Management › Tillage › Tillage system → Properties

Zero tillage → pH

A clear tendency, not consistent

55 %

of 67 studies with a clear result report a significant decrease

-3 %

typical change (50 studies with numbers)

studies · 105 findings

Count each study by

70 studies · 105 findings

What the studies show

37 of 67 studies report a significant decrease (55 %, 95 % confidence interval 43–67 %).

By the direction of each study’s results, significant or not: 17 of 60 studies with a direction point up (28 %, 95 % confidence interval 19–41 %; sign test p = 0.001).

↑ 15 increase
↓ 37 decrease
⇅ 5 both
= 10 no effect
? 3 unclear

How large: typically -3 % (middle half -7 % to +1 %), from 50 studies with numbers
Basis: 70 studies, 105 findings; 6 entered by hand, 64 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, pH goes up in 26 % of the studies under zero tillage, stays the same in 8 % and goes down in 58 %.

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…