Some producers had started applying nitrogen before the recent storm dropped 6-10 inches of snow across much of the state. In this week's CropWatch Soil Scientist Charles Shapiro discusses the role of residual nitrates, as one of several stories focusing on corn production. Photo by Brett Hampton

April 11, 2003

Simulations identify appropriate plant populations

Many surface soil samples are showing elevated nitrate levels this year. The University of Nebraska Cooperative Extension does not recommend adjusting nitrogen rates based on a surface sample for nitrate. A minimum two-foot sample is needed to adjust nitrogen rates. Because nitrates can move with soil water and roots can grow 3-5 feet below the surface, deep soil samples are the only way to estimate soil nitrates. Soil sampling immediately before planting gives the best estimate of soil nitrates since there is less chance of nitrate losses before the crop needs the nitrogen.

Under limited moisture conditions corn will still respond to nitrogen fertilizer additions, what changes is the magnitude of the increase. Economic analysis of nitrogen rate studies has shown that the cost of nitrogen has to increase to more than double normal prices before rates are decreased. This is because nitrogen use is extremely profitable when the proper rate is applied.

Nitrogen use becomes less profitable when the nitrogen applied does not increase yield further. This is the year to take credit for previous crops, soil nitrogen, manure nitrogen and irrigation water nitrogen.

Herbicides recommended for broadleaf weed control in winter wheat include 2,4-D, Aim, Ally, Amber, Banvel, Clarity, Buctril, Curtail, Express, Finesse, Harmony Extra, Peak, Rave, and Starane. Some of these products should be combined to control a wider spectrum of broadleaf weeds in winter wheat. See pages 59-61 in the 2003 Guide for Weed Management for more information on recommended herbicides and herbicide combinations for winter wheat.

Herbicide combinations also are recommended to help manage the potential development of herbicide resistance in weeds. For example, recent screening work in the Nebraska Panhandle identified numerous kochia populations that were resistant to dicamba (Banvel or Clarity). This is in addition to known populations of kochia and Russian thistle that are resistant to ALS- inhibitor herbicides such as Ally, Amber, Finesse, and Peak. Chemical control of these weeds will require herbicide combinations involving products with different modes of action such as Aim, Buctril, or Starane.

Many broadleaf weeds commonly found in Nebraska winter wheat fields can be controlled at a modest price with amine or ester formulations of 2,4-D. Generally, ester formulations of 2,4-D are used at lower rates and provide better broadleaf weed control than amine formulations because they are oil soluble and readily penetrate plant foliage. Winter wheat must be between four tillers and joint stage when growth regulator herbicides such as 2,4-D, Banvel, Clarity, Curtail, or Rave are applied. In Nebraska, winter wheat generally is in the proper growth stage for these products in March to early May, depending on the planting date, season, and location. Wheat injury and yield loss can be significant if growth regulator herbicides are misapplied. The risk of wheat injury also increases with the addition of liquid nitrogen fertilizers (UAN) with herbicide mixtures. Do not add surfactant to the liquid fertilizer-herbicide mixture.

Crop report For the week ending Sunday, April 6, fieldwork was active as producers prepared for spring planting, according to the USDA’s Nebraska Agricultural Statistics Service.. Moisture, mostly in the form of snow, was received late in the week. This improved topsoil moisture supplies which are now a little better than a year ago. However, subsoil moisture supplies are beginning the crop year 85% short and very short, unchanged from last fall. Planting of oats and sugar beets was underway. Wheat condition improved slightly and rated 6% very poor, 18% poor, 42% fair, 33% good, and 1% excellent. These ratings are similar to last year. Oat seedings progressed to 28% complete and compared to 36% last year and an average of 34%. Sugarbeet planting had begun in the Panhandle and Southwest districts. This release is based on reports and data from FSA county directors, county extension educators, NOAA, and the High Plains Climate Center. For current and historic reports see: http://www.nass.usda.gov/ne/cropwthr/cmts_cur.htm

Ally+2,4-D from Dupont is for use in grain sorghum. It now has a Section 3 label. It consists of Ally at 1/20 oz and 2,4-D at 1/4 lb per acre. Do not use a surfactant with it. Apply when the crop is 3-15 inches high. If sorghum is over 10 inches, use drops.

Beyond from BASF contains imazamox. It can only be used post-emergence from the third leaf-stage to before jointing on IMI or Clearfield wheat. It controls pennycress, shepherdspurse, tansy mustard, jointed goatgrass and downy brome.

Camix from Syngenta contains mesotrione (Callisto) and s-metolachlor (Duall II Magnum). It can be applied preplant, preemergence or early postemergence in field and seed corn. Its strength is control of black nightshade, lambsquarters, pigweed, sunflower, velvetleaf, waterhemp ( including ALS-resistant types), foxtail and crabgrass.

Cimarron from Dupont contains metsulfuron. It is a postemer-gence herbicide for annual and perennial broadleaf weeds in pastures.

Cimarron Max from Dupont contains metsulfuron plus Dicamba and 2,4-D, which are growth regulators. It is for post application for broad spectrum annual and perennial broadleaf weed control in pastures.

Cinch from Dupont contains s-metolachlor. It is for preplant, pre-emergence or early postemergence control in corn.

Cinch ATZ from Dupont is Cinch with atrazine for corn.

Cinch ATZ Lite is similar to Cinch ATZ, only with less atrazine.

Equip from Bayer contains foramsulfuron (Option) and iodosulfuron for use postemergence for corn less than 12 inches tall. It should provide increased broadleaf control, especially for up to 4-inch sunflower, velvetleaf, lambs-quarters, and cocklebur.

Gangster from Valent is a copack of Valor and FirstRate intended for use as a pretreatment in soybeans. It is being marketed for use before Roundup Ready soybeans.

G-Max Lite from BASF contains Dimethenamid-P and atrazine. It can be used preplant, preemergence or early postemergence (under 12 inches) in field, seed or sweet corn. It has less atrazine than Guardsman Max. It is for control of black nightshade, pigweed, waterhemp, foxtail and crabgrass.

Keystone from Dow contains acetochlor and atrazine. It can be used preplant, preplant incorporated, preemergence, or early post-emergence (under 11 inches) in field or sweet corn. It is for control of black nightshade, kochia, lambs-quarters, pigweed, waterhemp, foxtail, and crabgrass.

Lumax from Syngenta contains s-metolachlor, atrazine, and mesotrione (the active ingredients in Bicep II Magnum and Callisto). It can be used preplant, preemergence, or early postemergence in field and seed corn. It controls black nightshade, kochia, lambsquarters, pigweed, sunflower, velvetleaf, waterhemp (including ALS-resistant types), foxtail and crabgrass.

Roundup WeatherMAX from Monsanto contains a potassium salt of glyphosate. It is labeled for many of the same uses as other glyphosate products including Roundup Ready crops. It is rainfast 30 minutes after application. Weathermax contains 5.5 lbs of active ingredient and 4.5 lbs of the acid equivalent. Roundup original had 4 lb a.i. and 3 lb a.e. This results in 22 oz of WeatherMAX equaling 1 quart Roundup or 32 oz of Roundup Original.

Steadfast ATZ from Dupont contains nicosulfuron and rimsulfuron and atrazine. It is for postemergence application in corn. It contains the same active ingredients as Steadfast only with more broadleaf weed control.

Planters and drills are now being built stronger and heavier with larger-diameter disk seed-furrow openers, making no-till easy. Check the double-disk seed-furrow openers on your planter now, before the planting season, for wear and proper adjustment. The individual disks can be adjusted inward as they wear by removing spacer washers from behind them. This keeps the two blades of the seed-furrow opener working together as one cutting edge.

If the two blades are mounted side-by-side, like on John Deere, Kinze, and White planters, there should be about 2 inches of blade contact on the leading edge. On staggered disk seed-furrow openers, like on Case-IH and Deutz Allis planters, the rear disk should be tucked in behind the leading disk, just touching. Adjust the disks or replace them to maintain the proper configuration. When properly adjusted, these seed-furrow openers can easily cut residue and penetrate the soil without coulters or row cleaners.

When no-tilling on well drained or highly erodible soils, leave the row cleaners up; residue left over the row will absorb raindrop impact. This will reduce erosion and crusting in the row and be a mulch to reduce drying of the seed zone. On poorly drained soils “spider wheel” row cleaners could be used to move the residue off the row to aid in soil drying. Unlike disk row cleaners, the spider wheel residue movers can be set to move only residue. If the soil is moved, any previously applied herbicides could be moved out of the row or the crop may be planted deeper into cooler soil. It also might form a furrow, which may wash out or crust over. In addition, if the soil under the residue is wet, soil disturbed by row cleaners or coulters will stick to the planter’s depth gauge wheels and other components.

Getting the seed down through the residue and into the soil is the second important step of the planting process. The seed must be placed into moist soil, at a depth suitable for proper rooting and growth, 2 to 2.5 inches for corn. To ensure penetration to desired seeding depth, downpressure springs may be needed to transfer weight from the planter toolbar to the individual row units. There must be sufficient weight on the units to keep the depth gauge wheels in firm contact with the ground to control planting depth. If the gauge wheels are loose, tighten the downpressure springs or add heavy-duty springs. In addition, there needs to be enough total weight on the toolbar to keep the planter drive wheels in firm contact with the ground to prevent slipping and to help keep the planter on the row.

Having enough weight becomes more of a problem with drills simply because of the number of rows per unit width. For instance, a six-row planter on 30-inch row spacing may require more than 3,000 pounds of weight just for cutting the residue and penetrating the soil (six rows times 500 pounds per row). Whereas, a drill of the same width on 7.5-inch row spacing has 24 openers and may require more than 12,000 pounds.

Sufficient weight must remain on the press wheels to ensure firming of the seed into the soil. Wet soil is easily compacted and care must be taken not to over pack the soil, making it difficult for seedling roots to penetrate the soil. In dry soil conditions, extra closing force may be needed. The key is to evaluate seed-to-soil contact, not the top of the seed-vee. As long as the contact is there, something as simple as a harrow that acts to close the top of the vee and pull light residue cover back over the vee may be all that is needed. This is a common practice on drills that use a narrow press wheel.

A wide variety of attachments are available to improve seed-to-soil contact and seed-vee closure. Unfortunately, some were designed to overcome specific problems and may be less effective or even detrimental in other conditions. Before buying attachments, evaluate any planter problems and how the attachment may function to solve the problem or if it just creates another problem.

With appropriate weight, downpressure, and adjustments, most current planters and drills will perform well in no-till conditions. A little time spent now will help avoid headaches and delays later during the planting season.

Once the planter is leveled, try blind planting with empty seed boxes. Stop with the planting units in the ground and check to see if the depth gauge wheels are in firm contact with the soil surface. If they are not, tighten the downpressure springs and try planting again. You may have to add weight to the planter for the springs to work against and to keep the drive wheels firmly on the ground. By putting a small amount of seed in a couple of rows, seed-to-soil contact and seed-vee closing can be observed as well. However, all these items should be rechecked when actual planting begins and as conditions change during the planting season.

Check the planter’s performance by evaluating the four functions of seeding equipment. By checking residue cutting and handling, soil penetration, seed-to-soil contact, and seed-vee closing, one can make the adjustments or modifications necessary to solve any problems encountered. There is plenty of time to make adjustments or buy attachments, if needed, before planting begins.

With any piece of equipment, the owner’s manual is the starting point for the initial settings and for making any adjustments. Valuable recommendations and trouble-shooting tips are in the manuals and also available from others who own and operate similar equipment.

Adding planter weight

Today’s planters have no trouble planting through heavy residue as long as weight has been added to the row units so they don’t ride up over the residue, leaving the seed on the soil surface. For most planting conditions, raise residue movers so they run about 2 inches above the soil surface. At this height, they act as a “V plow” to lay the stalks to the side so that you only have to cut the stalks near the base.

For corn planting, set the depth control for about a 2.5- to 3-inch planting depth on bare soil so that when the depth gauge wheels run on the residue and over the root stumps, you are still putting the seed into the soil to at least a 2-inch planting depth. This is why weight is added to the planting units. Slow the planter to 4.5 or 5 mph so that you don’t bounce over root stumps and add a “walking beam” depth control stop to John Deere planters if they don’t already have one. If your double disk seed furrow openers are sharp and working together, they will cut down through the old root stump and put the seed into soil, even through residue from 250 bu/ac corn production. (Remember, the root mass you see forms about 1 inch above the seed at the nodal roots.)

For no-till, especially under heavy residue conditions, put a pop-up fertilizer in furrow, regardless of the soil phosphorus level (ie: 5-7 gal/ac 10-34-0). With the heavy residue, the soil may be a little cooler than if you moved the residue aside so the slower growing roots may have a temporary nutrient deficiency. The pop-up gets that seedling going and overcomes that problem.

Research in Minnesota on flat, poorly drained soils showed a yield response to pop-up fertilizer in heavy residue (regardless of soil phosphorus level) and showed a yield response to moving some residue out of the row, but not an additive effect. For Nebraska’s conditions, most no-tillers should use the pop-up because shortly after planting, they will wish they had the residue back over the row to reduce soil crusting, conserve moisture, and reduce erosion. Also, disturbing the residue at planting makes planting much more difficult if the soil is wet under the residue. Without disturbing the residue, the depth gauge wheels of the planter ride on the residue and don’t mud up, making planting depth much more uniform.

After planting, that residue over the row reduces the night time cooling of the row area by reducing the amount of heat radiating from the soil surface. The cooling when residue is removed leads to more stress on the seedlings because the seed zone isn’t “buffered” with insulating residue. With the drainage of most of our Nebraska soils, the soil temperature difference isn’t usually enough to worry about moving residue at planting time.

Seed placement

Many no-tillers also equip their planters with either Keeton Seed Firmers or Schaffert Rebounders to make sure that all the seeds are in the bottom of the furrow. Both of these devices can be set up to put the pop-up fertilizer in the furrow. The Keeton has the advantage of firming the seed into the seed-vee while the Rebounder is less likely to “mud up” in sticky clay soils. These devices quickly pay for themselves with more uniform seedling emergence. When it comes to yields, non-uniform emergence hurts you far more than non-uniform spacing.

In poorly drained soils

Some producers are no-tilling into heavy residue on poorly drained soils where moisture conservation and erosion control aren’t concerns. They try to dry out the seedbed at planting time and don’t want any residue over the row.

These producers maintain as much standing, anchored residue as possible to maximize air flow down to the soil surface. They run a large diameter fertilizer opener on their planter to cut the residue and to provide for 2x2 placement (nitrogen and any higher salt content fertilizers that might be needed). They run residue movers, usually free floating ones, very shallow to part the residue (easy to do as the residue has already been cut). They also use a pop-up fertilizer in-furrow.

Many of them run spoked closing wheels to further till the soil so that it dries out and drag chains behind the wheels to smooth the soil surface. Most of these producers plant either in the row middles or slightly off the existing row rather than down the old row, however some notice reduced yields in the wheel track rows.

Almost any successful no-tiller will tell you that crop rotation is a key to success, especially under heavy residue conditions. Very few like to no-till corn-on-corn. Those who do say weight for penetration, a pop-up fertilizer, a soil insecticide, and the right hybrid to handle the stress are keys to making it work.

With the cooler soil temperatures, germination and seedling development are slower in the spring. The cool soil environment tends to make a mid-season hybrid planted into standing wheat stubble about as late as a full-season hybrid grown in a tilled system.

The use of spider wheel residue movers on the planter will help warm up the soil and also reduce or eliminate hairpinning residue in the seed furrow. Be careful not to remove the herbicide if applied preplant. Also, starter fertilizers applied in or near the seed furrows will help the young corn plant become established. Crop producers must give as much thought to hybrid selection as any other management decision. Using the wrong hybrid can wipe out all the potential gains from other correct decisions.

Hybrid maturity

Full-season hybrids have the greatest yield potential. A mid-season hybrid at one location may be a full season at another location as length of season varies greatly across the state. Length of growing season is affected not only by the number of days from the last frost in the spring until the first frost in the fall, but also by latitude and altitude. The field microclimate associated with residue cover greatly influences plant response to climatic conditions.

The biggest risk is selecting hybrids that are too extreme in maturity. A short-season hybrid has a lower yield potential in comparison with a long-season hybrid; however moisture limitations and/or frost may limit performance of the long-season hybrid in some years. The most frequent problem is with corn hybrids that are too full season. If a full-season hybrid has been used under conventional farming methods, it probably will be too late for a no-till system. A mid-season hybrid for the area probably will be preferred.

Available soil moisture

At planting time, the only real guide to the crop year is the amount of stored moisture in the soil profile. Within limits, it can be used to help decide how late the hybrid maturity should be. The more stored soil water available, the later you can stretch the maturity range in hybrid selection. But use this guide sparingly. Do not go to the extreme unless you are ready to assume the risk of a crop badly damaged by early frost or drought.

Full-season hybrids also are more risky if high populations are used. The better option with higher amounts of soil moisture is to use a mid-season hybrid, but increase the planting rate. If full-season hybrids are used, reduce the plant population.

Hybrid characteristics

A hybrid that has good tolerance to stress is important in non-irrigated conditions. This includes the ability to produce at least some yield under low soil water conditions and the capability to produce a high yield when adequate soil water conditions are present. Also, tolerance to seedling diseases, extended periods of hot weather, high winds and low humidity are important.

A hybrid that can produce good yields at lower plant populations also is critical. Because of limited moisture, no-till, dryland corn is planted at lower plant populations than irrigated crops, but the hybrids need to be able to respond when adequate moisture is present.

There are a number of other factors that need to be included in the selection of corn hybrids. These include plant and ear height, resistance to corn borer, resistance to stalk rot, stalk strength and strong root systems.

Hybrid information

The most important source of data is a farmer’s own yields under specific soil, climatic and management conditions. There are other ways to obtain comparative yield data on hybrids, as well.

One objective source is the latest report on the Nebraska Corn Hybrid Test. Several of these tests are conducted annually across the state, and the results are published in UNL Extension Circulars. Farmers can check the data from the sites closest to them to get an idea of how various hybrids performed under comparable conditions.

Each company is limited in the number of hybrids it can enter in these tests. The data from the tests include yields, plant populations, moisture at harvest, broken plants and dropped ears. This information is most valuable if averaged over several years, since yields of only one year may be influenced by environmental extremes.

Seed company tests are another source of yield information. The closer the test conditions are to a farmer’s conditions, the more reliable the data. These tests are most valuable in comparing hybrids within a company. Farmers should do some experimenting with hybrids on their own farms, as well.

On-farm hybrid tests

Try one bag of each of several hybrids that have the potential to be grown on your farm. It is important to check the hybrid at least two years before planting a sizeable acreage. Use every available source of information to make this difficult decision.

Soils under residue are cooler than bare soils. Early plantings generally yield higher than later plantings, but keep in mind that soils early in the season will be cooler. If you want to plant corn in late April or early May, pay particular attention to the five day weather forecast. If the forecast is for normal or above normal temperatures and sunny days, it probably will be fine to plant corn. If the prediction is for cloudy days and cool temperatures, you probably should wait for more favorable conditions.

By mid-May, plant corn regardless of the predictions, since warmer temperatures are ahead and the cool soil shouldn’t last long enough to damage germination too badly.

Many of our biggest success stories with forage and pasture crops recently have come from using annuals. No matter when you could use something to graze, including winter, an annual plant exists that could work well if managed properly. Many times a small grain like oats or rye fits our needs or a brassica like turnips or a millet may fit the bill. Also consider, however, the potential for later frustrations, one of the biggest of which are problems related to herbicide carryover. Many annual forages are sensitive to herbicide carryover, especially atrazine. Often we identify a forage crop to plant but the risk of failure is too high due to herbicides. This problem isn’t limited to annual forages. Perennial cool-season grasses and alfalfa also are sensitive to herbicide carryover.

If you answer yes to one of the following question, you might want to reassess your herbicide options this spring. Interested in flying rye or turnip seed into your standing corn later this year for extra fall pasture? How about planting triticale this fall or oats next spring? Or maybe irrigated pasture or alfalfa.

These options may not be available if you use herbicides like atrazine, Pursuit, Hornet, Command, or Treflan. Rethink your herbicide plans and keep your options open. Maybe you can control weeds and maintain the flexibility to plant forage later.

A large area of central, north central and western Nebraska continues in an "extreme drought," while the picture improved slightly for extreme northeastern Nebraska which is showing abnormally dry to normal conditions. (Drought monitor map provided by the National Drought Mitigation Center at UNL. Click on it to see the full U.S. map.)

Since the large snow storm hit Colorado in mid-March, there has been a regular procession of storm activity across the central plains, with the strong systems occurring at 7-10 day intervals. The upper air low in the Gulf of Alaska continues to shoot energy into the central Rockies, which in turn is helping generate strong low pressure at the surface. As long as this pattern continues, Nebraska should receive normal to above normal precipitation.

As these lows move from the central Plains east-northeast, they are weakening and losing their ability to tap the Gulf of Mexico for additional moisture. The eastern Corn Belt has been receiving precipitation, but levels have been 30-50% below normal for this season. If this continues into early summer, the eastern Corn Belt may be looking at serious drought concerns.

The latest information on levels for Lake McConaughy were released at the Governor’s Climate Assessment Response Committee (CARC) meeting April 3. Lake McConaughy is expected to peak at 815,000 acre/feet. Currently it stands at 800,000 acre/feet, compared to the 2002 spring peak of just under 1.1 million acre/feet. Approximately 70,000 acre/feet is reserved for the wildlife trust account. The Central Platte Public Power and Irrigation District (CPPID) representative could not specify when this water would be released for downstream wildlife issues; however, CPPID guarantees a full water allocation for this year’s growing season.

Current flows downstream of Lake McConaughy resulted from CPPID releasing water to help fill small irrigation lakes such as Sutherland reservoir. The CPPID representative stated that if normal temperatures and precipitation return to the state during the growing season, lake McConaughy levels would dip to 500,000 acre/feet by the end of the irrigation season. However, if this summer is a repeat of last summer, the lake level could drop to 300,000 acre/feet of water.

The heavy snows in Colorado and Wyoming likely will not have a significant bearing on the Platte River unless there is rapid runoff due to much-above-normal temperatures. This type of situation would result in above normal flows on the southern Platte River, which in turn would allow CPPID to hold back more water instead of releasing it to meet downstream needs. Normal temperatures and precipitation this spring would delay water deliveries into June and extend the resource into late August or early September.

The Republican River basin continues to be a problem. Accumulated streamflow volume since Jan. 1 is considerably below last year’s record setting year. Although rainfall and snowfall have been welcome over the last 30 days, three plus years of drought without significant snowfall have taken their toll on the basin. Unless heavy rainfall and associated flooding occur throughout the valley this spring, water restrictions may be likely for irrigators.

Impact sprinkler nozzle wear depends on the quality of the water and the system operating pressure. Heads on sprinkler systems operating at high pressure with low quality water will need to be replaced more often than those on low pressure systems. Inspect the system to identify sprinklers that are plugged, badly worn or not operating properly. Consider replacing sprinkler heads after about 6,000-7,000 hours of operation. Systems that pump a lot of sand may need to be replaced more often.

Sprinkler wear occurs at the nozzle outlet and at the seal located at the base of the sprinkler. Wear to the nozzle outlet allows increased flow that could potentially decrease water distribution uniformity. Check nozzle wear by inserting a properly sized drill bit into the nozzle opening. You will need drill bits with size increments of 1/128 inch to test all possible nozzle openings. If the drill bit moves easily from side to side, the nozzle is badly worn and may need to be replaced. This is also true for the nozzle portion of spray heads.

The seal at the base of the impact sprinkler is the wear plate that allows the sprinkler to rotate. After years of wear, the seal begins to leak, beginning with a small dribble and increasing to streams that can begin to impact sprinkler rotation. When leaks become noticeable, replace the sprinkler head.

Sometimes a sprinkler or nozzle fails or is lost from the pivot pipeline during operation. Producers often have spare sprinkler heads in their pickups for just this occasion. Unfortunately, only on rare occasions does the available sprinkler head match the one needing to be replaced. Now is the time to check through all the systems and make sure that the sprinklers are on the system in the right places.

Water application uniformity hinges upon having the right sprinklers in the right places. This is particularly true during abnormally dry summers because non-uniform water application can mean lost yields. Applying as little as 10% less water per revolution could mean up to 10 bushels less corn yield for the acres irrigated by that one sprinkler.

Some sprinkler issues can be identified by keeping good records. Regularly recording system flow rate and pressure may indicate that the nozzle opening has changed or leaks have developed. Each year take time to verify that the sprinklers are functioning properly.

With ground and surface water levels declining, Nebraska growers need an irrigation strategy to ensure systems pump efficiently and distribute water consistently, said Dean Yonts, irrigation engineer at NU's Panhandle Research and Extension Center at Scottsbluff. Growers need to be sure their sprinkler irrigation systems are applying water uniformly, which is especially important this drought year, the Institute of Agriculture and Natural Resources specialist said.

"If we apply too much water to one spot and not enough to another, we've not effectively used that water to the best of its ability to do something for us."

Yonts advises against running sprinkler irrigation systems to apply light, frequent applications early in the season when much of the water can be lost to soil evaporation, he said.

"Before the crop canopy develops, the water evaporates with each application," he said. "Once a canopy is established, the protection beneath the canopy allows the crop to use the water before it's evaporated in the air." Sprinkler height also is important. Yonts said sprinklers closer to the ground won't necessarily save growers a lot of water compared to those located above a corn canopy.

"Evaporation loss is not all that critical compared to what the runoff may be," he said. "Sprinkler devices in the canopy lose the ability to spread water over a large diameter. When sprinklers are in the corn canopy, they can only shoot water four or five feet at most."

Soybeans and dry beans could benefit from sprinklers closer to the ground, but if the field is in a corn rotation, it may not pay to risk the runoff in the corn, he said. If growers have the water available, creating a reservoir of water for the crops will be important.

"If you are going into the season knowing it will be dry, you may want to apply a little bit of water going into planting. Sugar beets would especially benefit from this," he said.

Farmers in areas facing restrictions will have to reduce pumping by decreasing how much water the crops consume. For example, corn can be stressed early in the season and then irrigated starting about two weeks before tasseling. Surge irrigators that lack the means of reusing irrigation flows from the lower end of a field may want to stress the lower end rather than to allow the water to run off.

Yonts said "the real criterion in a short water situation (with all types of irrigation systems) is to apply as much water as you can, but don't get runoff."

Crop choices also can be changed, he said. Shorter season crops or something that uses less water, such as soybeans or sorghum, is another option. Crop residues are another important tool in conserving water this year, Yonts said. Good residue cover reduces evaporation losses and saves moisture.

Also, maintenance and equipment readiness will save time when irrigation is critical this summer, Yonts said. Repair leaky gates and gaskets and look at spray nozzles.

"Check nozzles that had to be replaced last year," Yonts said. "We have to remember one or two of those sprinklers cover a lot of area. We could be applying way too much or not enough."

1. Change the engine oil and filter.
2. Clean and replace the air filter.
3. Check drive belts (if any).
4. Grease all drive shafts on pump and motor.
5. Clean, gap or replace spark plugs on gas or propane engines.
6. Replace fuel filters.
7. Check and clean the battery power cables.
8. Drain, flush and refill the cooling system.
9. Drain and replace the lubricating oil in the pump gear drive.
10. Refill the drip oil reservoir and allow approximately 1/2 gallon of oil to drain into the drip line.
11. Check the gear drive to be sure it is free moving and clean the nonreverse pins with an emery cloth; lubricate each pin.
12. Make sure all safety shields are in place.
13. Start the motor and allow it to run at 1000 rpm for 30-60 minutes to distribute the oil and check for leaks in the oil or cooling systems.
14. Check the operation of the chemigation safety equipment.