1. Field of the Invention
This invention relates to a method of fertilizing leguminous plants for increased yield using methanol and urea based nitrogen fertilizer.
2. Description of the Prior Art
Legumes constitute some of the world's most important agricultural crops. Examples include peas, beans, peanuts and soybeans. Leguminous plants are characterized by their ability to fix nitrogen microbially from the atmosphere, usually in nodules connected to their root systems, and their ability to use fixed nitrogen to produce proteinaceous seeds. The commercial products from leguminous plants are primarily seeds enclosed in true pods which are generated from the plants' flowers. Few of the flowers of these plant are normally converted to seed pods. Most flowers are aborted because of the inability of the plant to supply the nutrients required during period of stress when flowers are converted to mature seed pods among other reasons. Another critical stage in the development of this type of plant is the seed formation stage within the pods of these plants. In soybeans, this is the R5 stage.
A soybean plant's (e.g. Glycine max L. Merr.) growth and yield are dependent on many factors including environment, management and physiological changes that occur during its reproductive growth stages as taught by Gardner et al. article "Physiology of crop plants", Iowa State University Press: Ames, Iowa 1985. Earlier studies suggested that soybean like most other C3 plant species, has a lower photosynthetic ability than C4 plants in Hartman et al.'s article "Photosynthesis, respiration and translocation", pp. 145-167 in Plant Science: Growth, Development and Utilization of Cultivated Plants, 2nd ed. Prentice Hall, N.J., U.S.A.1988. Under optimum conditions of light, nutrients, favorable temperature, adequate moisture and atmospheric CO.sub.2, the photosynthetic capacity of soybean declines with increased demand for photosynthates during reproductive growth stages, see Gay et al.'s article "Physiological aspects of yield improvement in soybean", Agron. J., 72:387-391, 1980. It was further suggested that during flowering and pod-filling stage, vegetative and reproductive organs compete for photosynthates and nitrogen. It has also been reported that during R5 (beginning pod fill and seed growth), R6 and R7 reproductive growth stages, carbohydrates and nitrogen are redistributed from vegetative parts to seed development. These developmental growth stages are well known and defined in Fehr et al.'s article "Stages of Soybean Development", Iowa State University Press: Ames, Iowa 1977. Furthermore, the length of effective pod-filling period correlated with soybean yield. Some studies with CO.sub.2 enrichment and foliar application of nitrogen contributed to significant yield increases and the increased yield was attributed to the extended effective pod-filling period.
Nonomura et al.'s article "The path of carbon in photosynthesis: Improved crop yield with methanol", Proceedings of National Academy Science, U.S.A., 89, 9794-9798 1992, reported that foliar sprays of aqueous (10-50%) methanol increased growth and yield of C3 crop plants in arid environments. C3 is defined as plants that fix CO.sub.2 by forming (3-carbon acid), i.e. 3-phosphoglyceric acid. This article teaches in general of plants such as wheat (Triticum durum), cotton (Gossypium hirsutum), eggplant (Solanum melongena) and tomato (Lycopersicon esculentum) that are treated with nutrient-supplemented methanol that resulted in up to 100% increase in yield. This teaching further suggests that the effect of foliar methanol on growth was far beyond that expected of any foliar nutrient. This article goes on and suggest that the use of carbon from methanol was more reactive and easily metabolized by these plants as compared to CO.sub.2 enriched environment to enhance photosynthesis. Additionally, this article reported that urea fertilizer was applied along with methanol to maintain acceptable carbon/nitrogen ratios. Use of urea nitrogen with methanol suggested that nitrogen was vital to the assimilation and fixation of carbon. However, this article does not suggest or teach of: i) a foliar fertilization method for leguminous plants with critical amounts to be applied during a critical R5 growth stage in soybean plants or seed development stage in other leguminous plants as required by the instant invention; ii) optimal percentages of methanol and nitrogen fertilizer to be applied to leguminous plants for optimal yield; and iii) the synergistic effect of the proper amounts of fertilizer that must be applied at the leguminous plant's seed growth stage.
Another article related to the use of methanol with fertilizer is Nishio et al. article "Physiological aspects of methanol feeding to higher plants" In L. Ferguson (Ed.) Proceedings of twentieth annual meeting Plant Growth Regulator Society of America, pp. 8-13 1993; the teaching discusses a 30% increase in dry matter weight and accelerated rate of development of soybean plant with foliar-applied 15% methanol with fertilizer on a daily rotated basis. This teaching is concerned with the inherent vegetative growth of the plant in general, not the actual seed yield as is the purpose of the instant invention. This teaching does not teach or suggest of: i) a fertilization method at a critical R5 growth stage of a soybean plant in particular or the seed forming stage in other leguminous plants; ii) a synergistic effect of the instant invention's method of foliar-applied methanol and fertilizer at a critical seed growth stage of a leguminous plant and the optimal amounts of fertilizer as taught by the instant invention.
Another teaching recently reported that use of methanol alone without additional fertilizers on plants such as wheat or corn does not increase yield, see Radin's brief article "No yield boost from methanol", Agricultural Research, p. 19, 1994.
other teachings where urea fertilizer was primarily used alone on soybean plants includes Hanway's article "Foliar fertilization of soybeans during seed-filling", In F. T. Corbin (Ed.) World Soybean Research Conference II: Proceeding 409-416, 1979. This article teaches of significant yield increases occur when foliar fertilization of soybean with urea at the pod-filling R3 and R4 stages. This teaching also suggest that foliar nitrogen stimulated leaf activity, lengthened the effective pod-filling period, prevented early defoliation and senescence but did not increase the rate of photosynthesis.
Soybean yield increase has also been obtained from using urea as a source of nitrogen by foliar fertilization between various stages of the soybean plant growth, see i) Watanabe et al. article "Response of soybean to supplemental nitrogen after flowering", In S. Shanmugasundaram and E. W. Sulzberger (Eds.); ii) "Soybean in tropical and sub-tropical cropping systems", proceedings of a symposium, pp.301-308, Tsukuba, Japan: Fortune Printing Co., Ltd. Taiwan, 1983; and iii) Hanway's article "Foliar fertilization of soybeans during seed-filling", In F. T. Corbin (Ed.) World Soybean Research Conference II: Proceeding, pp.409-416, 1979. These teaching do not teach or suggest using foliar-applied methanol with a nitrogen based fertilizer material at the R5 growth stage of a soybean or seed growth stage in other leguminous plants.
U.S. Pat. No. 4,297,130 entitled "Method For Increasing the Number of Pods in Legumes By Foliar Feeding" by Moore which teaches of a method for the foliar feeding of leguminous plants with a nonburning nitrogenous plant food which is applied to the foliage of the plant at the R1-R4 flowering stage. Again, this teaching does not teach or suggest using foliar-applied methanol with a nitrogen based fertilizer material at the R5 growth stage of a soybean or seed growth stage in other leguminous plants.
Moreover, the effect of foliar application of nitrogen fertilizer alone at various stages of growth on soybean plants does not correlate with consistent yields as taught by Ashour et al. article "Effect of soil and foliar application of nitrogen during pod development on the yield of soybean (Glycine max (L.) Merr. )", Field Crops Research, 6, pp.261-266, 1983. Vasilas et al.'s article "Foliar fertilization of soybeans:absorption and translocations of 15 N-labeled urea" Agron J , 72-271-275, 1980, reported a response to the nitrogen fertilization in 1 of 2 years. Syvrud et al.'s article "Foliar fertilization of soybeans (Glycine max L)" in Commun. Soil Sci. Plant Anal. 11: 637-651, 1980, reported a response to foliar applied nitrogen but little effect from a NPKS combinations, i.e. nitrogen-phosphorous-potassium-sulpher fertilization combination. From no response as discussed in Boote et al.'s article "Effect of foliar fertilization on photosynthesis, leaf nutrition and yield of soybeans", Agron. J. 70:787-791,1978, to even yield reduction as discussed in Parker et al.'s article "Foliar injury, nutrient intake and yield of soybeans as influenced by foliar fertilization", Agron. J. 72:110-113, 1979, in soybean has also been observed due to leaf burn or damage from foliar fertilization.
To date, no work has been reported on the effect of foliar-applied methanol and nitrogen on leguminous plants in general and soybeans in particular at the critical seed growth stage for improved seed yield. Thus, the present invention provides such a method.