|Foster, Joyce - Retired Ars Employee|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2012
Publication Date: 3/29/2012
Citation: Cassida, K.A., Foster, J.G., Gonzalez, J.M., Zobel, R.W., Sanderson, M.A. 2012. Available soil phosphorus affects herbage yield and stand persistence in forage chicory. Agronomy Journal. 104:807-816.
Interpretive Summary: Forage chicory typically displays poor persistence in the Appalachian region, a problem which may be related to the low soil P fertility that often limits productivity in the region. We evaluated chicory forage yield and stand longevity under variable rates of P fertilizer and established critical soil P thresholds for effective P fertilizer usage. We also established threshold plant density for evaluating stand productivity. This work is useful because it provides the first estimate of critical soil P thresholds for efficient forage chicory production and offers threshold stand densities for evaluation of chicory stands. The work will help producers and agricultural professionals make informed recommendations on phosphorus management of pastures, and benefit the public by improving pasture productivity as a source of livestock for meat and milk, while reducing excessive use of phosphorus fertilizers.
Technical Abstract: Forage chicory displays poor persistence in the Appalachian region, possibly because of the low soil P fertility that is common to regional soils. We evaluated the effects of available soil P (ASP) on forage yield and stand persistence of three chicory cultivars differing in root morphology at locations with low (Pennsylvania, Hagerstown silt loam) or high (West Virginia, Gilpin silt loam,) soil P-binding potential. ‘Grasslands Puna’, ‘Forage Feast’, and ‘INIA le Lacerta’ chicory were established in 2004 and harvested three to five times per year in 2005 and 2006. Low (LP), medium (MP), and high (HP) ASP treatments averaged 6, 27, and 41 mg kg-1 of Bray-P for LP, MP, and HP in WV, and 30 and 41 mg kg-1 for MP and HP in PA. All cultivars increased dry matter yield (DMY) in response to ASP in the first harvest year, but only Forage Feast increased DMY in the second year. Yield increases for Lacerta were related to increased bolting under greater ASP levels. Increasing ASP improved stand persistence over time, but the effect was small relative to the large overall decline in plant population density and DMY over time for all cultivars. Stand decline in Forage Feast was related to high rates of frost-heaving. Across all cultivars, stand densities of less than 50 plants m-2 in September indicated unacceptable cumulative DMY in the following year. Phosphorus fertilization improved forage chicory DMY and persistence, but was encouraged bolting in some cultivars at rates greater than 30 mg kg-1 Bray-P.