Data from: Field-scale experiments reveal persistent yield gaps in low-input and organic cropping systems

Knowledge of production-system performance is largely based on observations at the experimental plot scale. Although yield gaps between plot-scale and field-scale research are widely acknowledged, their extent and persistence have not been experimentally examined in a systematic manner. At a site in southwest Michigan, we conducted a 6-y experiment to test the accuracy with which plot-scale crop-yield results can inform field-scale conclusions. We compared conventional versus alternative, that is, reduced-input and biologically based–organic, management practices for a corn–soybean–wheat rotation in a randomized complete block-design experiment, using 27 commercial-size agricultural fields. Nearby plot-scale experiments (0.02-ha to 1.0-ha plots) provided a comparison of plot versus field performance. We found that plot-scale yields well matched field-scale yields for conventional management but not for alternative systems. For all three crops, at the plot scale, reduced-input and conventional managements produced similar yields; at the field scale, reduced-input yields were lower than conventional. For soybeans at the plot scale, biological and conventional managements produced similar yields; at the field scale, biological yielded less than conventional. For corn, biological management produced lower yields than conventional in both plot- and field-scale experiments. Wheat yields appeared to be less affected by the experimental scale than corn and soybean. Conventional management was more resilient to field-scale challenges than alternative practices, which were more dependent on timely management interventions; in particular, mechanical weed control. Results underscore the need for much wider adoption of field-scale experimentation when assessing new technologies and production-system performance, especially as related to closing yield gaps in organic farming and in low-resourced systems typical of much of the developing world.

当前关于生产系统性能的认知，大多基于试验田尺度（experimental plot scale）的观测结果。尽管田块尺度（plot-scale）与田间尺度（field-scale）研究间的产量差距已得到广泛认可，但二者的影响范围与持续程度尚未得到系统性的试验验证。我们在密歇根州西南部的一处试验站点开展了为期6年的试验，旨在验证田块尺度的作物产量结果能否为田间尺度的研究结论提供可靠依据。本试验采用随机完全区组设计（randomized complete block-design），选取27个商业规模农田（commercial-size agricultural fields），针对玉米-大豆-小麦轮作系统，对比了常规管理与替代管理（即减投入管理与基于生物原理的有机管理）的实施效果。邻近的田块尺度试验（面积区间为0.02公顷至1.0公顷）则用于对比田块与田间尺度的表现差异。研究结果显示，常规管理下的田块尺度产量与田间尺度产量匹配度较高，但替代管理系统则未呈现这一特征。就三种供试作物而言：田块尺度下，减投入管理与常规管理的产量水平相近；但在田间尺度下，减投入管理的产量低于常规管理。大豆方面，田块尺度下的生物有机管理与常规管理产量相近，而田间尺度下生物有机管理的产量低于常规管理。玉米方面，无论是田块还是田间尺度，生物有机管理的产量均低于常规管理。小麦产量受试验尺度的影响较玉米与大豆更小。常规管理对田间尺度的各类挑战具备更强的恢复力，而替代管理模式则更依赖及时的管理干预措施——尤以机械除草为甚。本研究结果凸显了在评估新技术与生产系统性能时，更广泛地采用田间尺度试验的必要性，尤其在涉及缩小有机农业与发展中国家普遍存在的低资源投入系统的产量差距方面。