Carbon Sequestration in Native Prairie, Perennial Grass, No‐Till, and Cultivated Palouse Silt Loam

Abstract

Comparative assessments for evaluating soil organic C (SOC) and its characteristics were made at different soil (Palouse silt loam) depths (0–5, 5–10, 10–20, and 0–20 cm) among sites with seven contrasting management histories: conventional inversion tillage (CT) followed by no‐till (NT) for 4 (NT4) and 28 (NT28) yr; bluegrass (Poa pratensis L.) seed production for 9 yr followed by NT for 4 yr (BGNT4); a sequence of 10 yr NT, 3 yr CT, and 1 yr NT (NTR); CT followed by 11 yr perennial grass under the Conservation Reserve Program (CRP); long‐term >100 yr CT; and native prairie (NP). Overall ranking of SOC, particlulate organic C (POC), and microbial biomass C (MBC) at 0 to 20 cm was NP > NTR > NT4 = NT28 > CRP > BGNT4 = CT. Greater SOC, POC, and MBC in NTR than NT28 indicated that tillage rotation could result in more soil C sequestration, primarily by increasing C stocks in 5‐ to 20‐cm depths. The POC was labile in nature as it highly correlated with Cmin (r = 0.69, P < 0.01) and MBC (r = 0.86, P < 0.01) as well as SOC (r = 0.89, P < 0.01). We concluded that: (i) neither NT nor conversion to perennial vegetation would attain the SOC found in NP over 10 to 30 yr; and (ii) medium duration of NT (10 yr) combined with short intervals of CT (3 yr) followed by NT might increase SOC compared with continuous long‐term NT under annual cropping.