Productivity and water use in intensified forage soybean-wheat cropping systems of the US southern Great Plains

• Published in: Field crops research Vol. 265; p. 108086
• Main Authors: Baath, Gurjinder S., Northup, Brian K., Rao, Srinivas C., Kakani, Vijaya Gopal
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.05.2021
• Subjects: DSSAT-CSM; Maturity groups; Summer fallow; Water use efficiency; Yield trade-off; Summer fallow; DSSAT-CSM; Water use efficiency; Yield trade-off; Maturity groups
• ISSN: 0378-4290; 1872-6852
• DOI: 10.1016/j.fcr.2021.108086

Agro-ecological intensification of continuous dryland wheat (Triticum aestivum L.) systems with forage soybean [Glycine max (L.) Merr] in lieu of summer fallow could provide nutritious summer forage for livestock, reduce requirements for inorganic N fertilizer for winter wheat, and ameliorate sustainability issues associated with summer fallow, such as soil erosion and low precipitation use efficiency (PUE). This modeling study utilized DSSAT-CSM to assess: the yield and water use of three cultivars of forage soybean of diverse maturity groups (MGs) harvested at three different dates [60, 90, and 120 days after planting (DAP)]; and their influence on performance and water productivity of subsequent winter wheat, and overall double-cropping systems in comparison to the fallow-wheat system. Crop yield and evapotranspiration (ET) data, collected from continuous field experiments at El Reno, Oklahoma (35.57 °N, 98.03 °W) during 2002–2006, were used for calibration and validation of soybean and wheat models. Long-term simulations conducted using historical weather data (1994–2019) suggested that mid-maturity group (MGV) soybean could provide greater forage yields and higher water use efficiency (WUEB) than later-maturing soybeans (MGVI & MGVII) when harvested at 90–120 days after planting (DAP). Double-cropping forage soybean and winter wheat caused a reduction of 1.4-2.1 Mg ha−1 grain and 4.7-5.6 Mg ha−1 and biomass by wheat, and higher seasonal ET losses of 77−132 mm than the fallow-wheat system. However, trade-offs in yields between forage soybean and winter wheat were effective when precipitation was >180 mm during the first 60 d of growth by soybean. Despite yield losses in winter wheat, double-cropped forage soybean-wheat systems could be a viable option based on its economic competitiveness and other ecological benefits.