Agronomy Notes

October, 2004

COTTON BY DR. TOM BARBER

The Mississippi cotton crop has made a turn for the better despite previous setbacks. The majority of the Mississippi cotton acreage dodged a bullet when Hurricane Ivan took an eastward turn just before landfall.

Cotton harvest and defoliation in the Delta region was not affected by the hurricane and has been going full force. A few eastern and southeastern Mississippi counties were not so lucky, however, and in some cases 50% to 60% of the early crop may have been lost due to high winds and pounding rain.

Overall cotton yields, however, have exceeded many expectations. Earlier in August many, myself included, had a pessimistic view on the yield potential of the 2004 crop. However as we moved through September, defoliated and began harvest, yields have been shocking. I have had reports on yields ranging anywhere from 800 to 1600 lb., with the majority coming in around 1000 lb.. Harvest weather so far has been outstanding and the forecast looks good. So, hopefully with another two weeks of good weather we can put this season into the books.

There are many lessons to be learned from the 2004 season. To maintain a high yielding cotton crop, a good nutrient management plan is essential. Cotton is an intensely managed crop and requires high levels of fertility to produce acceptable yields. While cotton farmers generally practice good soil fertility programs, there is still a lag in fertility levels. This year many cases of potassium and nitrogen deficiencies were seen due to heavy rains which led to losses from denitrification and leaching and resulted in poor cotton root systems.

The three most important decisions that need to be made before the 2005 season are variety selection, soil fertility, and drainage. Most importantly, it is soil fertility management. If it has been several years since you have tested your soil, then it is time to do so now. You should test your soil at a minimum of once every three years, and if you are in a rotation program such as cotton and corn, or cotton and grain sorghum, then you should test every year. One of the main things to look for in soil test results is the pH levels. Low pH levels (<5.5) can reduce root growth and reduce nutrient uptake by the plant. If pH levels are low, applied nutrients such as nitrogen, potassium (especially phosphorous) will not be as effective. Fall is the preferred time to apply lime. Lime should be incorporated for best results several months before planting. Remember that all MSU lime recommendations assume a Calcium Carbonate Equivalent (cce) rating of 100, therefore it is important to know the CCE of the lime you are using and calculate your rate accordingly. Fall is also an acceptable time to apply mixed fertilizer to soils with a CEC of 7 or greater. Applications of mixed fertilizer to soils with a CEC lower than 7 could result in losses of the nutrient levels due to leaching. When basing your mixed fertilizer recommendations on the MSU soil test data remember that a 50% increase in potassium is warranted if realistic yields are over two bales per acre.

Right after harvest is also an excellent time to sample for Nematodes. Nematode populations are increasing, especially Reniform. Therefore if you have been experiencing problems with erratic growth and yields in a field or parts of a field, then it would be a good idea to test your soil for nematode populations. Using nematicides and/or rotating cotton with corn or grain sorghum have proven to provide significant yield increases in Reniform infested fields.

When considering land preparation for the 2005 season, keep drainage in mind. A lot of the problems that were seen this year with the June rain could have been eliminated with good drainage programs and land management. No-till systems are good agronomic practices in that they build up organic matter and tilth to the soil as well as reduce costs. However, after a year like 2004, where a record rainfall fell in June, it might not be a bad idea to go in and at least re-hip the beds. The worst cotton this year was no-tilled on flat ground and it did not fare well after all the rain. What did survive was delayed much longer than the cotton that was grown on a bed. At the very least, re-hipping in the fall with a stale seedbed, or winter cover crop would be a sound management decision to help alleviate problems associated with poor drainage.

SOYBEANS BY DR. ALAN BLAINE

Preliminary Yield Data is available on the web at www.msucares.com.

Soybeans yields vary every year, but the gap in Mississippi appears to be greater this year than last. So far I am aware of yields from 90 bushels per acre, on 40 acres of pastureland, to the low 20's on flat, irrigated buckshot. Regardless of where your average falls, yields are above average, and I believe our per acre average will exceed last year.

We had the highest percentage of early-planted soybeans ever. Eighty-three percent of the Mississippi crop was planted by mid-May. By Sept. 2, 50 percent of the crop was harvested (78 percent prior to Hurricane Ivan). This includes a sizable portion of dryland acreage (70 to 75 percent of Mississippi's soybean crop is non-irrigated and will be cut first, with some exceptions).

Yields were most affected on heavy ground, planted flat, or when irrigation had occurred prior to heavy rains. This is usually the most consistent yielding acreage, especially when rain does not interfere with irrigation. Problem areas had 12 to 20 inches of rain in June and could not overcome the effects of that much rain.

The larger the plant, the more capable it is of withstanding stress. Some acreage that received the heavy rains in mid-June were affected season-long. Planting beans on a row or bed, however, made all the difference.

The last two years have been "bean years," but more could have been done in some fields to improve yields.

Rowing up or using a wide bed is not in everyone's plans, but it will provide benefits in a year like this.

High yields were due to several inputs, but the one that pushed many fields to new levels was early planting dates. Research has shown that the earlier planting the better. Pushing planting dates too early can get you in trouble, but mid-March is not a major concern.

Failure of soybeans to yield well were due to stressed plants, aborted root systems, and above average disease pressure. Most of these problems are hard to overcome, but this year most acreage would have benefited from a well-timed fungicide application.

Improving drainage, utilizing fungicides/insecticides, and scouting fields are essential to higher yields. No one input, but a season-long combination of them. Fail to pull them all together and you will not consistently harvest high yields.

I am convinced earlier planting dates allowed many farmers to reach new plateaus. Some are still skeptical and fine-tuning will be required in many operations.

Let me put this in perspective. A north Mississippi grower (non-irrigated) last week said his best beans cut 74 bushels per acre. They were planted March 23, had two frosts, and were snowed on once.

Much of Mississippi was spared the wrath of Hurricane Ivan. Areas affected most were approximately two counties west of the Alabama state line from the coast to the Tennessee border. Rain amounts varied westward (one to four inches) with virtually no precipitation falling west of I-55.

Much of the area affected was dry and appears to have handled the rain, but a small amount of flash flooding occurred. The biggest concern was wind damage. Most of the crop in this area, however, was not as far along as the crop in the Delta. Being slightly later in maturity, this crop was in a better position to handle the weather. Areas south of Meridian were at a much greater risk.

As we continue harvest, reflect on problems and successes. Every year will be different, and it is easy to say what you should have done after the fact. Attempt to minimize the extremes by (1) improving drainage (consider rowing up, wide beds, pulling tail ditches, installing larger drain pipes); (2) picking the proper varieties (yield potential, disease package); (3) planting early; and (4) scouting weekly. Accomplish these objectives and year after year you will be in a position to maximize returns.

RICE BY DR. NATHAN BUEHRING

Harvest season for many rice producers within the state has come to a close. There is approximately 5% to 10% of the crop remaining in the field. Most of these acres were planted in fields that were precision graded this spring. Rice yields have been above average for many producers. USDA has the state average set at 6900 lb./A right now, which is 100 lb./A over last years record yield.

From my estimations and talking with producers across the state, the state average will be near or above last year's record. Several factors are responsible for these excellent yields: 1) good weed control, 2) good weather, and 3) good disease control.

This year we have had one of cleanest crops of rice that I have seen. More acres are moving into the Clearfield system due to increased seed availability. Keep in mind, CL 161 is not typically a high yielding variety, as shown in the variety trials. However, the value of having a clean rice field brings a greater benefit, especially when heavy red rice populations are present.

Clincher has also allowed producers to clean up any late grass escapes. One aspect that worries me, is that producers and consultants are waiting and relying on Clincher to control these escapes after the flood has been established. Some of the earlier work done by Dr. R.J. Smith indicated that 17 days of barnyardgrass competition reduced 'Newbonnet' yields by 10%. The yield reductions were almost double with 'Lemont', a semidwarf variety, in this experiment. So, the point I am trying to make is that producers need to do everything they can to control grasses as early and as much as possible, to achieve maximum yields. If all else fails, lets look at using salvage treatments.

The weather for this growing season was exceptional for growing rice. At Stoneville, there were only eight days that temperatures were above 95°F. The average high from May 1 to Oct 1 was 88°F and the average low during this time was 68°F. The below normal temperatures observed during flowering added to the yields by producing bigger kernels, which resulted in higher test (cup) weights as well. Also, there was no excessive rainfall during flowering to affect pollination, which was observed in Louisiana.

The occurrence of sheath blight was above average across the state this year, which was expected due to the cool/wet conditions during midseason. With this expectation, producers made more preventive applications to protect the crop from sheath blight. Therefore, a fungicide application resulted in a return on the investment more times than not.

With this year winding down, producers still need to think about finishing this year on a good note in preparation for next year. With the current drier weather, producers need to take advantage of this time to finish land preparation. Also, go ahead and open all drainage ditches so fields will be easier to drain in the spring.

A stale-seedbed approach has worked and will continue to work for many producers, especially on the heavier soils. To achieve maximum yields in rice, a crop rotation with soybeans will be necessary. Roundup Ready soybeans have not cleaned up the red rice infested fields as we initially thought. With these reduced tillage systems, there are only one or two flushes of red rice emerging. Therefore, we are not depleting the seedbank of red rice seed. So keep all of this in mind when rotating back to a conventional system. Our recommendation is still one year of Clearfield rice followed by two years of soybeans.

Another consideration this fall is winter weed management. Most of the fields that will be planted with rice next year will be clean and slicked off by the end of the month. Right now there is a lot of talk about fall Valor applications. If you plan to use Valor for winter weed management, target that application around mid-November to early December or spring to make the residual last until planting. I will discuss winter weed management in more detail in the up- coming months.

FORAGE BY DR. RICHARD WATSON

How much N should you apply on your cool-season pastures?

With low stores of good quality hay around the state, producers will need to maximize their cool-season forage production. Nitrogen (N) fertilization is one way that cool-season pasture production can be boosted to reduce our reliance on hay.

In many cases we tend to apply N rates above maintenance levels for our pastures plants (enough to keep them alive and able to complete their life cycle). However, N differs from the other major nutrients in that we can use it as a strategic mechanism to increase growth over and above maintenance levels. For example, 100 lb. of N/acre is generally more than adequate to maintain a healthy tall fescue or ryegrass pasture, but you could expect a linear growth response to applications up to 400 lb. N/A. So how much N should you apply? The answer to this question lies in economics (as it should for most decisions on the farm). If you look at N applications to your cool-season pasture as an investment, then you need to consider the expected return from that investment when deciding on how much to apply.

The response in cool-season grass growth for N applications will typically vary between a 10:1 and 15:1 response, up to 400 lb./A. This means that for every extra pound of N applied/acre above maintenance, you will grow an extra 10-15 lb. of forage. This response will vary depending on soil and plant growing conditions but using a 10:1 response is a good rule-of-thumb.

The table below shows the response of Gulf annual ryegrass to different rates of N in a study conducted by Louisiana State University.

Table 1. Growth Response of Gulf Annual Ryegrass to Different Rates on N

Nitrogen Rate
(lb. of actual N/A)

Forage Production
(lb./A)

Increase in Production
(lb./A)

0

4720

-

100

6885

2165

200

7419

534

300

9076

1057

400

10118

1042

500

10652

534  

 

Adapted from Robinson et al., 1987 LSU Agric Exp. Sta. Bull. 784.

Assuming these growth responses, the economic returns of N application will depend on how the extra forage production is used. For example, if increasing your N application rate on a ryegrass or tall fescue from 100 lb./acre to 200 lb./acre grew an extra 1000 lb. of forage dry matter (based on a 10:1 response), then the return on the extra 100 lb. of N would be determined by the use of this 1000 lb. of extra forage. You could use the extra 1000 lb. of forage to add one more stocker animal per acre for 90 days. If this animal grew at 2 lb./day, then your gross return on the extra N would be 180 lb. beef x $85/cwt = $153. If the extra 100 lb. N cost $32/acre (based on Ammonium Nitrate @ $240/ton) then your net return would be $121, making this a pretty good investment. In a cow-calf operation, an extra 1000 lb. of ryegrass or tall fescue dry matter could reduce hay feeding to your dry cows by 1-2 rounds bales of hay/acre, saving around $25-$50/acre (cost of making hay). In this situation the additional N application may or may not be a good investment depending on your hay quality and levels of waste, (for example, if it saves you 1 bale/acre it may not be economic but if it saves you 2 bales then it is). If cows with calves use the extra forage then the level of return may be better as there is generally more weight gain in the calf when better nutritional quality is provided.

The main point of this is that you need to consider how you will use the extra forage in justifying additional N applications. Obviously the price of nitrogen fertilizer, hay, and cattle are big factors in determining the feasibility of strategic N applications.

When to apply N fertilizer to your cool-season pastures?

In addition to N rate, the timing of N application to cool-season pastures is also important. Nitrogen is a very mobile nutrient and can be lost if not used efficiently by the plant. Plants are most able to use N when other conditions are good for growth, i.e. mild weather and adequate moisture. Therefore, there is not much point in applying large quantities of N when other conditions are not good for grass growth. The Best Management Practice is to apply N to cool-season grasses just before they are about to begin a period of rapid growth. For ryegrass and tall fescue, this rapid growth period is generally from March through early May. At this time these species will yield two thirds of their yearly total. Nitrogen applications shortly before or during this time will achieve the greatest response. Applying 70-100 lb. of N/acre in mid to late February is generally enough to support this rapid growth. There will also be an increase in growth from late September through October, particularly with tall fescue. Mid to late September applications of N (30 lb./acre) are recommended for this growth period. If you want to increase N applications to grow more forage, then the spring will achieve the best response. To avoid losing N from leaching and denitrification it is better to apply your N in several split applications rather than one big one. Denitrification and leaching loss of N will be greatest on waterlogged soils, so it is advisable to wait until these soils have dried out before applying N.

The most important thing to remember is that if you do not efficiently use the extra forage produced, there was no point in applying the extra nitrogen.

CORN/WHEAT BY DR. ERICK LARSON

CORN

Why were corn yields down? - Although Mississippi will likely set a new state record average yield this year, many growers accustomed to producing high-yielding irrigated corn were somewhat disappointed in their corn yields this year. Lower top-end corn yields can be attributed to the excessive rainfall primarily during June. Excessive rain saturated soil, stunted plants and caused denitrification (nitrogen loss), and promoted the infection of Northern and Southern corn leaf blight. Management options to address these problems will be addressed in future newsletters. Cloudy weather also reduced corn photosynthetic rates during the critical early grain filling stages. These factors reduced corn yield potential. However, the state average yield is predicted to be good because the detrimental effects of these factors did not usually accumulate until the latter grain filling stages (most corn was planted very early this year). Also, moisture levels were sufficient during early grain filling stages, when moisture supply is critical, particularly for dryland culture. The rainfall also caused more pollination failure (normally blank spots scattered around the base of ears) than normal this year. However, this effect was usually very insignificant.

Addressing Fertility Problems - Fall is the best time of year to address many fertility problems. Soil acidity is a perennial problem due to our warm, rainy climate. Applying and incorporating lime during the fall allows pH neutralization before crop growth begins and will substantially improve nutrient availability. The increasing use of corn in crop rotations has also contributed to phosphorus and potassium deficiencies. Phosphorus deficiency is especially prevalent when corn is grown following a rice crop, because the absence of a flood reverts soluble ferrous phosphates to unavailable ferric phosphates. Thus, considerable phosphorus application is required to overcome this phenomenon. Phosphorus deficiency also often occurs following cotton or soybeans, because corn requires double the amount needed for cotton or soybeans. Potassium deficiency often occurs following a high-yielding soybean crop, since 70 bu./a. soybeans remove about 100 pounds of potassium from the soil. Yearly soil testing generating recommendations for corn will prevent these problems. Take soil samples this fall, so that incorporation and neutralization of lime and broadcast fertilizer may occur before next spring. However, delay application of potassium on low CEC soils until spring because of leaching problems.

Fall Corn Borer Control - Southwestern corn borers overwinter as larvae underground inside the extreme base of the corn stalk. Disruption of this site using various tillage practices will theoretically reduce the survivability of larvae during the winter. Thus, producers with corn borer infested fields should consider this opportunity to alleviate next year's problem. Discing is considered the most effective (disruptive) treatment, due to its cutting, shredding and turning activity. Stalk shredding is essentially ineffective, since the Southwestern corn borer larvae are underground, inside the base of the corn stalk.

Fall Weed Control - Fall is the best time to reduce populations of some tough perennial weeds, including Johnsongrass and Bermudagrass. These perennial weeds are most susceptible to chemical application at this time of year, because they are storing energy in their rhizomes in preparation for winter. A translocated herbicide, such as Roundup or Touchdown, will be drawn into the rhizomes and have a higher likelihood of killing these reproductive organs. Chemical applications should be made when weeds are actively growing and at least two weeks before the normal first frost date. Tillage or stalk shredding should not be done after harvest, unless Johnsongrass has time to regrow to the boot stage. Successive tillage after chemical application should preferably be delayed 4-6 weeks.

WHEAT

Wheat Short List: A list of the wheat varieties which have had superior yields over the past several years is now available on the MSUcares website (listed in Frequently Asked Questions as "What are some good wheat varieties?") or at your county extension office. Plant characteristics, maturity, straw strength, disease resistance and other helpful information are noted for each variety.

Keys to High Yields: Drainage and fertility are two extremely important factors governing wheat yields which should be addressed in the fall. Wheat is grown during the rainy season, potentially exposing it to saturated conditions at any time. Thus, field selection and physical improvements, such as multiple surveyed water furrows and clean ditches, capable of improving drainage should enhance wheat yield potential tremendously. Wheat can be successfully grown using no-tillage culture, but compacted soil either near the soil surface or in a hardpan layer can limit drainage and root growth, which will reduce yield potential. Because wheat is a relatively inexpensive crop, growers often overlook fertility needs with the exception of nitrogen. Wheat is a very shallow rooted crop grown during the wet season, making it very nearly impossible to mine nutrients from the soil profile, particularly if substantial amounts of mixed fertilizer have not been recently applied. Therefore, growers will likely need to supply enough phosphorus and potassium to meet crop uptake and apply lime to correct soil pH, if needed, or yields will suffer.

Don't Plant Wheat Early: Early planting unnecessarily exposes wheat to potential development, fertility, weed and numerous pest problems which ultimately reduce yield potential. Early-planted wheat may proceed past the tillering stages (when it is most tolerant of sub-freezing temperatures) before winter induces dormancy, particularly during a warm winter. This substantially increases the likelihood of winter or spring freeze damage and nitrogen deficiency related to excessive fall development. Early planting also promotes infestation of insects and disease infection by increasing exposure. Lush vegetative development encourages fall infestation of aphids, Hessian flies and Fall armyworm. Aphids vector Barley yellow dwarf, a disease which stunts wheat development and may cause substantial yield reduction, particularly from fall infection. Fall infestations of both Hessian flies and Fall armyworms may destroy stands. Hessian flies also cause broken stems and lodging in the spring. The development of Take-all, a fungus which prematurely kills plants by rotting the lower stem and root system, is also encouraged by early planting. Early planting promotes winter weed problems by allowing the entire winter weed seed bank to potentially emerge and compete with the wheat crop. Delayed planting allows a flush or two of winter weeds to germinate before planting commences. Thus, producers may control these weed flushes with fall tillage or burndown herbicide application to reduce the potential weed population.

This is particularly important for hard to control winter annual grass species, such as ryegrass and cheat.

Optimum Planting Dates: The suggested wheat planting dates (within 1014 days of the average first frost date in the fall) should provide warm enough temperatures and long enough days for seedling emergence and tillering to begin before dormancy occurs. This normally corresponds to:

North and Central Mississippi: October 15 November 10

Delta Region: October 20 November 15

South Mississippi: November 1 November 25

Coastal Region: November 15 - December 10

Seeding Rates: Wheat growers should strive to establish 1.0 to 1.3 million plants per acre or 23 to 30 plants per square foot. Assuming 85% successful emergence planting with a grain drill, you will need a seeding rate of 1.2 to 1.5 million seeds per acre. Using the number of seeds per pound listed on the seed tag, you can then calculate how many pounds of seed per acre are needed. For example, 1.35 million seeds per acre divided by 13,500 seeds per pound is 100 pounds of seed per acre. This seeding rate is equivalent to 18 seeds per foot with a seven-inch drill spacing. If planting with a drill is not feasible, assume about 70% emergence with broadcast seeding combined with mechanical incorporation, or 55% emergence with aerial/broadcast seeding.

No-Till Production: Wheat can be successfully grown using no-tillage production by making some minor adjustments to compensate for leftover plant residue from the previous crop, compared to conventional seedbed preparation:

1. Adjust combine to spread residue evenly during harvest of the previous crop to allow subsequent planter operation and evenly distribute recycled nutrients.

2. Adjust drill to ensure proper penetration, seed placement, and furrow closure. Producers will likely need to reduce drill operating ground speed, compared to a conventionally prepared seedbed. Planting depth should be 1 to 1.5 inches below the soil surface. Planting success is highly dependent upon moderate soil and residue moisture content. Planting at an angle different than the previous crop row pattern may improve drill performance by reducing residue accumulation in specific locations on the equipment. Narrow drill row spacing (less than 7 inches) may compound equipment operation in heavy residue.

3. Growers may need to increase seeding rate 10-15% or to about 1.5 million seeds per acre for difficult planting conditions, particularly for heavy corn or sorghum residue. This may not be necessary when planting into well distributed soybean or cotton residue.

4. Use a burndown herbicide to kill existing weed vegetation before planting or wheat emergence. This weed control is particularly important for minimizing competition from winter annual weed species, such as ryegrass, Bromus species, and chickweed.

5. Phosphorus, potassium and lime should be applied in the fall before planting. These fertilizer applications should be based upon soil test analysis recommendations. If wheat will be subsequently double-cropped, phosphorus fertility should be based upon wheat uptake needs and potassium fertility upon soybean or grain sorghum uptake requirements. Nitrogen needs will primarily depend upon amount of crop residue present and the previous crop/N fertility program.

CERTIFIED CROP ADVISER (CCA) UPDATE

Certified Crop Adviser (CCA) Exam will be offered on February 4, 2005, at Mississippi State University. Registration deadline is December 17, 2004, no exceptions. For an application or study material please call Emily Rose at (662) 325-2701 or visit http://www.agronomy.org/cca/.

COTTON SHORT COURSE

GENERAL PROGRAM INFORMATION

The Cotton Short Course will be held at the Bost Extension Center on the campus of Mississippi State University December 8-9, 2004.

The short course will start on December 8th with registration at 9:00 a.m. followed by the welcome at 10:00.

On December 8th topics will include the following: OVT's, industry updates in variety technology, pest management (plant and stink bugs), new BT technology, flex, liberty link, new herbicides, and nematodes. An industry update will conclude the day around 4:00 p.m.

On December 9th the short course will resume at 8:00 a.m. with a quality session focusing on variety trial economics, quality and cost importance, harvest preparation, and gin aspects. The afternoon sessions will consist of agronomic and economic aspects in cotton/corn rotation, marketing cotton, plant population (till vs. non-till), subsoil vs. irrigation, soil fertility/nutrient management, and precision agronomics with variable rates will conclude the cotton short course around 5:00 p.m.

Pre-registration is $60.00, deadline is December 3rd. On-site registration is $80.00 starting December 8th at 9:00 a.m.

For additional information please contact Dr. Tom Barber, tbarber@pss.msstate.edu or Emily Rose, erose@pss.msstate.edu, or telephone (662) 325-2701.

 

Dr. Michael Collins, Department Head
Department of Plant and Soil Sciences
Box 9555
Mississippi State, MS 39762
(662) 325-2701

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