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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, 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.
Use of Poultry Litter on Soybean
Nathan Slaton, Professor & Director of Soil Testing University of Arkansas Division of Agriculture
nslaton@uark.edu
(479) 575-3910
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.
Economics News
Bob Stark, Agricultural Economist, SEREC & UAM School of
Agriculture, Monticello
stark@uamont.edu
(870) 460-1091
This market economics component looks at cash market and forward pricing quotes from selected markets as reported to National Agricultural Statistics Service in Arkansas.
Arkansas soybean markets had another strong week of trading after retreating 8 cents over the weekend. The Arkansas cash market opened on Monday at $13.46 and posted gains every trading day of the week (Figure 1). The market leveled off on Friday to close the week at $14.01, a gain of 55 cents during the week and 47 cents over the previous Friday closing mark. High individual market daily average for the week was $14.24 at West Memphis on Friday with Helena two cents behind at $14.22 on the same day. Half of the 14 reporting markets finished the week above the $14.00 level. The lowest individual market daily average was found on Monday with $13.21 reported at both Jonesboro and Wheatley.
Forward booking prices for 2011 crop beans had similar movements to the cash market, but the size of the movements was considerably smaller. Over the weekend, the forward market lost only 5 cents to open at $13.09 (Figure 2). New crop bean prices showed added strength throughout the week before weakening on Friday. The closing price for the week was $13.45, a 31 cent improvement from the prior Friday closing mark. West Memphis topped the week with a $13.69 quote on Thursday. Helena was second with $13.63 on Thursday. The lowest price of the week was $12.85 at Wynne on Monday. Jonesboro, Wheatley, Augusta, and Des Arc were also under $13.00 to open the week. All markets ended the week above the $13.21 level, a marked increase from the $12.90 price floor of the previous week close. The previously shrinking price margin between cash market old crop beans and new crop booking prices expanded further to 56 cents, a 16 cent widening from the previous week and a total increase of 32 cents over two weeks.
(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.)
Contact Information
Please contact your local County extension agent in Arkansas or the author(s) if you have questions or comments regarding the newsletter. You may also contact Jeremy Ross, Extension Agronomist for Soybeans at jross@uaex.edu or (501) 944-0621.
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