Nuttall, W.F.

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Nitrogen and phosphorus fertilizer response on Conquest barley as related to soil tests for nitrogen and phosphorus on stubble

University of Saskatchewan Research Archive

- 83 -Nitrogen and Phosphorus Fertilizer Response on Conquest Barley as Related to Soil Tests for Nitrogen and Phosphorus on Stubble W. F. Nuttall Research Station Melfort, Saskatchewan Eighteen field experiments were set out in 1969, 1970 and 1971 with Conquest barley on second or third crop after sumrnerfallow on Blaine Lake loam, Nipawin loam, Arborf1ield clay, Melfort silty clay, Etomami clay and Waitville loam. The fi'eld' design was a factorial, composite design, (5N x 2P) + (2N x 3P) giving 16 treatment combinations with 5 rates o£ nitrogen at 0, 22, 45, 67 and 134 kg N/ha and 5 rates of phosphorus at 0, 10, 20, 30 and 39 kg P/ha. Soil tests for exchangeable ammonium-N, nitrate-N and sodium bicarbonate soluble phosphorus were measured at depths of 0-15, 15-30 and 30-60 em depths in the fall and spring. Yield response to nitrogen and phosphate fertilizer was obtained by subtracting the control with no fertilizer applied from the remaining 15 treatment combinations. Soil tests for nitrogen (spring sampling) and phosphorus were related by multiple x;egression analyses to yield response (Table 1). In every regression equation with the exception of the 0-20, N-P treatment, the soil test for nitrogen was significant in accounting for among-site variation in yield response. The soil test for phosphorus was not significant in accounting for yield response variation for fertilizer treatments not receiving phosphorus. Also, the soil test for phosphorus was not as consistent as the nitrate test in significantly reducing among-site variation on plots receiving phosphorus. A highly significant relationship between cont~21 yields and the soil tests for nitrogen ~nd phosphorus was obtained (R = 83.3%). As 1969-71 were average to above average years in precipitation, giving fairly ~onsistent soil moisture reserves, differences ·in fertility status of the soils accounted for most of the among-site variation. The relationship between 3 soil test for nitrogen and phosphorus and 5 rates of nitrogen and phosphorus fertilizers is shownin Table 2. The table is not complete with 9 missing of the 25 values required to complete the table. An estimation of these missing · values can be made by interpolatibn and in some cases extrapolation. For example, with a soil test of 15 \.IS N/ 4g soil (30 lb N/ a c) and 6 llS PIg soil (12 lb P/ac), interpolation between 796 and 1553 kg/ha (67-0 and 67-20 treatments) gives an estimate of 1275 kg/ha for the 67-10, N-P treatment or interpolation between 931 and 1599 kg/ha (134...:10 and 45:...10 treatments) gives 1098. An average of these two values, 1187 kg/ha, would give a reasonabl¢ estimate of yield response. Yield response to nitrogen is shown in the~table to be reduced consistently with higher soil test values for nitrogen. This is not so for the phosphorus test as the estimate of yield response for the 45-20, N-P treatment is 1169, 833 and 1127 for 6, 12 and 18 llS P/g soil. Since the phosphorus test on these estimates are related on a curvilinear basis, the upper limit of the phosphorus soil test (18 !Jg P/g) may not give the best estimate of minimum yield response. By adding control estimates to the yield response values, potential yields could be estimated and would help in giving a better understanding of marginal yield response. (Fig. 1) Table 1. Regression Coefficients of Soil Tests used to Estimate Yield Response of Conquest Barley from Nitrogen and Phosphorus Fertilizer Application Coefficients Fertilizer rate, kg/ha Nitrate:....N Estimate kg/ha N p Intercept wg N/4g soil (Nitrate-N) 2 M Yield Contro: yield 22 45 67 134 0 22 45 67 134 45 45 45 134 134 134 0 0 0 0 0 20 20 20 20 20 10 30 39 10 30 39 0 1233 1910 2354 3741 668 1862 3055 3257 4920 2475 2616 2514 4056 4786 4519 -1700 -72. 9** -96.2** -128.1** -215.0** -27. 6* -73.6** -79.5** -194.8** -93.9** -61.4** -96.5** -197.7** -204.2** -191.8** 193.4** * F te~t was significant at 5% probability level. ** F test was significant at 1% probabjlity level. + F test was significant at 10% probability level. .956~ 1.149 l. 615+ 2.97* .259 .830~ .668 2.59* 1. 21* . 722* 1.46* 2.67** 2.73** 2.48* -2.7!t** of soil test NaHC03-P wg P/g soil -94.7* -164.2* -214.0+ -136. 7* -196.0 -91.6 -158.3** -57.7 -15.4 -72.2~ -45.0 325.6 values 3.:?8+ 6.41* 8. 77* 4.39 9.01 3.94 5.78* 1.43 -14.69** I S'ymbol indicates increase in yield over control from application of nitrogen and phosphor~s fertilizer. 75.8 69.9 6fi.8 74.1 40.1 62.5 78.4 74.5 78.5 75.5 79.6 60.6 77.3 82.3 81.5 83.3 Table 2. · m ..c: ......... p.. 0 10 20 30 39 Relationship,nf Yield Response of Conquest Barley to NP Fertilizers and NP Soil Tests Soil N - 15 llg N/4g Soil N - 30 \..g N/4g Fertilizer N (kg/ha) Fertilizer N (kg/ha) 0 22 45 67 134 0 22 45 67 134 0 PhosEhorus Soil Test - 6 ug P/g Soil 0 355 726 796 1184 0 -94 0 931 1599 339 436 221 751 1169 1553 1729 221 513 626 811 555 22,1 1116 1904 682 683 1100 1920 638 727 S,d I ;..: - 45 Lg 'f../4g Fertilizer l~ (kg/ha) '22 45 67 134 -112 292 474 314* 390 455 370 547 420 573 692 550 833 640 545 ~ ------------------------------------------------------~------------------------------------------------,... Q) N •r-i ,.....; •.-I +J ,... Q) r:z. Q) .1-1 m ..c: 0. (/] 0 ..c: p.. !hosEhorus Soil Test - 12 \.18 P/g Soil 0 0 355 726 796 1184 0 -94 0 -112 10 807 1506 215 343 168 382 222 20 18 459 833 1207 1526 18 219 288 465 352 18 97 119 24 344 217 30 790 1471 356 251 247 259 116 39 908 1660 447 457 641 370 275 -----------------------------------------------------~----~----------------------------------------~---PhosEhorusSoi1 Test..., 18 .,;g P/g Soil 0 0 355 726 796 1184 0 -94 0 10 967 1414 375 251 20 628 1127 1177 1972 388 583 435 798 30 881 1038 447 39 819 1390 358 187 Lb/ac = .9 x kg/ha * Minimum response which is at a soil test value less than 45 ug N/4g soil .--112 327 266 413 338 553 ·.289 130 790 . 663 100 5 00 CJ1 4000 0 .s:::. ' ~ ~ g3ooo w ->->-~2000 ct: ~ r-(f) ~ 1000 c z 0 u - 86 -·-------· -- ... - -~- - --- ----- ------- -CONTROL YIELD I 20 KG P/HA 0 0 KG P/HA o~--~----~----~------------------0 22 45 6 7 N FERTILIZER 134 kg/ha Fig. 1 Conquest barley yield related to nitrogen and phosphorus fertilizer for years 1969-71 at· soil tests of 15 J.l9 N/4g soil (30 lb N/ac) and 6 J.l9 P/g soil (12 lb P/ac). 

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Nitrogen and phosphorus fertilizer response on Conquest barley as related to soil tests for nitrogen and phosphorus on stubble

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