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Changes in the Physical Aspects of Soil After Four Years of Cover Cropping and Organic Soil Amendments

Volume 5 Issue 10

Chris Benedict, Whatcom County Extension Agent


Evaluate measures to improve soil health including the use of ground covers and soil amendments.


Irrigation Regime (main-plot) –

1.) Tensiometer Driven 2.) Grower Standard

Cover Crop (split-plot) –

a.) Fall planted b.) Fall + Spring Planted (site 1) c.) Perennial Turfgrass (site 2) d.) No cover crop

Soil Amendment (split split-plot) –

i.) Composted Dairy Solids (site 1) ii.) Composted Dairy Solids + Brassica Seed Meal (site 1) iii.) Separated Dairy Solids (site 2) iv.) Separated Dairy Solids + Brassica Seed Meal (site 2) v.) No amendment

Fall Cover Crop – ‘Wheeler’ rye (50 lbs/A) + oats (50 lbs/A)

Spring Cover Crop (site 1) – Oats (10 lbs/A) + ‘Piper’ Sorghum X Sudangrass (20 lbs/A) + ‘Tillage’ Oilseed radish (10 lbs/A)

Perennial Turgrass (site 2) – Dwarf tall fescue + Fine leaf fescue

Composted Dairy Solids (site 1) – 10 tons/A (d.w. basis)

Separated Dairy Solids (site 2) – 3,500 gals/A (w.w. basis)

Brassica Seed Meal – 1 ton/A

Treatments initiated in fall 2011/spring 2012.

Table 1. Dry matter weights and days to harvest (DTH) of covere crops planted itno res raspberry alleyways, 2012-2016 Site 1.

Figure 1. Alleyway soil compaction in red raspberries with/without cover crops and/or composted dairy solids. Those treatments within a year and soil depth with different letters are considered statistically different (p = 0.05).

Take Home Messages

  • Soil compaction was reduced by year two (CC, CDS), but differences existed between treatments. These differences were less pronounced by year five.
  • Infiltration and bulk density was reduced in all treatments by year five.