The California Department of Food and Agriculture (CDFA) Fertilizer Research and Education Program (FREP) Grant Program annually funds research projects related to the environmentally safe and agronomically sound use and handling of fertilizing materials in California.
The following project was recently completed and added to the FREP Research and Project Database.
Pima Cotton Nitrogen Management, Uptake, Removal – Impacts of Varieties, Subsurface Drip and Furrow Irrigation
Project Location: Kern, Kings, Fresno, and Merced county-sites
Overview: This FREP-funded project evaluated the impacts of nitrogen (N) application rates, varieties, and irrigation methods (subsurface drip versus furrow) on total plant N uptake and harvest removal for Pima cotton and a widely planted Upland variety in the Central Valley. In addition, to better understand Pima N requirements, this project determined total aboveground plant N uptake at early open-boll timing, and N removal with harvest in three grower fields.
Highlights:
- Both Pima and Upland cultivars had similar yield responses to fertilizer N rates under furrow and subsurface drip irrigation
- The most N-deficient treatments resulted in lower yields and had significantly lower seed N concentrations and removal
- There were no significant, consistent differences in seed N concentrations between Upland versus Pima varieties
- Yields peaked for both Pima and Upland cultivars at N application rates based on 75% and 100% of the N requirement, while fertilizing at 125% of the estimated N requirement tended to reduce yield.
- No trends toward impacts of N treatments and irrigation methods on important fiber quality parameters were observed (data not presented in this blog post)
Click here to read more about this project in a FREP Research Update blog.