JDUtah
06-19-2008, 03:40 AM
Today I was not out in the field as I am waiting for the back to calm down (I know I am WAY to young for back problems but they are there). Anyways, I did some reading out of a textbook from a botany class I took a couple years back and also some reading of a great article about “Mineral Nutrient Depletion in US Farm and Range Soils”. http://www.americanlongevity.net/misc/mineraldepletion.php and it got me thinking. I’m lying in bed and the brain isn’t shutting off. I doubt it will until I get this idea recorded, so for now I am using this post as a journal of an idea that I would love to perform a test on sometime.
The idea is related to watering practices for turf and what they really do, not only in root growth promotion, but in soil fertility.
To start there is the common idea that to encourage grass roots to grow deeply you need to water deep but infrequently. The roots do not necessarily look for the water but they can grow in the right environment. So the idea is when you have control over the environment, try to create the right environment to occur as deep in the soil as the grass roots can tolerate, thus they will be less affected by drought situations should they arise.
This is where the reading comes in. In both the article and the textbook reading it talks about the minerals in the soil leaching. The textbook reads, “In desert areas, for example, there is little weathering by rain, and soils are poorly developed. In areas of moderate rainfall, however, well-developed soils are common. In some areas of high rainfall, the excessive flow of water through the soil may leach out important minerals. Similar leaching out of important minerals may occur when garden sprinklers are left on all night.”
The article reads similar, “Soil erosion is particularly devastating on older, more highly weathered soils in the southeast U.S. since the supply of tiny nutrient-rich primary minerals is already limited. Erosion removes the soil organic matter where much of the soil's nutrient reserve exists. Soils that are low in organic matter, or have lost much of it through erosion exhausts the soil's native nitrogen supply quickly compared to soils unaffected by erosion or low organic matter. Erosion of soil organic matter not only causes nitrogen loss, but also loss of other nutrients, including sulfur and boron.”
The questions begin here. Does deep watering encourage deep roots strictly because of water availability or are the roots more prone to develop lower because the nutrients are leached deeper into the soil? If the leaching of nutrients is a factor, those southeastern states (which the article claims has more mineral leaching problems) would generally find deeper roots than comparable moisture environments with nutrient soil ready available on the surface. That would explain why out here I do not seem to find grass roots much deeper than 4-6 inches even with deep and infrequent watering practices, but I hear of people in Florida who find roots down to 2 feet? (Of course grass variety plays a factor but i think the queston is worth ignoring that debate for now…)
Perhaps the watering is also affecting the depth of soil fertility which in turn affects root growth depth? How can one test this?
Basic concepts of test… partition a plot into 3 zones of equal fertility and soil structure. Keep all variables the same except the watering variable. I would recommend not adding any form of fertilizer during the test period. On one zone, water the traditional 10 minutes every day, on the other water the new idea of 45 minutes 2-3 times a week (that’s the recent buzz time out here). On the third plot, test until you find the appropriate watering time that will allow 6”? of soil to be moist when tested 1 hour? after watering. Then only water that plot after the top 1”? of soil has completely dried out.
Periodically test how deep the moisture is in each area. Continue this watering schedule for 2-3 years and at the end of the test measure soil fertility on each plot at different depths. (1-3”, 4-7” 12-15”?) Also determine root depth on each plot. Compare data.
You can even set drought conditions and test actual plant ressilience.
I think it would be an interesting test; my theory is that the third plot would have the least amount of nutrient leaching (comparable to plot 2) with more tolerable root depth than plot 1.
Anyways I do need to sleep and this is enough recorded to refer to and expand on later. Any input or ideas to refine the theory and test idea? Happy dreams.
The idea is related to watering practices for turf and what they really do, not only in root growth promotion, but in soil fertility.
To start there is the common idea that to encourage grass roots to grow deeply you need to water deep but infrequently. The roots do not necessarily look for the water but they can grow in the right environment. So the idea is when you have control over the environment, try to create the right environment to occur as deep in the soil as the grass roots can tolerate, thus they will be less affected by drought situations should they arise.
This is where the reading comes in. In both the article and the textbook reading it talks about the minerals in the soil leaching. The textbook reads, “In desert areas, for example, there is little weathering by rain, and soils are poorly developed. In areas of moderate rainfall, however, well-developed soils are common. In some areas of high rainfall, the excessive flow of water through the soil may leach out important minerals. Similar leaching out of important minerals may occur when garden sprinklers are left on all night.”
The article reads similar, “Soil erosion is particularly devastating on older, more highly weathered soils in the southeast U.S. since the supply of tiny nutrient-rich primary minerals is already limited. Erosion removes the soil organic matter where much of the soil's nutrient reserve exists. Soils that are low in organic matter, or have lost much of it through erosion exhausts the soil's native nitrogen supply quickly compared to soils unaffected by erosion or low organic matter. Erosion of soil organic matter not only causes nitrogen loss, but also loss of other nutrients, including sulfur and boron.”
The questions begin here. Does deep watering encourage deep roots strictly because of water availability or are the roots more prone to develop lower because the nutrients are leached deeper into the soil? If the leaching of nutrients is a factor, those southeastern states (which the article claims has more mineral leaching problems) would generally find deeper roots than comparable moisture environments with nutrient soil ready available on the surface. That would explain why out here I do not seem to find grass roots much deeper than 4-6 inches even with deep and infrequent watering practices, but I hear of people in Florida who find roots down to 2 feet? (Of course grass variety plays a factor but i think the queston is worth ignoring that debate for now…)
Perhaps the watering is also affecting the depth of soil fertility which in turn affects root growth depth? How can one test this?
Basic concepts of test… partition a plot into 3 zones of equal fertility and soil structure. Keep all variables the same except the watering variable. I would recommend not adding any form of fertilizer during the test period. On one zone, water the traditional 10 minutes every day, on the other water the new idea of 45 minutes 2-3 times a week (that’s the recent buzz time out here). On the third plot, test until you find the appropriate watering time that will allow 6”? of soil to be moist when tested 1 hour? after watering. Then only water that plot after the top 1”? of soil has completely dried out.
Periodically test how deep the moisture is in each area. Continue this watering schedule for 2-3 years and at the end of the test measure soil fertility on each plot at different depths. (1-3”, 4-7” 12-15”?) Also determine root depth on each plot. Compare data.
You can even set drought conditions and test actual plant ressilience.
I think it would be an interesting test; my theory is that the third plot would have the least amount of nutrient leaching (comparable to plot 2) with more tolerable root depth than plot 1.
Anyways I do need to sleep and this is enough recorded to refer to and expand on later. Any input or ideas to refine the theory and test idea? Happy dreams.