In response to questions being asked by tobacco growers about the effectiveness of sulfate of potash magnesia (SPM; 21% K2O and 11% Mg) as coinpared to sulfate of potash (SP; 50% K2O), field studies were conducted during 1993-1994 to compare the two potassium (K) sources for use on burley tobacco. Any effect of SPM on yield of tobacco should be due to Mg since the only difference between the two sources in kind of nutrient contained is the presence of magnesium (Mg) in SPM. To compare the two K sources, we selected field sites low enough in soil test K levels that normally would result in increased tobacco yields due to application of fertilizer K

Dollarhide, James E.

Reese, Mark

Wells, Kenneth L.

English

University of Kentucky

University of KentuckyUKnowledgeSoil Science News and Views Plant and Soil Sciences1995The Effect of Rate and Source of PotassiumFertilizer on Cured Leaf Yield of Burley Tobaccoand Leaf Content and Soil Test Levels of Potassiumand MagnesiumKenneth L. WellsUniversity of KentuckyJames E. DollarhideUniversity of Kentucky, james.dollarhide@uky.eduMark ReeseUniversity of KentuckyRight click to open a feedback form in a new tab to let us know how this document benefits you.Follow this and additional works at: https://uknowledge.uky.edu/pss_viewsPart of the Soil Science CommonsThis Report is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in Soil ScienceNews and Views by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu.Repository CitationWells, Kenneth L.; Dollarhide, James E.; and Reese, Mark, "The Effect of Rate and Source of Potassium Fertilizer on Cured Leaf Yieldof Burley Tobacco and Leaf Content and Soil Test Levels of Potassium and Magnesium" (1995). Soil Science News and Views. 145.https://uknowledge.uky.edu/pss_views/145UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE Lexington, KY 40546-0064 COOPERATIVE EXTENSION SERVICE Department of Agronomy Soil Science News & Views Vol. 16, No. 5, 1995 The Effect of Rate and Source of Potassium Fertilizer on Cured Leaf Yield of Burley Tobacco and Leaf Content and Soil Test Levels of Potassium and Magnesium K.L. Wells, J.E. Dollarhide, and Mark Reese In response to questions being asked by tobacco growers about the effec-tiveness of sulfate of potash magnesia (SPM; 21% K,O and 11% Mg) as coinpared to sulfate of potash (SP; 50% K,O), field studies were conduct-ed during 1993-1994 to compare the two potassium (K) sources for use on burley tobacco. Any effect ofSPM on yield of tobacco should be due to Mg since the only difference between the two sources in kind of nutrient con-tained is the presence of magnesium (Mg) in SPM. To compare the two K sources, we selected field sites low enough in soil test K levels that normal-ly would result in increased tobacco yields due to application offertilizer K. Field Studies Conducted Studies were conducted on two con-trasting soils (Maury silt loam and Lowell silt loam) in Scott County, Ken-tucky in 1993. The Maury soil is representative of the deep, well-drained limestone-derived upland soils of the Inner Bluegrass Area, and the Lowell soils are representative of the deep, well-drained limestone/shale derived upland soils of the Outer Bluegrass and Hills of the Bluegrass Regions. In these two trials, there was no significant yield response to either Kor Mg application on the Maury soil, despite the initially low level of soil test K. While there was a significant (p = . IO) yield response to applied Kon the Lowell soil, the higher average yields for the SPM treatments were not sig-nificantly different (statistically) from the SP treatments at 200 and 400 lbs J(,O/acre. Two sites were selected for more detailed studies in 1994. A Lowell silt and 2 years of sod and had been in tobacco during 1992 and 1993, it was kept in tobacco in 1994 to enable the study to be conducted. An Allegheny loam soil was located in Pendleton County, KY, for a similar study. The Allegheny soils are deep, well-drained, terrace position soils developed in old alluvial deposits. Treatments of K-source and rates of K and Mg were established in a randomized block experimental design with 4 replications. Individual plots were 4 rows wide and 40 ft long. The K fertilizers were broadcast by hand and then disked into the soil just ahead of transplanting the tobacco. The to-bacco producer at each site applied all other nutrients needed except for K, onto the experimental area. Yield was loam soil was selected in Scott County, measured by weighing the cured leaf KY,locatedverynearthesamefieldin from 5 sticks (30 stalks) from the 2 which the 1993 study had been con- centerrowsofeachplotandextrapola-ducted. Although the field was nor- tingthe average leaf weight per stalk to mally in a rotation of 2 years tobacco an acre basis. Cured leaf composition Educational programs of the Kentucky Cooperative Extension Service serve an people regardless of race, color, age, sex, religion, disability, or national origin. UNIVERSITY OF KENTUCKY, KENTUCKY STATE UNIVERSITY, U.S. DEPARTMENT OF AGRICULTURE, AND KENTUCKY COUNTIES, COOPERATING Soil Science News & Views of K and Mg and soil test levels of K and Mg after harvest were also deter-mined. Leaf composition was deter-mined from a composite sample of I 0 leaves ran-increase soil test and leaf content ofMg as shown by the highly significant rela-tionship between soil test Mg and leaf Mg in Table 5. Soil test K levels were leaf yields, and leaf K content was significantly correlated with leaf yields. Although soil test Mg was not well correlated with leaf yield, it was signif-icantly domly se-1 e ct e d while strip-Table 1. Effects of K rate and source on cured leaf yield, cured leaf content, and soil test levels of K and Mg - Lowell soil, 1994. correlated with leaf content of ping from lbs/A Applied stalk posi- K-Source K10 tionsabove the flyings. SPM Soil sam- SP SPM SPM SP SP 0 100 200 200 300 400 600 Mg 0 52 0 104 156 0 0 pies were taken from each indi-vidual plot immediate-ly follow-ing harvest. LSD (p = 0.05) CV(%) lbs/A Leaf. Content~ DMJ Lea( Yield K Mg 2120 3.47e 0.57c 2349 3.86de 0.56c 2317 4.14cd 0.45d 2293 4.35bcd 0.67b 2192 4.6lbc 0.75a 2094 4.77ab 0.47d 2361 5.27a 0.43d NS 0.59 0.07 14 9 8 D a t a Averages followed by the same letter are not different Soil Test Let>els {lbs/Al* K Mg 382c 210b 393c 244b 402c 193b 532b 372a 528b 406a 588b 202b 727a 195b 94 58 13 15 collected in •Av. from samples taken immediately after harvest; initial soil test levels from a field . composite sample taken in March: pH 6.6, P 127, K 322, Mg 194. Mg. Leaf content of Mg was notsignif-i cant I y correlated with yield. At this site, there was a sig-nificant effect of increased soil test K levels de-1994 for 1!!::5:::z:::z:::z::::i::::z:::=:::=:::=:::=:::=:::z:::=:::=:::========================:::J the Lowell pressing leaf content ofMg, even though this did not affect leaf yields. and Allegheny soils are summarized in Tables I and 2. Correlation coeffi-cients for various comparisons of yield, leaf content, and soil test levels of K and Mg are shown in Table 3. The results show that there was no leaf yield response to fertilizer Kor Mg on the Lowell soil. The somewhat lower than usual yields from this field were attributed to a possible low-level build up of black root rot disease organisms in the soil from not rotating out of tobacco after 2 years. Results from previous field studies in the Hills of the Bluegrass Area would have indicated a likely possibility for a K response, even at a soil test K level of 3 22 lbs/ A, on similar soils. Application of Mg did also increased by increased rates of K fertilization, and this also resulted in a highly significant effect on content of leaf K. Despite these effects, neither soil test levels nor leaf content ofK and Mg significantly affected yield ofcured leaf at this site. On the Allegheny soil, there was a significant effect of K rates on leaf yields, as shown in Table 3. However, leaf yields were not increased by the addition of Mg, even though Mg fertil-izer did increase soil test levels and leaf content of Mg as compared to no Mg at the 400 and 600 lb KaOIA rates. As shown in Table 5, soil test K levels significantly affected leafK levels and Page 2 Summary Results from 4 field trials conduct-ed to test the effect of Mg fertilization on tobacco production showed no sig-nificant yield increase due to the Mg. The use of fertilizer Mg did increase both soil test level and leaf content of Mg. We concluded from these studies that there is no difference in the effect of SPM on tobacco yields from that obtained with use of SP. ~~(J.~r-Extension Soils Specia~~ ---~--- ---- --------- -----------Soil Science News & Views Table 2. Effects of K rate and source on cured leaf yield, cured leaf content, and soil test levels of K and Mg - Allegheny soil, 1994. lbs/A App.lied lbs/A Lea[ Content~ DM) Soll Test Levels Obs/Al* K-Source KO Mt:. LeaCYield K Mt:. K Mt:. 0 0 0 2477c 1.98e 1.27a 147c 397bc SP 200 0 2959ab 3.35c 0.99b 195c 400bc SP 400 0 3193a 4.3lb 0.88bc 359b 399bc SPM 400 210 2994ab 4.33b 1.0lb 337b 473ab SP 600 0 2908b 5.13a 0.76c 477a 35lc SPM 600 315 3060ab 4.79ab 1.0lb 404ab 54la LSD (p = 0.05) 241 0.53 0.17 94 97 CV ~%l 5 9 II 20 15 • Av. from samples taken immediately after harvest; initial soil test levels from a field composite sample taken in March: pH 6.2, P 118, K 278 Averages followed by the same letter are not statistically different. ~,.,,_,_,~ ,, ,_. __ Table 3. Relationship between soil test levels , leaf content , and yield Correlation Coeffu:ient Comparison Allqrhenv Soil Lowell Soil Soil Test K vs Yield 0.47. 0.07NS Soil Test K VS LeafK 0.86 •• 0.77 •• Leaf K vs Yield 0.59 •• 0.23 NS Soil Test Mg vs Yield 0.33 NS -0.07 NS Soil Test Mg vs Leaf Mg 0.50 •• 0.82 •• Leaf Mg VS Yield -0.27 NS -0.15 NS Soil Test K vs Leaf Mg -0.53 •• -0.18 NS Soil test levels of K and Mg immediately following harvest Content (% DM) of cured leaf Yield of cured leaf, lbs/ A •=significant at p = 0.05; ••=significant at p = 0.01; NS = non-significant Page 3 COOPERATIVE EXTENSION SERVICE U.S. DEPARTMENT OF AGRICULTURE UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE LEXINGTON, KENTUCKY 40546 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 AN EQUAL OPPORTUNITY EMPLOYER BULK RATE POSTAGE & FEES PAID USDA PERMIT No. G268 

The Effect of Rate and Source of Potassium Fertilizer on Cured Leaf Yield of Burley Tobacco and Leaf Content and Soil Test Levels of Potassium and Magnesium

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The Effect of Rate and Source of Potassium Fertilizer on Cured Leaf Yield of Burley Tobacco and Leaf Content and Soil Test Levels of Potassium and Magnesium

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