Building Soils for Better Crops, Third Edition

Species Richness and Active Rooting Periods

SARE Outreach
Fred Magdoff and Harold van Es | 2010 | 294 pages
PDF (6.8 MB)

This title is temporarily out of print. We expect to publish an updated edition in the spring/summer of 2021.

In addition to the quantity of residues remaining following harvest, a variety of types of residues is also important. The goal should be a minimum of three different species in a rotation, more if possible.

The percent of the time that living roots are present during a rotation is also important. The period that active roots are present varies considerably, ranging from 32% of the time for a corn-soybeans rotation to 57% for a beans-wheat rotation to 76% for a three-year beans-wheat-corn rotation (table 11.1).

As mentioned above, when soils are covered with living vegetation for a longer period of time, there tends to be decreased erosion as well as a decreased loss of nitrate and less groundwater contamination.

Table 11.1: Comparison of Rotations: Percent of Time Active Roots Are Present and Number of Species

Active Rooting Period (%)
Number of Species

Dry beans-winter wheat
Dry beans-winter wheat/cover
Dry beans-winter wheat-corn
Corn-dry beans-winter wheat/cover
Sugar beets-beans-wheat/cover-corn