File: Agron. 2William J. Murphy (Department of Agronomy, College of Agriculture)Rev. 12/71/15M, 9/75/5

Murphy, William J.

English

University of Missouri: MOspace

• -· Scie11ee 1111d 7:eclt110/0111 GUIDE e ~ % Ci ~ u M C G'T11, ,.,, ii 111, C••p111 P11blisltetl 611 tlte ll11iversit11 of ,MissP11ri - 60/11111bi11txte11sio111JivisiP11~DucAl\~ Corn Planting Rates and Row Spacing in Missouri William J. Murphy, Department of Agronomy College of Agriculture Selection of planting rates and row widths are decisions that directly affect the yield of the corn crop. Yield potential varies more with plant population than it does with row width, but differences in yield for different row widths are sizeable. There are a number of factors that do influence response to planting ra tes so "pin-pointing" the rate that should give the most harvested grain from a particular field is difficult. The corn producer does have a measure of control over some of these factors, including: ( 1) The hybrid that is planted. There are differences in the way different hybrids respond to thick planting. There is strong emphasis by corn breeders toward developing hy-brids that will tolerate dense stands. (2) The amount of fertility available to the crop. More plants than will be properly nourished will reduce grain yields. (3) The moisture supply. This involves available mois-ture holding capacity of the soil, expected rainfall, the time it is received, and whether or not irrigation to supplement natural rainfall is available. ( 4) Production practices and treatments that contribute to higher yield levels. Experiments in recent years by the Agronomy Depart-ment, UMC, and the Soil and Water Conservation Research Division, ARS, U.S.D.A. in cooperation with Agricultural Experiment Station, UMC under both irrigated and non-ir-rigated conditions have given information that can be of value in selecting row widths and planting rates under Mis-souri conditions. Weir and Zuber conducted a series of experiments in 1966, 1967, and 1968 at Spickard, Columbia, Mt. Vernon, and Portageville with identical plantings in which planting rates and row widths were compared using three hybrids se-lected for known ability to tolerate high planting popula-tions. Fertilization was sufficiently high to eliminate it as a limiting factor. These were non-irrigated plots, except at Portageville. The relatively poor physical characteristics of the soil for corn production at Portageville, even though ir-rigated, did not permit yields to exceed those from the non-irrigated locations. Eleven of the twelve tests were successful and gave meaningful results. Most of these locations had ex-cellent corn growing seasons in 1967 and 1968, but 1966 was only a fair season. 4110 l 30 l 20 i.l ~ ~ I ll0 ~ l00 90 80 12,000 16,000 20,000 24,000 Pl ants per acre Figure I -Average corn yields at different plant populations during 3 years at Spickard, Columbia, Mt. Vernon and Portage-ville. Figure 1 gives the average yields over all row spacings at these four locations for each of the three years. Yields in-creased with each increase in population in the good sea-sons of 1967 and 1968, but there was little advantage for more than 16,000 plants in 1966. Figure 2 divides the tests on the basis of yield levels. The greatest advantage from high plant population came at high yield levels, intermediate yielding tests show a somewhat lesser advantage, and the tests with lower yields did not benefit from populations above 16,000. Figure 3 shows the yields for different row widths in these same tests. 20-inch rows outyielded 30-inch rows, and 30-inch rows outyielded 40 inch rows each year. The dif-ferences in favor of narrower row widths were greater as yields were higher, as indicated in Figure 4. Corn plants will be farther apart in the row in narrow rows than in wide rows if the per acre planting rate is the same. At high populations Samonte found that intensive in-row competition reduced optimum yield. This occurred when plants were closer than 8 to 11 inches, and he suggested that the hybrid he used should not be planted closer than 8 inches in the row. There is no indication that the planting rate should be increased because of changes to narrow row 150 l40 l30 l20 ll0 ., - - --Ave. 5 Tests with yields above 120 bu . • -•- Ave. 3 Tests wi t h yields between 100 - 120 bu . -- Ave . 3 Tests with yields be l ow 100 bu . ,,,. --·---· .__.. . .,,,,,,. .---·--·---,,.,,,,.· l00 ,,,,,· 90 80 70 ~----,-,t,:-c,o""oo:-----,-. -.o-oo----,-o,-oo-o----,-4,-oo_o __ Plants pe r acre Figure 2-Average Corn Yields at different plant populations during 3 years at 4 locations in relation to yield levels. widths. If high populations are used there will be added ad-vantage from using a row width that will keep away from this in-row competition. After selecting planting rate, Table 1 can be used to check for row widths that should avoid this effect. TABLE 1 - Plants per acre at various r ow widths. Inches between Plants 20" row 30 11 row 36" row 38 11 r ow 40 11 row in row 8" 39,240 26,140 21,770 20,630 19 , 620 9" 34,880 23 , 240 19,360 18,340 17,440 10" 31,400 20,920 17 , 420 16,510 15, 700 11" 28 , 460 18,960 15,830 15,020 14,230 12" 26,160 17,420 14,520 13, 760 13,080 13" 24 , 160 16,080 13,430 12, 740 12 , 080 14" 22 , 440 14,920 12,450 11 , 790 11, 220 15" 20,920 13,090 11,670 11 , 010 10 , 460 20" 15, 700 10,460 8, 710 8,250 7 , 850 Samonte's trials also confirmed the old rule that one-eared hybrids of the maturity range most commonly grown in Missouri usually give best yields when planting rates and growing conditions result in an average ear size of around ½ pound. The pattern of planting rate and row width effects have varied little between nonirrigated trials and the irrigated tests of Gaddy, of Samonte, and of Whitaker, Heinemann and Larson - although the latter did not receive yield in-creases from rows less than 30 inches wide. Irrigated corn can give substantially higher yield levels, as indicated by comparing variety yield tests of Horrocks and Cloninger. In 1970 they reported on nine trials without irrigation and five that were irrigated. Although the tests are not directly 130 120 ll 0 100 90 80 '------- --------------20" 30" 40" Row Width Figure 3-Average corn yields at 3 row w idths during 3 years at Spickard, Columbia, Mt. Vernon and Portageville. comparable, the nonirrigated trials had an overall average yield for all en tries of 90.9 bu/ A, and the irrigated trials averaged 130.3 bu/ A. Irrigated fields also have a more con-sistent production level from season to season, so choice of planting rate can be made with more confidence. The importance of considering harvestable yield in mak-ing plant population and row width choices is illustrated by measurements reported by Whitaker, Heinemann, and Larson from their 1966 irrigated trial at Elsberry as shown in Figure 5. Total yield was slightly superior at the 24,000 population, but the 20,000 population level gave a bit more harvestable yield. And 20-inch rows had decidedly more yield that was not harvestable than the wider row widths. This population level is supported by Gaddy's irrigated experiments where highest yields consistent with strong stalks were achieved at 20,000 to 24,000 plants per acre. Gaddy concludes that it would be better to use around 20,000 plants per acre to avoid undue crowding stress to corn plants since yield dif-ference between these populations was small. There are other reasons for caution. Stalk rots, stalk lodging, and barren stalks tend to increase as plant densities increase. Thicker plantings also retain "free" moisture on plant parts longer after rainfall or dew thus providing more favorable conditions for establishment of infestations of dis-eases such as Southern Corn Leaf Blight and Northern Corn Leaf Blight. Experimental trials furnish good guidelines, but adjust-ments may have to be made to fit individual farm and field situations. The overall results of the research discussed here, as well as that conducted in nearby states, is rather decisive in showing that a 20-inch row width can often be expected to grow more corn per acre than 30-inch rows. This is not likely to be true for harvested corn on most Missouri farms . Thirty-inch rows now seem near the practical minimum in 4110 ---140 130 120 110 100 90 80 ........ ....... ............... ... .... .... ............ ........ .... ....... - - - Ave. 5 Tests with yield s above 120 bus . • - • - Ave. 3 Tests with yields between 100 -1 20 bus . ....... ....... •...... --- Ave. 3 Tests with •--..._,_ • yields below 100 bus, --·-. 70 ~-----,,'°"o::-" - ------,,:-::-o,::-, ------,4""0·,-, --Row Wi dth Figure 4-Average corn yields at 3 row widths during 3 years at 4 locations in relation to yield levels. most instances, considering difficulty of weed control in the narrower rows when mechanical cultivation is needed, and added problems in harvesting the crop. Planting rates will need to vary because of expected dif-ferences in production levels on farms, and ofttimes by fields on those farms. The following steps are suggested for use in determining planting rates: 1. Set a yield goal for the field to be planted. It is usually practical for the producer who is striving to increase yields to set a yield goal some 10 to 15 bushels above average production obtained on that and similar fields in re-cent years, discounting abnormally good or poor years. When making drastic changes in production practices, the yield goal should reflect expected improvement from the change. 2. Use soil tests as a guide to supply sufficient plant food to meet this yield goal. 3. Calculate number of plants per acre needed at harvest to meet this goal. The use of ear size, trying for the ½ pound size men-tioned previously as most efficient, seems to be a practical method. Some variation may exist among hybrids, as well as at different population levels. But, in general, with one-eared hybrids a yield goal of 100 bushels/ acre would call for around 14,000 plants with ears at harvest; a 125 bushel goal would require some 17,500 plants; and a 150 bushel goal suggests 21,000 plants per acre. Early maturing natural-ly smaller eared hybrids might be more efficient at a smaller ear size. 4. Increase number of seeds per acre enough to obtain desired stand. One usually expects 85 to 90 stalks at harvest per 100 kernels planted when using treated seed with good germina-tion, application of a soil insecticide, moderate planting 411 0 ELSBERRY - 1966 - IRRIGATED Average of 2 hybrids ~ Total Yield D Harvestable Yield 160 M Plant Populations in thousands 150 140 130 120 110 100 40'' Rows 30'' Rows 20" Rows Figure 5-Total and harvestable yield at different plant populations and row widths. speed, optimum planting depth, and moderate planting rates in warm soil in a good seedbed. Early planting, planting under a mulch, planting at heavy rates, or in less than an ideal seedbed could reduce this to 75 to 80 stalks per 100 kernels. But at times one may obtain an almost perfect stand, so it seems unwise to increase kernels planted by more than 10% above the desired stand. It is better to underplant than to overplant. Corn that is overplanted will have more barren stalks, more lodged corn, more field loss from small ears that do not get in the com-bine, and poorer quality. Corn that is underplanted will make up part of the loss in yield by producing larger ears. 5. Select a hybrid that has ability to perform well at this stand count. Hybrid seed corn company representatives can usually give information as to the adaptability of their various hy-brids to different population levels. Missouri Hybrid Corn Yield Trial results published annually by the UMC College of Agriculture also contain information on some hybrids planted at "normal" as compared to " high" rates. ACKNOWLEDGEMENT The author is indebted to the following sources of ma-terial : University of Missouri Agronomy Department and Plant Science Research Division, ARS, USDA, - Unpublished re-sults, N . G. Weir and M. S. Zuber, 1966, 1967, 1968; Mas-ters Thesis, UMC, H. C. Gaddy, 1969, Corn Grain Yield as a Function of Plant Spacing ; 1970 Missouri Crop Perform-ance, R. D. Horrocks and F. D . Cloninger, Special Report 129, UMC, Jan. 1971. North Central Watershed Research Center, Soil and Water Conservation Research Division, ARS, USDA, in co-operation with the Agricultural Experiment Station, UMC, F. D. Whitaker, H. G. Heinemann, and W. E. Larson, Re-search Bulletin 961, UMC College of Agriculture, January 1969, Plant Population and Row Spacing Influence Maxi-mum Corn Yield. The interpretations made in this publica-tion from these sources are the responsibility of the author. Issued in furtherance of cooperative extension work, acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. Carl N. Scheneman, Vice President for Extension, Cooperative Extension Service, University of ~ Missouri, Columbia, Mo. 65201. The University of Missouri is an equal employment and educational opportunity institution. 19 4110 File: Agron. 2 R ev. 12/ 71/ JSM, 9/ 75/SM 

Corn planting rates and row spacing in Missouri

https://mospace.umsystem.edu/xmlui/bitstream/10355/69469/1/g4110-1975.pdf

Corn planting rates and row spacing in Missouri

Abstract

Similar works

Full text

Available Versions

University of Missouri: MOspace