P AND K IN POTATOES. Donald A Horneck Oregon State University Extension Service

Transcription

1 P AND K IN POTATOES Donld A Hornek Oregon Stte University Extension Servie INTRODUCTION Phosphorous nd potssium re importnt to grow high yielding nd qulity pottoes. Muh of the northwest hs hd trditionlly high soil test K levels. These soils hve historilly hd greter tht 2 ppm K, with mny higher thn 4, now hve less thn ppm K. Some of the sndier soils tht hve een in prodution for over 2 yers hve een testing less thn 3 ppm K. Pottoes hve high requirement for K nd during the growing seson petioles n drop to less thn 4% K on low testing soils. Work done in the Columi Bsin hs shown tht sesonl K uptke n e s high s 8 pounds per re with dily uptke rtes of 2 pounds per re per dy in 2. There hs een wide vriety of methods used to supply K to pottoes on some of these low K soils: inluding lrge mounts of K pplied pre-plnt, pplitions t plnting nd in-seson dditions ll with limited suess in rising petioles to levels onsidered dequte. Phosphorous hs lwys een ttle in potto prodution. Work done in Idho suggests.1% PO 4 is dequte. The Oregon Stte University Potto guide reommends miniml P is needed when soil P is greter thn 2 ppm. The enefit of in-seson phosphorous pplitions is diffiult in potto prodution. University guidelines tend to e ext, e.g. when soils re greter thn 2 ppm P no P is needed or when petioles re will drop elow.1% pply P. Life is rrely so esy. METHODS Uptke nd Biomss Potto nutrient uptke nd iomss prodution hs een mesured over period of yers strting in 1999 through 24. Uptke is sed on n verge of three different hrvested res tht represent field or tretment uniformity. Where uptke is mesured in onjuntion with n experiment one smple is tken from eh replition. Smples re hrvested, ut up, dried, ground nd nlyzed for N, P, K, S, C, Mg, Zn, Mn, Cu, Fe nd Al. Potssium A tril ws estlished in 22 on oth Shepody nd Russet Burnk potto grower fields. Three K rtes were used, 1X nd 2X. The one nd two X rtes for the Russet Burnk rop ws 35 l/ K nd 7 l/ K or 44 nd 88 l K 2 O/, respetively pplied ll s KCl in front of dm nd diking. The K pplition would hve ourred shorly fter emergene. This pplition time ws sed on informtion from the 1999 nd 2 uptke studies. The Shepody K rtes were 3 nd 6 l K/ or 375 nd 75 l K 2 O/ pplied similrly. Biomss smples were hrvested during the growing seson, dried ground nd nlyzed for N, P, K, C, Mg, S, B, Zn Mn, Cu, Fe, Al nd Cl. Chloride nd potssium re onfounded in this experiment; however previous work indites tht the responses re minly due to K. The experiment hd three replitions. Pottoes were yielded nd grded. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 8

2 Phosphorous A grower s field ws used to do pre-plnt nded P study using Atlnti pottoes. Soil test ws modertely high t 3 ppm whih would hve generted P reommendtion of 8 l P2O5/ if erly plnted nd no P for lter plnted potto rop. This study hd three P rtes O, 139 nd 278 l/ P 2 O 5 pplied. Results Uptke of nutrients were higher thn previous studies hve mesured. Uptke rtes for N exeeded 7 l N /-d s shown in Figure 1. All nutrients mesured hd pek uptke t the sme time exept phosphorous whih uptke peked lter in the seson. Phosphorous lso hd muh roder pek for uptke whih oinides with dry mtter umultion. Drymtter uptke l/-d Mr 2- My 9-Jul 28- Aug dm n k p 17- Ot 15 5 N, K, C & P uptke l/-d Figure 1. Dily uptke rte of N, K, C, P nd Drymtter for 1999 Russet Burnk rop. Potssium pplitions inresed yield in Russet Burnk nd Shepody potto rops. The yield inrese in shepody ws liner where s only the first K pplition inresed yield over the hek in Russet Burnk s shown in figure two. Speifi grvity ws deresed in the shepody rop due to KCl pplition. Grvities were not impted in the Russett Burnks however the trend ws the sme s wht ws oserved in the Shepody field. The interesting prt to this work is the nutrient intertion, hloride uptke nd hloride onentrtion. Petioles in the Russet Burnk rop where dequte for oth K tretments s shown in figure 3. Potsium pplition inresed oth K nd Cl onentrtion in the tops nd tuers t hrvest (figures 5, 6, 7). Chloride uptke t hrvest went from 23 l/a for the hek to 13 l/ for the 2K tretment in Shepody. Chloride uptke in the Russet Burnks ourred ording to Figure 4. Tuer onentrtion of other nutrients tended to e unffeted y K pplition rte. The exeption ws nitrogen whih tended to derese with inresing K rte. Conentrtion in the tops ws muh more impted y K ddition thn ws onentrtion in the tuers. Nitrogen whih deresed with inresing K rte in the tuers ws unffeted in the rest of the plnt. Nutrients suh s C, Mg nd S ll deresed in the tops with inresing K. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 9

3 Phosphorous response ws for the most prt not sttistilly different on n erly potto rop. However, yield on verge ws inresed three tons per re where P ws dded, the differene ws not signifint. P onentrtion in the tuers ws not impted y P-rte. P in the tops inresed slightly nd P uptke inresed with inresed P pplition, omintion of inresed yield nd inresed P in the tops omined to mke P uptke signifintly different. 45 yield, t/ K 1K 2K 15 5 RUSSET RUS > 4 oz SHEPODY SHEP >4OZ potto vriety Figure 2. Yield for Russet Burnk nd Shepody from K pplitions. PETIOLE K, % K 1K 2K 5/9 5/29 6/18 7/8 7/28 8/17 9/6 DATE Figure 3. Russet Burnk weekly petiole K for three KCl tretments. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 1

4 2 Cl UPTAKE, #/A 15 5 K - K -1 K -2 4/19/21 6/8/21 7/28/21 9/16/21 11/5/21 DATE Figure 4. Russet Burnk hloride uptke urves for three KCl tretments K Cl Conentrtion, ppm K 2K 5 tops tuers tops tuers Russet shepody Figure 5. Chloride onentrtion on Tops nd Tuers for Russet Burnk nd Shepody for three K tretments. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 111

5 3 Nutrient, % K 1K 2K.5 N P K C Mg S Nutrient Figure 6. Impt of three K tretments on nutrient onentrtion of Russet Burnk tops (no tuers) t hrvest Conentrton, % N P K C Mg S Nutrient x 1x 2x Figure 7. Impt of three K tretments on nutrient onentrtion in Russet Burnk tuers t hrvest. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 112

6 totl yield t/ >2.5 yield yield, t/ x 2x P-rte Figure 8. Yield of Atlntis from P pplition P 1 P 2 P P uptke, l P/ 15 5 tops tuers oth Figure 9. P Uptke for Atlntis for tops, tuers nd omined tops plus tuers.25 tops tuers.2 P onentrtion, % P 1 P 2 P P-rte Figure. P onentrtion in tops nd tuers for Atlntis for three P-rtes. Western Nutrient Mngement Conferene. 25. Vol. 6. Slt Lke City, UT. Pge 113