Soil test analysis questions.

[Dennis Griffith]

Will do.

 

[Masbustelo]

I'm starting to think that the soil tests for grapes aren't very helpful, because we don't know how deep the roots are or to where they have wandered. I'm going to try petiole testing next year.

 

[Dennis Griffith]

I only test the soil prior to planting, so that I can amend the soil properly. And you are right, once they are growing, it's best to test the plants. I'd wait until at least the second year until after the vine has become established. I have found a lab that prefers leaves over petioles for testing, so check with the lab you are using prior to harvesting test material.

 

[Dennis Griffith]

BTW, here is the lab nearest me that had an agronomist on staff with experience in viticulture. They prefer leaf testing over petioles. He has some interesting insights on soil. Their prices are extremely reasonable.

http://www.spectrumanalytic.com/

 

[RonObvious]

I was very happy with Double A's soil test service. It was pretty cheap and they got back to me with recommendations specific to grapes. I'm in a similar situation as you, masbustelo - low K, Petite Pearl and other hybrids. In my case though, the Mg was also low. The soil doctor at Double A also pointed out the importance of watching the Cation Exchange Capacity (CEC) because Mg and K (and other ions) can all compete for sites on soil particles. Since my CEC is low too, he said to not overdo it with the lime because that could make it harder to correct the potassium. Actually, that brings up another thought - you say you added lime, but do you know if it was calcitic or dolomitic? Dolomite contains Mg, whereas calcite does not (at least not in any significant amount).

 

[Dennis Griffith]

I always use pelletized dolomitic lime. It has a slower release time and I add it in the late winter time frame.