Management › Fertilization › Type of fertilizer → Properties › Biology › Plants

Nitrogen fertilizer → Aboveground biomass

Consistent result

81 %

of 16 studies with a clear result report a significant increase

+90 %

typical change (10 studies with numbers)

studies · 19 findings

Count each study by

17 studies · 19 findings

What the studies show

13 of 16 studies report a significant increase (81 %, 95 % confidence interval 57–93 %).

By the direction of each study’s results, significant or not: 15 of 16 studies with a direction point up (94 %, 95 % confidence interval 72–99 %; sign test p < 0.001).

↑ 13 increase
↓ 1 decrease
= 2 no effect
? 1 unclear

How large: typically +90 % (middle half +52 % to +118 %), from 10 studies with numbers
Basis: 17 studies, 19 findings; 0 entered by hand, 17 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 81 % of the studies under nitrogen fertilizer, stays the same in 13 % and goes down in 6 %.

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…