Management › Tillage › Tillage system → Properties › Biology

Zero tillage → Yield

The studies disagree

35 %

of 154 studies with a clear result report a significant increase

-1 %

typical change (93 studies with numbers)

165

studies · 279 findings

Count each study by

165 studies · 279 findings

What the studies show

54 of 154 studies report a significant increase (35 %, 95 % confidence interval 28–43 %).

By the direction of each study’s results, significant or not: 63 of 127 studies with a direction point up (50 %, 95 % confidence interval 41–58 %; sign test p = 1).

↑ 54 increase
↓ 46 decrease
⇅ 12 both
= 42 no effect
? 11 unclear

How large: typically -1 % (middle half -9 % to +11 %), from 93 studies with numbers
Basis: 165 studies, 279 findings; 28 entered by hand, 137 read by the library

5 findings on relative measures (shares, stratification ratios, values per unit) or on fractions and other compartments are not counted in this answer.

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, yield goes up in 35 % of the studies under zero tillage, stays the same in 27 % and goes down in 30 %.

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…