Management → Properties › Biology

Cover crops → Yield

A clear tendency, not consistent

43 %

of 35 studies with a clear result report a significant increase

+6 %

typical change (26 studies with numbers)

studies · 69 findings

Count each study by

37 studies · 69 findings

What the studies show

15 of 35 studies report a significant increase (43 %, 95 % confidence interval 28–59 %).

By the direction of each study’s results, significant or not: 18 of 27 studies with a direction point up (67 %, 95 % confidence interval 48–81 %; sign test p = 0.122).

↑ 15 increase
↓ 5 decrease
⇅ 4 both
= 11 no effect
? 2 unclear

How large: typically +6 % (middle half -8 % to +17 %), from 26 studies with numbers
Basis: 37 studies, 69 findings; 1 entered by hand, 36 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, yield goes up in 43 % of the studies under cover crops, stays the same in 31 % and goes down in 14 %.

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…