Organic fertilizer amounts

[lee53011]

My last soil test said I needed to add .3 pounds of high nitrogen fertilizer per 100 square feet. I use alfala meal and blood meal, as well as my own compost. It also stated I had plenty of potassium and phosphorous, a PH of 7.2 and 8% organic matter. I am trying to calculate how many cups or pounds of alfalfa or blood meal to use. Any help?

Thanks,
Lee

[bower]

Hi Lee, welcome to TJ.

Blood meal is usually 12-0-0 so that fills the bill for high nitrogen with no extra K or P you didn't need.
So a third of a pound per 100 sq ft, pretty straightforward.

I haven't used alfalfa (not available or common here) but I read the NPK value is about 3-1-2, so you would be adding almost as much K and P as N if you used that.

[lee53011]

Thank you! Now do you think I should add that much at the start of the season, and more again later? I plan on growing tomatoes, corn, cabbage, carrots, etc., intercropped. Mostly indeterminate tomatoes. Right now the beds are covered with about a foot of shredded leaves for winter, and in spring I will add a couple inches of homemade compost, consisting of lots of pumpkins, kitchen scraps, garden scraps, and branches all run thru my chipper/shredder and left to hot compost for a couple months.

[bower]

I think the needs of those vegs may be somewhat different - at least, it's not recommended to give carrots extra N, that I know of. I believe they say it causes them to fork (I haven't verified that myself). For tomatoes, it is a good idea to feed them again when they start to ripen their crop. It helps to prevent leaf losses and disease, IMO. Best results are probably from feeding them weekly from the time when you see the first tomato blush. I think cabbages may like some extra N ferts, as that is pretty much the rule for the greens crops. Corn, I really don't know!

I often will watch for signs that the crop is wanting something, before I worry about extra ferts. For some reason I worry more about it than actually doing it, but with the tomatoes it is definitely worthwhile. I do sometimes wait until I see lower leaves yellowing, then I clean it up, fertilize, and they bounce back and carry on.

You may want to use the alfalfa instead of blood meal though, as an added fert later in the season. Balanced fert is better for the tomatoes, for sure.

[MsCowpea]

If you want to be specific and need .3 pounds of nitrogen per 100 square feet than there is a method for determining a specific amount of fertilizer:
If you use blood meal (13-0-0) you would need 2.30 pounds.
If you use alfalfa (2.5-.5-2.5) you would need 12 pounds ( but would have too much P and K for your situation,as Bower says, though alfalfa has other benefits.)
Hope my math is correct???

Formula: just convert the percentage of N to a decimal and then divide the N recommendation by that decimal.)

https://www.spectrumanalytic.com/suppor ... esults.htm

(You could follow the instructions on the bag as well though that would be for general use. And you could also take into account nutrients your compost may supply to reduce fertilizer input.)

[brownrexx]

Nitrogen is very volatile and most soil test reports recommend adding a standard amount. It is not measured on the soil test.

If you add it at the end of the season, a lot of it will be gone by the next growing season so always add nitrogen at the beginning or during the growing season.

Use the calculation attached by [mention]MsCowpea[/mention] BUT that calculation is for 1000 square feet not 100 square feet so you will need to further divide the answer by 10.

.3 (your N recommendation) divided by .12 (% nitrogen in the blood meal) = 2.5 lbs./1000 sq. ft. so divide by 10 and you will get .25 lbs./100 sq. ft. which is an area 10' x 10'.

I do not use blood meal around my plants because the skunks dig it up so I add a handful of feather meal (12-0-0) that I buy from Amazon to the planting holes when I plant my tomato seedlings. I do not measure it and I do not use it on the rest of the garden.

[bower]

Yes, I should say I took your words literally ".3 lb of high N fert" and did not realize there was a calculation needed to measure the amount of N itself.
brownrexx makes a good point about using ferts in the planting holes vs broadcasting into the ground. I use bone meal in the hole for tomatoes and for garlic as well, and for greens crops I dig ferts like blood/bone meal or chicken pellets into the bottom of the drill for my row. This is also probably a best method for intercropping intensively as you planned to do, where the crops have different fert needs. It is a more efficient use of N ferts to provide it exactly where it's needed, and I've read that this also reduces the amount of N lost to the atmosphere as a greenhouse gas as well as any runoff due to rain. Your rich compost soil would help to retain nutrients as well.
I do sometimes use the broadcast and dig it in method with a fert such as chicken pellets, similar to the NPK for alfalfa meal, when my aim is to raise the overall fertility of the bed, and especially if there is other coarse organic material (kelp meal) which the extra bit of N will help to break down while the plants are growing. I could definitely see broadcasting alfalfa meal as a general amendment, where the N in it will help to break down the organic material it is made of into the soil. With the blood meal being all N, it stands to reason it is more likely to be lossy as a general amendment.

[worth1]

78% of the earths atmosphere is nitrogen.
How you get it in the soil is up to you.
Hot composting organic material such as leaves isn't the way because it uses the nitrogen in the plant to break down the material into compost.
Even composting chicken manure is sort of a waste because your loosing much of the nitrogen.
In my opinion just use less chicken manure like we did growing up.
It's a wonderful way to add nitrogen if used sparingly.

[lee53011]

Worth1, I have no access to chicken manure, but easy access to blood meal. Wish I could get chicken manure!

[lee53011]

When you add it to the hole, do you dig the hole, add blood meal, add about an inch of soil, and then the plant? I'm thinking the roots may burn if placed in contact with the bloodmeal.

[bower]

Lee, when I make a planting hole I dig the hole, add the ferts, dig them in at the bottom and as you say, if any concern about contact with the roots put some soil or compost in between roots and ferts until it grows down into it.

[MsCowpea]

Brownrexx,

Good catch, I thought the formula was only calculating the amount needed of a particular fertilizer to get the recommended amount of N ( or P or K) you need.

You are saying that the amounts would have to be divided by 10 for 100 square feet. 2.3 pounds of blood meal would be .23 pounds (about a quarter of a pound.) 12 pounds of alfalfa would be 1.2 pounds.


There is an online calculator I use for fertilizer exchanges that is much easier to use. No figuring at all— you just plug in the recommendation you got and
then what fertilizer you want to use and for what size area and then it tells you how much to use. I will try and find the link.

[lee53011]

[mention]MsCowpea[/mention] were you able to find that online calculator?

[MsCowpea]

http://aesl.ces.uga.edu/soil/fertcalc/

[stone]

With only bloodmeal and alfalfa pellets to choose from.... I think I'd broadcast these processed products over the top of the soil AFTER planting.

At my house, ALL the garden waste, the plants removed to make room for the more desirable ones (no weeds at my house), blemished fruit, plants covered in bugs... it goes to the chickens... Who eat the bugs, seeds, and keep the rest stirred up until I put the compost back out on the garden.

As I plant in the winter as well as the summer, there's less concern about nutrients leaching away before the plants can take advantage of them.

Up in WI... I think maybe you might be jumping the gun a bit.

Personally, I'd be looking for less processed sources of organics to work with.

Wisconsin is the dairy state... Any cow herds nearby?

[lee53011]

[mention]stone[/mention] Yes, I won't be doing anything in the garden for at least a few months! Other than harvesting from my low tunnel. No cow manure, but horse manure goes into the compost bin to kill off the weed seeds. I add at least 4" of comppost every spring. I was given a 50# bag of both alfalfa meal and blood meal, so I have plenty for many years!

compost bin.jpg

low tunnel 1.jpg

[stone]

No such thing as "weeds" at my house.
When I was able (pre-covid) to get horse poop, I'd top dress the soil (with un-composted horse manure) prior to planting.
At my house in the bottomless sand... I need something (organic) to plant in... that sand is miserable.