Our pastures rarely need any nitrogen. Maybe it's from the clover or maybe it's just pasture rotations puts most of it back on the ground. Our hay fields are the places we have to use nitrogen every other year or so. Haying mines nutrientsplumber_greg":11cxeh9n said:Dun, I bought in to Gerrish's theories one year of 5lbs. red clover and mig replacing fertilizer needs. The main trouble I had the one year I tried it was that we ususally turn out last week of April, and it was a little dry that spring and I had no grass. Slapped some nitrogen down, had little shower and the grass came on. I think if you want to depend on clovers for nitrogen, it may work in a hayfield, but pastures still need the early spring push. Do you remember the experiment MU ran about cows needing no shade? A 40 percent conception rate on black cows killed that one. gs
Some N is available from the nodules. The majority is from the foliage. After decomposition of the leaf and stem (mowing or death of plant) in the ground it becomes available. The other way is through fecal mater decomposing in the ground. Microorganisms needed to produce nodules (inoculate). Then more Microorganisms to convert the forage or fecal mater into usable food for the other plants.dun":3crkr3af said:There has in the past been discussions about clover, etc. and it's nitrogen producing/fixing qualitys. The proper inoculant is required but when is the nitrogen made available to the other plants?
Stocker Steve":1ztbzuiu said:I think there are a couple drawbacks to not applying N. N is not available when soil is cold in spring or fall, and some grasses are heavy users of N. I usually put on 40# per acre as soon as I can drive on sod, and consider a second application on anything I stockpile in the fall.
The mob grazing guys brag about how they increase the organic matter a couple percent in one year, but I do not understand how that is possible :???: I realize they are putting more litter on the ground (due to lower forage utilization) compared to someone who is grazing at a shorter height...
The theory is that if you allow the grass to get close to maturity in height and only graze it down by 40 or 50% then the root system is not hurt and allows the grass to grow faster. When grasses are grazed short the root system responds equally, it too is short, therefore the grass grows slower plus the fact that they will not have the depth to pick up the nutrients and water necessary throughout the seasons. There is not enough leaf to shade the soil and no thatch to feed the microorganisms.[/color]
Have you seen any believable soil test data on mob grazed ground?
plumber_greg":2g96osgj said:Dun, I bought in to Gerrish's theories one year of 5lbs. red clover and mig replacing fertilizer needs. The main trouble I had the one year I tried it was that we ususally turn out last week of April, and it was a little dry that spring and I had no grass. Slapped some nitrogen down, had little shower and the grass came on. I think if you want to depend on clovers for nitrogen, it may work in a hayfield, but pastures still need the early spring push. Do you remember the experiment MU ran about cows needing no shade? A 40 percent conception rate on black cows killed that one. gs
fargus":7yrn8uco said:I have heard about the study that talks about pasture coverage by cattle manure. We intensively graze, and get the benefits of increased stocking rate, better production during drought, etc.
Keep in mind, that an acre furrow slice (6" of topsoil on 43,560 square feet) is somewhere in the neighbourhood of 2 MILLION pounds. To raise your OM test 1% that is 20,000 lbs of extra residue LEFT. That is similar to growing a phenomenal crop of Winter Wheat (about 100 bu/ac or better) incorporating all of the grain and the straw, and losing none of the carbon. (It would all have to be assimilated into the soil carbon pool.) You aren't gonna do that in just a year. I apologize if my math is a bit rough, those numbers are all off the top of my head.
I did my own calculations and found I was way wrong. After further research found this article. http://www.soilhealthknowledge.com.au/i ... &Itemid=85JRGidaho`":3su2dm4y said:fargus":3su2dm4y said:I have heard about the study that talks about pasture coverage by cattle manure. We intensively graze, and get the benefits of increased stocking rate, better production during drought, etc.
Keep in mind, that an acre furrow slice (6" of topsoil on 43,560 square feet) is somewhere in the neighbourhood of 2 MILLION pounds. To raise your OM test 1% that is 20,000 lbs of extra residue LEFT. That is similar to growing a phenomenal crop of Winter Wheat (about 100 bu/ac or better) incorporating all of the grain and the straw, and losing none of the carbon. (It would all have to be assimilated into the soil carbon pool.) You aren't gonna do that in just a year. I apologize if my math is a bit rough, those numbers are all off the top of my head.
fargus, I think your math is correct and the 20,000 lb OM is what would have to be added to raise 1%. Next to impossible to grow 20000 lb forage in most of US & Canada, let alone have that much returned to the soil. When I take soil samples, I always scuff away the debris layer on the soil surface (which really isn't humus yet) and put the probe directly into the mineral soil. If you take a sample punching down through the litter layer, you will get an inflated OM reading.
Another real easy way to double your organic matter is change from taking 6-8" soil cores to just taking 3-4" cores. The lab will still calculate all your analysis based on the 6" plow layer unless you told them it was a shallow sample.
I think their figures are based on crop removal and not pasture, but it would still fall short of the numbers I posted.(recent data suggests an additional 2 t/ha of plant residues retained each year for 20 years can increase SOM by only 0.5%).
JRGidaho`":2103u1uc said:I've probably mentioned it before, but there were only three occasions in the 22 years we ran cattle and sheep in north MO that we ever used N-fertilizer. We ran a cow-calf equivalent year-around on just over 2 acres of grass-legume pasture.Here in ID we use no N and are harvesting over 300 CDA (or about 5 ton/acre).
Stocker Steve":33k97ztm said:JRGidaho`":33k97ztm said:I've probably mentioned it before, but there were only three occasions in the 22 years we ran cattle and sheep in north MO that we ever used N-fertilizer. We ran a cow-calf equivalent year-around on just over 2 acres of grass-legume pasture.Here in ID we use no N and are harvesting over 300 CDA (or about 5 ton/acre).
Is your point that N was not economical most years or that you were understocked or that you had great legume stands?
Stocker Steve":1yna2sra said:I think I get it. So I let the forage get taller, flatten it with mob density, take a shallow 3" deep sample including as much litter as possible, and then brag about my OM. ;-)
On a more serious note, one of the reasons given for the typical forage production decline a couple years after tillage - - is that the OM exposed by mechanical tillage has been consumed.
JRGidaho`":abmp2gis said:fargus,
I'm still missing something. What was wrong with your calculation? An acre 6" slice does weigh 2,000,000 lb and one percent of that would be 20,000 lb. So a 1% increase in OM would be 20,000 lb more OM added to the soil.
I know 20,000 lb crop residue would not translate to 20,000 lb OM. Is that where you're saying you were off?
What gives?
jr