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Sprinkler Irrigation Effects on Determinate Soybean Yield and Lodging on a Clay Soil
Author(s) -
Boquet D. J.
Publication year - 1989
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1989.00021962008100050020x
Subject(s) - irrigation , yield (engineering) , cultivar , agronomy , field experiment , soil water , mathematics , loam , horticulture , environmental science , biology , soil science , materials science , metallurgy
Drought stress can reduce the yield of soybean [ Glycine max (L.) Merr.] grown in the middle and lower Mississippi River Valley. A 3‐yr field study on Sharkey clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) determined the effects of four soil water levels and two row spacings on the growth and yield of cultivars Forrest (MG V), Centennial (MG VI), and Braxton (MG VII). Irrigation was applied in the four treatments when (i) soil water matrix potential ( Ψ s) at both the 15 and 30 cm depths reached −70 J kg −1 (I1), (ii) Ψ s at all depths between 15 and 76 cm reached −70 J kg −1 (I2), (iii) the same as in I1, but only after the R1‐R2 growth stage, and (iv) there was no irrigation (NI). Soybean was planted at interrow spacings (RS) of 0.5 and 1.0 m. Irrigation significantly increased yield of each cultivar at each RS in each year, but there were no yield differences among I1, I2, and I3 regimes at either RS. Average NI yields were 2.86,3.20 and 2.97 Mg ha −1 in 1982, 1983, and 1984, respectively. Yield increase from irrigation was 10,8, and 16% in 1982, 1983, and 1984, respectively. Irrigated yields of Forrest, Centennial, and Braxton were 3.47, 3.17, and 3.40 Mg ha −1 , respectively, but water use efficiency was greatest with Forrest. Irrigation prior to R2 increased lodging up to 100%, and up to 50% when irrigated after R2. Severe lodging may have reduced irrigated yields. Relative yield increase from irrigation was limited by adequate rainfall and soil water storage, which resulted in high NI yields. The most efficient water regime was one based on an early maturing cultivar and γ s measured at a depth of 76 cm.