Narrow row spacing (<76 cm) could improve crop competitiveness, suppress weeds and might provide yield advantage. Many studies have been conducted to evaluate the impact of narrow row spacing; however, no quantitative synthesis of these studies exists. The objectives of this meta-analysis were to (1) quantify the overall effect of narrow row spacing (<76 cm) on weed density, biomass, control, weed seed production, and yield in corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] compared with 76-cm row spacing, and (2) assess the influence of agronomic management decisions (tillage type, weed management, herbicide application frequency and time) on effect of narrow row spacing on weed suppression and corn and soybean yield. We compiled 1,904 pair-wise observations from 35 studies conducted in 12 states in the United States during 1961 to 2018. Averaged across individual observations, narrow row spacing suppressed weed density by 34%, weed biomass by 55%, and weed seed production by 45%, while it improved weed control by 32% and crop yield by 11% compared with 76-cm row spacing. Narrow row spacing in soybean suppressed weed density by 42%, weed biomass by 71%, and increased crop yield by 12% compared with 76-cm row spacing. Although narrow row spacing had a nonsignificant effect on response variables in corn, the number of studies (n = 1 to 6) and observations (n = 1 to 59) addressing each response variable were limited. Tillage type (conventional and reduced) did not influence the response of weed density, control, and seed production in narrow row spacing; however, weed biomass and weed seed production were more greatly reduced with the sequential application of herbicides compared with a single application. Thus, narrow row spacing in soybean can be integrated with other options for management of herbicide-resistant weeds.

窄行距（<76 厘米）可以提高作物竞争力、抑制杂草并可能提供产量优势。已经进行了许多研究来评估窄行距的影响；然而，这些研究还没有定量综合。该荟萃分析的目的是（1）量化窄行距（<76 cm）对玉米（ Zea mays L.）和大豆杂草密度、生物量、控制、杂草种子产量和产量的总体影响。Glycine max (L.) Merr.] 与 76 厘米行距进行比较，(2) 评估农艺管理决策（耕作类型、杂草管理、除草剂施用频率和时间）对窄行距杂草抑制效果的影响以及玉米和大豆产量。我们从 1961 年至 2018 年间在美国 12 个州进行的 35 项研究中收集了 1,904 项成对观察结果。对各个观察结果进行平均，窄行距将杂草密度抑制了 34%，杂草生物量抑制了 55%，杂草种子产量抑制了 45%。 %，与 76 厘米行距相比，杂草控制效果提高了 32%，作物产量提高了 11%。与 76 厘米行距相比，大豆的窄行距可将杂草密度抑制 42%，杂草生物量抑制 71%，并使作物产量提高 12%。尽管窄行距对玉米的响应变量影响不显着，但针对每个响应变量的研究（n = 1 至 6）和观察（n = 1 至 59）数量有限。耕作类型（常规耕作和减耕耕作）不影响窄行距下杂草密度、控制和种子产量的响应；然而，与单次施用相比，连续施用除草剂的杂草生物量和杂草种子产量大大减少。因此，大豆窄行距可以与其他抗除草剂杂草管理方案结合起来。