Management › Fertilization → Properties › Physics

Organic fertilizer → Bulk density

A clear tendency, not consistent

71 %

of 31 studies with a clear result report a significant decrease

-7 %

typical change (15 studies with numbers)

studies · 36 findings

Count each study by

32 studies · 36 findings

What the studies show

22 of 31 studies report a significant decrease (71 %, 95 % confidence interval 53–84 %).

By the direction of each study’s results, significant or not: 3 of 28 studies with a direction point up (11 %, 95 % confidence interval 4–27 %; sign test p < 0.001).

↑ 4 increase
↓ 22 decrease
= 5 no effect
? 1 unclear

How large: typically -7 % (middle half -9 % to -6 %), from 15 studies with numbers
Basis: 32 studies, 36 findings; 2 entered by hand, 30 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 18 % of the studies under organic fertilizer, stays the same in 9 % and goes down in 73 %.

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…