Management › Tillage → Properties › Biology › Plants

Conservation tillage → Aboveground biomass

The studies disagree

41 %

of 29 studies with a clear result report a significant increase

+1 %

typical change (18 studies with numbers)

studies · 43 findings

Count each study by

29 studies · 43 findings

What the studies show

12 of 29 studies report a significant increase (41 %, 95 % confidence interval 26–59 %).

By the direction of each study’s results, significant or not: 14 of 23 studies with a direction point up (61 %, 95 % confidence interval 41–78 %; sign test p = 0.405).

↑ 12 increase
↓ 8 decrease
⇅ 1 both
= 8 no effect

How large: typically +1 % (middle half -5 % to +20 %), from 18 studies with numbers
Basis: 29 studies, 43 findings; 1 entered by hand, 28 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 41 % of the studies under conservation tillage, stays the same in 28 % and goes down in 28 %.

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…