Managing water in alfalfa (Medicago sativa L.) production is crucial for sustaining the limited surface and groundwater resources. A 3‐year study in eastern New Mexico, USA, compared nine irrigation strategies that included various combinations of in‐season irrigations for six harvests (1–2–3–4–5–6, 1–2–3–4–5, 1–2–3–5, 1–2–3, 2–3–5, 1–2–5, 1–5, and 2–3) plus unirrigated control (none) to evaluate the dry matter (DM) yield production capability and irrigation efficiency. The number in each treatment structure represents irrigation provided for each cutting. For example, number ‘1’ represents irrigation provided for the first cutting; number ‘2’ represents irrigation provided for the second cutting, and so on. The results suggested that terminating irrigation for the last harvest (1–2–3–4–5), equivalent to 96 mm water saving, had no significant negative impact on annual DM yield of established alfalfa compared to season‐long full irrigation (1–2–3–4–5–6) (14.4 vs 13.3 t ha⁻¹; P > 0.05) during the 3‐year study period. Irrigation water productivity was doubled when alfalfa was irrigated during the first three harvests (1–2–3), compared to 1–2–3–4–5–6 (0.050 vs 0.027 t ha⁻¹ mm⁻¹). The second and third harvests provided the greatest DM yields in alfalfa. The DM yields declined drastically after the third harvest, with the exception of the third year. Therefore, irrigating alfalfa early in the season during the initial three harvests is an important strategy when water is limited.

中文翻译：

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半干旱亚热带环境中灌溉方式对苜蓿干物质产量和水分生产率的影响*

苜蓿中的水管理（紫花苜蓿L.）生产对于维持有限的地表和地下水资源至关重要。在美国新墨西哥州东部进行的一项为期三年的研究中，比较了九种灌溉策略，其中包括六个收获季节的不同季节灌溉组合（1-2-3-4-5-6、1-2-3-4-5 ，1-2-3-5、1-2-3、2-3-5、1-2-5、1-5和2-3）加上未灌溉的对照（无）来评估干物质（DM）提高生产能力和灌溉效率。每个处理结构中的数字表示为每个切割提供的灌溉量。例如，数字“ 1”表示为第一次切割提供的灌溉；数字“ 2”表示为第二次切割提供的灌溉量，依此类推。结果表明，终止最后一次收获的灌溉（1-2–3–4–5），相当于节水96毫米，^-1 ; P > 0.05），为期三年。在前三个收获期（1-2-3年）灌溉苜蓿时，灌溉水生产率翻了一番，而在1-2年-3-3-4-5-6年（0.050对0.027 t ha ^-1 mm ^-1）。第二和第三次收获提供了苜蓿最大的干物质产量。在第三次收获后，第三年除外，DM产量急剧下降。因此，在水量有限的情况下，在最初的三个收获季节中，在季节初期灌溉苜蓿是一项重要的策略。