Page 26—Com Talk, Lancaster Farming, Saturday, October 12, 1996 PSNT FOR CORN Doug Beegle Pertn State Soil Fertility Specialist The Presidedress Soil Nitrate Test (PSNT) for com has been used successfully in Pennsylvania for several years. This nitrogen soil testing ap proach is based on taking soil samples just before sidedress ing after the spring wet per iod but before the period of major nitrogen demand by com and determining the nitrate nitrogen available in the soil at that lime. If the test level is greater than 21 parts per million NO,-N, no sidedress nitrogen is recommended. If the test is below this level, the results of the test are then used to make sidedress nitrogen recom mendations. This test is primarily recom mended for use on fields where there are significant organic ni trogen contributions such as a history of manure applications or forage legumes in rotation. It does an excellent job of veri fying when these organic sour ces of nitrogen are adequate for the crop. This lest is of limited value on most fields without organic nitrogen contributions, because these fields generally have low levels and thus the standard recommendations are suitable. Since this test is somewhat unique compared to regular soil tests, it is probably worth while to review the procedures for using the PSNT since it will soon be time to test. The PSNT procedure is as follows: 1. Only apply a minimum of fertilizer nitrogen in the spring. (Starter fertilizer and/or nitro gen used as a herbicide car rier.) 2. Apply manure based on the history of the field, a man ure analysis, how the manure will be handled, and on crop re quirements for nitrogen esti mated from the expected yield and crop history. 3. Take soil samples when the com is 12 inches tall or at least a week before planned sidedressing. 4. Sample the fields by tak- ing 10 to 20 cores to a 12-inch depth if possible. If not sample as deep as you can. Avoid start er bands and other atypical areas. Because of sampling problems, this test cannot be used on fields that received in jected fertilizer or manure. 5. Combine and crumble the cores and dry as quickly as possible. Spread the samples out in the sun or under a heat lamp in a well ventilated area to dry. The samples must be dry within 24 hours. 6. The sample can be sent to a reputable soil testing lab for soil nitrate-nitrogen analysis. A reliable field test kit for soil nitrate-nitrogen can be used to determine the nitrate-nitrogen level in the sample. 7. Calculate the adjusted ni trogen recommendation from the worksheet below. There are several areas that seem to cause the most prob lems with the PSNT. First, many people try to take the test too early. It is important for the test to work properly that the com be at least 12 inches tall at the top of the whorl when you sample. A second problem re lated to timing of sampling is taking samples immediately af ter a heavy rain. Experience has shown that the test works best if you allow 2 to 3 days following a heavy rain before sampling for the PSNT. Sampling too soon after a rain can give a false low read ing indicating that there is less nitrogen available than there really is. Third, and this is the tough one, for the test to work the best the samples should be taken to a 12-inch depth. Unlike phosphorus and po tassium, nitrate will readily move deeper into the soil. Everyone complains about this deep sampling but it could be worse because taking deeper samples would be even better. Some states recommend two or even four-foot deep samples for nitrogen testing. This 12-inch depth seems to be a reasonable compromise between optimum accuracy of the test and sampling practi cality. Finally, the samples need to be dried immediately. They should be completely dry within one day of when they are taken. I have seen sample nitrate nitrogen levels increase by a factor of 2 to 3 times just from sitting around damp over a weekend. Agronomy Factsheet #l7 “Presidedress Soil Nitrate Test for Com,” which explains the PS NT in detail, is available from Penn State Cooperative Extension offices. Statewide Com Checkoffs What Is a Checkoff’ I1 111 ' ,1 s|M < | {|i (| Mt< 111 ( 111 I kill ( 1- m\ i >i< d I>\ tin mHi t in iin n llk I,ii iih t diii-i tin ' aNo him *.i in tin Da • 0 a- v \hil ( ulmadu (>t umjui lllinni- 111< llill l,t low a kaii'.i' Kt mm k\ Louisiana* Man laiul Mu Incan MllllU Mil.l Mi-Mnin \i hra^ka New V»rk Noiili ( aiohiin Noiili I).ikol.i Ohio \\ nri'\l\ani.i South ( aiohna South Dakota 1( mu t 1< \.i' \ irjimia \\ i-c \lnhainn mill I tnw.imm tin mil Inn i '.luh nwm millin'. NCGA-NCDF Pennsylvania Corn, Soybean GRANTVILLE (Dauphin Co.) Plans are nearly com plete for the 1997 Com and Soybean Conference scheduled Feb. 7 at the Holiday Inn at Grantville. This year’s program prom ises to be a good one and will feature Dave Cruse, an enter taining ag broadcaster from lowa, who will provide us with his forecast for the 1997 com and soybean markets. The program will also fea ture a recap of the growing sea son for com and soybeans by agronomist Mike Brubaker, president of Brubaker Agro nomic Consulting Service. Dr Jim Bierlien from Penn State’s R.K.IAIOGT 1225 > Colebrook Rd. BUYING BAR CORN. SHELLED CORN & WHEAT (717) 653-2510 1 (800) 654-2510 Spot or contract prices available EAR CORN FOR SALE DELIVERED TO THE FARM I miiidatiun w hit li i- tin fmaiM ml w alt h *lci*i u| tin National ( urn (.iunmm- \«(i( ki Ih»i i llk ii on a national lc\«1 N( (, \ m\i ( Ik ( Lull dullai- in i< -i an ii ni.ttk< i ill u lujiini in ami i dm aiiun w nli tin nn*-iun to i nliam i < mu |iiu|itaUilii\ ,iikl ii“,iL'( iumi|)iu\( da ijiialiu ul lift in a i luiiiirniu wuild C' (2 t a r ' i i ' ►’asst' 1 !l 1% 1/2 i< in 1/2 nl 1% 1 11 111 1/2 mu 1/2 mu 1 /H i ■ 111 1/2 mil 1M ul 1% 1/2 mu 1/2 mil 1 mil 1/1(1 mil an update on some of the added value soybean varieties that are being developed. The conference will also include ag industry exhibitors, Five Acre Com Club and Soy bean Yield Contest awards, and reports from the Pennsylvania Master Com Growers and the Pennsylvania Soybean Board. More information on registra tion will be available soon. Mark your calendars and plan to attend. ATTENTION FARMERS: Roll Your Own Com with a H ROLLER MILL It are machine cut from a continuous length of carbon steel. Fatigue-proof shafts in heavy ship-channel frame withstands tremendous pressure. Built To Last - Priced To Sell!