The Impacts of Soil Amendments On Organic Rice Production.

The major challenges in organic rice production include nutrient improvement, weed management, and variety selection. In this study, we tested the effects of two soil amendments on organic production in southcentral USA. The 2011-12 winter cover crops were established successfully with full coverage. The amount of dry biomass were 5257 and 5780 kg/ha for clover and ryegrass, respectively. Plots were cultivated and drill seeded but high weed pressure in the fallow plots resulted in very poor stands. Only results of rice grain yields from clover and ryegrass treatments were presented. Cover crops had a similar effect on rice grain yield, although numerically, rice grain yield under ryegrass treatment was higher than that under clover treatment. Compared to Presidio, Tesanai had significantly higher grain yield. Soil amendments did not have significant effect on rice grain yield. Compared to the control, the 150 lb N/acre and 210 lb N/acre soil amendment rates increased rice grain yields by 11%. There was no difference in rice grain yields between the two N rates, indicating that 150 lb N/acre was sufficient for organic rice production in terms of N supply. Compared to Presidio, Tesanai had greater plant height and appeared to be more competitive with weeds. Aboveground biomass of the rice crop was affected by the rate of soil amendments rather than the type of soil amendments. Rice milling yield was significantly affected by cover crop and rice variety.