Management › Fertilization → Properties

Organic fertilizer → pH

The studies disagree

59 %

of 64 studies with a clear result report a significant increase

+5 %

typical change (45 studies with numbers)

studies · 76 findings

Count each study by

67 studies · 76 findings

What the studies show

38 of 64 studies report a significant increase (59 %, 95 % confidence interval 47–71 %).

By the direction of each study’s results, significant or not: 40 of 58 studies with a direction point up (69 %, 95 % confidence interval 56–79 %; sign test p = 0.005).

↑ 38 increase
↓ 17 decrease
⇅ 2 both
= 7 no effect
? 3 unclear

How large: typically +5 % (middle half -1 % to +11 %), from 45 studies with numbers
Basis: 67 studies, 76 findings; 1 entered by hand, 66 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 89 % of the studies under organic fertilizer, stays the same in 0 % and goes down in 11 %.

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…