Long-term crop rotation affects crop yield and economic returns in humid subtropical climate

Long-term tillage and crop management studies are useful for determining crop production practices that are conducive to securing sustainable yields and profits. The overall goal of this study was to evaluate the effects of 17-year, long-term crop rotations involving cotton, corn, and soybean on yield and profitability. The study was established in 2004 at the Delta Research and Extension Center, Stoneville, Mississippi with six crop rotations. The crop rotations were continuous cotton (CT), corn-cotton (CR-CT), corn-cotton-cotton (CR-CT-CT), corn-soybean (CR-SB), soybean-corn-cotton (SB-CR-CT), and soybean-corn-cotton-cotton (SB-CR-CT-CT) with every crop in a rotation planted yearly. Thirty years of historical (1974–2003) and 17 years (2004–2020) of precipitation data during the 2nd (Q-2: 21 March to 21 June) and 3rd quarters (Q-3: 22 June to 22 September) were used to identify dry, normal, and wet precipitation quarter weather classifications (WC). Both seed cotton and lint yields were greatest in the wet-dry WC and least in the dry-wet WC under all the crop rotations. The normal-normal WC resulted in highest corn grain yields under all rotations, whereas dry-dry resulted in lowest grain yield. Soybean yield was highest under the dry-wet WC for each crop rotation including CR-SB, SB-CR-CT, and SB-CR-CT-CT. The most profitable rotation was CR-CT-CT followed by CR-CT with annual expected profit of $1042 ha −1 and $1024 ha −1, respectively. The CR-SB rotation was the least profitable rotation in the study.