Soybean Response to Foliar Applied Methanol in Humid and Semiarid Environments

Abstract

Recent research from a desert environment in Arizona suggested that foliar application of dilute solutions of methanol substantially increased yield, quality, and water‐use efficiency of several C 3 plant species. However, soybean [ Glycine max (L.) Merr.], which is one of the major agronomic C 3 crops of the USA, was not included. Therefore, this research was initiated to compare effects of methanol solution concentrations applied to soybean at different reproductive growth stages under field conditions in humid and semiarid environments. The experiment was conducted in 1994 and 1995 at two irrigated (limited and full) locations in semiarid, northwestern Kansas and at one dryland location in humid, southeastern Kansas. Soil moisture was determined for these growing seasons. Each of two methanol concentrations (20 and 40%, v/v) was applied either in a single application at growth stages R1, R3, and R5 or in multiple applications involving all combinations of these three for a total of seven treatments involving stage of growth. One untreated control plot was maintained in each replication. Neither methanol concentration nor time of application affected grain yield, yield components, or seed quality or soil‐plant water relations. In addition, no difference was detected between the average responses to methanol application and the untreated control. Thus, we conclude that soybean responses to foliar applications of methanol are not effective under either humid or semiarid conditions typical of those found in Kansas and much of the Great Plains. Research Question Much publicity resulted from research findings in Arizona indicating that foliar applications of methanol could cause substantial increases in yield, quality, and water‐use efficiency of several C 3 crops under irrigated desert conditions. Would similar results be obtained with soybean grown in humid and semiarid environments? The objective of this study was to compare effects of methanol solution concentrations applied to soybean at different reproductive growth stages under field conditions in humid and semiarid environments. Literature Summary Recent research from a desert environment in Arizona suggested that foliar application of dilute solutions of methanol substantially increased yield, quality, and water‐use efficiency of C 3 plants. This work also implied that high‐intensity light conditions may favor plant response to methanol applications. Consequently, environments with more cloudy conditions could be expected to benefit less, if at all, from methanol applications. Regardless, the potential for increasing yield and growth of C 3 plants by application of a relatively cheap and easily obtained product has generated interest in testing the technology in other environments on a variety of plants. In general, minimal response to foliar applications of methanol has been reported on crops such as tall fescue, creeping bentgrass, potato, tomato, melon, and sour orange tree in a variety of environments. However, data are lacking for methanol applications to soybean grown in the Great Plains region of the USA. Study Description The experiment was conducted in 1994 and 1995 at two irrigated (limited and full) locations in semiarid, northwestern Kansas and one dryland location in humid, southeastern Kansas. Soils at all locations were classified as silt loams. Soybean varieties both years were Pioneer brand 9341 at the irrigated locations and Medallion brand Flyer at the dryland location. May‐through ‐September rainfall totaled 11.2 in. during 1994 and 17.3 in. during 1995 at the irrigated location; and 22.0 and 32.0 in., respectively, at the dryland location. All plots at the irrigated locations received preplant irrigation to refill the profile and in‐season amounts totaling 2.3 in. during 1994 and 4.0 in. during 1995. Limited‐irrigation plots received an additional 2.5 in. during 1994 and none in 1995; full‐irrigation received an additional 6.2 in. during 1994 and 4.0 in. during 1995. Each of two methanol concentrations (20 and 40%, v/v) was applied either in a single application at growth stages R1, R3, and R5 or in multiple applications involving all combinations of these three for a total of seven treatments involving stage of growth. One untreated control plot was maintained in each replication. Quantity of soil water was determined for the growing seasons. Soybean grain yield, yield components, and seed quality were determined. Applied Questions Does the technology of foliar application of methanol to crops transfer to soybean grown in humid and semiarid environments? Precipitation and solar radiation received at the dryland and irrigated locations in Kansas during the 1994 and 1995 growing seasons. Rainfall Solar radiation Location Year May Jun Jul Aug Sep Season May Jun Jul Aug Sep Season ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ in. ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ g cal/sq cm per d ‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐ Irrigated 1994 0.68 3.45 5.63 0.53 0.88 11.17 574 618 632 529 434 557 1995 7.34 2.98 4.23 1.37 1.36 17.28 314 522 565 551 393 469 LTA 2.94 3.12 2.95 2.22 1.46 12.69 516 585 568 498 416 517 Dryland 1994 4.26 1.92 7.32 4.68 3.83 22.01 459 452 495 478 380 453 1995 9.85 10.10 3.77 6.85 1.38 31.95 307 432 535 499 338 422 LTA 5.26 4.61 3.15 3.63 4.80 21.45 455 514 543 494 387 479 LTA = Longtime average. Under the climatic conditions of humid and semiarid extremes in Kansas, the use of methanol was ineffective for increasing yield. We found no practical beneficial effect of either methanol concentration or time of application on soil water depletion or on soybean grain yield, yield components, or seed quality. The average responses of measured parameters to methanol application were not different from those in an untreated control. Does the potential for yield increases outweigh the potential handling hazards associated with methanol? Based on the general lack of crop response obtained in this and other studies, little incentive seems to exist for producers to experiment on their own. Unless additional research discloses procedures that will result in more success, producers need not contend with this potentially dangerous, flammable product.

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