Management → Properties › Biology › Plants

Cover crops → Aboveground biomass

The studies disagree

58 %

of 12 studies with a clear result report a significant increase

+26 %

typical change (6 studies with numbers)

studies · 18 findings

Count each study by

12 studies · 18 findings

What the studies show

7 of 12 studies report a significant increase (58 %, 95 % confidence interval 32–81 %).

By the direction of each study’s results, significant or not: 7 of 10 studies with a direction point up (70 %, 95 % confidence interval 40–89 %; sign test p = 0.344).

↑ 7 increase
↓ 3 decrease
⇅ 1 both
= 1 no effect

How large: typically +26 % (middle half +16 % to +54 %), from 6 studies with numbers
Basis: 12 studies, 18 findings; 0 entered by hand, 12 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 layers of unstated depth, aboveground biomass goes up in 58 % of the studies under cover crops, stays the same in 8 % and goes down in 25 %.

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…