Soil fertility and fertilizer use in rice across the Sacramento Valley
Kaden Koffler, Chris Hartley, Bruce Linquist, Cass Mutters, Chris Greer, William Horwath, and Chris van Kessel
Department of Plant Sciences, University of California, Davis
The main goal of this project is to understand how large scale increases in rice straw incorporation, due to California legislated reductions in rice straw burning over the last 15 years, have affected nitrogen (N) fertilizer management. Since 2003 we have been working with growers across the Sacramento Valley to evaluate the impact of 25 lb N / acre increases and reductions in pre-plant aqua-ammonia-N fertilizer application rates on mid-season fertility indicators and yield. In 2005, a zero N plot (0 lb N / acre) was also established in each field to determine N-use efficiency of the different fertilizer rates. Since 2003, we have worked with over 100 growers in over 150 fields located throughout the major rice growing areas of the Sacramento Valley.
Extensive soil and plant sampling to identify trends in overall fertility across a variety of soils under different straw management practices have been conducted throughout each season. To date, the research has provided substantial insights into grower fertility management practices, the impact they have on nutrient availability, and the potential for improvements in current fertility management guidelines.