| Kura clover (Trifolium ambiguum M. Bieb.) persists better in the North Central states than traditional legumes. However, little information exists on the performance of kura clover in grass mixtures, particularly for stands more than three or four years old. I compare the fertilizer N replacement value (FNRV) of kura clover and birdsfoot trefoil (Lotus corniculatus L.) and evaluate the long-term performance of kura clover in binary mixture with Kentucky bluegrass (Poa pratensis L.), smooth bromegrass (Bromus inermis Leyss), or orchardgrass (Dactylis glomerata L.). Yield, fertilizer N use efficiency (NUE), and apparent N recovery (ANR) of these grasses in monoculture are also compared across two soil types. Kura clover and birdsfoot trefoil yield-based FNRV, averaged over years and locations, were 251 and 269 kg N {dollar}rm hasp{lcub}-1{rcub}{dollar} in Kentucky bluegrass, 186 and 231 kg N {dollar}rm hasp{lcub}-1{rcub}{dollar} in smooth bromegrass, and 93 and 113 kg N {dollar}rm hasp{lcub}-1{rcub}{dollar} in orchardgrass, respectively. Yield-and-intake-based FNRV for kura clover and birdsfoot trefoil increased these values for all grasses. Sward composition trends suggested that the FNRV of birdsfoot trefoil would be greater than kura clover over the short term but less over the long term. Forage yield during the {dollar}rm 4sp{lcub}th{rcub}, 5sp{lcub}th{rcub}{dollar} and {dollar}rm 6sp{lcub}th{rcub}{dollar} year of production was 5.5 Mg {dollar}rm hasp{lcub}-1{rcub}{dollar} for kura clover monoculture and between 6.5 and 7.5 Mg {dollar}rm hasp{lcub}-1{rcub}{dollar} in grass mixtures. Kura clover proportions of binary mixtures ranged from 49 to 67%. Increasing the cutting frequency from 3, to 4 or 5 times a season reduced kura clover yield and total yield in all sward types, while varying cutting height had less effect. Adding kura clover to grasses increased crude protein concentration, estimated digestibility, and intake potential to approximately equal bud-stage alfalfa. Grass NUE and ANR were similar across species and soil types for fertilizer rates of greater than 112 kg N {dollar}rm hasp{lcub}-1{rcub}.{dollar} Finally, with adequate suppression, kura clover can be managed as a living mulch in corn without reduced corn whole-plant or grain yield and will recover to full production within 12 months without replanting. I conclude that kura clover provides additional options to producers seeking long-term forage based cropping systems. |
