Management → Properties › Physics

Cover crops → Bulk density

A clear tendency, not consistent

62 %

of 21 studies with a clear result report a significant decrease

-4 %

typical change (12 studies with numbers)

studies · 25 findings

Count each study by

21 studies · 25 findings

What the studies show

13 of 21 studies report a significant decrease (62 %, 95 % confidence interval 41–79 %).

By the direction of each study’s results, significant or not: 2 of 17 studies with a direction point up (12 %, 95 % confidence interval 3–34 %; sign test p = 0.002).

↑ 2 increase
↓ 13 decrease
⇅ 1 both
= 5 no effect

How large: typically -4 % (middle half -7 % to -3 %), from 12 studies with numbers
Basis: 21 studies, 25 findings; 4 entered by hand, 17 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

In the top 10 cm, bulk density goes up in 14 % of the studies under cover crops, stays the same in 29 % and goes down in 43 %.

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…