To Lime or Not To Lime

Nearly 20% of the samples received every year by the Soil Testing and Research Lab get a lime recommendation. Of all the crops we grow, soybean is probably the crop most affected by low soil pH as the activity of the nitrogen fixing bacteria slows down considerably and with it, the ability to form sufficient nodules to produce good yields.



The graphs show the cumulative yield response of soybean to Ag and pelletized lime. The objectives of this test were 1) to assess the yield response of soybean growing in soil with pH around 5.0, and 2) to compare the relative performance of Ag lime and pelletized lime.


Ag lime was applied at incremental rates equivalent to 700 lb/acre, while pelletized lime was applied at incremental rates equivalent to 500 lb/acre. Current lime recommendation for soybean in a silt loam is between 4,000 and 5,000 lb/acre Ag lime. At that application rate, a cumulative yield increase of more than 20 bu/acre was obtained. Pelletized lime at 500 lb/acre resulted in basically no yield gain after 2 years.


A significant yield increase was observed when pelletized lime was used, but at rates significantly higher than the 300 lb/acre commonly recommended by some fertilizer dealers. Results from this study clearly indicate that the best option to correct soil acidity is to use Ag lime.


A minimum of 1000 lb pelletized lime per acre were needed to obtain a significant yield increase, but such increase was only half of the yield gain observed when the full rate of Ag lime was applied. Lime tends to work best when applied preplant, at least 30 days before planting, and if it is incorporated.


Provided by:
Leo Espinoza, Associate Professor & Extension Soil Scientist
University of Arkansas
Division of Agriculture
lespinoza@uaex.edu - (501) 671-2168

Use of Poultry Litter on Soybean

Nathan Slaton, professor and director of soil testing with the University of Arkansas Division of Agriculture, talks about using poultry litter as a fertilizer option on soybean - taking advantage of the litter's phosphorus and potassium components.

What is the availability of P and K in poultry litter?
The availability of P and K in litter is generally believed to be similar to that in inorganic fertilizers like muriate of potash (0-0-60) and triple superphosphate (0-46-0). Some state recommendations suggest that only 60 to 90% of the P is available during the first year after application. Arkansas research with rice and soybean suggests that plants fertilized with equal amounts of P and/or K from poultry litter and commercial fertilizers take up similar amounts of P and K. Thus, we would recommend that the P and K in poultry litter be considered as 100% available during the first year. Because the nutrient content of poultry litter is not guaranteed, a representative sample should be collected and analyzed to determine how much P and K it contains per moist ton.

Will the nitrogen in poultry litter inhibit nitrogen fixation by soybean?
University of Arkansas scientists (and scientists at other universities) have researched soybean response to manure application and found that by the end of the season plants receiving manure had similar nitrogen uptake as plants that received no manure. Nodule formation may be inhibited or N fixation by the soybean nodules may be delayed when the soil contains moderate to high amounts of inorganic nitrogen from residual fertilizer or manure. However, so long as the proper bacteria or inoculum is present, nodules can still form and begin actively fixing atmospheric nitrogen when plant uptake or N loss pathways removes the extra inorganic nitrogen from the soil. In all the trials we have conducted in Arkansas, poultry litter has never reduced soybean yield, but, in several instances, has increased yields more than that of equivalent rates of commercial fertilizer.

I applied poultry litter in the fall and soil sampled several weeks afterward and my soil test results recommended that more P and K should be applied. What happened to the P and K from the poultry litter and do I need to apply more fertilizer?
This has been a common question for the last four or five years. If the nutrient content of the litter was known and the rate of litter application was uniform and sufficient for the soil, you must trust that the P and K are still in the soil and will be available to the crop. One must remember that the numbers on your soil test report represent neither the total amount of P and K nor the total amount of plant available P and K in the soil. The nutrient values on your soil test report are simply an index of availability with availability increasing as the soil test value (index) increases. Arkansas research shows that less than 50% of the elemental K fertilizer applied in the fall or winter, 3 to 5 months before soil sampling, shows up on your soil test report. Only about 20% of the applied elemental P was reflected on the soil test report 3 to 5 months after fertilization. There are multiple reasons for this. First, P and K fertilizer units are expressed as the oxide form (K2O and P2O5) rather than the elemental form (as expressed on your soil test report). For example, 100 pounds of triple superphosphate (0-46-0) contains 46 lb of P2O5, but only 20 pounds of elemental P. The depth of the soil sample would also influence how much of the applied P and K fertilizer could possibly increase soil test values. Finally, chemical and biological reactions in the soil will begin immediately after fertilizer application, transforming the solubility and availability of P and K in the soil.

Provided by:
Nathan Slaton, Professor & Director of Soil Testing
University of Arkansas
Division of Agriculture
nslaton@uark.edu - (479) 575-3910

Considering an Insecticide Seed Treatment?

Insecticide seed treatments (IST) have provided a positive return in the Mid-South in nearly 80% of research trials when compared to an untreated check (with a fungicide) according to multiple studies conducted over seven years by entomologists from the University of Arkansas Division of Agriculture, Louisiana State University, the University of Tennessee and Mississippi State University.

There may be several reasons for this but changes in production practices in recent years have changed the pest spectrum and made ISTs a very viable option for growers. Many growers are moving toward reduced tillage production practices which are more favorable for soil dwelling insects. Increasing costs of production along with the increasing value of soybeans add more pressure to growers and make it even more important to get the crop up to a good, healthy start. Soybeans grown under the early season soybean production system face the most stress. Often when growers plant in early-April or even late-March it can turn cold and wet making it a struggle for plants to survive. While these plants are stressed, pests can attack and cause damage to the developing plant.

With over 110 trials conducted in the Mid-South, we see an average yield increase of about 3.5 bu/A with ISTs. However, when evaluating early planted fields in these trials, average yields almost double to over 6 bu/A.

We have documented control of several pests including grape colaspis (lespedeza worm), thrips, grubs and threecornered alfalfa hoppers as well as suppression of bean leaf beetles. Another positive attribute to ISTs is an increase in plant stand and vigor, while not as consistent as the insect control, it is often observable and the more stressful the situation the more pronounced it can be seen.
ISTs are especially useful if you have had a history of pests in a field, have a lot of plant residue in the field at planting, have other stress factors associated with the field or if you’re concerned about weather.

Growers have several IST choices for 2011. Cruiser and Gaucho were the first products available and the ones we have the most data on, however, there are two new seed treatments which should provide similar attributes. These are the Inovate system and Acceleron. We encourage growers to price these seed treatments being careful to consider fungicide packages along with the IST component to get the best value. Based on this research data, ISTs can provide real value to growers.

Provided by:
Gus Lorenz, Extension Entomologist
University of Arkansas
Division of Agriculture
glorenz@uaex.edu - (501) 676-3124

University of Arkansas Division of Agriculture releases 2010 Soybean Updates and 2011 SOYVA Program

The 2010 University of Arkansas Division of Agriculture Soybean Updates are ready!

This annual publication details research data for the 2010 Soybean Performance Early Planted and Full Season and Double Crop Roundup Ready soybean variety screening trials. Useful data in the update includes yields, disease ratings, agronomic characteristics, herbicide tolerance, and more. These publications provide growers with current varietal performance and characteristic data to aid in their variety selections.

Varieties included in the update were tested in both the Division's 2009 and 2010 variety testing program. Since performance may vary from year to year, and two-year yield averages are better predictors of performance than data from a single year. Superior performance across several locations suggests that a variety has wide adaptability, thus multiyear and multi-location yields are particularly useful for making variety selection decisions.

The updates are available both online and in print format.

To access the updates online go to:
http://www.aragriculture.org/crops/soybeans/varietyyields/default.htm#Soybean Updates

Or, from the main Cooperative Extension Service homepage, click on "Agriculture", then "Soybean", then "Soybean Updates" from the list of bulleted items on the Soybean home page. Updates are separated into Early Season Roundup Ready, Full Season Roundup Ready and Full Season Non Roundup Ready (Conventional & LibertyLink). Updates from 2009 and 2008 are available for reference from this site as well.

Also, SOYVA 2011 is now available at http://soyva.uaex.edu/.

This program, designed by the University of Arkansas Division of Agriculture, is designed to assist clientele with soybean variety selection. Variety selection should consider yield potential and avoidance of environmental, cultural and disease problems.

Printed copies of the Early Season and Full Season and Double-Crop Roundup Ready Soybean Performance Results were shipped to County Extension Offices in soybean-growing counties on January 27. Contact your local County Extension Office for a copy or more information. Or, contact Jeremy Ross, soybean agronomist for the Division.

Provided by:
Jeremy Ross
Extension Agronomist - Soybean
University of Arkansas Division of Agriculture
jross@uaex.edu - (501) 944-0621

2011 New Crop Soybean Booking Prices

Forward booking prices for 2011 crop beans followed a pattern similar to the cash market, but with less size of movement. New crop beans opened the week at $13.22, an 11 cent loss over the weekend. A decline of 24 cents on Tuesday was partially recovered on Wednesday before the market essentially went flat, closing on Friday at $13.08, a 25 cent overall loss from the previous Friday closing price. West Memphis had the top daily price of the week with $13.43 on Monday. Old Town/Elaine at $13.37 and Helena at $13.36 were the only other reporting markets exceeding $13.27 on the same day. The lowest price of the week was $12.73 at Wynne on Tuesday. The price margin between cash market old crop beans and new crop booking prices increased from 65 to 73 cents, a reversal from the price narrowing that had been seen just one week earlier.

(Market average prices stated in this report are unweighted averages of the state markets surveyed by NASS. Price data was based on USDA LR GR111 Arkansas Daily Grain Reports.)

Provided by:
Bob Stark, Agricultural Economist
Southeast Research & Extension Center
University of Arkansas at Monticello
stark@uamont.edu - (870) 460-1091

2010 Crop Soybean Cash Market Prices (1/24/11 - 1/28/11)

The Arkansas cash soybean market lost 7 cents over the fourth weekend of January and opened at $13.88. The trading week lost another 30 cents on Tuesday before steadily regaining most of the lost ground and stabilizing to end the week at $13.81, an overall 14 cent decline from the previous Friday closing price. Cash beans have now lost a total of 26 cents since their last weekend close above $14.00, the January 14 closing mark of $14.07. High individual market daily average for the week was $14.15 at West Memphis on Monday. The lowest individual market daily average was found on Tuesday with $13.39 reported at both Jonesboro and Wheatley.

(Market average prices stated in this report are unweighted averages of the state markets surveyed by NASS. Price data was based on USDA LR GR111 Arkansas Daily Grain Reports.)

Provided by:
Bob Stark, Agricultural Economist
Southeast Research & Extension Center
University of Arkansas at Monticello
stark@uamont.edu - (870) 460-1091