Join the discussion July 23
About this Event
Three part webinar lecture series, staring speakers in industry, government, and the university system; covering the following soil health topics:
soil organic matter – interpreting soil test results – structure & function of plant roots – Mycorrhizae 101 – compost & cover crops – microalgae – biochar – FDA soil health perspectives – conservation tillage – organic production – pesticide effects – soil borne pathogens – ag engineering pest control.
PCA, CCA, and Pest Control continuing education credits requested for AZ, CA, NM, and NV.
More details to come on the CEU process.
Module 1: Defining Soil Health
8:00am - 10:30am
Soil Science PHD Student: UC Davis
Defining Soil Health in the American Southwest
Dr. Joey Blankinship
Soil Science Professor: University of Arizona
Soil Organic Matter in Desert Agriculture
Interpreting Soil Test Results
Dr. Glenn Wright
Extension Horticulturalist: University of Arizona
Structure and Function of Plant Roots
Director of R&D: Mycorrhizal Applications LLC
Module 2: Practices to Improve Soil Health
10:30am - 3:00pm
Dr. David Johnson
Adjunct Professor: New Mexico State University
Composting and Cover Crops
Dr. Kristine Nichols
Research Director: MyLand Company
The Role of Microalgae in Soil Health
Dr. Catherine Brewer
Assistant Professor: New Mexico State University
Biochar Production and Application Methods
Dr. Ataullah Khan
Senior Research Scientist: InnoTech Alberta
Biochar Application Development
Consultant: BioAg Product Strategies
Alternative Soil Amendments for Soil Restoration and Sustainability
Dr. David Ingram
Consumer Safety Officer: FDA-CFSAN Produce Safety Staff
FDA Perspectives on Soil Health
Dr. Michele Jay-Russell
Project Director: UC Davis Western Center for Food Safety
Organic Production Soil Health Considerations
Dr. Jeff Mitchell
Cropping Systems Specialist: UC Davis
Conservation Tillage in Vegetable Cropping Systems
Conservation Education Director, AZ Association of Conservation Districts (AACD)
Funding for Soil Health Programs
Module 3: Soil Pest Control
3:00pm - 6:00pm
Dr. John Palumbo
Extension Entomologist: University of Arizona
Soil Applied Insecticides
Extension Weed Scientist: University of Arizona
Persistence of Herbicides in the Soils of the Low Desert
Dr. Stephanie Slinski
Associate Director: Yuma Center for Excellence in Desert Agriculture
Soil Borne Pathogens
Dr. Channah Rock
Extension Water Quality Specialist: University of Arizona
Water Treatment Effects of Soil Borne Pathogens
Dr. Mark Siemens
Extension Ag Engineer: University of Arizona
Point Injection Systems – Fertilizer/Pesticide Application with Minimal Soil Disturbance
- Author: Kristian Salgado
For more information on the CDFA Healthy Soils Program: Click here
Kristian M. Salgado
Community Education Specialist 2 (CES2)
Climate Smart Agriculture
Under our feet, in the soil, is a wealth of microbial activity. Just like humans have different metabolisms and food choices, so do those microbes. In fact, microbes play an important role in making nutrients available to plants.
A recent review paper from Xinda Lu and his team looks at different roles that various soil microbes have in soil's nitrogen cycle. Lu is a researcher at Massachusetts Institute of Technology.
According to Lu, "Soil microbes catalyze most of the transformations of soil nitrogen into plant-usable forms. Diverse microbes use different processes - and sometimes work together. Knowing the various styles of soil microbes, and linking microbes to specific soil processes, can be important knowledge for farmers."
Modern nitrogen fertilizers are applied in the form of ammonium. Through a biological process called nitrification, soil microbes convert ammonium to nitrates that plants can absorb. In order to be efficient at this process, microbes need oxygen. Researchers are studying nitrification because it can be linked to greenhouse gases and loss of fertilizer.
Although microbiologists have been studying the nitrogen cycle for over a century, not all steps were well understood. New microorganisms have recently been identified. A type of prokaryote (single-celled organism) called archaea has also been playing a role in nitrification.
Archaea are not technically soil bacteria, due to their structure. These are newly a newly classified group that really do some amazing things. There are many more archaea that contribute to nitrification in some soils than there are bacteria responsible for the same activity. Including the role of archaea in nitrification has broadened the understanding of scientists and researchers.
Researchers reviewed various studies of soil nitrification. This included the abundance of microbes in soil in relation to various environmental factors. Soil pH, temperature and the ratio of soil carbon to soil nitrogen were all compared to the number of microbes in each soil sample. Soil depth and other factors also influence microbe abundance.
Previous studies have shown, for example, that nitrification archaea are more abundant than bacteria in warmer temperatures. Other microbes thrive in lower temperatures.
Soil pH also influences how active soil microbes are in the nitrification process. Soil bacteria Nitrospira were more dominant in acidic soils, including forests and farm fields.
Researchers have also studied how various microbes "talk" to each other. This keeps the nitrification process running smoothly. Various mechanisms have been proposed, including cell signaling. The presence of nitric oxide in soils may enhance interactions between microbes.
Soil scientists are sure they have not found all the microbes that contribute to the vast array of services soils provide. Just as astronomers discover new stars in the sky as tools advance, so will soil microbiologists find new soil microbes. Some may be involved in nitrification.
Collecting and cataloging the type, abundance and location of soil microbes will continue to advance the knowledge we have about the soil nitrogen cycle.
Crenarchaeota are involved with nitrification in the soil. Here's a cell of this group infected by virus STSV1 observed under microscopy.
While domestication of plants has yielded bigger crops, the process has often had a negative effect on plant microbiomes, making domesticated plants more dependent on fertilizer and other soil amendments than their wild relatives.
In an effort to make crops more productive and sustainable, researchers recommend reintroduction of genes from the wild relatives of commercial crops that restore domesticated plants' ability to interact with beneficial soil microbes.
Thousands of years ago, people harvested small wild plants for food. Eventually, they selectively cultivated the largest ones until the plump cereals, legumes, and fruit we know today evolved. But through millennia of human tending, many cultivated plants lost some ability to interact with soil microbes that provide necessary nutrients. This has made some domesticated plants more dependent on fertilizer, one of the world's largest sources of nitrogen and phosphorous pollution and a product that consumes fossil fuels to produce.
"I was surprised how completely hidden these changes can be," said Joel Sachs, a professor of biology at UC Riverside and senior author of a paper published today in Trends in Ecology and Evolution. "We're so focused on above ground traits that we've been able to massively reshape plants while ignoring a suite of other characteristics and have inadvertently bred plants with degraded capacity to gain benefits from microbes."
Bacteria and fungi form intimate associations with plant roots that can dramatically improve plant growth. These microbes help break down soil elements like phosphorous and nitrogen that the plants absorb through their roots. The microbes also get resources from the plants in a mutually beneficial, or symbiotic, relationship. When fertilizer or other soil amendments make nutrients freely available, plants have less need to interact with microbes.
Sachs and first author Stephanie Porter of Washington State University, Vancouver, reviewed 120 studies of microbial symbiosis in plants and concluded that many types of domesticated plants show a degraded capacity to form symbiotic communities with soil microbes.
"The message of our paper is that domestication has hidden costs," Sachs said. "When plants are selected for a small handful of traits like making a bigger seed or faster growth, you can lose a lot of important traits relating to microbes along the way."
This evolutionary loss has turned into a loss for the environment as well.
Excess nitrogen and phosphorous from fertilizer can leach from fields into waterways, leading to algae overgrowth, low oxygen levels, and dead zones. Nitrogen oxide from fertilizer enters the atmosphere, contributing to air pollution. Fossil fuels are also consumed to manufacture fertilizers.
Some companies have begun selling nitrogen-fixing bacteria as soil amendments to make agriculture more sustainable, but Sachs said these amendments don't work well because some domesticated plants can no longer pick up those beneficial microbes from the soil.
"If we're going to fix these problems, we need to figure out which traits have been lost and which useful traits have been maintained in the wild relative," Sachs said. "Then breed the wild and domesticated together to recover those traits."