Karamanos, R.

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Nitrogen fertilizer placement – an important component in the 4R nutrient stewardship

University of Saskatchewan Research Archive

Nitrogen Fertilizer Placement An Important Component in the 4R Nutrient Stewardship  Rigas E. Karamanos Viterra Inc. 10517 Barlow Trail SE, Calgary, AB  Introduction  The 4R Nutrient Stewardship (Right Source applied at the Right Rate, Time and Place) should be the guiding principle in fertilizing crops. The fertilizer industry’s nutrient stewardship concept links management of plant nutrition to sustainability. The fertilizer 4R’s are connected to the goals of sustainable development (Fig. 1). For stakeholders, the 4Rs support an accurate understanding of the big picture, even for those who may not understand all the details of managing crop nutrients.    Figure 1. The 4R nutrient stewardship concept defines the right source, rate, time, and place for fertilizer application as those producing the economic, social, and environmental outcomes desired by all stakeholders to the plant ecosystem (Bruulsema, 2009)  Placement is an important component of the 4R nutrient stewardship, especially since fertilizer management practices need to adapt to the ever increasing trend in conservation farming that includes zero till and direct seeding as common practices.  Generally, there are four methods of precision placement of fertilizer at seeding time, namely, placement of fertilizer directly with the seed, side-banding, midrow banding and paired row placement (Fig. 2).  Application of (N) directly with the seed can result in very efficient crop uptake of the applied nutrients. Some of the main factors that affect the decision for placing fertilizer N with the seed are listed in Table 1 along with some generalized conditions that render seed-placement a favourable or unfavourable practice. However, in most cases, the amount of N that can be applied in this manner is insufficient to obtain optimum/maximum yields. Further, excessive amounts of seedrow-applied N cause seed and seedling damage that can result in a delay in crop maturity and reduced yields.  Karamanos et al. (2008a) suggested a modification of the existing (Saskatchewan Agriculture and Food 2006) guidelines for safe seedrow N placement under “favourable” conditions based on spring moisture conditions and soil organic matter and attempted to quantify “favourable”.   This research resulted in the development of a safe rate seedrow N placement calculator (available from the author) and modified guidelines (Fig. 3; Table 2).  Table 1.  General factors that can influence decisions to place N in the seedrow Factor Favourable Unfavourable Crop Grown Cereals Oilseeds, Pulses Seedbed Moisture Good, Moist Poor or Dry Soil Texture High Clay Content Sandy Soils Type of Opener Wide Spread Confined Rows Row Spacing Narrow (6”) Wide (9-12”) Uniformity of Field Uniform Landscape Rolling, Eroded Hilltops N source Ammonium Nitrate Urea Free Lime in Soil Absent or Low Moderate to High Soil Organic Matter High OM Level Llow OM Level Seeding Depth Shallow (to moisture) Deep    Figure 2.  Common precision N placement techniques.  Placement of Liquid vs. Dry N Fertilizer  Often it is received that the fertilizer use efficiency of liquid is greater than that of dry fertilizers and that with liquid fertilizer it is possible to put more nutrition closer to the seed than with dry. Although this would be true when liquid fertilizer is applied with the seed in wide spread (2-inch) seedrow (Fig. 4), placement of liquid N fertilizer in narrow seedrow (11% SBU) is just as damaging as that of UREA (Fig. 5).    Figure 3.  View of a tool developed to derive safe seedrow placed N rates with common crops in western Canada (Karamanos et al. 2008b).      Figure 4.  Liquid fertilizer applied in wider bands, e.g., 2” width is less injurious to seeds, as a seed has a greater probability to be adjacent to a 46-0-0 granule(left) than to the “stream” of 28-0-0 (right).  1401501601701801902000 30 60 90Nitrogen rate, kg N ha-1Wheat planr population, plants m-2UREAUAN Figure 5.  Effect of UREA (46-0-0) and urea ammonium nitrate (UAN, 28-0-0) placed directly with the seed in a narrow (11% SBU) seedrow on the plant population of wheat (Karamanos, unpublished data).  MeanSpring Soil test N SelectSoil moisture Soil test N lb N/acre (0-24") before seeding after seeding typeType A Dry High 90±40 3±3 2±2Type B Borderline Low-Medium 46±22 4±7 4±4Type C Moist Low-Medium 43±26 4±3 7±7FertilizerFill in when AS is used   CropSeed Spread inches 1Row spacing inches 9TextureMedium (Loam to clay loam)Organic matter % 5Calculated SBU 119029 lbs N/acreImpact of applying more N:* This is a guideline only based on average data and does not imply any guarantees of no damage to crop *Karamanos et. al. 2004. Can. J. Plant Sci. 84: 105-116.    Plant stand data for canola adapted from: http://www.canola-council.org/PDF/CPCfertilizer.pdf Rationale for 85 % Plant Stand Minimum safety*Cells in color can be modifiedRainfall, mmGuideline* for seedrow placed Nwithin 48 hoursEstimated plant stand, %SEEDROW FERTILIZER APPLICATION RISK ASSESSMENT TOOLEstimatedPlant stand, % 80Applied rate:(lb N/acre) 50Urea(46-0-0)WheatType AType BType C25354555657585951050 18 27 36 54 71Nitrogen rate, lb/acreRelative plant stand,% or DTM, days/yr4550556065Grain yield, bu/acrePlant Stand DTM Yield505560657075808590951000 18 27 36 54 71Nitrogen rate, lb/acreRelative plant stand,% or DTM, days/yr556065707580Grain yield, bu/acrePlant Stand DTM YieldBarleyWheatI d e a lTable 2.  Comparison of the generally accepted guidelines for safe rates of fertilizer placed with the seed in Saskatchewan (Saskatchewan Agriculture and Food 2006) and those derived from Karamanos et al. (2008a).  1 inch spread1 2 inch spread1 3 inch spread1  (disc or knife)2 (spoon or hoe) (sweep)  Row spacing Row spacing Row spacing  6” 9” 12” 6” 9” 12” 6” 9” 12”  SBU3 SBU3 SBU3 Soil texture 17% 11% 8% 33% 22% 17% 50% 33% 25% Light (sandy loam) 204 15 15 30 25 20 40 30 25 Type A 0 0 0 15 10 0 20 15 10 Type B 25 15 15 40 30 25 45 40 35 Type C 40 30 25 65 50 40 70 65 55           Medium (loam to clay loam) 30 25 20 40 35 30 50 40 35 Type A 10 5 5 25 15 10 30 25 20 Type B 35 25 25 50 40 35 55 50 45 Type C 50 40 35 75 60 50 80 75 65           Heavy (clay to heavy clay) 35 30 30 50 40 35 60 50 40 Type A 15 10 10 20 20 15 35 30 25 Type B 40 30 30 55 45 40 60 55 50 Type C 55 45 40 80 65 55 85 80 70 1Width of spread varies with air flow, soil type, moisture level, amount of residue and other soil conditions, so it must be checked under field conditions. 2Some openers give less than 1” spread. 3SBU (Seedbed Utilization) is the amount of the seedbed over which the fertilizer has been spread. Thus, it is a reflection of the relative concentration of fertilizer. SBU (%) is the width of spread divided by the row spacing multiplied by 100. For example, if the seeding implement has a six-inch spacing and spreads the seed and fertilizer over two inches, the SBU would be 2 ÷ 6 x 100 = 33 per cent. The higher the SBU, the more fertilizer that can safely be applied with the seed. Although some openers will also spread seed and fertilizer vertically, SBU does not take this into account, since it is generally recommended that all seed be placed at an even depth for even germination and emergence. 4 Underlined values represent Saskatchewan Agriculture and Food (2006) guidelines. The impact of Urea (46-0-0) or Urea Ammonium Nitrated (28-0-0) placed in a variety of ways was assessed in a two-year (1999-2000) program in Saskatchewan (Karamanos, unpublished data).  Specifically, 46-0-0 was placed with the seed and side banded one inch to the side and one inch below the seed, whereas 28-0-0 placed with the seed, dribbled banded on the surface or placed off the seed row by ¼ of and inch (Fig. 6).  Adhering to the 4R stewardship principle, seed placement of excessive rates of N would result in reduction in seed emergence and plant counts and eventually yield loss and, therefore, should be avoided.  Under best management practices (BMP), UREA (46-0-0) may be placed with the seed according with the guidelines described in Table 1 and UAN (28-0-0) can be directly placed with the seed in wider seedrows.  The results from the above experiments (Fig. 7) corroborate with these observations and, furthermore, suggest that given the right placement, both UREA and UAN performed equally.   Figure 6.  Schematic representation of methods of UREA and UAN placement in the placement experiments. 253035404550550 27 54 81Nitrogen rate, lb N/acreGrain yield, bu/acreSide Band 46-0-0Dribble Band 28-0-0Seedrow 46-0-0Seedrow 28-0-0Off Seedrow 28-0-0 Figure 7.  Effect of UREA and UAN placement on the yield of wheat at various fertilizer N rates.  Placement of Enhancement Products  The use of a number of enhanced efficiency products has been advocated in order to overcome the restraint of the rates of N that can be safely placed with the seed.  Recent research has focused on two such products in particular, NBPT (commonly Agrotain) and polymer coated urea (ESN).    Reduction in seedling damage when of urea treated with Agrotain® is seed-placed has been attributed to an increase in the duration of urea diffusion away from the seedrow, as a result of the reduction in urea hydrolysis with application of Agrotain® (Malhi et al 2003); it has been shown to occur with a number of crops, such as barley (Grant and Bailey 1999; Pauly et al. 1996), wheat (Xiaobin et al. 1995; Pauly et al. 1996; Malhi et al. 2003), canola (Pauly et al. 1996; Malhi et al. 2003) and corn (Schlegel 1991).  Grant and Bailey (1999) observed that improvement in seed-placed urea safety with Agrotain® was dependent on the environmental conditions occurring after seeding.  This was verified in a study by Karamanos et al. (2004); however, increase in stand density as a result of less seedling damage was greater in barley (Fig. 8) than wheat (Fig. 9) or canola (Fig. 10).  Further, reduction in emergence counts by 15% compared to the control had no impact on either yield or days to maturity.  Treating urea with Agrotain® at rates as low as one third of the recommended rate overall produced similar results to those of the recommended rate. RSDNBPTtreated = 100.56 - 0.1385Nrate - 0.0013Nrate2, R2 = 0.3627RSDuntreated = 101.04 - 0.3562Nrate - 0.0023Nrate2, R2 = 0.60950204060801001200 10 20 30 40 50 60 70 80 90Nitrogen rate, kg N ha-1Relative stand density, %UntreatedNBPT treated Figure 8.  Effect of Agrotain® treatment of urea on the stand density of barley.  RSDNBPT treated = 101.85 - 0.4681Nrate, R2 = 0.8349RSDuntreatred = 101.21 - 0.7954Nrate, R2 = 0.8950204060801001200 10 20 30 40 50 60 70 80 90Nitrogen rate, kg N ha-1Relative stand density, %UntreatedNBPT treated Figure 9.  Effect of Agrotain® treatment of urea on the stand density of wheat. RSDNBPT treated = 100.69 - 0.6471Nrate, R2 = 0.6796RSDuntreated = 97.221 - 0.8694Nrate, R2 = 0.85390204060801001200 10 20 30 40 50 60 70 80 90Nitrogen rate, kg N ha-1Relative stand density, % Figure 10.  Effect of Agrotain® treatment of urea on the stand density of canola.  General guidelines (Tables 3 and 4) for applying seedrow Agrotain® treated urea N were developed from the above work that based on the following conditions: (a) an application rate of 5.2 litres of Agrotain® per tonne of urea, (b) optimum seedbed preparation, (c) less than 15% seedling damage and (d) no impact on days to maturity.  Proper application of Agrotain™ on urea is predicated on following these guidelines.   Table 3.  Guidelines for applying seedrow Agrotain® treated urea N with cereals (except hulless barley).  Maximum Seed-placed rate (lb N/acre as urea)  Light Texture Medium Texture Heavy Texture  S to SL L to SL C to HvC SBU No Agrotain +Agrotain No Agrotain +Agrotain No Agrotain +Agrotain 10% 15 25 25 40 30 50 20% 20 30 35 50 40 60 30% 30 40 45 60 50 70  Table 4.  Guidelines for applying seedrow Agrotain® treated urea N with canola, flax and hulless barley.  Maximum Seed-placed rate (lb N/acre as urea)  Light Texture Medium Texture Heavy Texture  S to SL L to CL C to HvC SBU No Agrotain +Agrotain No Agrotain +Agrotain No Agrotain +Agrotain 10% 5 15 10 20 15 25 20% 15 25 15 25 25 35 30% 20 35 25 35 35 55  Polymer coated urea (such as ESN) can afford an excellent means to increase safety of N fertilizer placed with the seed.  The average effect of blending polymer coated urea with uncoated urea at a rate of 67 lb/acre on the grain yield of barley and wheat are illustrated in Fig. 11 and 12.  104110113 113 1151089095100105110115120Grain yield, bu/acreUrea 19 40 60 81 100Portion of polymer coated urea in the blend, % Figure 11.  Effect of blending uncoated and polymer coated urea in seedrow placement with SBU of 11% on the yield of barley (Karamanos, unpublished data – nine site years). 50.953.656.2 56.659.062.24550556065Grain yield, bu/acreUrea 13 27 40 54 67Portion of ESN in the blend, lb/acre Figure 12.  Effect of blending uncoated and polymer coated urea in seedrow placement with SBU of 11% on the yield of wheat (Karamanos, unpublished data – eighteen site years).  Application of Anhydrous Ammonia at Seeding Successfully applying ammonia at seeding requires good ammonia retention in the soil, seed and fertilizer separation, which are directly associated with the type of opener and soil conditions, and, accurate metering and uniform distribution of ammonia. Factors that can influence good serration between ammonia (Fig. 13) and the seed include opener design (Fig. 14) and condition (Fig. 15), speed of application, spread of ammonia in the zone of application and soil type (texture, CEC and organic matter in particular).  Avoiding “Hot Bands”  A “hot band” is generated as a result of dual banding N and phosphorus (P), or placement of N and P in the same band, when N rates are very high, especially at wider row spacing, which leads to higher N concentrations in the band (Fig. 16).  They are a result of the high solubility of N, which tends to dissolve faster than P and create a “hallow” around the P fertilizer granules, thus preventing plant root from reaching P that is trapped in the centre of the hallow.    Figure 13.  Lateral key separation of ammonia from the seed is key to successful application at seeding.     Figure 14.  Unpublished data from early 1990’s work on impact of openers on application of ammonia with the seed by Westco agronomy.     Figure 15.  Worn off openers can lead to reduced separation between fertilizer and seed.  Figure 16.  Schematic representation of a “hot band” that leads P being trapped due to the high solubility of N that migrates around the P fertilizer granules in a dual band. Some general guidelines based on some earlier Westco research are summarized in Table 3.  Table 3.  General guidelines of maximum limits over which the probability of creation of a “hot band” increases (Westco, unpublished data)  Maximum rate Row Spacing (lb/acre) 12 80-90 16 60-70 24 40-45  References  Bruulsema, T. 2009. Recommendation development under 4R nutrient stewardship, in Proceedings North Central Extension-Industry Soil Fertility Conference. Volume 25. Des Moines, IA Grant, C.A. and Bailey, L.D.  1999.  Effect of seed-placed urea fertilizer and N-(n-butyl)thiophosphoric triamide (NBPT) on emergence and grain yield of barley. Can. J. Plant Sci. 79: 491-496. Karamanos R. E., Harapiak, J. T., Flore N. A. and Stonehouse, T. B. 2004. Use of N-(n-butyl) thiophosphoric triamide (NBPT) to increase safety of seed-placed urea. Can. J. Plant Sci. 84: 105–116. Karamanos, R.E. Harapiak, J.T. and Flore, N.A. 2008a.  Revisiting Seedrow Nitrogen Placement with Barley and Wheat, Can. J. Plant Sci., 88:1073-1086. Karamanos, R.E. Harapiak, J.T. and Flore, N.A. 2008b.  Criteria for Seedrow Nitrogen placement with Barley and Wheat, Proc. Soils and Crops 2008, Extension Division, University of Saskatchewan, Saskatoon, SK Malhi, S.S., Oliver, E., Mayerle, G., Kruger, G and Gill, K.S.  2003.  Improving effectiveness of seedrow-placed urea with urease inhibitor and polymer coating for durum wheat and canola.  Comm. Soil Sci. Plant Anal. 34: 1709-1727. Pauly, D.G., Nutting, M.D., Dowbenko, R.E. 1996.  Using a urease inhibitor, n-butyl thiophosphoric triamide (NBPT) for seed-placing nitrogen with wheat, barley and canola in Proceedings 33rd Annual Alberta Soil Science Workshop, Feb. 20-22, Edmonton, AB. Saskatchewan Agriculture and Food.  2006.  Guidelines for safe rates of fertilizer placed with the seed. [Online] Available: http://www.agriculture.gov.sk.ca/Default.aspx?DN=e42316e3-15ea-4249-ac0e-369212b23131  [21 Jan, 2008]. Schlegel, A.J. 1991.  Reduced ammonia phytotoxicity from UAN solution by the urease inhibitor N-(n-butyl) thiophosphoric triamide. J. Fert. Issues 8: 40-44. Xiaobin, W, Jingfeng, X., Grant, C.A. and Bailey, L.D.  1995.  Effects of placement of urea with a urease inhibitor on seedling emergence, N uptake and dry matter yield of wheat.  Can. J. plant Sci. 75: 449-452.  

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Nitrogen fertilizer placement – an important component in the 4R nutrient stewardship

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