Biomass and N estimates

[shawnv]

I was watch a seminar last night present by the University of Cornell and thought this tidbit might be useful to some of you who use cover crops in your plots.

Most non-woody legumes produce 2,000 lbs of dry matter per acre per 6" of growth. For each additional inch of growth add 150 lbs. If the area is not saturated with cover-crop, multiply the result by the % of ground covered.

How does CC relate to N:

Annual legume prior to flowering 3.5-4%N, flowering 3-3.5% N, after flowering <3%

So how much N are you adding? Dry matter x flowering stage % = N weight

 

[wiscwhip]

So a solid acre of 6" tall clover @ 3% N would give you 60lbs of N. Nice thanks shawn! I had seen an equation similar to this before, but I had lost it and couldn't remember where I saw it. I think it might have been in a report from the SARE group?

 

[scott44]

Thanks for sharing this.

 

[shawnv]

Another good piece of information I picked up for those that use buckwheat. It appears cowpeas are able to grow right along with buckwheat unlike other legumes that might not like the competition.

"Adding cowpeas to the buckwheat cover crop reduces your need to add a layer of compost before seeding your fall garden since you greatly increase the amount of available nitrogen produced. Like many legumes, cowpeas fix nitrogen out of the air, and they do that even better when there's very little nitrogen in the soil for them to suck up. Buckwheat steals soil nitrogen from its neighbors, tricking the cowpeas into fixing more nitrogen than they would if grown by themselves in the same soil. "

For those that are not aware, buckwheat will only keep the N that would otherwise leach away on bare soil. What buckwheat steals in N is returned to the soil when its turned over.

 

[LessRice]

Very cool. You know what the seeding rate should be for buckwheat and cowpeas mix?

 

[shawnv]

Very cool. You know what the seeding rate should be for buckwheat and cowpeas mix?

2:1 buctwheat to cowpeas is what I've heard.

 

[tooln]

2:1 buctwheat to cowpeas is what I've heard.

Thanks for the info. Last year I put some buckwheat in and really liked it. Was planning on more this year. I have some left over AWP's could I sub these for the cow peas?

 

[wiscwhip]

What buckwheat steals in N is returned to the soil when its turned over.

Along with all the P, K, and micros that it uptakes while growing as well. BW is a very efficient miner of stray nutrients. To receive maximum benefit from this process it is best to terminate after it starts to flower(20% - 25%), but before the BW starts to set seed.

Tooln, I see no reason why AWP could not be substituted for the cowpeas if that is what you have on hand. Growth rate and form are very similar. I'm guessing it wouldn't be a stretch to say that soybeans could be substituted as well. Remember, in order to receive maximum N benefit from the legumes, use fresh inoculant before planting.

 

[shawnv]

I haven't sorted out all of the difference to give a good answer or if it matter but their range seem to be slightly different. Here is a good description of each.

http://www.sare.org/Learning-Center...on/Text-Version/Legume-Cover-Crops/Field-Peas

http://www.sare.org/Learning-Center...ition/Text-Version/Legume-Cover-Crops/Cowpeas

 

[tooln]

Buckwheat & AWP it is this year in a section I'm looking to plant apple trees in next spring.

 

[wiscwhip]

Pics!!! Mainly because I am curious to see if the BW helps control the browsing on the AWP. AWP would normally get hammered to the ground within a few weeks of germination if unprotected.

 

[tooln]

Last year I planted some straight BW. Your right my AWP's got wiped out as fast as they came up. Mixing may work.

 

[wiscwhip]

Great looking plots tooln! Now to find out what it looks like when planted together!

 

[tooln]

Great looking plots tooln! Now to find out what it looks like when planted together!

I'll post pic when it comes up this year. This is an area I want to plant apple trees in next spring.

 

[wiscwhip]

What is your plan for it this fall?

 

[tooln]

I'm thinking of rye for a cover & clover/chicory mix. Come spring spray to kill the area's the trees are going into.

 

[huthut]

Shawn great information - thanks for sharing

 

[shawnv]

I did straight buckwheat in the past before planting my oat cover crop in my garlic fields or LC mix in my deer plots but will add the peas this year so I'll keep you posted how this works out.

 

[wiscwhip]

I'm thinking of rye for a cover & clover/chicory mix. Come spring spray to kill the area's the trees are going into.

So if you leave the clover and chicory as ground cover for the orchard, how big of an area do you spray around each tree planting? 10 feet?

 

[tooln]

So if you leave the clover and chicory as ground cover for the orchard, how big of an area do you spray around each tree planting? 10 feet?

I haven't really decided yet. I'm guessing in the 6-10' range