Management → Properties › Chemistry › Carbon compounds › Soil organic matter

Cover crops → Particulate organic carbon

A clear tendency, not consistent

100 %

of 3 studies with a clear result report a significant increase

+71 %

typical change (4 studies with numbers)

studies · 4 findings

Count each study by

4 studies · 4 findings

What the studies show

3 of 3 studies report a significant increase (100 %, 95 % confidence interval 44–100 %).

By the direction of each study’s results, significant or not: 4 of 4 studies with a direction point up (100 %, 95 % confidence interval 51–100 %; sign test p = 0.125).

↑ 3 increase
↓ 0 decrease
= 0 no effect
? 1 unclear

How large: typically +71 % (middle half +56 % to +85 %), from 4 studies with numbers
Basis: 4 studies, 4 findings; 0 entered by hand, 4 read by the library

Every study counts once, however many findings it reports: one with 40 sampling dates does not outvote ten others. A study with a significant increase and decrease (say at different depths) counts as "both". A first synthesis for orientation, not a substitute for a systematic review.

Where the studies are

goes up
stays the same
goes down
both ways

Through the soil profile

Each layer on its own: a study that reports the topsoil and the subsoil counts in both. Choose a layer to see what goes with it.

goes up
stays the same
goes down
both ways

What makes a difference

The conditions whose levels differ most clearly, each with the outcome that differs most between its levels of at least 10 study layers. Choose a layer in the profile to see them for that layer alone, or a level here to filter by it.

Testing every condition on every study layer…

Along the conditions

Testing every condition on every study layer…