Any type of N fertilizer can be applied after crop emergence. “Nitrate N is what you lost, so you ought to put a little back,” reasons. "It’s readily available to the crop and will go to work right away.” But other forms of N, such as ammonia and urea, are also desirable. "That time of year, ammonia and urea will break down into the nitrate form five to eight days after application. By using a combination of all three VANCO SALES R.D. 4, Box 300, Carlisle, Pa. 17013 Phone 717-776-3494 Please send free sample & installation instructions. NAME ADDRESS PHONE (Turn to Page 07)
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