Cover crop impact on crop production and nutrient loss in a no-till terrace topography

Abstract

Increased emphasis on implementation of conservation practices (terraces, conservation tillage including no-till or reduced tillage, and cover crops [CC]) have led to the integration of best management practices. However, research on integration of best management practices is limited. Therefore, a field trial was established at the University of Missouri Grace Greenley Research Center near Leonard, Missouri, to evaluate the effects of terraces with landscape positions and CCs on soil health parameters, CC biomass accrual, and no-till corn (<i>Zea mays</i> L.)–soybean (<i>Glycine max</i> [L.] Merr.) yields. Additionally, total suspended solids (TSS), nitrate-nitrogen (NO₃-N), and total phosphorus (TP) export and discharge were evaluated from terraces with or without CCs. Six parallel terraces were installed at 36.5 m spacing with each consisting of an individual underground tile outlet. Soybean was planted in 2016 and 2018, and a CC blend was overseeded at R6. Corn was planted in 2017 and cereal rye (<i>Secale cereal</i> L.) CC was drill-seeded after corn harvest. Soil health parameters had significant (<i>p</i> &lt; 0.10) year by landscape position interactions for magnesium (Mg), potassium (K), total organic carbon (C), and clay content. Each of these parameters was same among landscape positions before terrace construction, and at least one of the landscape positions differed following terrace construction. Cover crop in terraces reduced soybean and corn grain yield by 12% and 6% in 2016 and 2017, respectively, and increased soybean yield 4% in 2018. Crop yield was greatest at the shoulder landscape position and lowest in the channel in all years. Terraces with CCs reduced TSS between 363 and 4,713 g ha⁻¹, TP between 2 and 90 g ha⁻¹, NO₃-N between 147 and 3,407 g ha⁻¹, and discharge between 41 and 81 m³ ha⁻¹ compared to no CC terraces. Two-year cumulative TSS, NO₃-N, and discharge from CC terraces was 41%, 52%, and 43% lower than the terraces with no CC. Cover crops did not affect cumulative TP loss. Cover crops were an effective tool for reducing discharge and nutrient loss in a no-till tile-terrace field.