McDonald Iryna, Baral Rudra, Min Doohong
Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.
J Anim Sci Technol. 2021 Mar;63(2):305-318. doi: 10.5187/jast.2021.e33. Epub 2021 Mar 31.
Alfalfa ( L.) is an important forage legume grown in Kansas, USA and its productivity with cool-season grasses however is unknown. The objective of this study was to determine the dry matter yield (DMY) and forage nutritive value of alfalfa-grass mixtures compared to those of alfalfa and grasses grown in monoculture with and without nitrogen fertilization. Three different alfalfa varieties were planted (reduced-lignin alfalfa, Roundup Ready, and conventional alfalfa) and two kinds of cool-season grasses (smooth brome, Leyss, and tall fescue, Schreb) were planted as a monoculture or in alfalfa-grass mixtures. Nitrogen fertilizer (urea) was applied at green-up at a rate of 56 kg/ha and after the second cutting at a rate of 56 kg/ha in 2016 and 2017, respectively. and control treatments received no nitrogen. DMY was significantly higher in monoculture alfalfa and alfalfa-grass mixtures than in grass monocultures. Between alfalfa monoculture and alfalfa-grass mixtures, no significant differences in DMY were found. For all treatments, nitrogen application significantly increased DMY compared to the control. In 2016 and 2017, the low-lignin alfalfa monoculture had the lowest acid detergent fiber (ADF) and the grass monocultures had the highest ADF. In 2016 and 2017, neutral detergent fiber (NDF) in smooth bromegrass and tall fescue was higher than in other species treatments. A low-lignin alfalfa monoculture had significantly lower NDF concentration compared to alfalfa-grass mixtures. When averaged over 2016 and 2017, relative feed value (RFV) was highest in low-lignin alfalfa and lowest in the grass monocultures. In both years, nitrogen fertilizer application did not affect nutritive values.
紫花苜蓿（Medicago sativa L.）是美国堪萨斯州种植的一种重要豆科牧草，然而其与冷季型禾本科牧草混播时的生产力尚不清楚。本研究的目的是确定与单播且施肥和不施肥的紫花苜蓿及禾本科牧草相比，紫花苜蓿 - 禾本科牧草混播组合的干物质产量（DMY）和饲草营养价值。种植了三个不同的紫花苜蓿品种（低木质素紫花苜蓿、抗草甘膦紫花苜蓿和常规紫花苜蓿），并将两种冷季型禾本科牧草（草地早熟禾，Poa pratensis L.和高羊茅，Festuca arundinacea Schreb）单播或与紫花苜蓿混播。氮肥（尿素）分别在2016年和2017年返青期以56千克/公顷的用量施用，第二次刈割后也以56千克/公顷的用量施用，对照处理不施氮肥。单播紫花苜蓿和紫花苜蓿 - 禾本科牧草混播组合的DMY显著高于单播禾本科牧草。在紫花苜蓿单播和紫花苜蓿 - 禾本科牧草混播组合之间，未发现DMY有显著差异。对于所有处理，与对照相比，施氮显著提高了DMY。在2016年和2017年，低木质素紫花苜蓿单播的酸性洗涤纤维（ADF）最低，单播禾本科牧草的ADF最高。在2016年和2017年，草地早熟禾和高羊茅中的中性洗涤纤维（NDF）高于其他品种处理。与紫花苜蓿 - 禾本科牧草混播组合相比，低木质素紫花苜蓿单播的NDF浓度显著较低。2016年和2017年平均计算时，相对饲用价值（RFV）在低木质素紫花苜蓿中最高，在单播禾本科牧草中最低。在这两年中，施用氮肥均未影响营养价值。
