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Title: Water use by four warm-season legumes in the Southern Great Plains

item Rao, Srinivas
item Northup, Brian

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/30/2009
Publication Date: 11/6/2009
Citation: Rao, S.C., Northup, B.K. 2009. Water use by four warm-season legumes in the Southern Great Plains. ASA-CSSA-SSSA Annual Meeting Abstracts, November 1-5, 2009, Pittsburgh, PA. CD-ROM.

Interpretive Summary: Abstract only, interpretative summary not required.

Technical Abstract: Growing warm-season legumes during fallow periods of traditional systems of continuous winter wheat (Triticum aestivum L.) in the Southern Great Plains (SGP) can provide supplemental forage, biological N, and protection from soil erosion, provided they can tolerate drought stress and not deplete available water in the soil profile. Our objective was to quantify water use by five species of pulses {pigeon pea [(Cajanus Cajan (L.) Millsp.) cv. ‘GA-2’], guar [(Cyamopsis tetragonobloba (L.) Taub.) cv. ‘Kinman’], cowpea [(Vigna unguiculata (L.) Walp.) cv. ‘Chinese red’], mung bean [(Vigna radiata (L.) Wilcz.) cv. ‘Berkins’] and soybean [Glycine max (L.) Merr.) cv. ‘Hutcheson’ (the control)]} in comparison to summer fallow. Seeds were inoculated and planted after wheat harvest in mid-June 2003 through 2006. Amount of water in the upper 65 cm of the soil profile was measured on nine dates [from 45 d before planting legumes (mid-April) to 195 d after planting in late-December]. Significant (P<0.01) differences in amounts of soil water were recorded among treatments, dates, and years. Differences in soil water between fallow, cowpea and mung bean were less following the 2003 and 2004 summer seasons and most noticeable in 2005 and 2006. Mung bean, guar, soybean and pigeon pea used the greatest amounts of water in 2005, the wettest growing season, while cowpea and mung bean used the least in 2003. Mung bean, cowpea and guar generated smaller water deficits in three of four years, and available soil water with cowpea and mung bean was similar to fallow at wheat planting (October) in two of four years. These species could be effective components of wheat-summer legume rotations in the SGP, provided the system is used during years with precipitation capable of optimizing production.