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Nitrogen on Soybeans: Yes, No, or Maybe? 217 University of Minnesota and Minnesota Crop Protection Retailers CPM Short Course, Minneapolis, December 12-14, 217 Emerson Nafziger Crop Sciences University of Illinois ednaf@illinois.edu
Why fertilize soybeans with N? Yields keep going up, with field yields in the 8s almost routine in some areas. There s been some contention that soybeans can t fix all the N they need and make high yields as well too much energy used in fixing N? Soybean yield contest winners use N fertilizer, some repeatedly, so it must be necessary Some consultants suggest (or push) this
7 Illinois soybean yields, 199-217 Bushels per acre 6 5 4 3 2 1 2.9 bu/a/yr Rate of increase:.57 bu/acre/year = 16 bu/acre over 28 years 1985 199 1995 2 25 21 215 22 3
6 5 Minnesota soybean yields, 199-217 Yield, bu/acre 4 3 2 1 y =.4264x - 813.97 R² =.37 1985 199 1995 2 25 21 215 22
More response to N with high soybean yields? These are ONLY the sites in which N gave a yield increase ( about half of the 6+ sites) Salvagiotti et al., 28)
From Pioneer Crop Insight by John Schmidt adapted from Salvagiotti
If you accept that N fixation is limited (here, to 3 lb/acre) and the soil N supply is capped (1 lb/acre) you come up with this gap between requirement and supply Fluid J. Fall 216
How much N do soybeans take up? Yield average =82 bu/acre N in plants at maturity Yield level Seed Stover Total bu/acre ----------lb. N per acre---------- 82 261 5 311 66 27 42 249 54 168 36 24 Source: Gaspar et al., Crop Science 57:217-2182 (217) 3 275 25 225 2 175 15 125 75 5 25 lb. N/acre 9
Yield, bu/acre 9 8 7 6 5 4 3 2 1 Urbana 28-21 Non-irr-N Non-irr+N Irr-N Irr+N 28 29 21 Avg
Yield, bu/acre 9 8 7 6 5 4 3 2 1 Urbana 212-214 Non-irr-N Non-irr+N Irr-N Irr+N 212 213 214 Avg
Yield response to N, bu/acre 8 6 4 2-2 -4-6 -8 Urbana 28-1, 212-14 Non-irrigated y =.2447x - 14.688 R² =.994 Irrigated y = -.2934x + 22.497 R² =.879 5 55 6 65 7 75 8 85 Yield level, bu/acre
Yield response to in-season N, bu/acre 8 6 4 2-2 -4-6 33 Illinois trials, 21-214 3 4 5 6 7 8 9 Trial average yield, bu/acre
Yield, bu/acre 9 8 7 6 5 4 3 2 1 N on Soybean Urbana 214 74. 74.7 73.1 B 76.7 74.6 B B B B 8.5 Control Planting R1 R3 R5 Pl+R1+R3+R5 Application of 1 lb urea/acre + No effect of foliar N A
Chillicothe, 214 8 7 6 NS B B A Yield, bu/acre 5 4 3 2 Control Nitrogen Sulfur 1 Irrigated Dryland
Chillicothe 9/2/215 Loam (not sandy loam) soil at ~2% OM
Yield, bu/acre 1 9 8 7 6 5 4 3 2 1 N on soybeans, Urbana 215 96.1 96.1 91.1 92. 92.5 91.5 85.8 89. 88.8 b c ab ab b a a bc bc N application, 1 lb N/acre
N in top 2 ft., lb/acre 2 18 16 14 12 1 8 6 4 2 Soil N, Urbana 215 With crop, no N With crop, N at planting No crop, no N No crop, N at planting Planting R1 R3 R5 R6 R8 Sampling stage
Total N recovered, lb. N/acre 7 6 5 4 3 2 1 In plant In soil 42 314 314 39 14 44 44 7 24 43 Urbana 215 42 92 418 276 269 176 84 67 39 4 361 366 227 142 33 284 221 28 127 129 46 58 R1 R3 R5 R6 R8 R1 R3 R5 R6 R8 R3 R5 R6 R8 R6 R8 No N N at planting N at R1 N 4X N treatment and sampling stage
Yield, bu/acre 1 9 8 7 6 5 4 3 2 1 N on Soybeans, Chillicothe (irr.) 215 91.1 86.3 71.8 71.6 71.3 71.3 63.9 57.9 bc a b b b b a c Application of 1 lb N/acre
N in top 2 ft., lb./acre 2 18 16 14 12 1 8 6 4 2 Chillicothe, 215 With crop, no N With crop, N at planting No crop, no N No crop, N at planting Planting R1 R3 R5 R6 R8 Sampling stage
Total N recovered, lb./acre 7 6 5 4 3 2 1 In plant In soil Chillicothe, 215 321 265 386 37 278 264 32 247 14 31 319 235 39 24 111 45 25 19 33 5 111 1 38 22 32 48 115 21 36 63 128 119 R1 R3 R5 R6 R8 R1 R3 R5 R6 R8 R3 R5 R6 R8 R6 R8 No N N at planting N at R1 N 4X N treatment and sampling stage
Soybean yield, bu/acre 12 1 8 6 4 2 Yield and Plant N, 215 Chillicothe Urbana 2 25 3 35 4 45 N in plants at R6, lb N/acre
Yield, bu/acre 9 8 7 6 5 4 3 2 1 N on soybean Monmouth 215 79.6 79.9 83.1 79.1 79. 77.8 76.9 64.5 bc b bc bc bc c a d Treatment, 1 lb N each time
Yield, bu/acre 8 7 6 5 4 3 2 1 N on soybean Brownstown (SC IL) 215 67.1 61.1 62.3 62.2 61.4 56.6 58.4 56.2 bc c bc a ab ab c bc 1 lb N application
Yield, bu/acre 8 7 6 5 4 3 2 N on irrigated soybean at Chillicothe, 216 7.9 71.3 6.2 61.3 63.4 65.3 51.2 D AB C C C A BC 1 No N Planting R1 R3 R5 4X: Planting, R1, R3, R5 Application of 1 lb urea/46 lb N AMS at R3
lb N per acre 45 4 35 3 25 2 15 1 5 Chillicothe 216 Soil N at R6 Plant N at R6 345 265 294 232 25 227 244 36 36 44 51 43 68 81 229 253 37 39 N application
Yield, bu/acre Chillicothe, 216 9 8 7 6 5 4 3 2 1 15 2 25 3 35 4 Plant N at R6, lbs/acre
Yield, bu/acre 9 8 7 6 5 4 3 2 1 Irrigated soybeans, Chillicothe, 216 y = -.29x 2 +.5578x + 51.2 R² =.9991 Not only did N increase yield more N increased it more 2 4 6 8 1 N applied as urea at planting, lb. N/acre
SDS or NDVI (x1) 6 5 4 3 2 1 Chillicothe soybeans, 216 SDS NDVI x 1 N-fertilized soybean had less SDS why/how? 2 4 6 8 1 lb N as urea applied at planting
Yield, bu/acre 1 9 8 7 6 5 4 3 2 1 84.6 85.1 84.9 86.2 86.9 No N N on soybean at Urbana, 216 1 lb urea at planting 1 lb urea at R1 1 lb urea at R3 1 lb urea at R5 81.6 ----------------------No significant differences in yield----------------- 4X: planting, R1, R3, R5 84.8 46 lbs N as AMS, R3
N recovered at R6, lb N/acre 45 4 35 3 25 2 15 1 5 Plant N at R6 Soil N at R6 Urbana 216 354 326 298 3 317 313 34 29 29 3 32 45 49 52 UTC PT1U R1 R3 R5 4X AMS N application - 1 lb urea per acre
Yield, bu/acre Soy N Study, Urbana, 216 1 9 8 7 6 5 4 3 2 1 27 28 29 3 31 32 33 34 35 36 37 Plant N at R6, lbs N/acre
Yield, bu/acre 75 7 65 6 55 5 Orr Center N on soybean, 214-15 Optimum y = -.2x 2 +.63x + 65.978 R² =.9864 3 6 9 N rate, lb N/acre applied as urea
N on soybean, Urbana, 217 8 7 69.7 72.3 7. 72.2 7.8 75.4 73.7 6 Yield, bu/acre 5 4 3 2 1 B AB B AB AB A AB Nitrogen treatment, 1 lb urea each time
Yield, bu/acre 1 9 8 7 6 5 4 3 2 1 Chillicothe, Irrigated loam, 217 87.3 78.6 79.1 79.5 79.2 77.2 79.9 B B B B B A B No N Pl R1 R3 R5 4X AMS R3 N treatment
Soybean yield, bu/acre 6 55 5 45 4 Monmouth N x rotation, 28 yr 6 12 18 24 3 N rate on previous corn crop
Following 12 years of continuous corn: Urbana soybean input trial 215, 15 rows no N +N* Untreated check 94.9 93.1 Fungicide + insecticide 2x 1.4 15.5 All with Fung+Ins 2X Without With Fish-Seaweed extr. 14.7 1.7 Chicken litter 15.5 99.9 Gypsum 12.5 12.8 *Urea/AT + ESN 75+75
Soy mgt study, Urbana, 217 What worked; and what paid? Fungicide increased yield, but didn t pay Micro N (2X) Fungicide Insecticide Yield n n n n 74.3 bcd n n n y 75.3 abcd n n y n 73.8 bcd n n y y 78.5 a n y n n 76.5 abc n y n y 73.6 bcd n y y n 75.5 abcd n y y y 73.2 cd y n n n 73.4 bcd y n n y 74.8 abcd y n y n 77.4 ab y n y y 76.1 abc y y n n 71.8 d y y n y 73.4 Bcd y y y n 74.2 bcd y y y y 76.5 abc
N on soybeans: yes, no, maybe? We still typically see, in most Illinois soils, little or no response of soybeans to in-season fertilizer N There is no indication that higher-yielding soybeans might respond more to N We have evidence that planting-time N can increase soybean yield on lighter, lower-om soils We can often force higher yields by applying N 4 times; this is interesting, but not profitable
N on soybeans: yes, no, maybe? As a general practice, N fertilizer on soybean is unlikely to pay for itself, and some of it might end up in tile lines While yield contestants routinely include use of N, often along with fungicide and other stuff, there has been no indication that any of this increases yield It s possible that stimulating a lot of growth by using N under rainfed conditions can increase water use and limit yield So, the answer is NO, at least in most fields for now; MAYBE in lower-om soils but we have no idea when or if N will pay on ANY field
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