2. Right Product With higher prices for fertilizer nutrients, it becomes more important to use product s that provide high efficiency. Premiums previously considered unaffordable now become cost-effective. Controlled-release sources, or those with inhibitors slowing down the conversion to nitrate, can more efficiently deliver nutrients to the plant, provided they are applied in situations where their nutrient release matches the uptake needs of the crop.

3. Are controlled release products better than split applications of 100% available nutrient sources? Ongoing research is still needed to determine when they are or are not. A split application of soluble fertilizer entails different risks than those associated with a single application of a controlled-release product. The soil may be too wet at side-dress time to get on to the field. Or, in some years, soils may be so dry that side-dressed N—even in fluid form—does not get to the roots. Split applications also entail extra fuel costs.

4. Controlled-release products can potentially be more reliable and more convenient. But weather and many other soil factors can influence the rate of release, so it’s important to evaluate which product performs best in your own specific growing conditions. Limited research has been done on these products, so a combination of searching out relevant results and conducting on- farm trials is called for. Price changes may affect some products more than others. Compare price per pound of N in a variety of N sources. Make sure product are suitable for available application equipment.

5. What are efficiency fertilizers ? What are enhanced efficiency fertilizers ?

6. Enhanced efficiency fertilizers EEF are products with characteristics that minimize the potential of nutrient losses to the environment, as compared to products with 100% availability at the time of application. Have traditionally been used in specialty applications (e.g., turf, ornamentals, etc.) Over the past few years have been gaining in use and popularity in production agriculture

7. History of EEFs after Dr. J Robbins, U. of Arkansas 1924- UF (European patent); 1955 production in the U.S. Early 1960’s- crotonylidene diurea Late 1960’s- IBDU 1961- SCU (TVA); commercial production began in early 1970’s

8. Fertilizer history after Dr. J Robbins, U. of Arkansas 1967- Osmocote® 1985- Nutricote ® (Meister ®, Prokote ®, Escote ®) 1990- Polyon ® 1990- Multicote ® 1990’s- VCote ®, TR2 ®, ESN ®, Duration ®

9. Enhanced efficiency N Synthetic organic N compounds with lower solubility – e.g., urea-aldehyde condensation products, urea-formaldehyde reaction products, IBDU, triazines, etc. Physical coating or barrier around soluble N sources – e.g., SCU, PCU, combination products Stabilized materials – e.g., nitrification and urease inhibitors

10. Sulfur Coated Urea Mechanisms of N Release – pin holes, cracks – Microbial degradation Factors affecting N release –Coating thickness and uniformity  effective coating thickness is equal to thinnest area of coating –Temperature –Moisture

11. Polymer coated urea N release controlled by diffusion Major factors affecting release – coating thickness – temperature – moisture

13. N uptake curve (corn) and theoretical PCU release curve Schwab and Murdock. 2004.

14. Comparisons of pre-plant PCU with urea and UAN at equal N rates Compilation of data from source-rate studies and trials in the US Corn Belt, 2000-2005 - A. Blaylock 247 total Comparisons 26% lower yield 71% higher 3% no difference Lower yield Higher yield

15. Impact of urea/UAN and PCU on corn yield Urea and UAN PCU (ESN) Compilation of data from source-rate studies and trials in the US Corn Belt, 2000-2004 Blaylock and Tindall More sensitive to unfavorable weather

16. Effect of N sources on irrigated no-till corn yield Kansas, Crete silt loam Gordon. KSU Fertilizer Report. 2006. 3-year average Zero N control- 127 bu/A

17. Impact of rainfall on corn yield response to ESN vs. Urea

18. Nitrification…a natural process in soils Nitrification inhibitors interfere with activity of Nitrosomonas bacteria, slowing the nitrification process This leaves more N in ammoniacal form, thus reducing the chance of leaching and denitrification NH 4 + NH 3 NO 2 - NO 3 - Nitrosomonas Nitrobacter -H + +H +

19. Some patented nitrification inhibitors Frye. 2005.

20. Frye, 2005. Urea or UAN surface applied Effect of nitrification inhibitor on no-till corn yield Kentucky

21. Research throughout the Midwest has shown that nitrification inhibitors only pay for themselves environmental conditions favor high losses of nitrate. When inhibitors are applied preceding higher than average rainfall, increases in corn yield range from 10 to 30 bushels per acre; when moisture conditions are normal or dry, nitrification inhibitors produce little to no increase in yield. In general, poorly or imperfectly drained soils tend to benefit the most from nitrification inhibitors. Moderately well- drained soils that undergo frequent periods of 3 or more days of flooding in the spring also benefit. Coarse-textured soils (sands) are likely to benefit more than soils with finer textures because the coarse-textured soils have a higher potential for leaching.

22. Urea hydrolysis Urease inhibitors interfere with the process of urea hydrolysis The slowing of conversion of urea to ammoniacal N can significantly reduce the potential for NH 3 volatilization CO(NH 2 ) 2 + H + + H 2 O 2NH 4 + + CO 2 urease UREA

23. Effect of N placement, source, and NBPT on irrigated no-till corn yield Kansas, Crete silt loam Gordon. KSU Fertilizer Report. 2006. 2-year average Broadcast

24. Apparent N fertilizer recovery in no-till cotton Mississippi, Marietta fsl Earnest and Varco. 2006. Surface dribbleBroadcast

28. Traditional applications – Turf, ornamentals, nurseries, etc. Production agriculture – High value crops – Crops with shallow root systems – Where potential for N loss is large (surface application, sandy soil, high rainfall, etc.) – Environmentally sensitive areas Enhanced efficiency fertilizer are well suited for:

29. Potential benefits of EE fertilizers include: – match the timing of nutrient release with the timing of plant demand for nutrients – improved yields – Improved nutrient use efficiency – reduction in nutrient loss (leaching, denitrification, volatilization...) – reduced application frequency – more uniform plant growth

30. Right Rate Corn normally shows a diminishing response as the rate of N increases. The economically optimum rate occurs where the yield increase no longer pays for the last increment of fertilizer. As price ratio increases, the optimum rate decreases. When prices for both corn and fertilizer increase proportionally, the optimum rate does not change, but the consequences of a non- optimal rate are more costly. It becomes more important to use every means at your disposal to get the best estimate possible of the optimum rate. For N, this can be difficult. A pre-sidedress soil nitrate test (PSNT), taken when the corn is 6 to 12” tall, can help guide decisions on sidedress N applications. For an in-season assessment, a SPAD meter (chlorophyll meter) has proven effective and many universities provide guidance on using it. For an end-of-season assessment, stalk nitrate tests are recommended.

31. The N rate that results in maximum return on investment decreases as the price ratio increases. 60 cents / $3 = 0.20 30 cents / $6 = 0.05

33. No fertilizer needed

34. Readings are taken from the uppermost leaf with the collar visible until the VT stage (tassel emergence), and then from the ear leaf. Average 15-30 representative readings per field location or reference strip location. Relative Minolta SPAD 502® chlorophyll meter value and N rate to apply. * Relative values calculated by dividing readings from the area of interest by readings from the well-fertilized reference strip. Readings taken from approximately the V10 to VT corn growth stage. Relative SPAD Value*N Rate to Apply lb N/acre < 0.88100 0.88-0.9280 0.92-0.9560 0.95-0.9730 > 0.970

35. High N strip

36. For nutrients less mobile than N—like P and K—increasing price ratios may also lead to lower “optimal” application rates Soils with response probabilities less than 50% are often fertilized only for maintenance. Soils where response is very unlikely are often not fertilized at all. A short-term strategy of reduced application rates when price ratios are high is not likely to reduce yield and may increase profit. However, the consequent decline in soil fertility for future crops needs to be considered. High price ratios increase the profitability of sound soil testing to identify fields and areas within fields where rates below removal may be justified for one or several years.

37. Right Timing Spring applications of N are nearly always more effective than fall applications. In IL, ~ 15 % of N applied in the fall is lost but the amount can be much higher. At best, fall applications can only equal the effectiveness associated with spring applications. Fall applications are made to manage other risks – primarily logistical ones. Fall applications take advantage of typically drier soil conditions and the greater availability of days suitable for field work. They also allow some of the tasks to be moved from a busy spring to a less busy fall, increasing the chances that the spring tasks will be timely. High fertilizer prices tend to favor an investment in equipment to apply N in the spring. Nitrogen should only be applied in the fall after the average daily soil temperatures at 4 to 6 in. deep (measured mid-morning) go below 50 ºF and are sustained at or below this for the winter. Nitrification inhibitors can increase the effectiveness of fall N.

39. In Iowa, research with controlled-release urea products (PCU), has found an average 4 bu/A corn yield increase compared to fall-applied urea. However, the fall-applied PCU produced 4 bu/A less yield compared to spring- applied urea which had an 8 bu/A yield advantage for over fall-applied urea. In the eastern Corn Belt, fall-applied N tends to be more unreliable and inefficient than in IA. Even when all N is applied in the spring, split applications are normally more effective than single applications of %100 available N sources.

40. There are two things you can estimate more accurately in June than at planting: one, the soil’s ability to supply N, and two, the crop’s need for N. While corn doesn’t take up much N during the first month after emergence, it needs a good supply from the start. Applying some N at planting or pre-plant and a larger dose when corn is > 6” tall normally increases yield and N-use efficiency.

41. Right Placement Corn has a special need for P early in the growing season. Placement with the seed in small amounts, and near the seed in larger amounts, provides maximum availability to young seedlings. Applying P in bands below the soil surface reduces the risk of it moving to water by surface runoff and reduces fixation by the soil. Early phosphorus also promotes early dry down which can help lower grain drying expenses. Research suggests that combinations of N and P work most effectively, and that K is an important component of starter fertilizer for corn grown with reduced or no tillage.

42. Volatile sources of N should be incorporated or injected! When N sources containing urea or ammonium (urea, urea- ammonium nitrate, anhydrous ammonia, ammonium nitrate, and ammonium sulfate) are surface applied without incorporation, ammonia losses can be high especially when soil pH is high and/or residue levels are high. Broadcasting UAN solution (28 percent to 32 percent N) is not recommended when residue levels are high because of the potential for the N in the droplets to become tied up on residue. Dribbling the solution in a surface band will reduce tie- up on residue, and knife or coulter injection will eliminate it. Volatilization losses can be minimized by incorporating urea/UAN as soon as possible.

43. Source: Lowenberg-DeBoer, 1997

45. Precision Services Used Midwest dealers use more precision services than other states: 69.2% vs. 43.1% Whipker & Akridge, 2003

46. Precision Services Offered Midwest dealers offer significantly more precision services except satellite imagery. Whipker & Akridge, 2003

47. Soil Sampling Methods Whipker & Akridge, 2003

48. Variable Rate Applications Midwest has generally greater than twice the adoption rate of variable rate application compared to other states. Whipker & Akridge, 2003

49. Dealer Estimate of Total Market Area Using Precision Services Whipker & Akridge, 2003

50. Summary of first 15 years Technology has developed rapidly Scientific basis for explaining and responding to variability lags behind expectations Economics have not met expectations

51. Economic Analyses of Published Studies Results are mixed: – 25% clearly profitable – 25% clearly unprofitable – 50% partially Depends on analysis assumptions

52. Profitability in SSM Studies CropInputs Grid Area SSM>WF sugarbeetN2.752/2 wheat, barley N, P, K 3.01/5 corn P, K 3.05/12 corn, soybean P, K 2.515/18 irr. corn N0.752/4 corn P, K 2.15/5 Swinton and Lownberg-DeBoer, 1998, J. Prod. Agric. 11(4):439-446