Management › Tillage › Tillage system → Properties › Physics

Reduced tillage → Bulk density

The studies disagree

44 %

of 43 studies with a clear result report a significant decrease

-3 %

typical change (27 studies with numbers)

studies · 71 findings

Count each study by

48 studies · 71 findings

What the studies show

19 of 43 studies report a significant decrease (44 %, 95 % confidence interval 30–59 %).

By the direction of each study’s results, significant or not: 18 of 40 studies with a direction point up (45 %, 95 % confidence interval 31–60 %; sign test p = 0.636).

↑ 14 increase
↓ 19 decrease
⇅ 2 both
= 8 no effect
? 5 unclear

How large: typically -3 % (middle half -7 % to +1 %), from 27 studies with numbers
Basis: 48 studies, 71 findings; 10 entered by hand, 38 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 11 % of the studies under reduced tillage, stays the same in 28 % and goes down in 50 %.

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…