Agronomy Notes

April, 2003

COTTON

Dr. Will McCarty

Mississippi cotton acreage is still a little uncertain as this is written. Spring rains have delayed corn planting and rainfall in late March / early April will definitely have an impact on corn and cotton acreage. If corn planting slips behind forecast, cotton acreage could go up 10% from last year. Mississippi growers harvested 1,150,000 acres in 2002 and averaged about 826 pounds of lint per acre. Planted acreage for 2003 could go from 1,170,000 acres to well over 1,200,000. Regardless of acreage planted, timeliness is critical. Producers must do everything possible to reduce costs, reduce trips across the field, and try to survive 2003. 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 includes 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 cost and harvesting cost, especially in dry-land cotton. (2) 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. (3) If wet weather has kept you out of the field and ruts can't be filled in a timely manner, think outside the box. Look for non-conventional ways to fix ruts. Under some circumstances the use of a roller may allow "getting by" this year. Only use extensive tillage where absolutely necessary. Heavy tillage will dry the soil and increase compaction at the bottom of the plow layer. If seed-beds are dried extensively it will place dependency on getting rain before planting can occur.

Surface Drainage-Cotton cannot tolerate wet field conditions. Regardless of soil type, drainage is critical and must be managed. 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 after 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.

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 2003 Weed Control Guidelines for Mississippi, Extension/MAFES Publication 1532.

At Planting Fungicides - Planting cotton the first time is expensive and replanting can be even more costly. Even if you participate in a program that replaces your technology fee and your seed dealer feels sorry for you and gives you the replant seed - no one can give you back the two or three weeks that you have lost - period. If you have to replant, make sure it is for reasons other than "stuff" you can control. Seedling diseases can contribute to replanting, and non-lethal effects may contribute to reduced yields. 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 non-lethal 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 68º F 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 1/2 to 1 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 F) 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. Avoid the temptation of reducing seeding rates solely in an attempt to reduce per acre technology fee cost. It is much cheaper to plant a couple of extra seed than to have to replant.

Common sense must apply at planting time. Read the weather and take the necessary time to set the planter properly.

Plant Populations - Final 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 1363, Understanding and Using Results of Cottonseed Germinations Tests.

Pre-plant and Pre-emergence 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 Information Sheet 1619, Preplant and Preemergence Weed Control of Cotton.

 

SOIL AND NUTRIENT MANAGEMENT

Dr. Larry Oldham

According to various industry sources, nitrogen fertilizer supplies are adequate to meet the demand. Production is not a problem. Several facilities have restarted after suspending production when natural gas prices went over $10. Natural gas accounts for 70 to 80 percent of the cost of producing nitrogen fertilizer, therefore production closely depends on that market. As with other energy markets, it has been rather volatile following the war situation in recent months.

With an adequate supply, most fertilizer availability problems are tied to distribution concerns. Prices seem to be about $30 to $40 per ton higher than one year ago.

Remember to fully compare nitrogen prices, you should look at the cost per pound of actual N in the products. Multiply the decimal value of the N content of the fertilizer by 2000, then divide the price per ton of fertilizer by that product.

example 1:
UAN at $175 per ton with 32% N content
($175/ton) / (2000 lbs/ton x 0.32 N) = $0.273/lb N or $0.27 cents per pound of N

example 2: Ammonium nitrate at $245/ton with 33% N content
($245/ton) / (2000 lbs/ton x 0.33 N) = $0.37/lb N

 

FORAGE AND PASTURES

Dr. David Lang

Be Knowledgeable About Forages.

Growing grass is the first key to successful cattle production. If you take care of your land and your forages, you will be able to grow economical feed for your livestock. Many times, some people (and not just those new to the cattle industry) think about buying animals before they realize it's going to take a lot to feed them. Cattle eat forages at about 2-3 % of their body weight every day on a dry matter basis (not 'as-fed'). For example, hay is 80 to 85 % dry matter so it takes 25-35+ lbs of hay every day to meet the needs of a 1000 lb cow, if no other feed is available. That amount usually exceeds an animal's intake capacity, so it takes a mixture of higher quality forages or purchased supplements to meet all her nutritional needs. Can you afford to buy as much as she needs, or are you willing to grow enough of your own high quality forage ?

In order to grow the best possible forages on your own land, you need to become knowledgeable about soils and which forages are best suited to your situation. The best place to begin learning about the type of soil you have on your farm is from your county soil survey. You can find one at your local county extension office or local natural resource conservation service (NRCS) office. The NRCS will help you develop a farm plan and provide you with details concerning the suitability of your soils to grow particular forage crops, trees, or row crops. Once you know your soils, you can make decisions about which crops to plant. Don't try to grow plants which are not best suited to your soil type(s). Heavy clay soils are best suited to dallisgrass, tall fescue, some clovers, and johnsongrass. If clay soil is well drained, it may be suitable for bermudagrass. Bahiagrass grows best on sandy or silt loam soils, but bermudagrass will also do well on these lighter soils. Alfalfa must have a well drained loam soil to survive in Mississippi. The soil test from a chemical laboratory will tell you the amount of fertilizer or lime you need, but it will not tell you about the type of soil you have unless you ask for a soil texture test. This is generally an unneeded expense, since you can find out from your soil survey, or by simply rolling some moist soil between your fingers. If it sticks together into long, sticky "bread rolls", it has a lot of clay; if it crumbles easily, it has a lot of sand. Silt is powdery. Anything in between is called a loam.

It's your responsibility to gain the knowledge about your land and the types of forages best suited to your situation. Take the time to get to know the people in your local county extension and NRCS offices. Mississippi Cooperative Extension has several area agents who specialize in animal science/forages distributed throughout the state. The individual nearest to you with knowledge about forages may or may not be in the county you reside, but they have responsibility for helping folks in nearby counties. You can find answers by joining your local cattlemen's association and participating in their regular educational meetings. The Mississippi Forage and Grassland Council hosts an annual hay day. This year it will be in June 7th at Raymond, MS. Another educational opportunity is the national meeting of the American Forage and Grassland Council. This year it's being held at Lafayette, Louisiana so take advantage of it being within a day's drive of most of Mississippi. Monday, April 28th is set aside for producers. You can learn more about this meeting by visiting their web site: http://www.agctr.lsu.edu/forage/2003afgc.htm

Focus on your forages. Knowledge will save you time and make you money!

 

RICE

Dr. Joe Street

Planting. Rice planting was progressing well in the south Delta until the rains occurred the last week of March. Very little rice has been planted north of highway 82. Although the price in moving upward, I still expect the acreage to be down. Cocodrie will be the primary variety followed by Priscilla and Wells. The mills like the large grain of Priscilla but they cannot pay a premium for it. There is limited seed available of Francis, a high yielding variety from Arkansas. It is susceptible to blast so do not plant it in fields where the flood cannot be maintained.

Weed Control. 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. We are working on an aerial label for Command in Mississippi but it may not be approved prior to the use season. The rate of one gallon to 5 or 6 acres has worked well in most cases if adequate water is applied for activation. 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. While you cannot expect to make it to flood without additional grass control, it is possible in some fields if the permanent flood is established within three weeks after emergence.

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 rice meeting, 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. With the current formulation, mixing should not be a problem. As a precaution, mix the Command with water prior to adding it to the spray tank. 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. Bolero is still an effective treatment for residual barnyardgrass and sprangletop control plus aquatic activity. Newpath is good soil applied herbicide for Clearfield rice. Water management is critical for effective Newpath activity.

For early-planted rice, a soil applied herbicide is a good idea to provide residual grass control and keep you out of trouble should we have another cold period in May as we did last year. Some herbicides don't work in cold weather so having a residual herbicide is good insurance during periods of cold weather.

Fertility. If you have not taken a soil sample recently, it is still not too late. Phosphorus and Potassium can be beneficial if added during the growing season. Where phosphorus is deficient, it should be applied to two-to four-leaf rice. If potash deficiency symptoms occur, deficiencies can be corrected with an application of potash up to mid-season. It is uncertain if there is a yield benefit from potash application after mid-season.

 

SOYBEANS

Dr. Alan Blaine

Planting season is fast approaching. In recent weeks, I know many wondered whether the weather was ever going to change. Although very limited, a few days have afforded the opportunity for some planting of corn and soybeans in March.

Given our weather since late January, it has been difficult to make much progress. Some areas of the state were able to work some rutted fields for several days in mid-January, but many fields still remain rutted. With all this rain, many fields that were tilled have appeared as if re-seeded with vegetation.

Hopefully, most of the burndown materials have been applied by now. I realize that only in recent days has the weather been somewhat cooperative, but time is of the utmost importance if burndown materials have not yet been applied.

Even if you plan on working a field, any amount of green vegetation, particularly if it is rank, will cause fields to stay wet and cooler longer. If fields are rutted, odds are this will make planting of this crop later than most would like. Later plantings this spring may set us up for a later than normal fall once again.

Look at fields individually even if you plan on tilling. Some fields may benefit from a burndown to help dry them out. Keep in mind the burndown restrictions in the delta. As vegetation gets larger, do not fail to adjust rates accordingly.

Scout fields for weed species that are present and size. This is probably more important today than a month ago. Regardless of timing, attempt to get the job done as inexpensively as possible. I recognize there are numerous options, but at times some mixes and rates that are applied amaze me.

Many have been concerned about being late getting burndowns applied. I know in the last 10 days tremendous pressure has been put on pilots and ground rigs in an attempt to get burndowns out. For those that were able to catch a window early, that was great. However, this winter has been different than the past several years. It has been extremely wet which has kept vegetation suppressed to some degree. However, the extended, cold weather we have experienced coupled with extremely wet fields has delayed growth.

My point is that I do not feel most areas were late as of mid-March, but given the amount of available moisture this picture is changing rapidly. Many weeds are already blooming, so additional growth will be limited on some species. Small vegetation with a charged soil profile and 65 plus degree days will cause the picture to change rapidly.

Regardless of what has happened up to this point, "Think Early". As a whole, this crop is going to be more expensive than most, either due to the increased need for tillage, the need for a burndown, plus tillage, etc.

If tillage or a burndown have not been conducted/applied by now, it could further impact potential yields due to a delay in planting dates which might effect potential yields.

Even if a burndown is not 100% effective, it will slow the growth of existing vegetation. The use of Roundup Ready crops, or a second shot behind the planter can make a less than desirable burndown successful.

I am not going to address burndown options to any degree. However, a Roundup + 2,4-D tank mix is hard to beat in most situations. As vegetation gets larger adjust rates. Just adding additional Roundup can help you crawl out of a mighty big hole. I am concerned about the inconsistency of 2,4-D over the last 2 years. Based on this, all my 2,4-D recommendations will be with the amine formulation until we get a handle on what is happening and why. Gramoxone is a great option behind the planter, but many do not use it effectively. The reluctance in my opinion stems from the lack of control due to inadequate spray coverage/volume. In addition, Gramoxone benefits greatly from a tank mix partner, (Atrazine, Sencor, Canopy, Karmex, Cotoran, etc.) some type of photosynthetic inhibiting material.

A lot of interest has cropped up regarding planting of earlier maturing varieties (MG III's) given the variable weather pattern over the last two years. Remember, that earlier maturing varieties will be shorter in height and mature earlier as moved from north or south.

Early planting on cool, wet soils can cause plants to be even shorter. Plantings on mixed to sandy soils will not be effected as much as clays. Regardless, earlier maturing varieties are going to be shorter and mature earlier. It appears that some varieties are affected more than others. This effect on plant growth may be a photo-period effect or just due to the growth potential of a particular variety. For example, two that were planted last year were Delta King 3964 and Asgrow 3702. DK3964 has exhibited more growth early so it would be better suited for the early planting scenario.

An increase in growth of all Group III's and IV's can be achieved by delaying planting. Plant growth can be maximized by planting in a cotton window (April 20th - May 15th). Based on what we have observed thus far, maturity group IV's are going to be less effected by early planting than III's, so you may want to plant some IV's first and then some III's. Keep in mind though that IV's planted before III's will cause some acreage of both to mature at the same time. Utilizing this concept will not spread maturity like most attempt, but may be essential on some soil types.

One point we must remember this year is "seed availability". Do not push planting dates too early. We need to get a stand the first time because we cannot afford to replant, and if the need arises there is no doubt you will not replant with the same variety you planted the first time.

Don't get in too big a hurry to plant, but when you plant, do everything in your power to achieve a uniform, optimum stand. The use of the proper seed treatments, correct seeding rate, and optimum planting depth are all factors that must be given adequate attention.

 

CORN

Dr. Erick Larson

Don't speed - Don't try to make up time lost to wet conditions by planting corn fast. Poor corn plant spacing and seeding depth are common problems that can affect yield potential as much, or more than your actual plant population. Planter meter system tune-up and calibration can certainly improve planter performance, but performance also depends upon planter operation in the field. One common cause of seed distribution problems is excessive planter speed. A forty-inch row planter operating at 6 mph drops seeds at a rate 60% greater than the firing rate of a Thompson sub-machine gun. I would suggest keeping planter speed below 5 mph with vacuum planters and even lower for finger-pickup and plate planters. Fast speeds contribute to much poorer seed spacing and less seed depth uniformity because seeds may also roll and/or 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 rate - Nitrogen recommendations for corn in the midsouth are based entirely upon corn yield goal, since little if any nitrogen carryover lasts through the winter due to our wet, relatively warm climate. Growers should apply 1.3 pounds of nitrogen per bushel of yield goal.

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 reduced corn yield potential 9-23% compared to ammonium nitrate broadcast, N-sol injected, or anhydrous ammonia injected. This can reduce economic returns from $20-$80 per acre compared to ammonium nitrate 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 degrees F, 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.

 

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

Will McCarty, Ph.D.
Extension Leader

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