Management › Tillage › Tillage system → Properties › Chemistry

Reduced tillage → Exchangeable/available potassium

A clear tendency, not consistent

67 %

of 21 studies with a clear result report a significant increase

+16 %

typical change (17 studies with numbers)

studies · 25 findings

Count each study by

22 studies · 25 findings

What the studies show

14 of 21 studies report a significant increase (67 %, 95 % confidence interval 45–83 %).

By the direction of each study’s results, significant or not: 17 of 20 studies with a direction point up (85 %, 95 % confidence interval 64–95 %; sign test p = 0.003).

↑ 14 increase
↓ 2 decrease
⇅ 2 both
= 3 no effect
? 1 unclear

How large: typically +16 % (middle half +13 % to +28 %), from 17 studies with numbers
Basis: 22 studies, 25 findings; 2 entered by hand, 20 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, exchangeable/available potassium goes up in 82 % of the studies under reduced tillage, stays the same in 0 % and goes down in 18 %.

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…