Compost suppresses Pythium ultimum

In controlled studies, soil amended with 20% compost consistently suppressed Pythium ultimum, a soil dwelling pathogen that is part of the disease complex black root rot.  Cucumber seeds are highly susceptible to P. ultimum and were used as indicators of suppression.  Percent germination of seedlings suggests the level of suppression achieved by each treatment.  Soil […]

Compost can affect soil salinity

Two types of finished compost, manure compost and spent mushroom compost, both significantly increased soil salinity.  However, with sufficient irrigation, the spike in electrical conductivity was reduced to within optimal levels by January (1.5 months after compost incorporation) and possibly earlier.  In a field with deficit irrigation, high EC levels were still measured in soil […]

Compost buffers soil pH

In all of our field trials, compost significantly buffered soil pH .  When soil pH was low-mid 6, compost amended plots raised the pH to low-mid 7, and when the soil pH was closer to 8, it lowered it to mid-7.  Below are two examples from different fields.  

Tighter restrictions on chloropicrin

California Sets Nation’s Strictest Rules For Chloropicrin Pesticide Use   |  By By SCOTT SMITH Posted: 01/14/2015 10:32 am EST Updated: 4 hours ago FRESNO, Calif. (AP) — California farmers now must abide by the nation’s strictest rules for a widely used pesticide in a change designed to protect farmworkers and people who live and work near agricultural fields […]

Verticillium Wilt and Compost Amendments

  Verticillium Wilt and Compost Amendments Margaret Lloyd and Tom Gordon Department of Plant Pathology, University of California, Davis Verticillium dahliae is the cause of Verticillium wilt, a disease that affects strawberries and many other plant species, including annual vegetables, fruit trees, nut trees and fiber crops, as well as weeds and native plants in […]

Effect of compost on soil microbial activity

The following figure describes the effect of compost on microbial activity.  Four composts were added to each field at 30T/A, except vermicompost at 5T/Ac, and measured two weeks after incorporation.  Five field sites were evaluated, three on the central coast and two in the Sacramento valley.  Hydrolysis of fluorescein diacetate were used to measure microbial […]

Effect of compost on electrical conductivity

The following figure shows data collected from a commercial organic field in the Pajaro Valley with loamy clay soils.  Compost was incorporated into soil then sampled two weeks later on 11/8/14.  After four months, the plots were resampled and tested for electrical conductivity.