Direction: Read the following information carefully and answer the given questions.

Initiatives such as “4 per mille” and Terraton aim to sequester huge amounts of carbon in the soil. The 2018 U.S. Farm Bill includes the first-ever incentives for farmers to adopt practices aimed at improving soil health and sequestering carbon. But these initiatives are missing a key point: not all soil carbon is the same.

The very different lifetimes of particulate organic matter and mineral-associated organic matter have important implications for these efforts. For example, adding low-quality crop residues to agricultural fields would likely create more particulate organic matter than mineral-associated organic matter. This could increase soil carbon in the short term - but if that field later is disturbed by tilling, a lot of it would decompose and the benefit would be quickly reversed. The best practices focus on building up the mineral-associated organic matter for longer-term carbon storage, while also producing high-quality particulate organic matter with lots of nitrogen to help boost crop productivity.

Natural healthy soils show us that providing continuous and diverse plant inputs that reach all the way to deep soil is key for achieving both high mineral-associated organic matter storage and particulate organic matter recycling. There are many promising ways to do this, such as maintaining plant cover on fields year-round; growing diverse crops that include high-nitrogen legumes and perennials with deep roots; and minimizing tillage.

However, not all soils can accumulate both mineral-associated organic matter and particulate organic matter. Before implementing any management practices for carbon sequestration, participants should first assess the carbon storage potential of the local soil, much as a doctor studies a patient before prescribing a cure. Sequestering soil carbon effectively requires an understanding of how particulate organic matter and mineral-associated organic matter work, how human actions affect them, and how to build up both types to meet our planet’s climate and food security needs.