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Title: FORAGE FROM SOYBEAN PROVIDES AN ALTERNATIVE TO ITS POOR GRAIN YIELD IN THE SOUTHERN GREAT PLAINS

Author
item HEITHOLT, JAMES - TX AGRIC. EXP. STN.
item KEE, DAVID - TX AGRIC. EXP. STN.
item FARR, JOE - TX AGRIC. EXP. STN.
item READ, JAMES - TX AGRIC. EXP. STN.
item METZ, SUSAN - TX AGRIC. EXP. STN.
item Mackown, Charles

Submitted to: Integrated Crop Management Conference Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2004
Publication Date: 4/6/2004
Citation: Heitholt, J.J., Kee, D., Farr, J.B., Read, J.C., Metz, S., Mackown, C.T. 2004. Forage from soybean provides an alternative to its poor grain yield in the southern great plains. Integrated Crop Management Conference Proceedings. Available: http://www.plantmanagementnetwork.org/research/2004/soybean.

Interpretive Summary: Soybean producers in the Northern Texas Blacklands region of the southern Great Plains often must make decisions whether to harvest their crop for hay or grain. These decisions are based on climatic forecasts, available soil moisture, and occurrence of plant stress symptoms. Knowledge of cultural practices such as variety selection (traditional grain and new forage varieties), planting pattern (narrow vs. wide rows), and harvest date as well as the identification of a reliable, timely, and inexpensive method to estimate in-season forage have not been developed for soybean producers in the southern Great Plains. We compared the impact of cultural practices on forage quality and forage and grain yields, and the use of plant height and plate meter readings to predict forage yields of soybeans grown near Dallas, TX. Among the grain type soybeans, grain yields were often low and not affected by row spacing or clutivar selection. Forage type soybeans produce little or no grain yield. Forage quality was generally unaffected by cultural practices except that delayed harvest generally lessened the quality of the hay. Plate meter reading and plant height were good but inconsistent predictors of forage yield. Becasue of high forage quality and low grain yields in 2001 and 2002, harvesting any of the soybean cultivars for forage during early reproductive growth was more profitable than harvesting for grain. These results will be useful to soybean producers and consultants seeking to improve assessment of forage biomass and economic returns of growing a crop in the Northern Texas Blacklands region of the southern Great Plains.

Technical Abstract: The economic potential for soybean (Glycine max L. Merr.) as forage, compared to its potential as grain, creates a dilemma for soybean farmers in the southern Great Plains. To better understand these two potential uses, soybean cultivars differing in maturity and growth habit were planted in 14-inch and 28-inch rows on 11 May 2001 and on 16 May 2002 near Dallas, TX. The soil was a Houston Black Clay (fine, smectitic, thermic Udic Haplusterts). Plant height, plate meter readings, and forage biomass were measured in July and August and grain yield determined in September. Forage (1.26 - 2.13 tons/acre) and grain yields (9.3 - 20.9 bu/acre) were relatively low and similar between row spacings and between cultivars. Forage quality traits ranged as follows (by dry weight): N(1.39 - 2.76 % or 8.7 - 17.2 % crude protein), acid detergent fiber (24.1 - 33.6 %) and neutral detergent fiber (33.2 - 48.9 %), in vitro dry matter digestibility (69.2 - 78.6 %), and relative feed value (120 - 196). Plate meter readings and plant height were each correlated to biomass in one season but not both. Because of its relatively high forage qulity and low grain yields, harvesting any of the soybean cultivars for forage during mid season would have been more profitable than harvesting for grain.