Tillage involves the manipulation of soil for successful crop production, but the frequency and intensity of soil disturbance can affect the storage, release, or redistribution of soil organic carbon (SOC) and nitrogen (N), as well as emissions of greenhouse gases (GHG). In recent years, strategic occasional tillage has been increasingly implemented to harness the benefit of mixing residues and incorporating fertilizer while meeting conservation goals. However, how such disturbances affect SOC and N storage and GHG emissions has not been studied widely. This study was designed to evaluate the response of SOC and N fractions and GHG fluxes under one-time strategic tillage (OT) with chisel after nine years of no-tillage (NT) management compared to long-term conventional high-intensity tillage (CT), low-intensity strip tillage (ST), and NT. In the semiarid dryland cropping systems of New Mexico, the OT was implemented before winter wheat planting in the long-term NT winter wheat (Triticum aestivum L.)–corn (Zea mays L.)–sorghum (Sorghum bicolor L. Moench) four-year rotation. Soil samples were collected right after tillage and 8 and 12 months after tillage and analyzed for SOC, microbial biomass carbon (MBC), potentially mineralizable carbon (PMC), and total, labile organic, and inorganic N contents. Soil GHG fluxes were measured using a portable Gasmet GT5000 analyzer connected to an Eosense automated chamber. OT after long-term NT did not compromise the C sequestration benefit of NT over CT. Compared to SOC under CT, it was 19.3% greater under ST, 34.8% greater under OT, and 21.1% greater under NT. Total N contents under ST, OT, and NT were 16.9%, 38.5%, and 15.4% greater than CT. All conservation tillage systems (ST, NT, and OT) also removed more atmospheric methane (CH4) than CT. The principal component analysis reflected the association of labile C with carbon dioxide emissions and C:N ratio, and MBC with CH4 and nitrous oxide emissions. The SOC correlated positively with total and soil inorganic N. Occasional strategic disturbance could be considered an effective soil management strategy without compromising the benefits of NT on SOC sequestration and GHG emissions mitigation in semiarid dryland cropping systems.
Aryal et al. (Thu,) studied this question.