Management › Fertilization → Properties › Biology › Plants

Organic fertilizer → Aboveground biomass

A clear tendency, not consistent

65 %

of 20 studies with a clear result report a significant increase

+31 %

typical change (14 studies with numbers)

studies · 34 findings

Count each study by

21 studies · 34 findings

What the studies show

13 of 20 studies report a significant increase (65 %, 95 % confidence interval 43–82 %).

By the direction of each study’s results, significant or not: 13 of 17 studies with a direction point up (76 %, 95 % confidence interval 53–90 %; sign test p = 0.049).

↑ 13 increase
↓ 3 decrease
⇅ 1 both
= 3 no effect
? 1 unclear

How large: typically +31 % (middle half +15 % to +93 %), from 14 studies with numbers
Basis: 21 studies, 34 findings; 0 entered by hand, 21 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 layers of unstated depth, aboveground biomass goes up in 65 % of the studies under organic fertilizer, stays the same in 15 % and goes down in 15 %.

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…