Were Soil Test Levels Affected by 2012 Drought? Immobile Nutrients P, K, Zn, Cu Soil Properties Salinity Soil ph Mobile Nutrients N, S, Cl,
Temperatures exceed 120F in Australia! 122 129 F (had to add new color to map)
Olsen Phosphorus (P) - ppm Soil Phosphorus (P) Test Trend Ave. Olsen P test 1986-2012 88-89 Drought High P soil test = 15 ppm Benson Lab Northwood Lab Year
(P) - ppm Soil Phosphorus (P) Test Trend Ave. Bray and Olsen P 1986-2012 88-89 Drought Benson - Bray 1 Test Benson - Olsen Test Year
Potassium (K) - ppm Soil Potassium (K) Test Trend Ave. K test 1986-2012 88-89 Drought Northwood Lab Benson Lab High K test = 150 ppm Year
Potassium (K) - ppm Soil Copper (Cu) Test Trend 1988-2012 88-89 Drought High Cu test = 0.4-.6 ppm All samples tested in Northwood Laboratory Year
Zinc ppm (DTPA test Soil Zinc (Zn) Test Trend 1988-2012 High Zn test = 1.0 ppm 88-89 Drought All samples tested in Northwood Laboratory Year
Soil ph (1:1 routine method) Soil ph Trend (0-6 ) 1988-2012 NE ND 88-89 Drought Northwood Lab Year
Soil ph Soil ph Test Trend Benson Lab 1988-2012 562 zip code Benson Lab 88-89 Drought Year
% Soil Samples with Salts greater than 1.0 11% 17% 10% 8% 17% 23% MB 21% 17% 12% Fall 2012 Samples (0-6 samples) ND 2% 8% 4% 1% 15% 37% 10% 27% 19% 19% 6% 0% SD 2% 6% 21% 12% 11% 2% 4% 1% 3% 7% MN
Mmhos/cm (1:1 method) Average Salinity (0-6 ) 1988-2012 88-89 Drought Higher than 1988! NE ND Northwood Lab Benson Lab Year
% samples testing >1.0 salts North Dakota & NW Minnesota % Samples Testing with Salts Higher Than 1.0 582 NE ND 567 NW MN 587 NC ND 1:1 salt method expressed as mmhos/cm
% samples >1.0 Salts (mmhos/cm) South Dakota - % Samples Testing with Salts Higher Than 1.0 40% 35% 30% 25% 20% 15% 10% 5% 0% 572 Watertown 573 Huron 574 Aberdeen 582 Grand Forks 1:1 routine Salt Method 572 573 574 582 Grand Forks
The Salt Problem may be Worse than we think? Composite Field Samples Teach samplers to avoid areas that don t represent most of the field (white areas avoided) Zone sampling The salty zones often do not get tested or fertilized Many salty fields don t get tested at all!
Mobile Nutrients (Move with water) Sulfur (SO4 - ) Chloride (Cl - ) Nitrogen (NO3 - )
Sulfur Soil Test Trends % of Samples testing High (> 15 lb/a S in topsoil ) 88-89 drought Northwood Laboratory Year
Chloride Soil Test Trends %Samples Testing Higher Than 60 lb/a in 0-24 88-89 Northwood Laboratory Year *2007 data chloride testing was limited after Northwood tornado
Residual Nitrate Following Hot and Dry 2012 Higher Residual Nitrate Levels Common High N Fertilizer rates with early seeding Higher N Mineralization (warm) Lower crop use (yield reduction) No N losses to excess rainfall Leaching Denitrification
Average Soil Nitrate following Wheat in 2012 MB 44 48 Fall 2012 Samples (lb/a 0-24 samples) 38 43 64 65 41 42 ND 33 47 47 44 44 51 50 50 43 48 SD 42 50 57 67 MN 39 43
Average 2012 Soil N Following Wheat Increase Over 2009 (normal year) 0-10 lb/a 11-19 lb/a MB +3 +5 (lb/a 0-24 samples) 20-30 lb/a >30 lb/a +5 +14 +20 +20 +14 +10 ND +1 +13 +21 +22 +20 +15 +14 +21 +15 +24 SD +19 +17 +20 +29 MN +5 +2
Palmer Drought Severity Index May, 2012
Palmer Drought Severity Index June, 2012
Palmer Drought Severity Index May, 1988
Palmer Drought Severity Index June, 1988
Average Soil Nitrate Following WHEAT 1986-2012 27 Years of history! 120 100 80 60 40 20 64 59 107 96 81 88-89 Drought 68 60 56 50 5453 61 42 46 48 44 43 46 38 35 60 35 41 29 32 40 47 0 86 88 90 92 94 96 98 00 02 04 06 08 10 11 2012
Nitrate Category Total Nitrate 0-24" lb/a Soil Nitrate Variability Between Fields Following WHEAT in 2012 >100 81-100 6% 5% 61-80 11% 41-60 23% 21-40 39% 0-20 16% 0% 10% 20% 30% 40% 50% 60% % of Fields Testing in Each Category
Average Soil Nitrate following Corn in 2012 MB Fall 2012 samples (lb/a 0-24 samples) 89 63 113 ND 67 54 46 50 54 57 68 52 44 SD 64 77 56 63 MN 114 85 62 83
Average Soil N Following Corn Increase Over 2009 (normal year) 0-10 lb/a 11-19 lb/a MB Fall 2012 samples (lb/a 0-24 samples) 20-30 lb/a >30 lb/a +47 +18 +63 ND 0 +13 +15 +9 +14 +21 +13 +19 +12 SD +23 +27 +11 +13 MN +81 +85 +20 +14
Palmer Drought Severity Index July, 2012
Palmer Drought Severity Index August, 2012
Palmer Drought Severity Index July, 1988
Palmer Drought Severity Index August, 1988
Nitrate Category Total Nitrate 0-24" lb/a Soil Nitrate Variability Between Fields Following Corn in 2012 >100 11% 81-100 8% 61-80 14% 41-60 22% 21-40 30% 0-20 17% 0% 10% 20% 30% 40% % of Fields Testing in Each Category
Higher Soil N Test = Money Saved! If soil test is 20 lb/a higher that means $10- $12 less N fertilizer needed for each acre
Topsoil N Higher after Dry 2012 Crop Year Crop Grown Crop Grown Wheat 2012 Ave. 0-6 N Corn 2012 Ave. 0-6 N 2012 (hot and dry) 22 lb/a 25 lb/a 2009 (normal) 12 lb/a 13 lb/a
Nitrate - N 0-6 lb/a Average Topsoil N (0-6 ) 1988-2012 88-89 Drought Northwood Lab Benson Lab Year
Why So Much Topsoil N? Topsoil Got Dry- Few active roots in topsoil Some Fertilizer N not used (stranded) Mineralization Higher Mineralization Rates - Warm Season No N losses (hasn t happened for many years) Denitrification Leaching Crops Used N and Water Below 24 Some crops down to 6-8 feet
Denitrification Risk Higher With Lots of Nitrate in Topsoil? Denitrification: Loss of N to the atmosphere under wet conditions Denitrification requires Saturated surface soil Nitrate-N close to surface Common bacteria (Thiobacillus) Plentiful organic matter Moderate temperatures
Estimated Denitrification losses by soil temperature and days of saturation Soil Temperature (F) Day Soil Saturated Nitrate Loss % 55-60 5 10% 10 25% 75-80 3 60% 5 75% 7 85% 9 95% University of Nebraska U of Illinois estimates 4-5% of nitrate lost per day with 65 F soil temperature
AGVISE Laboratories %Zone or Grid Samples Tested Compared to Conventional Whole Field Composite Samples in 2012 Mostly Zone samples for soil nitrate 0-24
Soil Testing Drought Conditions Soil Testing is Critical Nitrogen residual is higher due to dry 2012 Most nutrients not greatly effected by Drought Soil Salinity does increase following dry years Management Decisions Drought causes more variability of N in fields Zone Soil Testing provides better information on N variability
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