Grain Sorghum Growth, Development and Yield in Long-Term No-Tillage and Cover Crop Systems in the San Joaquin Valley, CA.

Sorghum [Sorghum bicolor (L.) Moench] is a globally important crop, ranking as the fifth most important cereal crop in the world in terms of total production. The US is the world’s largest sorghum producer with the majority of production in KS and TX. Despite only limited production in CA, sorghum is an attractive crop for the state as a biofuel crop, a food grain crop, and as a potential replacement for silage corn. Following thirteen years of a tillage and cover crop comparison of tomato and cotton, we grew grain sorghum under standard tillage (ST) with (CC) and without (NO) cover crop and no-tillage (NT) with CC and NO in the San Joaquin Valley, CA, in 2014 and 2015. All systems were irrigated using subsurface irrigation. Residue cover averaged 97%, 71%, 27%, and 4% for the NTCC, NTNO, STCC, and STNO systems. Adequate plant populations were achieved on all systems in each year. Crop growth and development were monitored by destructive weekly harvests of aboveground crop biomass and indicated that in-season plant biomass accumulation varied little among the four systems throughout both seasons. Final aboveground biomass DWT averaged 94, 76, 81 and 71 g plant-1 for the STNO, STCC, NTNO, and NTCC systems in 2014 and 88, 103, 87, and 125 g plant-1 in 2015. 2014 grain yields were highest in the NTNO system (7.35 T ha-¹), lowest in the NTCC system (5.55 T ha-¹), and intermediate in the STNO (5.73 T ha-¹, and STCC (6.97 T ha-¹) systems.