10.2134/jeq2001.3051659x

ABSTRACT

Cover crops are a management option to reduce NO3 leaching under cereal grain production. A 2￢ﾀﾐ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￢ﾀﾓN leaching and availability of N to the main crop. Barley and ryegrass or barley alone were seeded in mid￢ﾀﾐMay 1992, in lysimeters (0.3￢ﾀﾐm diam. ￃﾗ 1.2￢ﾀﾐm depth) of an undisturbed, well￢ﾀﾐdrained, sandy loam soil. Fertilizer N was applied at the same time as labeled 15NH415NO3 (10 atom % 15N) at a rate of 100 kg N ha￢ﾈﾒ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￢ﾈﾒ1 at the time of incorporation the following spring. Recovery of fertilizer￢ﾀﾐ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￢ﾀﾓN in the leachate considerably (<5 mg L￢ﾈﾒ1, compared with 10 to 18 mg L￢ﾈﾒ1 without cover crop) at most sampling times from November 1992 to April 1994, and reduced the total amount of NO3￢ﾀﾓN leached (22 compared with 8 kg ha￢ﾈﾒ1).