Management › Tillage › Tillage system → Properties › Chemistry › Nitrogen compounds › Total Nitrogen › Total dissolved Nitrogen

Zero tillage → NO3-/Nitrate

The studies disagree

45 %

of 31 studies with a clear result report a significant decrease

-9 %

typical change (14 studies with numbers)

studies · 41 findings

Count each study by

31 studies · 41 findings

What the studies show

14 of 31 studies report a significant decrease (45 %, 95 % confidence interval 29–62 %).

By the direction of each study’s results, significant or not: 12 of 25 studies with a direction point up (48 %, 95 % confidence interval 30–67 %; sign test p = 1).

↑ 11 increase
↓ 14 decrease
⇅ 1 both
= 5 no effect

How large: typically -9 % (middle half -31 % to +20 %), from 14 studies with numbers
Basis: 31 studies, 41 findings; 5 entered by hand, 26 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, NO3-/Nitrate goes up in 50 % of the studies under zero tillage, stays the same in 25 % and goes down in 17 %.

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…