Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2007
Publication Date: 6/15/2007
Citation: Purakayastha, T. J., Huggins, D.R., Smith, J.L. 2007. Carbon Sequestration in Native Prairie, Perennial Grass, and No-Tilled and Cultivated Annual Crops in Palouse Silt Loam Soil. Soil Science Society of America Journal 72:534-540.
Interpretive Summary: Tillage of agricultural land has decreased soil organic carbon levels over time. Organic carbon, part of organic matter, helps soils retain water and plant nutrients and is important in reducing wind and water erosion. Agricultural management practices that enhance organic carbon levels are beneficial to crop production and society. We investigated management practices that may enhance soil organic carbon. We found that reduced and no tillage greatly increased soil organic carbon in surface soils. This was true even if the management was implemented over only a short time period. We also found that the carbon that increased in the soil was particulate in nature, which is the type of carbon most beneficial to increasing water holding capacity of the soil and reducing erosion. This research clearly demonstrates to scientists and agricultural producers the benefit of less tillage of agricultural soils. Scientists and producers will now develop cropping systems based on reduced tillage to preserve soil organic carbon.
Technical Abstract: Perennial vegetation and annual cropping with low soil disturbance are often considered the best alternatives to tillage-based cropping systems for increasing C sequestration in soil. Our main objective was to evaluate soil organic C (SOC) and various measures of SOC characteristics in Palouse silt loam soils with diverse management histories collected from southeastern Washington State. Comparative assessments were made among sites with seven contrasting management histories: no-tillage (NT) with differing time periods of establishment following tillage-based systems four y (NT4) and 28 y (NT28); Blue grass seeding for nine y following a history of NT for four y (BGNT4); NT for ten y followed by a short period of tillage for three y and re-establishment of NT for one y (NTR); long-term (> 100 y) inversion-based tillage (CT); perennial grass established for 11 y under the Conservation Reserve Program (CRP); and native prairie (NP). The cultivation of NP decreased the SOC by 70% at 0-5 cm soil depth in 80+ years while conversion of CT to NT and CRP greatly increased the SOC contents in all the soil depths. When compared with CT, NT28 had 164% increase in SOC at 0-5 cm soil depth. But SOC in the 0-20 cm soil profile was significantly higher in NTR than in NT28. When compared with CT, NT28 showed greater accumulation of particulate organic C (POC) (28%) at 0-5 cm, while the major increase in POC at 5-10 (110%) and 10-20 (187%) cm occurred in NTR soil. Conventionally tilled soil had higher microbial metabolic quotient (qCO2) than NT and CRP soils. Particulate organic C was labile in nature as it correlated well with both C mineralization and MBC. All the soil management practices increased C accumulations as compared to CT soils. The most spectacular result was obtained in NTR which emerged as the best among all the management practices followed by NT28 with respect to C sequestration in Palouse silt loam soils of Washington State. The adoption of tillage for a short period in long-term NT soil is required to preserve more organic C in sub surface soil layer as a means of C aggradations.