Tag: bulk density

28 Oct 2019

Change Over Time

Change Over Time

Late summer we had the chance to re-monitor some of our pastures to see how soil properties have changed in 3 years.  This was an opportunity for 3 of us (Megan, Chad G. and Jennifer) to learn the pasture monitoring methods.  Front Nippert field was first monitored in 2016 and the same transect was set up in 2019.  Vegetation, bulk density, soil carbon and water infiltration were all measured.  In the upper layer of the soil (0-10 cm), bulk density decreased from 1.28 to 1.18 g/cm3.  Both values are low enough for proper root growth.  Figure 1 shows infiltration improved over three years.  And Table 1 shows the carbon results.  Carbon in the lowest layer of soil increased over the 3 years.

–Jennifer

28 May 2019

What is Bulk Density?

What is Bulk Density?

Ask people what a plant needs to grow and you will probably get answers such as, “sun, water and soil”.  The soil provides important nutrients (and fungal associations) to the plant, but also needs to have right physical properties to allow a root to grow and penetrate. The physical growth of the root is quite dependent of the soil in which it is trying to grow.

One important measurement in determining the ability for a root to penetrate the soil is bulk density.  Bulk density is the weight of dry soil per volume (grams/cm3).  This value reflects soil texture and compaction.  In addition to affecting the ability of a root to grow, bulk density will affect infiltration, water capacity, porosity, nutrient availability and soil microorganism activity.

Bulk density can be measured by collecting a known volume of soil and then measuring the dry weight of the soil.  At Greenacres, we use one of two methods, depending on our location.  In the pastures, easily accessible by the soil probe, we can collect a sample in a plastic sleeve.  The tube is then cut into known lengths to determine volume and the soil sample dried.  In the woods, we collect the sample by hand by driving a cylinder (known volume) into the ground and collecting the sample.

Table 1 compares some bulk densities across Greenacres properties. In general, bulk densities below 1.6 grams/cm3 are good for root growth.  The soil in Lewis Township is more compact and has a higher bulk density compared to the pastures at Indian Hill.  The management of these soils contributed to this difference.

Table 1.  Bulk densities were measured across 3 Greenacres sites: Beech Maple Woods, Front Nippert Pasture and Lewis Township field.

Location Bulk Density (grams/cm3)
Beech Maple Woods (transect 1) (0-10 cm) 1.05
Front Nippert (pasture) (0-10 cm) 1.1
Lewis Township (historically soybean field) (0-10 cm) 1.61

 

–Jennifer