Tag Archives: essential nutrients

Straw Residue Prevents on Site Farm Nitrogen Loss?

ScienceDaily (July 26, 2010) — Scientists are exploring ways to reduce non-point pollution from agriculture. A new study finds that using straw residue in conjunction with legume cover crops reduces leaching of nitrogen into waterways, but may lower economic return.

Agriculture is the largest source of nitrogen non-point pollution to waterways in the United States, flowing into streams and rivers via erosion from farmlands, or through leaching of nitrate into groundwater. Once in aquatic systems, excess nitrogen leads to aquatic ecosystem degradation, including oxygen depravation that leads to fish kills and dead zones. If nitrates leach into drinking water supplies, they are a human health concern and have been linked to blue-baby syndrome, various cancers, and birth defects.

Legume cover crops, such as hairy vetch, have been considered as an alternative or supplement to synthetic nitrogen fertilizers that may improve the sustainability of agricultural systems. Such cover crops can contribute substantial amounts of nitrogen to subsequent crops, as well protect soils from erosion and promote overall soil quality. Legumes tend to release nitrogen more slowly than synthetic fertilizers, possibly being more synchronous with crop demand. That does not mean that nitrogen from legumes cannot be lost from the system.

One way to possibly minimize these losses may be to add more carbon to nitrogen-rich residues, such as those of cereal grain crops, during cover crop phase of the cropping systems.  read more

Grape Soil Problem

Flooded chardonnay vineyard: Lodi, California

This photo was taken yesterday 15 March 2010 east of Lodi, California. No… the chardonnay vineyard has not been irrigated [it’s a drip irrigation system], and there hasn’t been excessive amounts of rain, either. Yet, the entire bottom half of the vineyard is under water… a serious anaerobic condition for the vines. We are seeing more and more serious water penetration problems like this, and the primary problem is irrigation water that is snow-melt runoff contributing to serious soil structure issues. This soil condition can easily be corrected, but without help, the vineyard and the grapes are in serious trouble. If you have a water penetration problem like this, call us… we would gladly talk to you about our services and how we can help your crops, whether it be grapes, almonds, vegetables or field crops, …or something fun like pussytoes (Antennaria plantaginifolia) or red undies  (Begonia sinensis)… we can help you do a better job with your production.

More Gypsum Facts

Toxicity of Gypsum:  Some other folks are still teaching about “gypsum toxicity.” Facts:

1. There has to be approximately 20,000 ppm Ca2+ in the soil for calcium toxicities to exist…
2. There has to be approximately 800 ppm SO42- in the soil for sulfur toxicities to exist.

Both are extremely rare in productive, agricultural soils, even soils where gypsum has been applied in extreme excess.

Solubility of Limestone vs. Gypsum:

Gypsum--Hydrous Calcium Sulfate

The other gypsum myth I have heard is that as soil pH conditions reach values near 7.0, agricultural limestone becomes is a better choice for adding calcium to the soil rather that gypsum or anhydrite. First of all, agricultural limestone is always 150 times less soluble than gypsum or anhydrite under any conditions. Gypsum/anhydrite is never in any soil reaction (pH) or oxidation/reduction condition any less soluble than this.

However, note that all soluble soil calcium becomes insoluble at pH values near 8.0 So at these pH values, calcium is basically nonexistent in the soil for promoting good soil structure, and as an essential plant nutrient.  This is why we need to keep the soil pH values for most soils in California and the west at pH values about equal to 6.4.

Much more on this subject later….

And please write me with your gypsum/anhydrite/limestone questions…

Nutrient Mining Genes

ScienceDaily (Feb. 21, 2010) — Scientists from the John Innes Centre and the University of Oxford have discovered which genes control the specialized nutrient mining machine that develops on the surface of plant roots.

Root hairs develop on roots and burrow into the soil releasing acids and other scouring chemicals that crack open rocky minerals releasing valuable nutrients such as iron and phosphate that are necessary for plant growth.

It has long been known that when crops such as barley and wheat are grown on soils containing small amounts of phosphate, those plants with long hairs give higher yields than those with short hairs.

Similarly long-haired beans grown on nutrient poor tropical soils of Central America do much better than short haired varieties.

The mechanism that controls the growth of these nutrient excavating cells has eluded scientists until now. A group of UK-based scientists shed light on the mystery in a paper just published in Nature Genetics.

They discovered that a master regulatory gene called RSL4 acts like a switch; hair cells grow when the gene is turned on and growth stops when it is off.

When plants grow in conditions where there is insufficient phosphate they develop very long root hairs. This increases the amount of soil from which they can scavenge phosphate.

“When we discovered that RSL4 was a master regulator of hair growth we thought that perhaps the increased growth of root hairs in low phosphate soils might result from turning this gene on,” says Professor Liam Dolan, leader of the JIC team that discovered RSL4.

Dolan and co-workers were right. Growing plants in phosphate-poor soils turned the gene on resulting in the growth of very long root hairs. This gene is therefore not only a key growth regulator but also a critical cog in the mechanism plants use to cope with a lack of nutrients.

Given the ability of RSL4 increase root hair growth this discovery has the potential to help breeders develop crops that can grow on poor soils.

Most soils in Australia, extensive regions of sub-Saharan Africa and 30 per cent of China are not productive because plants cannot extract sufficient phosphate and iron form these soils.

“Our hope is that in the future someone will be able to use this gene to develop cultivars which enhance yields on poor soils,” says Professor Dolan. “This could have obvious benefits for developing world agriculture. Also as fertilizers become increasingly expensive we will need crops that are more efficient in nutrient uptake. This could have the added benefit of decreasing the amount of polluting phosphate that runs off into rivers and lakes.”

“What excites me most about this research is that we set out to answer a fundamental question in biology — how organisms control the size of their cells. In the end we discovered something that could have an important impact on world agriculture.”

Earthworms and Soil Organic Matter

A LinkedIn connection friend in Los Angeles contacted me this week with a question about his earthworms that he has in his ….house.  An interesting place to raise earthworms, but who am I to question this.   Anyway, here is his question:

“Dr. R:
I know just enough about worm recycling to get my self into trouble.  I have had a worm bin in my home since August.  There seems to be a “lot” of real black soil.  I am not sure what to do next.

If you need more info to advise, please ask.  I’ll answer anything.
Your friend in L.A., Don”

My response back to Don:

“Hi Don… Here is a real brief “lecture” on soil organic matter.  Humus is a substance that is a jet black, sticky [like Elmer’s Glue] substance that is high in available nutrients… especially nitrogen, phosphorus and sulfur, although generally all essential nutrients required by plants are present in the stuff…. (do you really want to know all of them??) O.K., here they are: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, chlorine, iron, molybdenum, manganese, and zinc.  Phew!!!  Humus is a really, really good thing to have in your vegetable garden …or almond orchard or orange grove, etc., etc., etc……. Besides being high in available essential nutrients, because it is sticky, it helps promote outstanding soil structure.. i.e., the black gluey stuff helps the sand, silt and clay particles in your soil “clump” or bond together so air and water and roots can move though the soil better.  In short, humus is something you want a lot of if possible for your garden, orchard, grove, etc., etc., ad nauseum…..

O.K…. worms: the worms, by running the soil medium through their warm bodies, create lots of humus [the black, sticky stuff described above].  So worms are really good guys to have around… To answer your question, Don, just use the worm casts in the bin for whatever you want around your garden, yard, orchard, vineyard, grove….. whatever…. Then add new medium for the worms so they can start the whole process all over again… and again… and again… and then use a few of them and go fishing!!!! Hope this helped a little bit…

My question is: why do you have the worms in your house in the first place?????

Dr. B.”

If any of you have any questions about your crops or your garden… or even your earthworms, please submit them to me and I will answer them in the order I receive them.  Thanks, and have a great and productive week.