Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2001
Publication Date: N/A
Interpretive Summary: Kura clover is a spreading-type, long-lived perennial that produces high quality forage for grazing livestock. The major limitations to widespread adoption of this species on American farms has been its low seedling vigor and slow stand establishment. Several approaches to improving seedling growth have been tried, and each has shown some improvement. We evaluated the response of kura clover and another forage legume, birdsfoot trefoil, to soil acidity and alkalinity. After adding lime to an acid soil, kura clover seedling growth increased up to 50%. The best soil pH for both crops was between 6 and 7, much the same as for other important legume forages like alfalfa, red clover, and white clover. Farmers who plan to grow kura clover have a greater likelihood of success if soils are tested and pH adjusted to near neutral.
Technical Abstract: Use of the rhizomatous perennial forage legume kura clover (Trifolium ambiguum M. Bieb.) has been limited by slow establishment. Mature kura clover responds to liming on some acid soils, but the soil pH required for vigorous growth of young plants is unknown. A factorial greenhouse experiment was conducted with two kura clover cultivars (Rhizo and Endura) and one cultivar of birdsfoot trefoil (Lotus corniculatus L., Norcen) planted in three soil types (Sartell loamy fine sand, Hubbard loamy sand, and Sanborg clay loam) amended with Ca(OH)2 to obtain six soil pH levels. The experiment was performed twice, once using soil taken directly from the field and once using steamed soil. Response of kura clover and birdsfoot trefoil to soil pH differed. Maximum yield increases in kura clover obtained by adjusting soil pH from 4.9 to 6.5 were about 50% on nonsteamed soil and more than 150% on steamed soil. Birdsfoot trefoil did not respond to liming on nonsteamed soil. On steamed soil birdsfoot trefoil response t liming was inconsistent. Optimal soil pH for growth of kura clover and birdsfoot trefoil was generally between pH 6 and 7. Biomass yield was correlated with nodulation in both kura clover and birdsfoot trefoil, but nodulation was correlated with nitrogen uptake only in kura clover. Increased biomass yield of young kura clover plants in response to liming was best explained by alleviation of Al, Zn, and Mn toxicities and increased availability of P and Mo at higher soil pH levels.