Abstract Agro-ecological service crops (ASCs), also known as cover crops, green manures or catch crops, can improve organic vegetable production in terms of weed suppression, nitrogen (N) recycling, or addition of N through symbiotic N2 fixation by legumes. Traditionally, ASCs are terminated through full incorporation into the soil (FI), but alternative termination without tillage is available by roller-crimping (RC). The applicability of RC to Northern and Western European climates has only been studied to a limited extend. The objective of this study was therefore to investigate the N dynamics involved in FI and RC of legume and cereal ASCs in organic cabbage production across Northern and Western European climates. Field experiments were conducted at one location in Estonia and in Denmark, and at three locations in Belgium during two cropping cycles (2015/2016 and 2016/2017) to assess the effect of ASC termination method in spring (FI and RC) and ASC species (pea, pea/cereal mixtures and cereals), compared with a bare soil control (BS), on soil mineral N content, N accumulation, yield, and root growth of a following crop of cabbage. Agro-ecological service crops, and in particular cereals, reduced N availability for succeeding cabbage compared with BS by 37–73%. Similar marketable cabbage yield was obtained under FI and BS in two out of four cases in Belgium, due to higher availability of soil mineral N when terminated earlier (April/May) than RC (May/June). However, FI reduced marketable yields by 36–98 % in the other cases in Belgium and in two out of four cases in Estonia and Denmark, where FI was conducted in May/June. Overall, cabbage marketable yields were reduced by 68–100% under RC compared to BS and FI in seven out of nine cases mainly due to reduced soil mineral N availability. Soil mineral N availability was lower under RC likely because of a slower mineralisation of ASCs and soil organic matter. Besides, the termination of ASCs close to the time of cabbage planting under RC increased pre-emptive competition on N. Cabbage marketable yield could be maintained under RC at fertilisation by 236 kg N ha−1 following pea in Denmark. Cabbage root growth was generally increased with higher above ground plant biomass across treatments in Estonia and Denmark, while the relationship was reverse under RC in East Flanders, indicating changes in resource allocation. Soil mineral N at harvest did not differ among treatments in deeper depth, showing no higher risk of N leaching from FI or RC. In conclusion, RC showed major yield reductions in the first and second year after conversion from spring tillage. Therefore, further investigations should verify improved yields under longer-term RC practice, e.g. due to build-up of soil organic matter, before implementation can be recommended in organic vegetable production in Northern and Western Europe.

中文翻译：

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农业生态服务作物的终止方法和时间影响北欧和西欧五个地点的土壤矿质氮、卷心菜产量和根系生长

摘要 农业生态服务作物 (ASCs)，也称为覆盖作物、绿肥或捕捞作物，可以在杂草抑制、氮 (N) 循环或通过豆科植物共生固氮增加氮等方面改善有机蔬菜生产。传统上，ASC 是通过完全融入土壤 (FI) 来终止的，但可以通过滚压 (RC) 来实现无需耕作的替代终止。RC 对北欧和西欧气候的适用性仅在有限的范围内进行了研究。因此，本研究的目的是调查在北欧和西欧气候下有机卷心菜生产中豆类和谷物 ASC 的 FI 和 RC 中涉及的氮动态。在爱沙尼亚和丹麦的一个地点进行了现场试验，并在比利时的三个地点在两个种植周期（2015/2016 和 2016/2017）期间评估 ASC 终止方法对春季（FI 和 RC）和 ASC 物种（豌豆、豌豆/谷物混合物和谷物）的影响，与裸土控制 (BS)，对下一季卷心菜的土壤矿物质 N 含量、N 积累、产量和根生长。与 BS 相比，农业生态服务作物，特别是谷物，将后继卷心菜的氮可用性降低了 37-73%。在比利时有四分之二的情况下，在 FI 和 BS 下获得了类似的可销售卷心菜产量，这是由于比 RC（5 月/6 月）更早终止（4 月/5 月）土壤矿物质 N 的可用性更高。然而，在比利时的其他案例中以及爱沙尼亚和丹麦的四分之二的案例中，FI 将可销售的产量降低了 36-98%，其中 FI 是在 5/6 月进行的。全面的，与 BS 和 FI 相比，在 RC 下，9 种情况中有 7 种情况下卷心菜的可销售产量降低了 68-100%，这主要是由于土壤矿物质氮的可用性降低。RC 下土壤矿物质氮的有效性较低，可能是因为 ASC 和土壤有机质的矿化较慢。此外，接近 RC 下白菜种植时间的 ASC 终止增加了对 N 的先发制人竞争。在丹麦豌豆之后，在 RC 下施肥时可以维持 236 kg N ha-1 的白菜可销售产量。在爱沙尼亚和丹麦的处理中，随着地上植物生物量较高，卷心菜根的生长普遍增加，而在东佛兰德斯的 RC 下，这种关系相反，表明资源分配发生了变化。收获时的土壤矿物质 N 在更深的深度处理之间没有差异，显示出从 FI 或 RC 中浸出 N 的风险没有更高。总而言之，在从春耕转换后的第一年和第二年，RC 显示出显着的减产。因此，在建议北欧和西欧的有机蔬菜生产中实施之前，应进一步调查验证长期 RC 实践下的产量提高，例如由于土壤有机质的积累。