Most soybean varieties used In Kentucky, whether grown full season or double-cropped behind wheat or barley, are from Maturity Groups (MG) IV or V. Some MG III varieties are also grown; however, virtually no MG 1/ or earner varieties are planted. Agronomists and soybean producers in Kentucky· have generally felt that MG IV and V varieties produce the highest yield. Since the driest months in Kentucky are August, September,and October, MG IV and V varieties frequently encounter moisture stress during the important seed fill stage. The use of earlier maturing varieties was initially proposed as a means of getting a major portion of seed fill to occur before the driest part of the growing season, thus getting higher yields in dry years

Egli, Dennis B.

Grabau, Larry J.

Kane, M. V.

Lin, H.

English

University of Kentucky

University of Kentucky UKnowledge Agronomy Notes Plant and Soil Sciences 3-1992 An Early-Planted, Early Maturing Soybean Cropping System: Yield and Harvest Losses Larry J. Grabau University of Kentucky, larry.grabau@uky.edu M. V. Kane University of Kentucky H. Lin University of Kentucky Dennis B. Egli University of Kentucky, degli@uky.edu Follow this and additional works at: https://uknowledge.uky.edu/pss_notes  Part of the Agronomy and Crop Sciences Commons Right click to open a feedback form in a new tab to let us know how this document benefits you. Repository Citation Grabau, Larry J.; Kane, M. V.; Lin, H.; and Egli, Dennis B., "An Early-Planted, Early Maturing Soybean Cropping System: Yield and Harvest Losses" (1992). Agronomy Notes. 55. https://uknowledge.uky.edu/pss_notes/55 This 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 Agronomy Notes by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. UNIVERSITY OF KENTUCKYCOLLEGE OF AGRICULTURELexington, Kentucky 4054600. COOPERATIVE EXTENSION SERVICE0"Vol. 25, No.2, March 1992AN EARLY·PLANTED, EARLY MATURING SOYBEAN CROPPING SYSTEM:YIELD AND HARVEST LOSSES.L.J. Grabau, M.V. Kane, H. Un, and D.8. EgliSoybean Yield:The primary objective of this researchwas to determine if soybean varieties from The highest yielding varieties, whenMG 00, 0, I, and II could produce yields averaged across all tests. were from MG IIcomoetitive with those of MG III and IV and III with MG I and IV somewhat lower'tducatronaTprograms of the "Kentucky Cooperative Ex/ension Service serve all people regardless 01 fEJes, color, age, sex, religion, handicap. or national origin.UNIVERSITY OF KENTUCKY, KENTUCKY STATE UNIVERSITY, U.S. DEPARTMENT OF AGRICULTURE, AND KENTUCKY COUNTIES. COOPERATINGMost soybean varieties used InKentucky, whether grown full season ordouble-cropped behind wheat or barley, arefrom Maturity Groups (MG) IV or V.· SomeMG III varieties are also grown; however,virtually no MG 1/ or earner varieties areplanted. Agronomists and soybeanproducers in Kentucky· have generany feltthat MG IV and V varieties produce thehighest yield. Since the driest months inKentucky are August, September,andOctober, MG IV and V varieties frequentlyencounter moisture stress during theimportant seed fill stage. The use of earliermaturing varieties was initially proposed as a "means of getting a major portion of seed fillto occur before the driest part of the growingseason, thus getting higher yields in dryyears.. There are, however, other potentialadvantages from the use of early maturingsoybean varieties. These varieties wouldhave less frost risk and harvest would becomplete before the cool, wet conditions of.November and December. In addition, anearly September harvest would provide moreflexibility in the choice of the following crop.Early harvest could allow planting of alfalfa,canola, barley, or wheat in fields which maynot normally be available for planting until thenext spring.varieties across a range of climatic and soilconditions. A second objective was tomeasure potential harvest losses of thesevarieties to determine if increased lossesmight keep farmers from using them.Materials and MethodsTwelve soybean varieties (two fromeach MG from 00 to IV) were planted in eachof six tests over four years. Row spacingwas 15 inches, planting rate was 160,000viable seeds/A, and conventional tillage wasused. Fertilizers were applied according toUK recommendations. Each variety wasplanted In plots 8 rows wide and 20 feet longwith 4 replications. Four center rows of eachplot were harvested at maturity with a smallplot combine. None of the experiments wereirrigated except in 1988 in Fayette County.Thfs experiment was irrigated with a sprinklersystem on a biweekly schedule. Table 1shows rainfall, planting dates, and harvestdates for elich of the six tests. Growingconditions varied from quite dry (Daviass1988) to very wet (Fayette 1988 irrigated).The experiments were planted well beforenormal planting dates in most studies.Results and Discussion(Table 2). Both MG 00 and 0 weresubstantially lower yielding, eliminating themfrom consideration for use in Kentucky.The individual tests showed a widerange of results. For the. Fayette test in1986, MG 00, 0, I, and II all averaged closeto 40 bu/A, while MG 1/1 and IV were muchlower. Yields in Daviess County in 1988were similar for all MGs, with the yield of thebetter variety within each MG not muchdifferent then the better variety in the otherMGs. In the non-irrigated test in Fayette Co.in 1988, yields were better for later MGs,since late August rains helped them but notearlier varieties, which were already close tomaturity by the time the rains started.Irrigation in 1988 greatly improved yields ofall MG 00, 0, I, and II varieties. However, MGIII and IV varieties did no better withirrigation, probably because excessive plantheight increased lodgin~ early· inreproductive growth. Thus, In the irrigatedtest, MG II varieties produced the highestyield. In 1989, rainfall was good throughoutthe season in Fayette County and yield ofthe better variety from MG II, III, and IV wasclose to 55 bu/A. There was no advantageto growing later varieties in that test.In summary, the MG which producedthe best yields depended on rainfalldistribution, and therefore varied widelyacross years and locations. Since MG IIproduced yields equal to or better than MGIV in five of the six tests conducted, growersmay want to consider using this MG for early / /planting. When averaged across all six tests,MG II matured 12 days earlier than MG IIIand 20 days earlier than MG IV. Thus, ourdata indicate that MG II will not only producecompetitive yields, but can also be harvestedearlier.Essex, a popular MG V variety in.Kentucky, was included in only three of thetests shown in Table 2: Fayette 1988(irrigated), Fayette 1989, and Simpson 1989.Since these were the three highest yieldingstudies, they should have given Essex agood chance to produce to its yieldpotential. The yield of Essex compared withElgin (the highest yielding variety tested in allsix environments) was 59.5 vs. 55.2 bu/A forFayette 1988 (irrigated), 54.5 vs. 53.4 bU/Afor Fayette 1989, and 38.0 vs. 50.4 bU/A for2Simpson 1989. Thus, Essex was no betterthan Elgin in two studies, but lower in thethird.The earliest varieties (MG 00 and 0)were usually harvested in early August, withMG I and II about 2 weeks later. Varieties·from MG III and IV were usually harvested inearly September, mainly due to the earlyplanting dates employed. The bestcombination of high yield and early harvestappears to result from early planting of MG IIvarieties.Stubble harvest losses:Kentucky farmers usually cut theirsoybean crops between 2 and 6 inchesabove the soil surface, with an averagecutting height of 4 inches. At any ofthosecutting heights, harvest losses wereexcessive for MG 00 and 0 varieties (Table3). The worst loss was with the very shortvariety Ozzie, which lost 37% of its yield if cut. at 6 inches. Varieties from MG 00, 0, and Ihad at least 2% losses with a 2 inch cuttingheight. However, cutting at 2 inchesreduced stubble losses to no more than the1% level for all MG II, III, and IV varieties. Atthe 4 inch height, stubble losses of MGIIvarieties were more-than those of MG III andIV varieties. If MG II varieties are to beadopted, farmers will need to achieve alower cutting height in order to obtain toobtain the full yield potential possible.ConclusionsKentucky tests have shown that MG IIvarieties produce better average yields thanMG IV varieties when planted earlier thannormal. This may partially result fromcompleting seed filling before the driestperiods of the summer. However, evenwhen moisture conditions were favorablethroughout the summer, later varieties didnot produce consistently higher yield thanMG II varieties. With the potentialadvantages of better average yield andearlier maturity (20 days), which leads to lessfrost risk and a greater range of choiceamong following crops, Kentucky farmersmay want to consider trying early maturingvarieties on a limited basis on their ownfarms.If a grower is interested in trying thissystem, we would encourage them to try MGII varieties. Preliminary data indicate thatplanting by May 15 is sufficiently early for thissystem. While our tests were all conductedin 15 inch rows, narrow row planting may notbe essential for MG II under early-plantedconditions, since the varieties we used haveproduced a closed canopy in 30 inch rows insix other tests. While the cropping systemwas hypothesized to result in more stableyields in droughty soils or dry years, itsapplication may not be limited to thoseSituations. Only two of the six studies hadbelow-normal August to September rainfall,while three were below normal for May toJuly rainfall. Thus, the data set does notappear to be biased in favor of earlymaturing varieties.Finally, we would encourageinterested Qrowers to try this early-planted,early-maturing cropping system on a portionof their soybean acres. If the farmer's resultswere favorable, we would still encouragegrowers to use it in combination with thetraditional later maturing package. Thatwould be expected to spread out the ever-present risk of inadequate moisture duringcritical growth stages.•34Table 1. Rainfall, planting date, and first and last variety harvest dates.Deviation from Harvest dateaverage rainfalla Planting First Lastcounty Year May-JulY Auq.-Sept. date Variety Variety•Fayette 1986 -3.5 +1.2 April 24 Aug. 5 Aug. 28Daviess 1988 -6.5 -0.1 April 29 July 27 Sept. 21Fayette 1988 -6.0 +0.8 May 11 Aug. 23 Oct. 17Fayette 1988 +3.8b +4.8b May 11 Aug. 11 Oct. 10(irrigated)Fayette 1989 +0.8 +2.8 April 25 Aug. 7 Oct. 2,-Simpson 1989 +8.5 -0.3 May 2 Aug. 8 Sept. 19aLong-term state averages for May-July are 12.7 inches, and for Aug.-Sept. are 6.4inches.bThis includes the 2.0 inches of irrigation water we applied 5 times during June andJuly, and 2 times during August. Rainfall was abundant in September 1988, so noirrigation was applied that month.5Table 2. Yields of soybean varieties for each of six tests.FayetteMaturity Fayette Daviess Fayette 1988 Fayette Simpson varietyVariety Group 1986 1988 1988 (irrigated) 1989 1989 means.----------------------------- bushels/A ------------------------------Maple Arrow 00 40.2a 25.1 30.7' 37.7 23.7 38.3 32.6McCall 00 44.2 17.2 17.8. 39.2 29.8 28.8 29.6ozzie 0 33.8 11.1 17.1 40.8 19.4 27.5 24.9Dawson 0 45.0 24.3 24.8 43.8 29.7 35.8 33.9Asgrow 1214b I 37.4 24.9 32.4 42.4 36.4 43.5 36.2Hardin I 43.6 20.9 34.3 47.3 40.7 46.0 38.8Elgin II 40.1 24.5 38.7 55.2\" 53.4 50.4 43.8Century II 36.8 28.5 36.1 49.6 46.0 45.3 40.4Pella 86 III 32.1 28.8 38.0 42.3 45.9 50.3 39.6Williams 82 III 26.6 28.8 42.1 45.6 55.4 37.7 39.4Union IV 20.8 24.9 41.4 43.6 49.3 35.5 35.9Douglas IV 17.4 24.5 45.7 42.9 55.9 38.0 37.4Test means 34.9 23.6 33.2 44.2 40.5 39.8a LSD(0.05) for comparing varieties within a test or tests within a variety was 7.3 bu/A. TheLSD (0.05) to compare test means was 3.9, and for comparing variety means was 2.8.b Asgrow 1214 was replaced by Asgrow 1525 in 1989.COOPERATIVE EXTENSION SERVICEU.S. DEPARTMENT OF AGRICULTUREUNIVERSITY OF KENTUCKVCOLLEGE OF AGRICULTURELEXINGTON, KENTUCKV 40546OFFICIAL BUSINESSPENALTY FOR PRIVATE USE. $300AN EQUAL OPPORTUNITY EMPLOYER'BULK RATEPOSTAGE & FEES PAIDUSDAPERMIT No. G268Table 3. Stubble harvest losses of soybean varieties averagedacross six tests.Maturity Stubble harvest losses at:Variety Group 2 inches 4 inches 6 inches-------------- % ---------------Maple Arrow 00 3b 9 18McCall 00 -'4 15 29/Ozzie 0 7 23 37Dawson 0 4 16 30Asgrow 1214a I 2 10 21Hardin I 2 7 16Elgin II 1 5 13Century II 1 3 9Pella 86 III 0 2 6Williams 82 III 0 1 4Union IV 0 1 4Douglas IV 0 1 2LSD(0.05) 1 2 2a Asgrow 1214 was replaced by Asgrow 1525 in 1989.b Percent of the total yield left on the stubble when cut at thestated height.

An Early-Planted, Early Maturing Soybean Cropping System: Yield and Harvest Losses

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An Early-Planted, Early Maturing Soybean Cropping System: Yield and Harvest Losses

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