Assessing benefits of artificial drainage on soybean yield in the North Central US region

Artificial drainage (AD) in producer fields can help avoid excess water and improve workability and timely fieldwork in comparison with soils that rely on natural drainage (ND). To date, most studies examining the effect of AD on crop yield were conducted at research stations and limited to a few sites and years. Here, we explored the influence of AD on soybean yield across the North Central US region (NC-US), which accounts for a third of global soybean production and where AD is widely used to prevent excess water early in the crop season. We used two sources of data: (i) records from 2805 soybean producer fields collected via a multi-year, multi-state survey of soybean producers in the NC-US region; and (ii) information from 47 site-year experiments that included paired AD-ND treatment comparisons. In all cases, AD corresponded to subsurface drainage, except for producer fields in North Dakota where AD corresponded to surface drainage. Producer fields were grouped into technology extrapolation domains (TEDs) delineating regions with similar climate and soils to allow comparison of yields in AD versus ND fields. In the case of subsurface drainage, average yield in AD versus ND was 8% higher (+275 kg ha(-1)) and 4% higher (+157 kg ha(-1)) based on analysis of experimental and producer data, respectively. Our analysis indicated that part of the AD-ND yield difference in producer fields can be attributed to a shift towards earlier sowing after AD adoption. Findings from this study explain the wide adoption of AD across the central and eastern areas of the NC-US region and provide a basis to determine the productivity and economic impact of AD installation at field and regional level.