- Safflower has value as a silage feed when harvested at a vegetative state in early spring following November planting.
- Safflower as winter forage has greater water use efficiency with a large amount of forage dry matter biomass.
- Safflower silage stored well and was stable over a six-month period, did not accumulate nitrate to excess, or result in harmful silage gas production under study conditions.
To determine the potential for safflower as a winter forage for dairy farmers by measuring safflower’s capacity to recover residual soil nitrogen and water from a deeper soil profile than other annual crops, and evaluating forage yield and feed quality of fall-planted safflower under different planting and harvest dates.
Background, Findings, and Outcomes:
Safflower is deep-rooted and can recover water and nutrients from deeper in the soil profile than any other annual crop. As a result, safflower could help dairy producers maximize water use efficiency across their crop production system and better manage nutrients in manure, especially nitrogen.
This was the first study in California to evaluate the potential for safflower as a winter forage for dairy cows. Safflower can be grown at any time of the year in California, but the researchers hypothesized that planting in fall would produce large amounts of total biomass that could be ensiled for feed use. They also predicted that safflower could be ensiled successfully and safely to preserve feed quality and without harmful off-gassing from potentially high-nitrogen biomass.
The study found that safflower used less than 1.5-acre feet of water from all sources to produce nearly seven tons of dry matter biomass per acre of silage by the late April 2020 harvest. Estimated water use in total was approximately 15 to 18 acre-inches. As predicted, winter forage production was more efficient in water use than summer production.
No direct comparisons for yield were made with cereal silages, but safflower was comparable in feed quality to cereal silages made from small grains like triticale and wheat, typically planted during the same period. Wrapped bales of safflower silage were stable over a six-month period, preserved easily, and had no harmful off-gassing under the study ensiling conditions.
Researchers documented soil water depletion to nine feet in the soil profile. Most nitrate uptake occurred in the upper portion of the profile, where roots were denser, but some uptake was observed at depths to nine feet. The limit for most competitive crops is four to six feet in the soil profile.
This study suggests that there are many benefits for using safflower as a winter forage for dairy producers in the San Joaquin Valley. Growing crops in winter rather than summer allows for greater water use efficiency, and growing deep-rooted crops, such as safflower, allows for recovery of nutrients and water left behind by shallower-rooted crops. This could help producers demonstrate regulatory compliance and sustain feed production with decreasing water supplies in the future.