Agronomy Notes

April, 2002

Contents:

CORN
GRAIN SORGHUM
PASTURE PRODUCTION FOR HORSES
SOYBEANS
RICE
COTTON

CORN

Dr. Erick Larson

Planting recommendations - If mother nature permits, there likely will still be ample time to plant the state's 2002 corn crop. Latest optimum corn planting dates range between April 10 and April 25 from central to northern Mississippi. Late planting increases the likelihood of yield reduction by subjecting corn to drought stress during pollination and grain fill, and increases the likelihood of insect and disease problems. Planting into a warm, moist seedbed should improve stand emergence considerably, so decreasing seeding rates to allow for near-perfect emergence would be appropriate.

Don't speed - Don't try to make up time lost to wet conditions by planting corn fast. Research studies indicate that many growers could improve yields 5-25 bu./a. by just improving seed spacing. The maximum speed for maintaining high planter performance for plate-type planters is 4.0-4.5 mph and vacuum-type planters is 4.5-5.0 mph. Speeds exceeding these values will cause much poorer seed spacing and less seed depth uniformity because seeds will roll and bounce in the seed furrow.

Scout fields - Scout corn for stand, insect and weed problems every 2 to 3 days until corn is about 12 inches tall, and be prepared to take control measures. Insects or weeds may quickly ruin a good stand or become too developed to control. Timely problem identification allows specific treatment selection and application timing, which likely will improve control and lower expenses.

Nitrogen sources and application - Corn yields may differ drastically depending upon nitrogen fertilizer source and application method. No-tillage research studies in Missouri and Tennessee show N-sol and urea (urea-containing nitrogen sources) broadcast on the soil surface reduce corn yield potential 9-23% compared to ammonium nitrate broadcast, N-sol injected, or anhydrous ammonia injected. This reduces economic returns (using current fertilizer prices, application costs, and these replicated research yields) $19-$83 per acre compared to ammonium rate or N-sol injected. The urea-containing nitrogen sources reduce corn yield potential because they are subject to volatilization when applied to the soil surface. Surface-applied urea sources readily volatilize when substantial crop residue or vegetation is present on the soil surface, temperatures exceed 55 degrees F, and when rates exceed 100 lbs. N per acre, until rainfall incorporates the nitrogen. Thus, corn producers should minimize or eliminate surface application of N-sol or urea in their fertility program.

Nitrogen application timing - Split application of nitrogen fertilizer generally improves corn nitrogen use efficiency. Corn extracts less than 15% of its seasonal nitrogen uptake before rapid vegetative growth begins. Maximum nitrogen use rate occurs just prior to pollination. During early growth stages, considerable nitrogen may be lost due to denitrification and leaching. Therefore, the bulk of a split nitrogen application should be delayed until just prior to rapid vegetative growth. This growth period begins at the V10 growth stage (10th leaf stage) which occurs about 40 days after plant emergence or when plants are about 30 inches tall. The normal nitrogen recommendation specifies applying 1/3 of the total N at planting and applying the remaining N about 30 days later.

GRAIN SORGHUM

Dr. Erick Larson

Don't plant too early - Grain sorghum will not germinate at soil temperatures less than 65 ºF, which will greatly increase likelihood of stand failure. Thus, the optimum planting dates for sorghum are similar to those for cotton: April 20 to May 15. Optimum seeding depth is 1 1/4 - 1 1/2", rather than a shallower depth at which cotton and soybeans are planted.

Don't plant too much seed - A final plant population ranging from 40,000 to 70,000 plants per acre should produce optimum grain sorghum grain yields grown in dryland culture. Grain sorghum has tremendous ability to increase yield potential if given favorable environmental conditions, especially if plants are spaced uniform. However, excessive stands compound drought stress, lower stalk quality and increase disease likelihood. Sorghum seeding rate should exceed the population goal by 10 to 20% depending upon seedbed conditions and planting date. This over-planting rate is relatively high because sorghum's seedling vigor is low, compared to corn.

PASTURE PRODUCTION FOR HORSES

Dr. Malcolm Broome

Feed is the single, largest cost item in maintaining horses and only a few horse owners utilize grazing to its best potential. Pasture is generally the least expensive way to meet part of the nutritional requirement of horses and offers the added advantage of exercise, however horses are limited in their ability to use low quality forages.

Research shows mature, idle horses can meet their needs with forage also yearlings can meet most of their needs on well managed, dense stands of bermudagrass. One to 2 acres of this type pasture will be sufficient for a mature horse compared to 5 acres of poorly managed. Even though horses are suited for grazing and have similar nutritional needs to beef cattle, consumption becomes the limiting factor. Thus forage quality must be greater for horses which means spending a little more per acre to develop good quality pastures.

Given a choice and sufficient time, horses seem to pick and choose one forage over another. Georgia research on winter annuals shows ryegrass, wheat, and oats being the most preferred of our cool season grasses. Correctly managed bermudagrass and bahiagrass are highly palatable for most horses. Availability of high quality forage in sufficient amounts is usually the limiting factor. Protein and energy are the two nutrients of most concern. The nutritive value of forage is determined by maturity, soil fertility, forage species and owner management. Proper grazing management prevents overgrazing by maintaining 50% leaf area, reduced plant stress, gives forage a rest period, and uses pasture size as a grazing management tool. A pregnant mare can range in forage consumption from 1.7 % dry matter(DM) before foaling to 2.4 % DM once she foals, also energy can be 10 to 20 percent below her need during lactation when left strictly to grazing.

Horses have a different grazing behavior than cattle resulting in a different or quicker effect on pasture grasses. Horses tend to bite plants to the soil line, regraze short new growth, trample forage in congregated areas, contribute to specific areas of manure buildup, and in turn, this favors competition by weedy species. The owner needs to manage the pasture to provide at least two weeks rest following each graze down, plus maintain proper fertility to produce a quality forage. This pasture will be well drained, free of holes or poisonous plants and surrounded by a safe fence. A source of shade and clean water is necessary along with a salt and basic mineral mixture.

Managed under the above conditions, a bermudagrass pasture could provide gains of 1.0 to 1.2 pounds per day and small grains less (0.8 to 1.0) due to the water content of these grasses. However, research has shown when 1% grain by body weight is fed along with pasture, gains are improved. When pasture is overstocked or grazed below a 3 inch grass height average daily gain is much less. Successful horse pastures depend on the selection of the right forage(s), maintaining a quality stand by using proper pasture management, and keeping that balance to favor forage growth over weeds. Ideally, a horse pasture will have high quality forage that will for the most part, depending on the age and use of the horse, provide optimum nutrients.

SOYBEANS

Dr. Alan Blaine

As planting season approaches, it appears that soybean acreage will increase. Although there is a lot of uncertainty, it appears that the increase in soybean acreage will be coming out of cotton. Given current commodity prices, there is certainly not a good reason to make this change. The main driving force is the fact that a soybean crop can be planted for much less than corn or cotton

Out of pocket expenses (not including equipment, management and rent) can be as low as $50 per acre. This all depends but it has been done in the past.

As we approach planting, I would encourage you to keep the following production thoughts in mind.

1) Planting Dates:

The bulk of our state acreage (dryland) needs to be planted as soon as possible. Late March, through early April, is an ideal starting time to consider. We do not have to rush planting of irrigated beans. If we can get this portion of our crop planted from mid-April - May 10, optimum yields from these plantings should be achieved.

The major input that will influence this is irrigation scheduling. Water the crop when it needs it, not based on what you have done in previous years.

I was in a meeting recently and heard two of my counterparts from other states address planting dates and maturity groups. When asked what was the optimum time frame for planting beans in Minnesota, his answer was that the best corn and soybean yields year in and year out were planted the week of April 15th. Give this some thought. If they want to plant in mid-April in Minnesota, we should have minimal concern in Mississippi. Our major concern is trying to dance around the heavy rain showers we often experience in April.

My counterpart in North Carolina stated that they have tested maturity Group IV's for several years comparing them to fuller season maturity Groups V-VII. Over the last several years, the Group IV's have out yielded the later maturity groups, but they still do not recommend the plantings of Group IV's. I will let you try to figure that out, because it makes little sense to me.

2) Minimize field preparation in the spring. Everything you do from harvest to planting should be centered around "earliness". Think early. Stale seedbeds, no-till, and early burndowns all are options that should be used to the fullest.

3) Use the proper seed treatment.

4) Calibrate planters each year. Check seeding rates when changing varieties. Base seeding rates on seed per foot of row, not pound per acre. In previous years, we have seen higher than expected emergence which is probably due to seed treatments. Do not overplant. It is imperative that you properly calibrate planters.

5) Plant shallow. Prior to May 1 plant for a rain. Many will disagree with this suggestion but it is a way to minimize stand problems. It is going to rain in late March and April (most of the time). Moisture loss is not very great this time of the year and the intensity of rains during this time can wreck havoc on emerging soybeans. Seed can lay in the ground a long time before emerging this time of the year due to cooler temperatures. Soil temperatures warm faster at shallower depths thus aiding in more rapid emergence.

6) If planting soybeans on fields where beans have not been planted in the last 3-5 years, innoculate the seed. This input is a minimal cost, but can be expensive if neglected. Several new innoculant (liquids) are available that may speed this process.

Fertility/pH. This is often not a concern where soybeans are rotated with other crops, but in a monoculture, problems occur more often. This fall over 50% of the samples we pulled in our SMART fields in the Delta were in need of additional nutrients. If you feel that because you are in the Delta fertilizer is not needed, you may need to reconsider. One of the least expensive inputs you can take advantage of is a soil test.

The need for burndowns has varied tremendously this year. Use has ranged from a full blown program to try to plant and wait. In many fields where Roundup Ready soybeans were planted, we added residual materials to the mixture hoping for some premergence maturity. Several tank mixes look great (several options are also available) and have offered broader spectrum control and faster activity based on a Roundup program alone. Our plans are to hopefully get enough residual activity to minimize postemergence applications on some fields.

For those of you planting early, keep an eye on weed emergence. Early planting can offer you a real advantage as far as weed control goes, but it requires a less than conventional approach. Watch weed pressure, keep track of when emergence occurs and control weeds for the first 4-5 weeks after emergence of the crop. You will find that with early planting, early emerged weeds don't grow off normally. Time your postemergence spraying to avoid competition but coincide with the crop canopying. It will not happen in all fields but many may only require 1 over-the-top application.

Remember drilled plantings will need spraying quicker than row plantings because of faster canopy closure.

In recent years we are seeing the benefits of increased management. Give some thought to farming soybeans. I truly believe your efforts will be rewarded.

RICE

Dr. Joe Street

Command has become a widely used herbicide for grass control in rice. It may be applied using ground equipment up to 14 days before planting or within 7 days after planting but prior to weed emergence. The rate of one gallon to 5 or 6 acres has worked well in most cases if adequate water is applied for activation. The dry conditions of last spring did remind us again that Command must have adequate moisture for maximum effectiveness.

For best results, apply Command after planting on dry soil and flush within 5 days if adequate rainfall has not occurred. Rolling the field with a flat roller after planting and before Command application improves effectiveness of the Command and decreases the potential for injury to the rice. Rolling will also improve the seed to soil contact and improve germination and result in a more even emergence. Command provides a maximum of 3 to 4 weeks of residual grass control. To get maximum benefits of Command, plant rice when the soil is warm enough for rapid germination which will allow the establishment of the permanent flood within 4 weeks after planting.

Command may be applied as an early postemergence treatment. For control of existing grass at the time of application, include a postemergence herbicide registered for control of the weeds present. At a recent meeting of the Mississippi rice consultants, there was considerable discussion on the compatibility of Command with several postemergence herbicides. There was no clear consensus but there was enough discussion to indicate that several growers have had problems when mixing Command with other herbicides or fertilizer. Some rice growers have been mixing Command with postemergence herbicides without a problem while some have experienced severe problems. We are not sure what is causing the problem but FMC, Extension, and Consultant personnel are working on the issue.

I am not ready to say do not mix Command with other products but I do recommend caution if you intend to mix anything with Command. The primary requirement is very good agitation and following exactly the mixing instructions on the Command label. It is a good idea to try the compatibility test as described on the Command label. When mixing Command, fill the tank one-fourth to one-third full of water and add the dry formulations first (if used), then add Command followed by any liquid or EC formulation.

Other soil-applied herbicides are also available. The tank-mixture of Facet plus Prowl is an effective weed control system to control grass and broadleaf weeds plus provide residual activity. You can expect about one week of control per tenth pound of Facet. Check the guarantee from BASF concerning retreatment if necessary following use of Prowl plus Facet. Bolero is still an effective treatment for residual barnyardgrass and sprangletop control plus aquatic activity. Newpath is also available for Clearfield rice.

COTTON

Dr. Will McCarty

It appears that Mississippi cotton acreage will be reduced in 2002. Mississippi growers harvested 1,600,000 acres in 2001 and may plant more than 400,000 less than this in 2002. Regardless of acreage planted, timeliness is critical. Producers must do everything possible to reduce costs, reduce trips across the field, and try to survive. Take a hard look at every operation; if you aren't sure it is necessary, eliminate it.

A couple of areas where trips can be reduced and money saved include the following: (1) If you aren't sure you can side-dress on time, put all nitrogen out pre-plant or at planting. Late side-dress applications, approaching first bloom, can delay maturity and increase insect control and harvesting cost, especially in dry-land cotton. (2) After three years of drought we should have learned to take care of our moisture. If you did not subsoil in the fall - the soil may be too wet this spring to give desired results. In this case perhaps you should not run your sub-soiler and op to rip the non traffic middles instead. Ripping the non- traffic middles with a chisel shank will increase water infiltration and may boost efficiency of sprinkler irrigation systems.

Surface Drainage - Cotton cannot tolerate wet field conditions. Regardless of soil type, drainage is critical and must be managed. With acreage expanding onto mixed-textured fields to clay fields historically planted to soybeans or rice, you must address drainage. Establish tall beds in fields that have been formed to flat grades; drains must be opened to allow rapid drainage of water away from the field. Fields not land-formed should have water furrows properly placed for rapid field drainage and drains opened to allow rapid movement of water away from the field.

Establish water furrows and field drains before planting, and clean out afer planting. The "ditcher" should keep up with the planter each day. Do not let the day end and catch you behind on water furrow placement. Adequate surface drainage is absolutely critical in cotton production. If no-till farming is used, you may eliminate in-season cleaning of the drains.

Adjust planters to consistently close the seed slot and to shape the row where water will drain into the middles and not into the seed slot. Regulate planters to a planting depth of 0.5 to 1.25 inches, depending on moisture. Seed-soil contact is critical, since the seed will not draw water from farther away than about 10 millimeters. - Remember: the three most important things in cotton production , 1) drainage, 2) drainage and , 3) drainage.

Timing is critical - If you look around, you will realize that most cotton farmers do the same types of things, but it is timing, and the soil they do them on that makes the difference.

Rotational Crop Restrictions - Many herbicides used in soybeans, rice, or corn have planting restrictions for cotton. Before planting cotton in fields where other crops may have been planted last year, determine the herbicide program used and evaluate the risk of planting cotton this year. Rotational-crop restrictions may be found on product labels, or for your convenience, this information is included within each crop section of the 2002 Weed Control Guidelines for Mississippi, Extension/MAFES Publication 1532.

At Planting Fungicides - Replanting is costly. Seedling diseases can contribute to replanting, and nonlethal effects may contribute to reduced yields. Seed supplies of popular varieties are short this year. With the probability of not being able to replant to the same variety, cost of seed, cost of replanting, potential yield reductions because of delays and nonlethal effects of seedling diseases - the use of an at-planting fungicide program is recommended. Several options are available to fit every planting situation. For more complete information, refer to Cotton Seedling Disease Control, Extension Publication 802.

Soil Temperature - You can plant high-vigor cottonseed when the soil is a minimum of 68 ºF in the top 2 inches, measured at 8 a.m., for 2 to 3 consecutive days. Also, a good 5-day weather forecast is important. Cotton is planted about 2 to : of an inch deep. At that depth, the soil is not well buffered against daily changes in temperature. By daylight, the seed-zone temperature will be within one degree of ambient temperature. The absorption of water that occurs in the first 24 to 36 hours after planting is critical. Unfavorable soil temperature (especially less than 60 ºF) during this period can result in root and seedling injury. Use standard germination and cool-test results to determine the planting order of seed lots or varieties and to determine seeding rates. Ask your dealer for the actual germination and cool-test values of your seed. It should be the seedsman=s responsibility to supply this information to your dealer. You want a warm germ above 80 percent, with a cool test of 60 percent or better. In some years, 50 percent in the cool test may be acceptable, but plant those seeds with a cool test below 60 percent only in very favorable conditions.

The cool test information is especially important. In most cases, the cool test data will more closely approximate the actual field emergence of a lot of seed than will the warm test. The conventional warm test is not a good indicator of the strength of a seed lot, only its viability.

Common sense must apply at planting time. Some varieties are apparently in short supply this year. It is possible that if we get into a real replant situation, there will not be enough seed of some varieties to resupply the market. Read the weather and take the necessary time to set the planter properly.

Plant PopulationsCFinal plant population should be 3 to 4 plants per foot of row in 38- to 40-inch rows, or 2.8 to 3 plants per foot of row in a 30-inch row. Long-term research indicates cotton is tolerant to a plant population range between 30,000 and 70,000 plants per acre with significant impacts on yield. A population in the 45,000 plants per acre range (row cotton), however, will produce a more uniformed plant shape and uniformed fruiting pattern.

Set planters to deliver a desired number of seeds per foot of row, based on desired stand and seed quality, rather than a specified "pounds per acre" of seed. Refer to Extension Information Sheet 1364, Understanding and Using Results of Cottonseed Germinations Tests.

Preplant and Preemergence Weed Control - Base your selection of pre-plant and pre-emergence herbicides on expected weed species and pressure. Rate selection should approximate the recommended rates for soil type. Calibration is critical. For help in selecting herbicides and rates, refer to Extension Publication 1619, Preplant and Preemergence Weed Control - Cotton.

 

 

Department of Plant and Soil Sciences
Box 9555
Mississippi State, MS 39762

Will McCarty, Ph.D.
Extension Leader

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