Objective Potato Yield Dig Method

Transcription

1 Objective Ptat Yield Dig Methd 5320 Suth 900 East, Suite Salt Lake City, UT June 9, 2011

2 Tp three advantages f cnducting an Objective Ptat Yield Dig 1. Alert sales staff t expected yields and prfile 2. Measure and track the difference between harvested yield and packed-ut yield 3. Cmpare yur farm s prfile and yield t thse f reginal and natinal cmpetitrs Equipment yu will need 1. Shvel ft measuring tape 3. Sizing ring 4. Scales (t be used indrs, nt in the field) 5. Clipbard and pen r pencil 6. Phtcpies f the wrksheet n page 7 f this dcument 7. Phtcpies f the Sample Tagging frms n page 9 f this dcument 8. Tw flagged stakes 9. Calculatr 10. Sample bags 11. Large bucket r sack t carry samples United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 1

3 Hw t cnduct an bjective ptat yield and prfile field dig This methd estimates yield at crp s end. It is nt t be dne mre than tw days prir t vine kill. Pst vine kill is preferred. This methd mdifies the Natinal Agricultural Statistics Service methd by simplifying it while maintaining reasnable accuracy. A pr stand makes this methd undependable. Three plants will be sampled at six precise lcatins acrss the field. See the drawing belw. Mre samples give better results. Samples encmpassing a greater prtin f the field give best results. In this mdel, 18 ptat hills are sampled in each field. Keys t the success f gathering statistical data are: 1) The bjectivity f the gathering system, and, 2) The number f samples gathered and measured. A C D B 30 paces C B A The figure abve represents a field that is circular, irregular, rectangular r square. Line AA represents the directin f the rws. Pint D is the starting pint within the field. Pint B is the starting pint fr all measurements and is at least 20 paces int the field frm pint D. Line BB represents acrss sufficient rws t best sample a field. Line CC represents 10 feet with rw directin. Pints O represent lcatins f sample digs. United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 2

4 Step 1 Measuring and nting rw width Miguel Mariscl, King Pak Ranch Freman, Edisn, Califrnia, cnducts a yield dig May 4, 2011 sn after vine kill. Turn t page 7 t find ut hw accurate Miguel s yield dig was. If rw width is knwn, it is nted n Line A f the Wrk Sheet n page 8 in feet, nt inches. If rw width is nt knwn, then, frm beginning pint D, the sampler walks at least 20 paces int the field and places a stake in the center f a rw which becmes pint B. The sampler then walks frm pint B acrss 10 rws and places anther stake in the center f the 10th rw which becmes pint B, line B-B n the drawing. The sampler measures the distance acrss 10 rws in feet and tenths f feet t determine rw width in feet, nt inches. The measurement is taken frm centerline f plants t centerline f plants. Example: If 10 rws measure 30 feet acrss, individual rw width is 3 feet acrss. If ten rws measure 28.3 feet acrss individual rw width is 2.83 feet acrss (34 inch rws). Hint: 36 inch rws are three feet acrss, 34 inch rws are 2.83 feet acrss and 32 inch rws are 2.67 feet acrss. Nte this measurement n Line A f the wrk sheet which is prvided n page 8 f this dcument. Rw width is measured nly nce. On the wrk sheet, divide ft² in an acre by rw width in feet and nte n Line B. This measurement gives the lineal feet f ptat rw in ne acre. Nte: Metal beef skewers wrk well as stakes by allwing the measuring tape t be fixed t a stake placed in the middle f the tp f the rw. An attached red ribbn makes the stake highly visible. Pinted metal stakes als penetrate sil easily and are reusable. United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 3

5 Step 2 Calculating the number f plants per ft f rw After walking acrss 10 rws frm the beginning pint and placing a stake in the center f the 10th rw, the sampler turns and measures 10 feet with the rw and places a secnd stake, line C C in the drawing. If the 10th ft stake lands directly upn a hill, that hill becmes ne half f a hill. The sampler then cunts the number f hills between the stakes and ntes this number in Bx C as Sample 1. Example: If the sampler cunts 10 hills, then there is ne hill every ft, and the number fr Sample l in bx C is 1 (ne hill/ft). If the sampler cunts 13.5 hills in ten feet in Sample 2, and the hill cunt is divided by ten feet (13.5 / 10 = 1.35 (1.35 plants/ft), then 1.35 is marked fr Sample 2 in bx C. The same prcess is repeated three times per field. Three such samples are nted in Bx C, and the average is calculated and nted n Line C f the wrk sheet. An imprtant rw cunting nte: In selecting the number f rws between 10 ft samples, the size and shape f the field must be taken int accunt. Fr example: In a center pivt, the utside tw twers traditinally express lwer yields than inner twers, and all twers must be cnsidered. A suggestin wuld be t begin the sample inside f utside twer span, then crss sufficient rws t sample at least 5 mre twers. Rws are always crssed at right angles as per the drawing n page 3. In sampling any field, sufficient rws shuld be crssed such that the entire field is sampled. If the field is estimated t have 300 rws, then crssing 40 rws t select the 10 ft sample area wuld be clse t representative. If a field r blck is estimated t have 100 rws, then crssing rws per sample wuld be representative. The sampler walks as nearly as pssible at a right angle t the rws when arriving at the determined rw and always places the stake in the first space between plants t the left f the spt where the ft falls, then measures 10 feet. United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 4

6 Step 3 Sampling The sampler digs three hills within each 10 ft area between the stakes, always digging hills #6, #7, and #8. The sampler must assure that all f the prductin and nly the prductin f each hill is placed int a mesh bag, all three hills int ne bag. Mesh wrks best because it allws adhering dirt t fall frm the sample making net ptat weight mre accurate. Even thugh mesh bags are used, since adhering dirt alters ptat weight, each ptat must be brushed hand wiping with glves suffices prir t being placed in the bag. The prductin f all three samples is placed in the same bag and labeled as Sample #1, including field (name r number), and variety (name r number). Sample Tagging Frms are n page 10. Nte: When weight varies significantly between samples, stand cunt r seed space accuracy cme int questin and this sample methd decreases in accuracy. See the Sample Tagging Frm n page 10 f this dcument that is t be placed in each sample bag. Shuld the ptates be cut r injured in the digging prcess, all pieces must be accunted fr and included in the sample. Cautin must assure that ptates frm plants that neighbr hills #6 and #8 d nt enter the sample bag. A sizing ring will identify sizes that will fall thrugh digger chains, and thse ptates will nt be included in the sample. United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 5

7 Step 4 Weighing Each sample within each field is weighed and the weights nted n Line E n the Wrk Sheet. Since the ttal f weighed samples fr a field includes 18 plants, yu must divide the ttal weight f the six samples by 18 t get the average weight f ne hill. The average weight fr ne hill times the ttal number f plants in ne acre equals the yield fr an average acre in the sampled field. Enter n Line F. Weighing shuld be dne the same day the sample is dug t minimize dehydratin lss in green samples. It is best t weigh in a lab, shp, garage r hme, nt in the field. Step 5 Prfiling See Page 9 fr mre infrmatin In prfiling a field, all russet samples must be weighed individually and separated by weight int size. The number and sizes f ptates in the 18 plants cllected cnstitute a viable size prfile fr the particular field. A 50 pund cartn f ptates cntains 800 unces f ptates and ptates are sld accrding t cunt (the cunted number f ptates within a cartn). In rund varieties, A s, B s and C s are sampled accrding t U.S. Department f Agriculture grade standards. Divide the ttal weight f the six samples by 18 t get the average weight f ne plant. Result: In the King Pak Ranch yield dig n May 4, 2011, the dig predicted a 301 hundredweight per acre yield. When harvested, the actual yield was 304 hundredweight per acre! United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 6

8 Wrk Sheet Frmula fr calculating a yield estimate Line A: rw width feet. Line A fr 32 rws 2.83 fr 34 rws Line B: divide (square feet in an acre) by line A 3.0 fr 36 rws equals ne acre f ptates in lineal feet / line A = lineal feet f ptates in ne Line B. 16,315 fr 32 acre at the Line A rw width. 15,392 ft. fr 34 14,520 ft fr 36 Line C: The number f hills per ft f rw is calculated by averaging their spacing measurements accrding t Step Tw, three times per field. Bx C Sample 1 Sample 2 Sample 3 Ttal / 3 Line D: The ttal number f hills/acre equals the lineal feet in an acre (Line B) multiplied by the number f hills/ft (Line C). Line B x Line C = Ttal number f plants per acre Line E: The average weight f ne hill, Line E Bx Ttal Weight Sample #1 Ttal Weight Sample #2 #3 #4 #5 #6 Ttal weight all samples / 18 Line C Line D Line E Line F: The average weight fr ne hill times the ttal number f hills per acre is equals the yield fr that acre. (Line D x Line E = yield /acre in ttal punds.) Line G: Ttal punds per acre divided by 100 equals cwt per acre. (Line E / 100 = cwt / acre) Line F Line G United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 7

9 Mre Abut Prfiling When prfiling a field, all sampled ptates must be weighed individually and separated by weight int size. The number and sizes f ptates in the 18 hills cllected cnstitute a viable size prfile fr the particular field. A 50 pund cartn f ptates cntains 800 unces f ptates and ptates are sld accrding t cunt (the cunted number f ptates within a cartn). The fllwing chart gives the exact weight fr ptates within a cunt. In actual practice, ptat weights may range frm 1 t 4 unces. within a cunt range. Size prfiling may be adjusted t prvide data specific t need such as percentage f 5 t 9 unces. cnsumer packs, percentages f B s, C s, etc. Prfile infrmatin fr a current year becmes increasingly valuable as several years f infrmatin accumulate fr cmparisn. Prfile Infrmatin Frm Field Number: Strage: Prfile parameters Number Percent cunt: 20 zs, 18 t 22 zs cunt: 16 zs, 14 t 18 zs cunt: 13.3 zs, 12 t 16 zs cunt: 11.4 zs, 11 t 13 zs cunt: 10 zs, 10 t 12 zs cunt: 8.9 zs, 9 t 11 zs cunt: 8 zs, 7 t 9 zs 8. % less than 7 zs 9. % 5 t 9 zs 10. % less than 5 zs 11. % chefs, greater than 31/4 12. % A s 1 7/8 t 3 1/4 13. % B s 1 ½ t 2 ¼ 14. % C s ¾ t 1 5/8 11. % less than 2 r min. dia. used United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 8

10 Cut ut these sample tagging frms, fill ut and place a frm in each sample bag. Sample Tagging Frm Sample Tagging Frm Sample Tagging Frm Sample Tagging Frm Sample Tagging Frm Sample Tagging Frm United Ptat Grwers f America Ptat Objective Yield Dig Methd Page 9