Normal Distribution. 10/7/09 We harvested 3.06 tons from block K5 this morning. The grapes arrived at the winery at 12:30pm. The forecast was 3.2 tons (3.6 tons with 11% dehydration). This corresponds to an average yield of 2.24 ton/acre for this 1.4 acre block. This block is not representative of the rest of the vineyard because about half of the fruit in this block comes from 2/3 the acreage of this block which was budded over from Malbec to Cab only 3 years ago.
10/3/09 Konrad and Holler picked 1155 lbs. from rows 27-29 above the lower berm with Jeff Fonatanella's approval to make a barrel of wine for Dr. Konrad. 168 vines were harvested in these three rows which means these vines yielded on average 6.9 lbs/vine or 3.1 tons/acre.
10/1/09 Block K1 was harvested this morning. The block is .98 acres and yielded 2.13 tons. My prediction was 2.3 tons before the heatwave and 10% less after the heatwave, which would be 2.1 tons. Can't do any better than that. This block is .98 acres which means the yield per acre was 2.1ton/acre. The pre heatwave forecast is at the bottom of this page.
9/16/09 yield estimation by bunch counting and bunch weighing.Block K6
| Row | Vine | Bunch count |
Bunch wt. | Vine Wt. |
| 15 | 6 | 38 | ||
| 15 | 38 | |||
| 30 | 35 | |||
| 8 | 42 | 27 | ||
| 28 | 31 | |||
| 12 | 34 | |||
| 20 | 6 | 14 | ||
| 7 | 28 | |||
| 20 | 41 | |||
| 30 | 32 | |||
| Average | 31.8 | 4.1oz. | 8.3 lbs. | |
| Stddev | 7.6 | 1.4oz | 3.4 lbs. |
Nominal K6 Yield = 32 bunches x 4.1/16 lb/bunch= 8.3 lbs/vine x 900 vines/acre = 7470 lbs/acre/2000lbs/ton = 3.7 tons/acre x 1.2acres = 4.5tons total
50% confidence interval per vine yield = 8.3 lbs/vine +/- 2.4 lbs (5.9-10.7 lbs/vine) using Student's t distribution with 10 degrees of freedom. RMS sigma
50% confidence interval per acre yield = 3.7 tons/acre +/- 1.1 tons/acre (2.6-4.8 tons/acre)
50% confidence interval total yield = 4.5 tons +- 1.3 tons (3.2-5.8 tons total)
Block K5
| Row/Block | vine | bunch count | bunch weight | vine weight |
| 3 (K5U) | 6 | 34 | ||
| 33 | 51 | |||
| 51 | 33 | |||
| Avg. | 39 | 4.1* oz. . | 10 lbs. | |
| stddev. | 10 | 1.4 oz. | 3.4 lbs. | |
| 24 (K5L) | 13 | 30 | ||
| Budded over from Malbec 2005 | 25 | 24 | ||
| 38 | 7 | |||
| 51 | 20 | |||
| 64 | 0 | |||
| 71 | 15 | |||
| Average. | 16 | 4.1* | 4.1 lbs. | |
| Stddev. | 11 | 1.4 | 3.1 lbs. |
*No bunch weights for this block, using K6 data.
Nominal Yield K5U = 39 bunches x 4.1/16 lb/bunch= 10 lbs/vine x 900 vines/acre = 9000 lbs/acre/2000lbs/ton = 4.5 tons/acre x .4acres = 1.8 tons total
Nominal Yield K5L = 16 bunches x 4.1/16 lb/bunch= 4.1 lbs/vine x 900 vines/acre = 3690 lbs/acre/2000lbs/ton = 1.8 tons/acre x 1.0acres = 1.8 tons total
Nominal K5 total = 3.6 tons
50% confidence interval = 3.6 tons +/- 1.1 tons (2.5-4.7 tons)
Nominal K5+K6 = 8.1 tons
50% confidnce interval assuming 10 degrees of freedom = 8.1 tons +/- 1.6 tons (6.5-9.7 tons)
| Row | vine | count |
|---|---|---|
| 11 | 20 | 36 |
| 40 | 17 | |
| 60 | 22 | |
| 80 | 37 | |
| 101 | 21 | |
| ave. | 27 | |
| stddev. | 9 |
using a weighted average bunch weight from block K3 samples.75x4.2 +.25x3.4=3.9oz.
Nominal K4U Yield = 27 bunches x 3.9/16 lb/bunch= 6.6 lbs/vine x 900 vines/acre = 5923 lbs/acre/2000lbs/ton = 2.9 tons/acre x .7acres = 2.1 tons total
Nominal K4L Yield = 27 bunches x 3.9/16 lb/bunch= 6.6 lbs/vine x 900 vines/acre = 5923 lbs/acre/2000lbs/ton = 2.9 tons/acre x .67 acres = 1.9 tons total
50% confidence interval per vine yield = 6.6 lbs/vine +/- 2.5 lbs(38%) (4.1-9.5 lbs/vine) using Student's t distribution with 6 degrees of freedom. RMS stddev.
50% confidence interval K4U total yield = 2.1 tons +/- .8 tons (1.3-2.9 tons total)
50% confidence interval K4L total yield = 1.9 tons +/- .7 tons (1.2-2.6 tons total)
| Row | vine | count | lbs/vine | avg. bunch wt. |
|---|---|---|---|---|
| 23 | 75 | 40 | ||
| 56 | 25 | |||
| 37 | 36 | |||
| 16 | 49 | |||
| 24 | 18 | 17 | 3.6 lbs. | 3.4oz. |
| 45 | 37 | 9.5 lbs. | 4.2oz. | |
| Avg. | 34 | 3.9 oz.* | ||
| Stddev. | 11 |
K3U bunch weights measured on row 24, 18 vines down from top, above the upper berm. 17 bunches, average bunch weight, 3.4 oz. stddev. 1.2 oz. total weight on vine, 3.6 lbs. This is a relatively weak vine relative to a typical vine for the whole vineyard but was representative of ~20 vines in this upper portion of K3.
K3U bunch weights measured on row 24 , approximately 45 vines down from the top between the two berms; 37 bunches, average weight, 4.2 oz. , stddev 1.8 oz. , total weight on vine 9.5 lbs.
*using a weighted average bunch weight .75x4.2 +.25x3.4=3.9oz.
Nominal K3U Yield = 34 bunches x 3.9/16 lb/bunch= 8.3 lbs/vine x 900 vines/acre = 7470 lbs/acre/2000lbs/ton = 3.7 tons/acre x .92acres = 3.4 tons total
Nominal K3L Yield = 34 bunches x 3.9/16 lb/bunch= 8.3 lbs/vine x 900 vines/acre = 7470 lbs/acre/2000lbs/ton = 3.7 tons/acre x .54 acres = 2.0 tons total
50% confidence interval per vine yield = 8.3 lbs/vine +/- 3.1 lbs (5.2-11.4 lbs/vine) using Student's t distribution with 6 degrees of freedom. RMS sigma
50% confidence interval K3U total yield = 3.4 tons +- 1.3 tons (2.1-4.7 tons total)
50% confidence interval K3L total yield = 2.0 tons +- 1.3 tons (1.3-2.7 tons total)
| Row | vine | count |
|---|---|---|
| 35 | 17 | 15 |
| 8 | 46 | |
| 34 | 12 | |
| 51 | 38 | |
| 68 | 35 | |
| Ave. | 29 | |
| Stddev. | 15 |
No bunch weights taken, using K3 bunch wts. 3.9 oz. std dev. 1.6oz.
Nominal K2U Yield = 29 bunches x 3.9/16 lb/bunch= 7 lbs/vine x 900 vines/acre = 6300 lbs/acre/2000lbs/ton = 3.1 tons/acre x .56 acres = 1.7 tons total
Nominal K2L Yield = 29 bunches x 3.9/16 lb/bunch= 7 lbs/vine x 900 vines/acre = 6300 lbs/acre/2000lbs/ton = 3.1 tons/acre x .47 acres = 1.5 tons total
50% confidence interval per vine yield = 7 lbs/vine +/- 3.2 lbs(45%) (3.8-10.2 lbs/vine) using Student's t distribution with 5 degrees of freedom. RMS sigma
50% confidence interval K2U total yield = 1.7 tons +- .7 tons (1-2.4 tons total)
50% confidence interval K2L total yield = 1.5 tons +- .7 tons (.8-2.2 tons total)
| Row | vine | count |
|---|---|---|
| 10 | 5 | 30 |
| 20 | 29 | |
| 35 | 22 | |
| 50 | 18 | |
| 65 | 34 | |
| Ave. | 27 | |
| Stddev. | 6.4 |
No bunch weights taken, using K3 bunch wts. 3.9 oz. std dev. 1.6oz.
2 weak areas in this block under oak and along west edge ~200 vines no fruit. 886-200=686 vines or .98 acre*686/886=.76 acres
Nominal K1 Yield = 27 bunches x 3.9/16 lb/bunch= 6.6 lbs/vine x 900 vines/acre = 5923 lbs/acre/2000lbs/ton = 3.0 tons/acre x .76 acres = 2.3 tons total
50% confidence interval per vine yield = 6.6 lbs/vine +/- 2.2 lbs (33%)(4.4-8.8 lbs/vine) using Student's t distribution with 5 degrees of freedom. RMS sigma
50% confidence interval K1 total yield = 2.3 tons +/- .7 tons (1.4-3 tons total)
| Block | |
|---|---|
| K1 | 27 |
| K2 | 29 |
| K3 | 37, 18, 45 |
| K4 | 27 |
| K5 | 24 |
| K6 | 32, 35 |
| Avg. | 29 |
| Std. Dev. | 6.6 (22%) |
| Block | Row | vine | #bunches | Ave Bunch Wt. | Std. Dev. | Total Wt. on Vine |
|---|---|---|---|---|---|---|
| K6 | 15 | 20 | 35 | 4.1 oz. | 1.4 oz. | 7.7 lbs. |
| K3U | 24 | 18 | 17 | 3.3 | 1.2 | 3.6 |
| K3mid | 24 | 45 | 37 | 4.2 | 1.9 | 9.5 |
| ave. | 3.8 | 6.9 | ||||
| std. Dev. | 3.0 (43%) |
Ave. Bunch count 29 x Avg. bunch weight 3.8 oz. = 6.8 lbs/vine. which agrees very closely with the average total weight/vine (6.9 lbs.) measured on the three vines that were fully stripped and weighed.
Using these average bunch counts and bunch weights the nominal total yield of the vineyard can be estimated.
900 vines/acre x 6.8 lbs/vine = 3.0 tons/acre.
3.0 tons/acre time 7.6 acres = 23.2 tons
A more meaningful pair of numbers is the confidence interval for the estimated tonnage which depends on the variance of the data used to estimate it. The variance of the total weight per vine is what we are most interested in. The bunch counts have much less variation than the bunch weights because we control the bunch counts with our pruning. Most of the variation comes from the bunch weights(40%) not the bunch counts(22%). Using a std. deviation of 40% which is what we observed for the bunch weights as well as the total vine weights we can make estimates of the confidence interval.
Normal Distribution.
Assuming the yield is normally distributed across the vineyard we can say that the true yield per acre is within one standard deviation of the average with 68% confidence which is equivalent to saying that the yield will be 3.0 tons/acre +/- 1.2 tons/acre and being right about it 68% of the time, approximately twice in 3 years.
68% confidence interval 1.8 tons/acre - 4.2 tons/acre --------In this case we would be wrong once in 3 years.
95% confidence interval .6 tons/acre - 5.4 tons/acre --------- In this case we would be wrong only once in 20 years but this estimate isn't useful. We know this without doing any sampling.
Best estimates of yield as of 9/18/09 by blocks.
| Area | vines | acres | Nominal Yield (tons) | Nominal Yield/acre | 50% confidence Yield Range Min--Max |
|---|---|---|---|---|---|
| K1 | 886 | .98 | 2.3 | 2.3 | 1.4-3 tons |
| K2U,K3U,K4U | 1965 | 2.18 | 7.2 | 3.3 | 2.3-12.1 tons |
| K2L | 420 | .47 | 1.5 | 3.2 | .8-2.2 tons |
| K3L, K4L | 1092 | 1.21 | 3.9 | 3.1 | 1.9-5.9 tons |
| K5,K6 | 2370 | 2.63 | 8.1 | 3.2 | 3.2-13 tons |
| Whole Vineyard | 6853 | 7.6 | 23 | 3.0 | 4.2-50 tons |
The 50% confidence intervals seem unreasonably large. I suspect I am missing something.
Bottom line at this point is that the yield is high but not outrageously high. 3.0 tons/acre is our best overall estimate at this time with only 68% confidence that the true mean will be between 1.8 and 4.2 tons/acre. Camalie Vineyards equivalent estimate is 4.2 tons/acre. The bunch weights are the main difference and the source of the largest variation. It is more important to sample bunch weights than bunch counts to make a good estimate.
Camalie Vineyards Yield Data for reference.
Data acquired and analyzed by M.Holler Camalie Networks
Last Updated 9/23/09 M.Holler