- Author: Ben Faber
From the UC Weed Science Blog
http://ucanr.edu/blogs/UCDWeedScience/
A repost and link today to a recent Weed Science Society of America press release entitled: "About Weed Seeds and Their Longevity" Click the link to go to the full article.
An excerpt from the press release and links to the free download:
Did you know some weed seeds can lie dormant in the soil for more than a century and then sprout when conditions are right? A new factsheet available for free download from the Weed Science Society of America (WSSA) dives into the topic of weed seed longevity, as well as how weed seeds travel, when and why they germinate, and ways they can be eliminated.
“Understanding weed seeds and their lifespan is critical for both farmers and backyard gardeners alike,” says WSSA member Greta Gramig, Ph.D., associate professor of weed science at North Dakota State University. “Seeds can remain viable in the soil for extended periods of time. That means if even a single weed is allowed to go to seed, you may be battling the aftermath for years to come.”
Here are just a few of the many facts about weed seeds that are covered in the new WSSA fact sheet:
- Moth mullein seeds buried by a researcher in 1879 were still able to germinate more than 130 years later.
- Weed seeds can easily be spread and transported far from their original location. Some have found their way into the earth's planetary boundary.
- Earthworms are known to collect weed seeds and move them into their burrows.
- Weed seeds that remain dormant in the soil will often germinate in response to changes in temperature, moisture, oxygen or light.
- Carabid beetles are voracious eaters and can consume large quantities of weed seeds that drop to the soil.
In addition to its fact sheet on weed seeds, WSSA offers a variety of other free fact sheets and educational materials online, including infographics and presentations on herbicide resistant weeds and their management.
/span>- Author: Ben Faber
Calcareous soils have often more than 15% CaCO3 in the soil that may occur in various forms (powdery, nodules, crusts etc…). They are relatively widespread in the drier areas of the earth. California is notable for its young soils, that is, soils that have a relatively high level of nutrients because low rainfall means that natural productivity has not been leached out. The potential productivity of calcareous soils is high where adequate water and nutrients can be supplied. Water is the most limiting input to making California soils productive.
The high pH associated with these soils, though, is not the level of calcium present. It is the carbonate in the soil or the bicarbonate associated with the waters found in those soils which controls the pH. The high pH then controls the availability of iron, zinc, manganese and copper. These nutrients need to be added as foliars or soil applied, or better yet, the soil pH needs to be dropped to around 7 to make these nutrients available.
Recently someone asked if replacing the calcium with potassium would change the pH. No, it won't. The carbonate needs to be removed. Calling it a calcareous soil confuses people about what caused the high pH. The carbonate or bicarbonate needs to be removed with acidification, it turning it into CO2 gas. This is done with urea sulfuric acid or sulfuric or sulfurous acid. There are actually magnesium dominated soils in the San Luis Obispo area that have high pHs due to carbonates. They are carbonateceous.
- Author: Ben Faber
I am frequently asked if I can recommend a book on Soils. And yes, I can. It is Soils: An Introduction by Michael Singer and Donald Munns. The sixth edition recently came out so there's a lot of older used copies floating around on the wed for under $10. This book takes a different tack on describing soils. Instead of tacking the tack of a chapter on Nitrogen another on Calcium etc., it weaves a story of how all the parts are related.
- Author: Ben Faber
It is more than just the confusion about the effects of phosphonates, but also how to spell the words associated with the P atom. Phosphorus with an ending in “us” is the element we know as P, while Phosphorous with a “ous” ending is the adjective of P. So an acid containing Phosphorous acid is written H3PO3 while phosphoric acid is H3PO4. These are both strong acids and can hurt and cause damage if splashed on the skin. When either is reacted with calcium or potassium hydroxide, a salt is formed which is less dangerous to users, but as with any chemical can be misused.
The salt formed from Phosphorous acid is called calcium phosphite or calcium phosphonate depending on what naming system is used to describe it. Whereas when these bases are reacted with phosphoric acid, the result is calcium or potassium phosphate. These salts are relatively benign in contact with skin. Labels on containers often call phosphorous acid, “soil applied” whereas the phosphite forms are called “leaf applied”. The “soil applied” when applied to a leaf can cause damage, whereas, the leaf applied is much less likely to cause damage to both plant and applicator. It can be applied to the soil, as well. It's much safer to use the leaf applied in either application technique.
The phosphites are often registered as fertilizers, but they have little nutrient effect. Most of their effect is to boost the plant's immunity to Phytophthoras and pythiums. This is called fungistasis and the material is called a fungistat. They don't act as a fungicide when normally applied to kill these organisms.
So you can see there is a lot of confusion in the phosphorous world. Knowing the proper spelling, pronunciation and use is note only good grammar, it makes good farming.
To read more, see:
http://plantscience.psu.edu/research/centers/turf/extension/factsheets/phosphonate-products
https://edis.ifas.ufl.edu/hs254
http://grammarist.com/spelling/phosphorous-phosphorus/
There are few documented cases of phosphorus (P) deficiency in tree crops in California.
- Author: Ben Faber
When we think about space missions, we tend to look toward the stars to planets like Mars where robotic rovers roam, gathering data and sending it back to Earth. Rarely do we think about missions closer to home. But a view of Earth from 426 miles above is helping us monitor droughts, predict floods, improve weather forecasts and assist with crop productivity. This year, the National Aeronautics and Space Administration (NASA) launched a new satellite called SMAP (Soil Moisture Active-Passive) with the help of a team that included U.S. Department of Agriculture (USDA) hydrologist Susan Moran at the Agricultural Research Service's (ARS) Southwest Watershed Research Laboratory in Tucson, Arizona, and physical scientist Wade Crow and hydrologist Thomas Jackson at ARS's Hydrology and Remote Sensing Laboratory in Beltsville, Maryland. ARS scientists played a key role in designing and implementing SMAP—an orbiting observatory that measures the amount of water in the top layer of the soil everywhere on Earth. SMAP gathers soil moisture data that can help track diseases and famine, predict weather and climate patterns, assist emergency workers' response to natural disasters and let farmers know what crops to plant. “We've seen impressive advances in our ability to produce crops on a given area of soil, but have also retained susceptibility to climate events, particularly droughts that occur when there is inadequate soil water for crops,” Crow says. “The idea is to better predict and monitor droughts so they don't turn into food crises, and soil moisture is the most direct and earliest indication of drought.” SMAP provides the best global view of soil moisture to date, Crow says. Therefore, it has the potential to help monitor global food production. It's the best soil moisture sensor ever deployed due to its resolution, accuracy, global coverage and repeat time. Before the satellite was launched, volunteer users around the world could put SMAP's simulated data to use, Moran says. “We wanted to make sure our products would be as good as possible and easy to access. In return, these users provided feedback on how SMAP could help them.” Early users included those in agriculture, weather, human health, emergency response and military readiness. Data were used to monitor droughts, predict floods and even to predict the water supply in New York City, Moran says. “Some used the data to predict large regional dust storms that affect the health of millions of people in Saharan Africa and throughout the Middle East,” she adds. “In Germany, the data were used to map sea ice in hopes of improving maritime navigation, and at Texas A&M University, researchers looked at the impact of hurricanes on power outages.” SMAP will release the first data products to the public in August. To learn more, go to http://smap.jpl.nasa.gov/. - See more at: http://blogs.usda.gov/2015/04/07/usda-nasas-global-view-of-earths-soil-holds-many-benefits/#sthash.okw1NTAN.dpuf