in-crop-weather State Indiana Crop Weather Week Ending Date August 22, 2005 Issue IN-CW3405 Agricultural Summary While many parts of the state received sufficient rainfall this past week, there are still areas that are dry, according to the Indiana Field Office of USDA's National Agricultural Statistics Service. While the rain will help the soybean pods fill, many reporters feel it came too late to help a major part of the corn crop. There is expectation that corn yields will be affected. Field Crops Report There were 5.1 days suitable for fieldwork. Corn condition is rated 41 percent good to excellent compared with 79 percent last year at this time. Eighty-seven percent of the corn acreage has reached the dough stage compared with 88 percent last year and 80 percent for the average. By area, corn in dough is 85 percent complete in the north, 86 percent complete in the central region and 93 percent complete in the south. Forty- three percent of the corn acreage has reached the dent stage compared with 49 percent last year and 38 percent for the average. Ninety-six percent of the soybean acreage is setting pods compared with 94 percent last year and 87 percent for the average. Soybean condition is rated 52 percent good to excellent compared with 73 percent last year. Third cutting of alfalfa hay is 67 percent complete compared with 62 percent last year and 63 percent for the average. Major activities during the week included spraying for aphids and spider mites, attending the state fair, baling hay, cleaning grain bins, hauling grain to market, mowing, working on harvest equipment, and attending outlook meetings and field days. Livestock, Pasture and Range Report Pasture condition is rated 1 percent excellent, 17 percent good, 38 percent fair, 29 percent poor and 15 percent very poor. Livestock are in mostly good condition. Feeding of hay continued on some livestock farms. Crop Progress Table ----------------------------------------------------- : This : Last : Last : 5-Year Crop : Week : Week : Year : Avg ----------------------------------------------------- Percent Corn in Dough 87 76 88 80 Corn in Dent 43 22 49 38 Corn Mature 2 NA 6 3 Soybeans Podding 96 90 94 87 Alfalfa Third Cutting 67 50 62 63 Crop Condition Table ---------------------------------------------------------- : Very : : : : Excel- Crop : Poor : Poor : Fair : Good : lent ---------------------------------------------------------- Percent Corn 6 17 36 36 5 Soybeans 4 12 32 45 7 Pasture 15 29 38 17 1 Soil Moisture & Days Suitable for Fieldwork Table -------------------------------------- : This : Last : Last : : Week : Week : Year : -------------------------------------- Percent Topsoil Very Short 12 20 3 Short 30 33 19 Adequate 56 46 71 Surplus 2 1 7 Subsoil Very Short 19 23 3 Short 39 38 19 Adequate 42 39 75 Surplus 0 0 3 Days Suitable 5.1 5.7 5.0 Contact information --Greg Preston, Director --Jamie Price, Agricultural Statistician E-Mail Address: nass-in@nass.usda.gov http://www.nass.usda.gov/in/index.htm --------------------------------------------------------------------------- Other Agricultural Comments And News ESTIMATING CORN GRAIN YIELD PRIOR TO HARVEST Fancy colored yield maps are fine for verifying grain yields at the end of the harvest season, but bragging rights for the highest corn yields are established earlier than that down at the Main Street Cafe, on the corner of 5th and Earl. Corn in IndianaSome patrons of the cafe begin "eyeballing" their yields as soon as their crops reach "roasting ear" stage. Some of the guys there are pretty good (or just plain lucky) at estimating yields prior to harvest, while the estimates by others are not even close to being within the proverbial ballpark. Interestingly, they all use the same procedure referred to as the Yield Component Method. Other pre-harvest yield prediction methods exist (Lauer, 2002; Thomison, 2005), but the Yield Component Method is probably the most popular because it can be used well ahead of harvest; as early as the so-called "roasting ear" or milk (R3) stage of kernel development. Under "normal" conditions, the kernel milk stage occurs about 18 to 22 days after pollination is complete (Nielsen, 2004a). Estimates made earlier in the kernel development period risk being overly optimistic if subsequent severe stresses cause unforeseen kernel abortion (Nielsen, 2004b). The Yield Component Method was originally described by the University of Illinois many years ago (Univ. of Illinois, 2005) and is based on the premise that one can estimate grain yield from estimates of the yield components that constitute grain yield. These yield components include number of ears per acre, number of kernel rows per ear, number of kernels per row, and weight per kernel. The first three yield components (ear number, kernel rows, kernels/row) are easily measured in the field. Final weight per kernel obviously cannot be measured until the grain is mature (kernel black layer) and, realistically, at harvest moisture. Consequently, an average value for kernel weight, expressed as 90,000 kernels per 56 lb bushel, is used as a proverbial "fudge factor" in the yield estimation equation. Crop uniformity greatly influences the accuracy of any yield estimation technique. The less uniform the field, the greater the number of samples that should be taken to estimate yield for the field. There is a fine line between fairly sampling disparate areas of the field and sampling randomly within a field so as not to unfairly bias the yield estimates up or down. 1. At each estimation site, measure off a length of row equal to 1/1000th acre. For 30-inch (2.5 feet) rows, this equals 17.4 feet. TIP: For other row spacings, divide 43,560 by the row spacing (in feet) and then divide that result by 1000 (e.g., [43,560/2.5] /1000 = 17.4 ft). 2. Count and record the number of ears on the plants in the 1/1000th acre of row that you deem to be harvestable. TIP: Do not count dropped ears or those on severely lodged plants unless you are confident that the combine header will be able to retrieve them. 3. For every fifth ear in the sample row, record the number of complete kernel rows per ear and average number of kernels per row. Then multiply each ear's row number by its number of kernels per row to calculate the total number of kernels for each ear. TIPS: Do not sample nubbins or obviously odd ears, unless they fairly represent the sample area. If row number changes from butt to tip (e.g., pinched ears due to stress), estimate an average row number for the ear. Don't count the extreme butt or tip kernels, but rather begin and end where you perceive there are complete "rings" of kernels around the cob. Do not count aborted kernels. If kernel numbers are uneven among the rows of an ear, estimate an average value for kernel number per row. 4. Calculate the average number of kernels per ear by summing the values for all the sampled ears and dividing by the number of ears. EXAMPLE: For five sample ears with 480, 500, 450, 600, and 525 kernels per ear, the average number of kernels per ear would be (480 + 500 + 450 + 600 + 525) divided by 5 = 511. 5. Estimate the yield for each site by multiplying the ear number by the average number of kernels per ear, then dividing that result by 90. The value of '90' represents the average number of kernels (90,000) in a bushel of corn. TIP: Use a lower value (e.g., 80) if grain fill conditions have been excellent (larger kernels, fewer per bushel) or a larger value (e.g., 100) if grain fill conditions have been stressful (smaller kernels, more per bushel). EXAMPLE Let's say you counted 30 harvestable ears at the first sampling site. Let's also assume that the average number of kernels per ear, based on sampling every 5th ear in the sampling row, was 511. The estimated yield for that site would (30 x 511) divided by 90, which equals 170 bu./ac. Repeat the procedure throughout field as many times as you deem to be representative. Calculate the average yield for all the sites to estimate the yield for the field. Remember that this method for estimating pre-harvest grain yield in corn indeed provides only an estimate. Since kernel size and weight will vary depending on hybrid and environment, this yield estimator should only be used to determine "ballpark" grain yields. Yield will be overestimated in a year with poor grain fill conditions (e.g., low kernel size and weight from a drought year) and underestimated in a year with excellent grain fill conditions (e.g., larger kernel size and weight from non-stress grain fill periods). You can try to improve the yield estimation for unusual grain fill conditions by adjusting the estimation formula. For example, if you believe that kernel weight will be lower due to stress during grain fill, you may elect to replace the value of "90" in the equation with "100" to reflect the potential for smaller and lighter kernels (i.e., more kernels per 56 lb. bushel). Conversely, in a good crop year, you may elect to replace the value of "90" in the equation with "80" to reflect the potential for larger and heavier kernels (i.e., fewer kernels per 56 lb. bushel). Recognize that the Yield Component Method for estimating corn grain yield is probably only accurate within plus or minus 30 bushels of the actual yield. Obviously, the more samples you measure within a field, the more accurately you will "capture" the variability of yield throughout the field. Use the yield estimates obtained by this method for general planning purposes only. RELATED REFERENCES Lauer, Joe. 2002. Methods for Calculating Corn Yield. Agronomy Advice, Univ. of Wisconsin-Madison. Online at . [URL verified 8/9/05]. Nielsen, R.L. (Bob). 2004a. Grain Fill Stages in Corn. Corny News Network, Purdue Univ. Online at . [URL verified 8/9/05]. Nielsen, R.L. (Bob). 2004b. Yield Loss Potential During Grain Fill. Corny News Network, Purdue Univ. Online at . [URL verified 8/9/05]. Nielsen, R.L. (Bob). 2005. Kernel Set Scuttlebutt. Corny News Network, Purdue Univ. Online at . [URL verified 8/9/05]. Thomison, Peter. 2005. Estimating Yield Losses in Drought Damaged Corn Fields. C.O.R.N. Newsletter, Ohio State Univ. Online at [URL verified 8/9/05]. Univ. of Illinois. 2005. Estimating Corn Yields. (An Online Calculator). Illinois Agronomy Handbook. Online at . [URL verified 8/9/05]. For other Corny News Network articles, browse through the CNN Archives at . For other information about corn, take a look at the Corn Growers' Guidebook at . Bob Nielsen, Department of Agronomy, Purdue University, West Lafayette, IN. The INDIANA CROP & WEATHER REPORT (USPS 675-770), (ISSN 0442-817X) is issued weekly April through November by the USDA, NASS, Indiana Field Office, 1435 Win Hentschel Blvd, Suite B105, West Lafayette IN 47906-4145. Second Class postage paid at Lafayette IN. For information on subscribing, send request to above address. POSTMASTER: Send address change to the USDA, NASS, Indiana Field Office, 1435 Win Hentschel Blvd, Suite B105, West Lafayette IN 47906-4145. --------------------------------------------------------------------------------- Weather Information Table Week ending Sunday August 21, 2005 ----------------------------------------------------- | Past Week Weather Summary Data |--------------------------------- Station | Air | | Avg | Temperature | Precip. |4 in. |---------------|------------|Soil |Hi |Lo |Avg|DFN|Total |Days |Temp ----------------------------------------------------- Northwest (1) Chalmers_5W 90 60 74 +3 0.71 4 Valparaiso_AP_I 85 57 73 +3 1.85 3 Wanatah 86 55 72 +3 0.86 4 77 Wheatfield 87 59 73 +4 1.03 5 Winamac 87 61 73 +4 0.23 3 73 North Central(2) Plymouth 86 59 73 +2 0.89 4 South_Bend 84 57 73 +3 0.65 3 Young_America 87 60 73 +3 0.21 2 Northeast (3) Columbia_City 85 58 72 +3 0.23 3 78 Fort_Wayne 87 59 73 +2 0.24 2 West Central(4) Greencastle 90 59 74 +1 2.15 3 Perrysville 99 58 75 +4 1.88 4 75 Spencer_Ag 91 62 75 +4 1.90 4 Terre_Haute_AFB 91 59 76 +4 0.80 2 W_Lafayette_6NW 89 59 74 +4 0.41 3 80 Central (5) Eagle_Creek_AP 88 61 75 +2 0.19 2 Greenfield 90 60 74 +2 1.16 4 Indianapolis_AP 90 63 76 +3 0.63 3 Indianapolis_SE 89 61 74 +2 0.74 4 Tipton_Ag 89 58 72 +3 0.92 4 77 East Central(6) Farmland 88 56 72 +3 1.58 4 71 New_Castle 90 56 72 +3 1.45 5 Southwest (7) Evansville 95 70 80 +5 2.14 5 Freelandville 92 66 77 +4 1.84 6 Shoals 92 65 77 +5 0.68 4 Stendal 96 67 79 +4 0.98 6 Vincennes_5NE 95 67 78 +5 1.42 4 78 South Central(8) Leavenworth 94 68 79 +6 1.37 5 Oolitic 92 64 76 +4 1.56 5 79 Tell_City 96 70 81 +6 2.35 6 Southeast (9) Brookville 93 62 76 +6 1.39 6 Milan_5NE 93 62 76 +4 1.47 6 Scottsburg 95 66 78 +5 2.80 6 ----------------------------------------------------- Weather Information Table (Continued) Week ending Sunday August 21, 2005 ------------------------------------------------ Accumulation -------------------------------- April 1, 2005 thru Station August 21, 2005 -------------------------------- Precipitation |GDD Base 50oF -------------------------------- | | | | Total | DFN |Days|Total| DFN ------------------------------------------------- Northwest (1) | Chalmers_5W |13.27 -4.66 47 2564 +211 Valparaiso_AP_I |12.44 -6.12 43 2427 +283 Wanatah |13.87 -4.24 51 2340 +288 Wheatfield |18.43 +0.78 89 2437 +333 Winamac |15.74 -2.17 53 2475 +305 North Central(2)| Plymouth |12.77 -5.42 52 2387 +116 South_Bend | 9.88 -7.56 50 2484 +351 Young_America |16.99 -0.11 48 2459 +232 Northeast (3) | Columbia_City |14.58 -2.73 51 2331 +298 Fort_Wayne |12.88 -3.29 51 2452 +224 West Central(4) | Greencastle |21.91 +1.59 43 2444 -63 Perrysville |15.61 -3.73 46 2657 +314 Spencer_Ag |19.92 -0.90 51 2480 +116 Terre_Haute_AFB |16.66 -2.68 45 2710 +212 W_Lafayette_6NW |12.00 -5.92 51 2525 +305 Central (5) | Eagle_Creek_AP |15.14 -3.08 47 2733 +256 Greenfield |21.56 +1.48 57 2516 +145 Indianapolis_AP |15.09 -3.13 47 2736 +259 Indianapolis_SE |15.76 -3.16 49 2536 +76 Tipton_Ag |19.12 +0.90 53 2342 +185 East Central(6) | Farmland |15.46 -2.25 50 2372 +267 New_Castle |18.35 -1.02 46 2228 +74 Southwest (7) | Evansville |14.70 -3.78 45 2977 +97 Freelandville |16.96 -2.29 47 2800 +220 Shoals |17.74 -3.15 57 2790 +298 Stendal |16.61 -4.02 44 2957 +246 Vincennes_5NE |21.82 +2.57 51 2899 +319 South Central(8)| Leavenworth |17.45 -3.94 46 2847 +364 Oolitic |17.80 -2.30 52 2574 +191 Tell_City |17.83 -3.25 38 3115 +364 Southeast (9) | Brookville |16.49 -3.01 49 2636 +375 Milan_5NE |18.58 -0.92 71 2595 +334 Scottsburg |17.89 -1.92 53 2748 +183 ------------------------------------------------------------------ DFN = Departure From Normal (Using 1961-90 Normals Period). GDD = Growing Degree Days. Precipitation (Rainfall or melted snow/ice) in inches. Precipitation Days = Days with precip of .01 inch or more. Air Temperatures in Degrees Fahrenheit. Copyright 2005: Agricultural Weather Information Service, Inc. All rights reserved. The above weather information is provided by AWIS, Inc. For detailed ag weather forecasts and data visit the AWIS home page at: www.awis.com