Bergström L F, Jokela W E
Dep. of Soil Science, Swedish Univ. of Agric. Sci., Uppsala, Sweden.
J Environ Qual. 2001 Sep-Oct;30(5):1659-67. doi: 10.2134/jeq2001.3051659x.
Cover crops are a management option to reduce NO3 leaching under cereal grain production. A 2-yr field lysimeter study was established in Uppsala, Sweden, to evaluate the effect of a perennial ryegrass (Lolium perenne L.) cover crop interseeded in barley (Hordeum vulgare L.) on NO3-N leaching and availability of N to the main crop. Barley and ryegrass or barley alone were seeded in mid-May 1992, in lysimeters (03-m diam. x 1.2-m depth) of an undisturbed, well-drained, sandy loam soil. Fertilizer N was applied at the same time as labeled l5NH415NO3 (10 atom % 15N) at a rate of 100 kg N ha(-1). In 1993, barley was reseeded in May in the lysimeters but with nonlabeled NH4NO3 and no cover crop (previous year's cover crop incorporated just prior to seeding). Barley yields and total and fertilizer N uptake in Year 1 (1992) were unaffected by cover crop. Total aboveground N uptake by the ryegrass was 28 kg ha(-1) at the time of incorporation the following spring. Recovery of fertilizer-derived N in May 1993 was about 100%; 53% in soil, 46% in barley, <2% in ryegrass, and negligible amounts in leachate. In May 1994, the corresponding figures were: 32% in soil, <3% in barley, and, again, negligible amounts in leachate. The cover crop reduced concentrations of NO3-N in the leachate considerably (<5 mg L(-1), compared with 10 to 18 mg L(-1) without cover crop) at most sampling times from November 1992 to April 1994, and reduced the total amount of NO3-N leached (22 compared with 8 kg ha(-1)).
覆盖作物是一种在谷物生产中减少硝态氮淋失的管理措施。在瑞典乌普萨拉开展了一项为期两年的田间蒸渗仪研究，以评估大麦（Hordeum vulgare L.）间种多年生黑麦草（Lolium perenne L.）覆盖作物对硝态氮淋失及主作物氮素有效性的影响。1992年5月中旬，在未扰动、排水良好的砂壤土质地的蒸渗仪（直径0.3米×深度1.2米）中播种大麦和黑麦草或仅播种大麦。与标记的15NH415NO3（10原子% 15N）同时施用氮肥，施用量为100千克氮/公顷。1993年5月，在蒸渗仪中重新播种大麦，但使用未标记的硝酸铵且不种植覆盖作物（上一年的覆盖作物在播种前翻入）。第1年（1992年）大麦产量以及总氮和肥料氮吸收量不受覆盖作物影响。次年春季翻压时，黑麦草地上部总氮吸收量为28千克/公顷。1993年5月肥料氮的回收率约为100%；53%在土壤中，46%在大麦中，<2%在黑麦草中，渗滤液中的量可忽略不计。1994年5月，相应数据为：32%在土壤中，<3%在大麦中，渗滤液中的量同样可忽略不计。在1992年11月至1994年4月的大多数采样时间，覆盖作物显著降低了渗滤液中硝态氮的浓度（<5毫克/升，无覆盖作物时为10至18毫克/升），并减少了硝态氮的淋失总量（分别为22和8千克/公顷）。
