Forage Fertilization 29 March 2018 Eastern Oklahoma Beef Cattle Summit Nathan Slaton Professor, Soil Testing Assistant Director, Agricultural Experiment Station nslaton@uark.edu 29 March 2018 Eastern Oklahoma Beef Cattle Summit

Tools You Can Use on Phone or Computer WebSoil Survey http://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm SoilWeb Ap for Smart Phone IPNI Nutrient Removal Calculator

Topic Outline Lime Nitrogen Potassium Particle size & effectiveness Pelleted lime vs ag lime Effect of N fertilizer source and rate on pH Nitrogen Productivity without N N sources and urease inhibitors Potassium Why, how and when K is needed!

Lime Fundamentals Source & Quality Lime basics Sources Soil test regularly Know your lime source Incorporate when possible Forage establishment Don’t wait too long! Subsoil acidity Sources Ag Lime Pelleted lime Poultry litter

Relative Effectiveness Avg Relative Effectiveness Effectiveness of Lime Particle Size Soil pH after 1 year Relative Effectiveness Avg Relative Effectiveness Calcitic Dolomotic mesh pH % avg No lime 5.0 4-8 5 8 20-30 5.6 5.5 54 39 47 40-50 5.9 5.8 74 65 70 60-80 6.3 6.2 96 84 90 100 6.5 6.6 Source: University of Idaho Pub #CIS0787, R. Mahler

Pelleted Lime vs Ag lime Pelleted lime often marketed as being much more effective than ag lime – NOT TRUE Typically Little, if any, difference in Purity Reaction speed Pelleted lime has advantage of smaller size, but disadvantage of binding agent Pelleted lime usually has a higher ECCE score BUT equivalent rates are usually only a few hundred pounds apart (See example on next slide)

Lime Quality – Compare $ources Overall Quality Score Lime Purity Lime Source CCE† Fineness Factor Information‡ ECCE§ Equal Rates¶ 10 mesh 60 mesh 100 mesh Fineness Factor   - - - lb/acre - - - Ag lime 91% 93% 44% 32% 62.4 56.8 2,000 Pelletized lime 80% 100% 100.0 80.0 1,420 †CCE, calcium carbonate equivalent. ‡The values in each column represent the percentage of material passing through a 10, 60 and 100-mesh sieves. Fineness factor coefficients of 0, 0.4, 0.9 and 1.0 are multiplied by the percentage of lime having a diameter of >10-mesh (7%), <10-mesh and >60-mesh (49%), <60-mesh and >100- mesh (12%) and <100-mesh (32%) were used to calculate the fineness factor. §ECCE, effective calcium carbonate equivalent, is the product of [fineness factor x (CCE/100)]. ¶Equivalent rates, the amount of lime needed from each source to neutralize the same amount of acidity. Calculated by [((Ag lime ECCE/pelletized lime ECCE) × 2,000 lb ag lime/acre) = lb pelletized lime/acre] Source: Arkansas Soybean Handbook, Chapter 5

Lime Rate on Captina Silt Loam Ag Lime rate ECCE Water pH Salt pH Jan 2007 April 2007 Dec 2007 Feb 2008 Jan 2007 April Dec Feb 2008 lb/acre - - - - - - Soil water pH - - - - - - - - - - - - - Soil Salt pH - - - - - - - -- 5.5 5.4 5.1 5.2 4.8 4.3 4.5 1250 56 5.0 4.4 4.7 2500 5.7 5.8 5.9 5.3 90 6.0 4.6 5000 6.4 6.1 56.3 ECCE for Mixture & 90 ECCE for Fines. Soil sample depth was 4 inches Lime applied in January 2007 and sampled in April and December 2007 and February 2008. Ag lime obtained from bulk lime pile in at Coop in Morrilton, AR 5000 lb Ag lime was UA recommendation.

Soil pH – Seasonal Variability 5.7 (high pH) 5.4 (mean pH) 5.1 (low pH) Source: Keogh and Maples, 1972 (AES Bull. #777)

Effect of N rate/source on Soil pH Effect of N Source (applied at 360 lb N/A) Effect of Annual N Rate Captina silt loam, After 2-years of N fertilization

Bermudagrass Response to N 2-yr study 4-yr study 2-yr study

Summary of Bermudagrass Yields Receiving no N-fertilizer Irrigated Non-irrigated ton/acre # %RY <1 1 8 5 10 1-2 3 18 26 2-3 4 39 3-4 37 2 52 4-5 77

Bermudagrass Response to N Rate No N yield range 1520 to 5940 lb DM/acre 80% Yield 274 lb N/acre 90% Yield 364 lb N/acre Maximum yield across sites was 7.5 ton/acre. Source: Seay and Slaton (2008, Forage & Grazinglands)

N Source Preferences Urea UAN NH4NO3 Ammonium Sulfate 5 to >20% of N loss via NH3 volatilization (typical) Apply to dry forage/soil Often cheapest per unit of N UAN Assume one-half of N loss from urea NH4NO3 Best forage N-fertilizer, if available and priced right Ammonium Sulfate Use to supply part of N where S deficiency occurs Controlling/Reducing Loss with Urea or UAN Apply before rain Amend with urease inhibitor Only NBPT-containing inhibitors are recommended (e.g., Agrotain, Arborite, Factor, N-Fixx, etc…)

N-Fertilizer Additives What are they? Nitrification inhibitors Delay conversion of NH4-N to NO3-N Probably not needed for actively growing forage Urease inhibitors Delay conversion of urea to NH4-N and reduce ammonia loss (NH3) when conditions are favorable Use with surface-applied urea or UAN. Urease inhibitors From a few to many products in past 10 years Should you use one? Check for NRCS incentives Depends on conditions and N source

Urease inhibitor reduces N loss from urea (or UAN) Ammonia Loss No NH3 loss from NH4NO3 Urease inhibitor reduces N loss from urea (or UAN) Majority of Urea-N loss occurs in first 2 to 3 days. Need 0.25 to 0.5 inch of rain within 24 to 36 hours after application to incorporate. Rain at 72 hours is too late… N loss becomes worse as temps increase Source: Massey (2007) Captina silt loam

Agrotain for Urea – 2007 Captina soil N rate NH4NO3 Urea Urea+Ag PPL lbs N/A lbs forage/A 4617 45 x 2 8151 7647 7537 6764 60 x 3 10120 9389 9168 7758 90 x 3 11718 10429 10259 9235 120 x 3 11017 10983 11012 10821 150 x 3 12528 11578 11994 12076 LSD0.1 766

Urease Inhibitor Benefits Use in Bermudagass Hay Production Fertilizer Yield Total Calhoun 2008 Calhoun 2009 Eatonton 2008 Eatonton 2009 Tons hay/acre/season (4 total cuttings) Ammonium Nitrate 10.1 a 9.6a 5.1 a 5.9 a Urea 8.7 cd 7.5 cd 4.2 b 5.4 ab Urea+NBPT 9.7 ab 8.8 ab 4.5 ab 5.7 a Urea+Nutrisphere 8.5 cd 8.2 bc 4.4 ab 5.1 b UAN 9.5 ab 7.8 bcd 5.5 ab UAN+NBPT 9.6 ab 7.0 d 4.8 ab 5.2 b No N 5.0 5.2 1.3 1.1 University of Georgia (Connell et al., 2011; Crop Sci.) N applied in two-split applications of 150 lb N/acre at spring greenup and after 2nd harvest. Site pHw ranged from 6.2 to 6.9.

Urease Research Summary Urease inhibitor NBPT applied to urea granules or UAN sometimes increase bermudagrass yield as compared to untreated urea. Forage fertilized with NH4NO3 tended to produce highest overall yields. Poultry litter, 50 to 70% N equivalence to inorganic fertilizer-N.

N Sources for Tall Fescue mid-March N (75 lb N/acre) Comparison Mt Vernon, MO Columbia, MO 2006 2007 2008 % Yield Difference (Urea as standard) Urea vs NH4NO3 4 8 16 14 2 Urea vs Urea+AS -3 7 19 -7 Urea vs Urea+NBPT 5 21 <1 Urea vs no N -46 -55 -50 -58 -54 Urea Yield (lb/acre) 7779 3680 3139 4037 4716 Source: Univ. Missouri http://aes.missouri.edu/pfcs/research/prop105c.pdf Bold red Values Indicate a significant difference at P=0.20 Positive values indicate urea yielded less than compared N source % Difference Calculation = [(N Source – Urea)/Urea] x 100

Nitrogen Sources for Tall Fescue mid-August N (75 lb N/acre) Comparison Mt Vernon, MO Columbia, MO 2005 2006 2007 % Yield Difference (Urea as standard) Urea vs NH4NO3 55 -13 -6 28 Urea vs Urea+AS 1 -3 <1 4 Urea vs Urea+NBPT 22 -15 18 Urea vs no N -61 -70 -78 Urea Yield (lb/acre) 1245 2201 2865 1935 Source: Univ. Missouri http://aes.missouri.edu/pfcs/research/prop105c.pdf Bold red Values Indicate a significant difference at P=0.20 Positive values indicate urea yielded less than compared N source % Difference Calculation = [(N Source – Urea)/Urea] x 100

Tall Fescue N Summary Spring/Greenup Application Urea & ammonium nitrate yields same in 3 of 5 years NBPT benefit only 1 of 5 years Positive yield response to ammonium sulfate was likely from N loss rather than S Late Summer/Fall Application Ammonium nitrate yields greater than Urea in 2 of 4 years Benefit from NBPT treated urea tended to be more common in fall (August application) than spring

Forage Needs POTASH

Forage Nutrient Removal P2O5 K2O IPNI Values lb nutrient/ton Bermudagrass 46 12 50 Fescue 37 54 Ryegrass 43 Bahiagrass 35 Arkansas Database Values Bermuda (ARK) 44 13 Fescue (ARK) 14 51 IPNI Nutrient Removal Calculator, https://www.ipni.net/app/calculator/home Davis (2000, AES Research Series #478)

P and K Value: Bermudagrass Hay Nutrient Unit Content Fertilizer Fertilizer Price Value lb P2O5/ton $/unit $/ton Phosphorus 13 DAP, 18-46-0 0.47 6.11 Potassium lb K2O/ton 50 Potash, 0-0-60 0.28 14.00 Sum (P and K) $20.11 Fertilizer Prices from https://agfax.com/2018/03/08/ $436/ton diammonium phosphate $335/ton potash $361/ton urea

Soil-Test K and K Fertilizer Rate Bermudagrass Hay Seay and Slaton (2008)

Soil-K Depletion Rate Bermudagrass hay Soil K depletion appears to be quadratic rather than linear for this system with large K removal and inputs. Do soils have an low equilibrium threshold for K? This has been suggested in the literature. Bermudagrass hay

K-Fertilizer Rate & Bermudagrass Hay Yield

Bermudagrass Yield Response to K K rate 5-yr Avg Yield % of Max lb K2O/A Ton/A/yr % 3.4 51 100 5.0 75 200 5.9 88 300 6.1 91 400 6.4 96 500 6.7 Slaton et al. (2006-2010, AAREC)

Soil Test K and Bermuda Forage Yield Potential for yield loss when soil-test K is <120 ppm and no K is applied Stand loss may/will begin if K is inadequate. Sufficient K helps plants assimilate nitrate Soil samples collected from 0-4 inch depth

Forage NO3-N and Potassium High NO3-N content of forage may be a sign of K deficiency Crude protein content of forage may also be higher in K-deficient forage Brown leaf spot is a sign of K deficiency Forage nitrate (ppm)

Luxury Uptake of K by Forage K Sufficient Source: Slaton et al. (2011, AES Research Series 588) Data from 5th year of fertilization and cropping

Luxury Uptake of K by Forage K Sufficient Source: Slaton et al. (2011, AES Research Series 588) 5th year of annual fertilization and cropping

Relationship of Forage RFV and Potassium Average RFV of 987 Bermuda Samples Grouped by Forage K Level : “Quality Forage” Program: 1998-2009 *Each bar represents average RFV for all samples within the forage K level group shown, when K is averaged in increments of 0.20% Source: Robert Seay (CEA-retired), Benton County, AR

K Fertilizer Management Summary Soil test routinely Avoid Luxury Consumption Split apply the K Blend with N Close to a 1:1 N:K ratio Monitor nutrient balance K input – Crop K removal

Thanks for Your Attention Questions?? nslaton@uark.edu

Cool-Season Grass & N Late summer and fall fertilization Apply 40-60 lb N/acre N from mid-August to early September to stimulate growth for grazing, hay or stockpiling Late-winter or early-spring fertilization Apply 40-60 lb N/acre at first sign of greenup usually in early to mid March For intensive hay management apply N after first hay cutting if moisture and temperatures are suitable Figure Source: Murdock (1982, Univ. Kentucky)

Critical Humidity & Urea Ammonia Loss Moisture moves from air to urea Moisture moves from urea to air Slide from Dr. David Kissel, Univ. Georgia

Luxury Uptake of P by Forage Source: Slaton et al. (2011, AES Research Series 588) Data from 5th year of fertilization and cropping

Luxury Uptake of P by Forage Source: Slaton et al. (2011, AES Research Series 588) 5th year of annual fertilization and cropping

Agrotain for Urea – 2007 Johnsburg soil N rate NH4NO3 Urea Urea+Ag PPL lbs N/A lbs forage/A 6224 45 x 2 9583 8591 9063 7339 60 x 3 10438 9437 10173 8651 90 x 3 10316 10027 10353 9575 120 x 3 11045 10432 10628 10558 150 x 3 11372 11053 10848 10466 LSD0.1 628

Biostimulents, Fertilizer Additives, and Alternative Fertilizers Product that stimulates plant physiological processes, ‘stress gene’ stimulents, or contains hormones, microbes, humic acids, etc… Usually applied at low rates Fertilizer Additives Urease and nitrification inhibitors Biostimulents (see above) Polymer coatings (some good & some bad) Alternative fertilizers Manures & biosolids Other products (e.g., liquid poultry litter)

Relationship of Forage Crude Protein and Potassium Average CP level of 987 Bermuda Samples Grouped by Forage K Level “Quality Forage” Program: 1998-2009 *Each bar represents average CP for all samples within the forage K level group shown, when K is averaged in increments of 0.20% Source: Robert Seay (CEA-retired), Benton County, AR

Relationship of Forage TDN and Potassium Average TDN of 987 Bermuda Samples Grouped by Forage K Level “Quality Forage” Program: 1998-2009 *Each bar represents average TDN for all samples within the forage K level group shown, when K is averaged in increments of 0.20% Source: Robert Seay (CEA-retired), Benton County, AR