Agronomy
How much lime do I need?
New farmer here. So after a really bad corn harvest I decided it was time for some soil samples. Unfortunately the coop I use is real crap and the attached photo is what I got for a report. It was only after I waited 6 weeks did they tell me the lab they use no longer gives recommendations for rates anymore. I’m pretty lost as to how to get how much lime I need to spread off of this information, even googling how to calculate it gives me few results with the information I’ve been given. Thanks for looking.
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One other item to keep in mind is that Lime typically takes three years to fully break down and be seen in new soil samples. You could expect to see 1/3rd of the applied lime benefits each year for three years. Don't be tricked by resampling in one year after the application and thinking you need to apply a large amount immediately again.
Good luck
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Im not an expert, but we put TONS of lime on all of our farms. We grid sample 2.5 acres, and apply variable rate. When we first started a lot of our acres were requiring 4 tons an acre. That was over 10 years ago. There is a lot of variation throughout the field. The spots on the farms near gravel roads are often 6.7 or above so they don't require lime because the dust from the road carries over. ...
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I'm new to farming as well. I wanted to get a good idea of my land as it was coming out of CRP for the first time in 40 years. I had a company come in and do a 2.5 ac grid on my 80 acres. 32 samples at 12.50 an acre so it cost me $1000.00 but I know CEC, organic mater, P, K, Mg, Ca, Na, soil ph, S, Zn, Mn, Fe, Cu, B, and soluble salts from 32 spots across the 80 acres. I will get recommendations ...
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It’s the best way to assure your fertility dollars are being well spent. Especially with the phosphate market in shambles.
2-3 tons an acre
Would like to see the buffer PH to determine the amount of reserve acidity in the soil structure.
Our grid samples around here are 2.5 acres, and manure management requires one every 10 acres so there wouldnt be any advantage over what you did then.
I had a field a couple years ago with similar Ph numbers. My cec numbers were 12.7 to 23. Some of the ground with 4.7-4.9 ph was calling for 4-5K lbs/acre of lime. My agronomist and another area farmer told me that much would be a waste of money. It was grid sampled so I half rated the variable rate. Two years later I wanted to plant some of the worst ph areas to alfalfa so I retested. The p...
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These are small fields, 3 acres for one and two and 7 acres for the third. If I can’t get the expected yield out of 13 acres I might as well not go any bigger.
The lime index( buffer pH) tells you how much lime to apply. Without knowing what lab ran the tests it’s hard to give an accurate recommendation. I would encourage you to simply call the lab yourself and ask a staff member. Another option would be to take another sample and send to a lab that can give a more detailed report.
Is each sample from a different field? When were the samples taken? What method did you use to determine where to pull samples? (Grid, zone, composite?). Lots of variability for only 3 samples, the higher CEC soil will need the 3 tons incorporated and the other two will take much less because of the lower cec and higher starting ph.
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Each sample is a different field, samples were taken on Nov 6, 2020, I pulled a plug out every 60’ to a depth of 6-8”, put all plugs into a bucket and then mixed the sample(per field). I’m not sure what method that would be called.
I would probably go with 3 ton per acre. From my experience 3 always spreads the best and it would not put you above 6.8-7.
I would personally put out no less than 2 tons per acre and incorporate it. Where the ph is 4.5 I would bump it up to 2.5 or 3 and resample in the fall of 21.
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