NPK and pH soil analysis

Thursday, January 25, 2007

Today was a lab day up at the train station. Cliff had finished taking cores from the rest of the vineyard. I started analyzing the soil samples for Potassium, Nitrogen, Phosphorous and pH. I got through seven of our 19 samples, each of which I randomly picked out of our bucket. It was tedious work. I used a splitter device to divide up the sample into halves until I had a tablespoon or so of sample (split about 5 times), which I then weighed out on a calibrated scale: 10g for pH testing, 1.5g for Phosphorous testing, 1g for Nitrogen testing, and 2g for Potassium testing. To test the sample for pH, I used a pH probe, which I standardized using standard solutions of pH 7 and 4.01. I then took my 10g sample of the soil and mixed it with 10mL of DI water in a beaker, swirled it and let it sit for around 10 minutes before testing it with the probe. The pH seemed to hover around 6.5-7. I used a test kit to test for P, N and K, which involved various indicator solutions, powders, and pills and mixing them in test tubes, ect. I found only trace amounts of P and N. The K levels were very high. While these results varied slightly with the different samples, they remained very similar across the board. It will be interesting to see if the rest of the samples continue this trend. I will probably continue/finish testing next Thursday. I also was going to use another test kit to analyze the samples for magnesium and calcium as well, perhaps at a later date…