Marginal Cropland to Grassland a Potential Method to Reduce Increases in Atmospheric Carbon Levels?

Is converting conventionally tilled, marginal cropland to grassland a potential method to reduce increases in atmospheric carbon levels?

Introduction

There have been estimates that up to 35% of soil carbon has been lost to the atmosphere since cultivation began. Conventional tillage crop production practices continue to add to increases in atmospheric carbon levels. Atmospheric carbon level increases can potentially be reduced by plant photosynthesis and subsequent sequestration in the soil as organic and inorganic carbon. Converting conventionally tilled, marginal crop producing soil to a more stable, uncultivated grass cover regime can reduce atmospheric carbon level increases by reducing original soil sequestrated carbon emissions from the soil, capturing and storing atmospheric carbon in the soil and reducing the generation of fossil fuel derived atmospheric carbon through decreased crop producing activities. Site specific assessment and management plans including consideration of soil properties, erosion potential, proposed grass characteristics, crop utilization, and fertilization requirements would be required to optimize the sequestration of atmospheric carbon.

Discussion

Yes. The reduction in tillage resulting from the conversion of crop land to grassland will increase atmospheric carbon sequestration in the soil. Dumanski et al. (1998) proposes that amongst the best management options, for increased organic carbon sequestration, is the conversion of summer fallow lands to hay land. Atmospheric carbon level increases are also impacted by reduced emissions of carbon to the atmosphere from reduced crop-related fossil fuel consumption. These researchers estimate that 50-75% of agricultural generated carbon emissions could be sequestered. They also state that there is a soil carbon sequestration limit that would be reached eventually.

Yes. Jansson et al. (2010) states atmospheric carbon assimilated by plant photosynthesis is partitioned to roots where it enters the pools of organic carbon and soil inorganic carbon and thus offers a method of terrestrial carbon sequestration. They also state perennial plants with deep, extensive root systems are better at sequestrating carbon than annual crops and any reduction in tillage will reduce carbon emissions to the atmosphere. They also propose that plant genetics and other research can optimize atmospheric carbon sequestration by plants.

Maybe. Grene et al. (2010) examines the increase in atmospheric carbon and ozone (both due partially to human activities) and their effect on plant cells and photosynthesis. Many plants are stressed by increased ozone that may affect their usefulness in sequestrating carbon and their role in producing food.

Yes. Burden et al. (2010) AgMRC, Iowa State University, in the Switchgrass Profile