Responses of Long-Term Cattle Manure on Soil Physical and Hydraulic Properties under a Corn–Soybean Rotation at Two Locations in Eastern South Dakota

Manure can enhance soil organic carbon (SOC) and soil hydrological properties, such as soil water retention (SWR) and water infiltration (qₛ), which are crucial for crop production. The present study was conducted to investigate the impacts of different rates of manure (low, medium, and high) and inorganic fertilizer (INF) on soil bulk density (ρb), penetration resistance (SPRc), SWR, and qₛ at two long-term experimental sites located in eastern South Dakota. The study sites were established under reduced-till corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation. Dairy solid manure was used for the Brookings site, whereas beef solid manure was used for the Beresford site. On an average, manure application (1.02 Mg m⁻³) reduced the ρb by 19% compared with INF application (1.27 Mg m⁻³) at 0- to 10-cm depth for the Brookings site and by 11% for the Beresford site (manure, 1.08 Mg m⁻³; fertilizer, 1.21 Mg m⁻³). Soil qₛ was significantly increased by 33 and 29% at the Brookings site and by 43 and 36% at the Beresford site under manure application compared with the INF and control. On average, SWR with manure application was higher compared with that of fertilizer at both depths for the Brookings and Beresford sites. Pearson correlation analysis showed that ρb and SPRc were negatively correlated and that SOC stock and qₛ were positively correlated with SWR and pore size distributions. This study showed that long-term manure application can be beneficial in enhancing soil physical and hydraulic properties, which can enhance crop production.