Root Exudates as Mediators of Mineral Acquisition in Low-Nutrient Environments Abstract Plant developmental processes are controlled by internal signals that depend on the adequate supply of mineral nutrients by soil to roots. Thus, the availability of nutrient elements can be a major constraint to plant growth in many environments of the world, especially the tropics where soils are extremely low in nutrients. Plants take up most mineral nutrients through the rhizosphere where micro-organisms interact with plant products in root exudates. Plant root exudates consist of a complex mixture of organic acid anions, phytosiderophores, sugars, vitamins, amino acids, purines, nucleosides, inorganic ions (e.g. HCO3<span>−, OH<span>−, H+), gaseous molecules (CO2, H2), enzymes and root border cells which have major direct or indirect effects on the acquisition of mineral nutrients required for plant growth. Phenolics and aldonic acids exuded directly by roots of N2-fixing legumes serve as major signals to Rhizobiaceae bacteria which form root nodules where N2 is reduced to ammonia. Some of the same compounds affect development of mycorrhizal fungi that are crucial for phosphate uptake. Plants growing in low-nutrient environments also employ root exudates in ways other than as symbiotic signals to soil microbes involved in nutrient procurement. Extracellular enzymes release P from organic compounds, and several types of molecules increase iron availability through chelation. Organic acids from root exudates can solubilize unavailable soil Ca, Fe and Al phosphates. Plants growing on nitrate generally maintain electronic neutrality by releasing an excess of anions, including hydroxyl ions. Legumes, which can grow well without nitrate through the benefits of N2 reduction in the root nodules, must release a net excess of protons. These protons can markedly lower rhizosphere pH and decrease the availability of some mineral nutrients as well as the effective functioning of some soil bacteria, such as the rhizobial bacteria themselves. Thus, environments which are naturally very acidic can pose a challenge to nutrient acquisition by plant roots, and threaten the survival of many beneficial microbes including the roots themselves. A few plants such as Rooibos tea (Aspalathus linearis L.) actively modify their rhizosphere pH by extruding OH− and HCO3− to facilitate growth in low pH soils (pH 3 – 5). Our current understanding of how plants use root exudates to modify rhizosphere pH and the potential benefits associated with such processes are assessed in this review. </span></span>
It still works great for agitating ground malted barley grains. And........it hasn't helped brew an ACT in 2 years!
I am new to this organics soil. Been here and posted before. Although I know this is not the place to really say it im going to anyways. And if someone can point me in the right direction instead of helping me with my question its totally fine and sorry for the disrespect on posting where I shouldn't. I am currently in my first run on this soil and im using 5gal smart pots. My kandy kush is in veg.. pretty much stopped growing for awhile now and hasn't gained height. Pretty sure rootbound but I've never had this problem before. This soil is amazing and as its probably double my roots in size from standard store bought dirt u add nutrients to. This morning I had noticed white things coming out the top of my soil. And as I look closer I see that it is roots! They are literally trying to come right out the top of my soil. . Anyone else have this happen? Im sure its due to this amazing batch of soil.. but want to make sure I just need to repot
im now interested... rootbound in a smartie? That would be a first I've. Heard of that!i thought they air prune your roots due to the pores?
A better understanding in this Smart pot.... I wouldn't call it root bound more so root restricted. there still a limited amount of space that the routes can grow in, there just being prunedas we hit the wall versus being rude bound around the bottom of the pot. I hope I'm explaining this correctly ___________________________ Check out my Journal!!! http://forum.grasscity.com/absolute-beginners/1307645-first-grow-organic-northern-lights-pc-grow.html
This happens to me as well.... This is me making sense of it....I had a piece of card board sitting on top of my soil so I can sit a fan on top of that. Because the cardboard covered the soil and basicly stopped the roots from being light/air pruned so they grew up. Again, no research, just what makes the most sense to me. Do you have anything covering the soil? ___________________________ Check out my Journal!!! http://forum.grasscity.com/absolute-beginners/1307645-first-grow-organic-northern-lights-pc-grow.html
I have my smart pots on the ground for capillary contact and usually have to cut under my pots after harvest due to the amount of roots that grow through the bottom so i dont understand the whole root restriction aspect im seriously just curious as i use many fabric pots!
Your roots, I imagine, can get restricted...can't grow 7gal of roots in a 5gal pot...if that makes sense. I wouldn't think you would have this problem if your roots are growing into the ground. I had my first girl in a 1gal and vegged too long, she started showing signs of being rootbound. I sat her on top of a container with additional soil and she bounce back, took her into flower like that... ___________________________ Check out my Journal!!! http://forum.grasscity.com/absolute-beginners/1307645-first-grow-organic-northern-lights-pc-grow.html
1Gal per foot of plant is what ive always heard, is the plant 5ft, i really am not being confrontational just trying to understand, ill be watching for resolution
I've always said the same thing! So I'm wondering what's going on with his.. No worries bro..your just helping us come up with a logical explanation ___________________________ Check out my Journal!!! http://forum.grasscity.com/absolute-beginners/1307645-first-grow-organic-northern-lights-pc-grow.html
Sorry for just getting back. Nope nothing over the soil. Just normal shit happening like anyone else except they are literally coming out the top. I understand that they air prune but my root ball is big big .Meaning smart pots can become too small even with air pruning. Just takes a lil longer.
I run only grow bag/earth bags and the only troubles. I've had arrived with autos not flowering but I think that's genetics...
ill try to get a pic tomorrow i have similar thing happening in the ground, i think its just a big shallow rootball growing in all directions the ones that surface and find there way back into the soil might get kind of barky and the ones that dont find the soil again will most likely die at the soil surface but i dont think you have much to worry about...imo im not stating as fact just speculating!
I think it could just be that the medium has slightly compacted since those roots have grown, from watering and whatnot pushing the soil down.
Doesn't look like much perlite in soil..maybe they aren't gettin enough air or good drainage and are being forced to grow up to the topsoil where the looser soil is
I've seen growers actually transplant and place the rootball in with about a half inch of it above the soil surface. I don't have an explanation for why. I also recall seeing a YouTube video of Soma doing this with potted plants outdoors. I have roots that have popped out but they ultimately end up air pruned and dry out. I don't think it has any negative impact on the plant. If your plant looks fine it should be all good.
That's a really rough rule of thumb. I've had plants totally rootbound in a 5 gal pot that were less than 2' tall. Of course, these were host plants (mothers), that had been in that container for some time. Roots grow where they will for their own reasons. Ever see Cypress 'knees'? They are humps in the roots that grow up so they will have oxygen available. Bald Cypress grows in swamps and very wet areas and are submerged for months at the time and the 'knees' grow to above the water level. Wet
I've read another rule of thumb too: 1 gallon of soil for every 1 month of growth. I'd probly adjust that depending on the plant, light source etc. TJ