FORAGE PRODUCTION OF CORN AND SUNFLOWER MIXTURES F. S. WARREN Research Station, Agriculture Canada, Ottawa, Ontario KIA 0C6. Received 9 Apr. 1980, accepted 25 July 1980. WennEN, F. S. 1980. Forage production of corn and sunflower mixtures. Can. J. Plant Sci. 60: 13771382. Two corn (Zea mays L.) hybrids were grown in mixtures with three sunflower (Helianthus. annuus L.) cultivars at Ottawa for forage. The species appeared compatible in mixtures but yields of forage dry matter were higher for corn alone at several plant densities than for any mixture. Dry matter content at harvest and in vitro digestibility were both lower for sunflower than for corn. Consequently, yield of digestible dry matter per hectare for the sunflower component ofthe forage was so low that growing mixtures of corn and sunflower could not be recommended. On a cultiv6 deux hybrides de mais fourrager (Zea mays L.) en m6lange avec trois cultivars de tournesol (Helianthus annuus L.) h Ottawa. Les espbces semblent compatibles en m6langes, mais les rendements fourragers de matibre sdche (MS) du mais utilis6 seul ) plusieurs taux de semis d6passent ceux de n'importe quel m6lange. La teneur en MS h la r6colte et la digestibilit6 in vitro sont plus faibles pour le tournesol que pour le mais. Il en r6sulte que le rendement de MS digestible d.l'hectare pour la composante togrnesol du m6lange est si faible qu'il es.t impossible de recommander la culture de ces deux espdces en m6lanses. Corn (Zea mays L.) is almost invariably grown as a pure species for either forage or grain in Ontario. Many other crops e.g. alfalfabrome, barleyoats etc. are frequently or regularly grown as mixtures of species to improve yield and/or quality of the product. In other countries, corn too is frequently grown with other crops such as peas, beans or lentils to make better use of the land (Enyi 1973; Okigbo and Greenland 1976; Willey 1979). Some compatible species that could be grown with corn in Ontario to improve the silage would provide a real advantage in a feeding program. At Ottawa, numerous species have been tried as possible companion crops with limited success. Various legumes including white beans, pole beans and soybeans were not successful; when they survived at all they made little or no contribution to yield. Sunflowers are frequently grown with sweet corn in gardens and appearquite compatible. Can. J. Plant Sci. 60: 137713t2 (October 1980) t37'7 Morrison (1956) suggested there might be some advantage in growing mixtures of corn and sunflower for forage in cool temperature regions. Both sunflower and sorghum have grown well in combination with corn over several years at Ottawa. This paper presents results obtained in 2 yr of experiments in growing several cultivats of sunflower in association with corn hybrids. The feeding value of the silage of each species was assessed by in vitro digestibility analysis. MATERIALS AND METIIODS Field experiments with combinations of corn hybrids and cultivars of sunflowers were grown for 2 yr at the Ottawa Research Station. Two corn hybrids were selected from the Ontario recommended list as an "early" (2500 CHU) and a "late" (2800 CHU) maturing type. The sunflowers were three commercially available cultivars, namely, Mammoth Russian, P.G.R. 102 and Valley. Each corn hybrid was grown alone at, andplants/haand in all possible combinations, with each sunflower
I 378 CANADIAN JOURNALOF PLANT SCIENCE cultivar at and plants/ha in a complete randomized block of l8 entries in four replications. The plot area was a gently sloping welldrained Grenville sandy loam which had been cropped to corn for several years and left fallow for the year prior to this experiment. Fertility levels were moderate to high. A general application of 8 I 6 I 6 at 560 kg/ha and I 12 kg/ha N was made just before planting. Plots consisted of three rows 9 m long spaced 90 cm apart. Seeding was done by hand at two seeds per place and later thinned to one plant. Spacing between plants was 19.2, 25.2 and37 cm for the 50 000, and plants/ha density, respectively. For the mixed plots of corn and sunflower. the sunflowers were seeded in every third space to provide a2'.1 ratio of corn to sunflower plants. The plot area was relatively free of weeds and the few weeds were controlled by cultivating and hoeing. Through the season. various agronomic data were collected including disease ratings, flowering dates, height, lodging and plant counts. At harvest, all the plants in a 6 m length of the center row of each plot were handharvested, weighed, and chopped; a 0 g sample was retained for moisture determination and digestibility analyses. In mixed plots, the corn and sunflower plants were harvested and weighed separately. Each silage dry matter sample was subsampled to provide material for in vitro digestible disappearance determination. The method used was a modified twostage, acidpepsin procedure (Tiiley and Teny 1963). At the conclusion of the digestion time, the suspension was filtered under vacuum through a previously weighed hardened paper filter (Whatman 54). The dry matter disappearance was calculated by difference and reported as percent digestibility. Applying these percentages to the dry matter yields provided data for digestible dry matter per hectare. RESULTS Growth and performance of corn alone and the various mixtures with sunflower was essentially similar in each of the 2 yr of field experiments. Plant height differences due to Table l. Maturity (dry matter content at harvest) of corn hybrids grown alone and in mixtures with cultivars of sunflower at Ottawa Early corn hybrid Corn alone P.G.R. 102 Valley Late corn hybrid Corn alone P.G.R.102 Valley SE of mean CY (9o) (plants/ha) DM Vo ar harvest (2yr mean) 36.9 39.8 40.7 40.2 3't.'7 38.3 3t.) 4t.9 J /.O 30. l 30.8 28.'7 26.8 27.6 26.6 26.4 28.4 26.7 1.142 9.7 Sunflower 20.0 23.O 22.O z5.j 25.0 24.O 20.4 1t A 2t.9 21.6 25.3 23.2.8't3 t6.4
WARREN CORN AND SUNFLOWER FORAGE MXTURES 1379 hybrids, cultivars and populations were small but consistent. Corn alone was consistently taller in the higher populations. In combinationwith sunflower, corn averaged 14 cm or about 7Vo shorter than when grown alone. Corn height was similar with all sunflower cultivars. Development, as indicated by date of flowering stages for sunflower and date of tasselling and silking of corn, was essentially the same for each cultivar or hybrid whether grown alone or in combination. Similarly, there was no significant difference in percent dry matter (DM) at harvest Corn hybrid 1976 Early Late LSD (0.0s) 1977 Early Late LSD (0.05) Mean (2 yr) Early Late LSD (0.05) due to the maturity ratings of both corn and sunflower entries (Table l). In total yield of silage DM, corn alone was higher in almost every comparison than the corresponding mixture of corn with any cultivar of sunflower (Table 2). The highest yields were produced by corn alone at the highest population, plants/ha. Yield of the cornsunflower combinations did not show large differences due to the cultivar of sunflowers except in the case of PGR 102 in 1976, for which the performance was highly variable in some combinations. The contribution of each crop to the total Table2. Drymatteryield(kg/ha)ofcornandcornsunflowermixtures, 1976and1977 (plants/ha) Cornsunflower mixture Corn alone P.G.R. 102 Valley 9 396 9 573 11 195 l0 005 9 185 l0 988 r0 213 10 129 1966 15.0 10 101 12 287 t4 292 t2 227 9 8'.77 13 4'.7 13 869 12 406 339 9.0 9 748 l0 930 12 744 tt 141 9 531 12 230 t2 041 tt 266 I t'72 12.0 9 050 8 825 8 938 8 432 9 246 8 839 l0 120 t0 675 l0 398 9 593 l0 758 r0 r'76 9 585 9 750 9.667 9 0r2 l0 003 9 507 8 947 to 544 9'746 '7 899 6 920 7 410 8 949 8 521 8 735 I 743 9 268 9 006 8 948 9 s33 9 241 8 32r 8 094 I20'7 mean 8780 9 043 8441 9 346 I I 195 861 I 9 417 8 814 8 583 9963 9 279 to 2r3 9389 I 942 9779 9 737 9941 l0 3s6 14 292 9860 l0 518 87'.79 9 248 9914 10 853 l3 869 934'7 10 4'75 9280 9 390 9r9t 9 851 t2 744 9236 9 967 8'.796 8 916 9938 l0 066 t2 041 9367 r0 341
1380 CANADIAN JOURNAL OF PLANT SCIENCE forage yield varied somewhat due to corn hybrid and sunflower cultivar, but the means for mixtures with early or late corn hybrids were the same (Table 3). Differences due to plant density were slight. In vitro digestible dry matter disappearance varied only within a niurow range for either corn or sunflower. For the corn portion of the silage, the range was from 66.6to 73.6 with a meanof 69.3Vo (Table3). For the sunflower portion, the range was much narrower: from 50.1 to 54.4 with a mean of 5l.9Vo. In neither case was any difference attributable to years, populations, hybrids or cultivars. The 17.4 percentage point difference between the means for corn and sunflower indicated a great loss in feeding value for sunflower silage. The yield of digestible dry matter for mixtures was considerably lower than for corn alone (Table 4). For corn alone, the higher plant populations generally produced more digestible dry matter per hectare. On the mixtures, population did not affect the yield of either corn or sunflower. Corn hybrid or cultivar of sunflower also had little effect on yield. DISCUSSION Researchers in other countries have reported important yield benefits from growing corn in association with peas, beans or lentils (Enyi 1973; Okigbo and Greenland 19761' Willey 1979). However, in these experiments, mixtures of corn and sunflowers invariably yielded less than corn alone. In addition, the digestibility of the sunflower silage was much lower than that of corn silage so that the production ofdigestible dry matter of any of the mixtures was at least l5%o lower than for corn alone. Chemical analyses of corn and sunflower silage listed in standard references show that corn is regularly higher than sunflowers in such important items as protein, TDN and NFE (Monison 1956). Thus from a quality Table 3. Proportions by crop in forage yield and digestibility of forage in cornsunflower mixtures Early corn hybrid P.G.R. r02 Valley Mean for mixtures Late corn hybrid P.G.R. 102 Valley Mean for mixtures SE of mean (plant/ha) s8 000 s8 000 Proportion ofdmvo Digestibility 7o Corn Sunflower Corn Sunflower 64 62 )v 59 66 64 63 6l 62 llj 59 68 69 63 ;, 38 4l 4l 34 36 JI ; 38 42 4l JZ JI )t 726 '10.4 69.4 69.1 68.7 70.7 '70.'7 73.6 72.0 70.8 69.5 68.5 67.6 6'7.4 6'1.6 67.s 66.6 68.5 67.1 67.8.878 54.4 50. l 5l.5 51.6 5r.7 52.'.l s2.o sl.l 52.5 )u. / 52. I 51.2 50.2 5r.'7 l.190
WARREN _ CORN AND STINFLOWER FORAGE MIXTURES l38l Table 4. Digestible dry matter production of corn hybrids grown alone and in mixtures with cultivars of sunflower (2yr mean) Early corn hybrid P.G.R. 102 Valley Mean Late corn hybrid P.c.R. 102 ValleY Mean LSD (0.0s) (plants/ha) aspect also, cornsunflower mixtures would be at a disadvantage compared to corn alone. During the course of these experiments, other factors were noted that would make growing mixtures unattractive. Planting mixtures of seeds as dissimilar as corn and sunflower in a desired ratio presents obvious difficulties with any but the most sophisticated equipment. Several of the better corn herbicides cannot be used on mixtures with sunflower, so weed control would be more difficult and more costly. Birds such as blue jays, gold finches and sparrows are strongly attracted to sunflowers and without protective measures could easily strip the seeds of most heads by the time of silage harvest. After the sample areas had been harvested, the remainder of the plots was removed with a forage chopper. The extra power required to harvest plots with sunflowers was readily apparent. While no measurements were taken, additional energy and machine wear could be important. Corn (ke/ha) 708 l '7696 8843 4206 4150 3'765 4006 4493 4262 5389 6626 8429 8r89 3741 4252 3295 3263 4133 4618 5t'72 Sunflower (ke/ha) l 896 t882 l 863 2005 1638 1727 I 835 185 I r940 1736 t7 t4 1406 15l8 1694 Total (kg/ha) 708 l 7696 8843 6102 6032 s628 601 I 6131 5989 66t2 6626 8429 8 189 s592 6t92 503 l 4977 5539 6136 630 I 833 13.0 Although com and sunflower can be grown in mixtures, these experiments failed to demonstrate any possible advantage over growing corn alone for forage. This means that the search should continue for some compatible species to grow with corn to improve forage production. ACKNOWLEDGMENT The author expresses his appreciation to Don Born who conducted the field experiments and performed the statistical analyses. ENYI, B. A. C. 19'13. Effects of intercropping maize or sorghum with cowpeas. pigeon peas or beans. Exp. Agric. 9: 8390. MORRISON, F. B. 1956. Feeds and feeding,22 ed. Morrison Publishing Co., Ithaca, N.Y. I165 pp. OKIGBO, B. N. andgreenland, D. L 1976. Intercropping systems in tropical agriculture. Pages 63102 re Multiple cropping. Spec. Publ. 27. Amer. Soc. Agron., Madison, Wis.378 pp.
t382 CANADIAN JOI.JRNAL OF PLANT SCIENCE TILLEY. J. M. A. and TERRY, R. A. 1963. A importance and research needs. Part I. Competitwostage technique for in vitro digestion of tionandyieldadvantages.part2.agronomyand foragecrops.,j. Br. Grassl. Soc.18: 104lll. researchapproaches. Yol.32, pp. l10,7381. WILLEY, R. W. 1979. Intercropping Its Amer. Soc. Agron., Madison, Wis'
This article has been cited by: 1. Anil, Park, Phipps, Miller. 1998. Temperate intercropping of cereals for forage: a review of the potential for growth and utilization with particular reference to the UK. Grass and Forage Science 53:4, 301317. [Crossref]