Nutrient Mining, Soil Testing and Plant Nutrient Cycling

Transcription

1 Nutrient Mining, Soil Testing and Plant Nutrient Cycling Ray Ward Ward Laboratories, Inc Kearney, Nebraska Guiding Producers Today to Feed the World Tomorrow

2 Nutrient Mining, lbs/bu WHEAT Nutrient lb/bu 60 bu/a Nitrogen,N Phosphorus, P2O Potassium, K2O Sulfur, S Zinc, Zn

3 Nutrient Mining, lbs/bu WHEAT Nutrient lb/bu 60 bu/a Chloride Manganese Copper Boron Molybdenum

4 Nutrient Content of Wheat Straw Nutrient lbs per ton Nitrogen, N 12 Phosphorus, P2O5 2.3 Potassium, K2O 29 Sulfur, S 4

5 Nutrient Mining, lbs/bu CORN Nutrient lb/bu 100 bu/a Nitrogen, N Phosphorus, P2O Potassium, K2O Sulfur, S Zinc, Zn

6 Crop Nutrient Mining, lbs/bu SOYBEAN Nutrient lb/bu 45 bu/a Nitrogen, N Phosphorus, P2O Potassium, K2O Sulfur, S Zinc, Zn

7 Soil Nutrients Mobile Nutrients Nutrients that are soluble in the soil Nitrate, Sulfate, and Chloride Immobile Nutrients Nutrients that are attached to soil particles CEC and other surfaces Phosphorus, Potassium, Calcium, Magnesium, Zinc, Iron, Manganese, Copper, Boron, and Molybdenum

8 Two Approaches for Interpreting Soil Test Values Nutrient Sufficiency Apply just enough to maximize profitability in the year of fertilizer application Build Maintenance Manage soil tests to desired soil test levels and then apply enough fertilizer to maintain the desired soil values

9 Which Interpretation is Correct? Depends on the Plant Nutrient Mobile Nutrients like nitrate have to be managed annually Immobile nutrients like phosphate and potash can be built up and maintained Depends on Land Tenure Short term land leases dictate using the sufficiency approach Limited Resources Cannot afford to build soil tests or fertilizer prices are high

10 Where are the Biggest Yields? Observations over the years I have concluded the best yields come from high testing soils. Research in Canada with small grains has shown higher yields on high testing soils than annual applications of fertilizer on low testing soils. Rothamsted Experiment station in England has demonstrated that yields were higher on high testing soils. Crops and Soils, ASA

11 Importance of Phosphorus Tribune (KSU)2004 N, lbs per acre Corn Yield, Bu/A

12 Importance of Phosphorus Tribune (KSU)2004 N+P2O5, lbs/a Corn Yield, Bu/A

13 Conclusions Highest crop yield are associated with high soil tests Can we continue to reach the higher yield if we use a fertility approach that minimizes fertilizer application, especially phosphorus and potassium?

14 Nitrate Mobile Nutrients Nitrate is soluble. It moves downward as water moves through the root zone. We only want to apply the amount of N that is needed for the current crop. Non legumes need more N than legumes (soybeans, alfalfa, and peanuts). The goal is to have 2 to 5 ppm NO3 N after harvest.

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16 Nitrogen Requirement Corn 1.2 lbs N/Bu Wheat 2.4 lbs N/Bu Milo 1.1 lbs N/Bu Grass 40 lbs N/Ton Sunflower 50 lbs N/1000 lbs

17 Nitrogen Recommendation N lbs/a = (yield * N req.) lbs of NO 3 N in 24 or 36 Legume credit Manure credit Irrigation water credit

18 Nitrogen Recommendation An Example Wheat 60 bu/a X 2.4 = 144 lbs of N required Subtract the following Soil nitrate = 30 lbs of N Past legume = 20 lbs of N Amount of N to apply = 94 lbs of N/A

19 Sulfur Sulfate is soluble and moves with soil water like nitrate. Do not try to build sulfate. Some soils have sulfate in the subsoil which reduces the need for sulfur. Apply sulfur when soil test for sulfate is low.

20 Sulfur Requirement Crop Yield Unit LBS of S Corn Bushel Soybean Bushel Wheat Bushel Alfalfa Ton Grass Ton

21 Sulfur Recommendation Example Wheat 60 bu/a Yield Goal Sulfur Requirement is 0.28 to 0.35 lb S/bu Total S Required is 17 to 21 lbs/a Sulfate Soil Test is 8 ppm S 8 X 2.4 = 19 lbs S/A Recommendation is 0to 5lbs S/A

22 Chloride Chloride is a soluble ion like nitrate, but does not move as fast as nitrate. Many soils are low in chloride where potash fertilizer is not used is potassium chloride, so it is 60 % K2O and 45 % Chloride Ammonium Chloride, dry or liquid, is very good chloride fertilizer

23 Soil test chloride interpretations and fertilizer recommendations for Kansas. Soil Chloride in a 0 24" sample Cl Recommended* Category lb/acre ppm lb/acre Low <30 <4 20 Medium High > 45 >6 0 *Recommendations for corn, sorghum and wheat only.

24 Phosphorus Recommendations Soil test ppm P Rating lbs P2O5/A 0 5 Very Low Low Medium High Very High None

25 Phosphorus (My Goals) Ideal Phosphorus Soil Test: Dryland areas = ppm P Irrigated/high rainfall areas = ppm P How to Get There Soil texture: loam or heavier 18 lbs of P2O5 to raise soil P test 1 ppm P Soil texture: sand to sandy loam 12 lbs of P2O5 to raise soil P test 1 ppm P

26 Phosphorus How to Get There Example for a silt loam Soil test is 15 ppm P and I want to get to 25 ppm P = 20 ppm increase 10 X 18 = 180 lbs of P2O5 180 /.52 = 346 lbs of How many years do you want to take to get there? Divide by the number of years. This application is in addition to amount you normally apply.

27 Potassium Recommendations Soil Test ppm K Rating lbs K2O 0-40 Very Low Low Medium High Very High None

28 Potassium (My Goals) How to Get There Example for a silt loam Soil test is 120 ppm K and I want to get to 160 ppm K = 40 ppm increase 40 X 9 = 360 lbs of K2O 360 / 0.60 = 600 lbs of How many years do you want to take to get there? Divide by the number of years. This application is in addition to amount you normally apply.

29 Zinc I have found that the best way to correct a low zinc soil test is to broadcast enough zinc sulfate (33 to 36 % Zn) to raise the zinc soil test above 1 ppm. One pound of actual zinc will raise the zinc soil test 0.1 ppm Zn. Zn recommendation = (1.0 Zn soil test) times 10 Zn soil test = 0.60: ( ) X 10 = 4 lbs of Zn/A

30 Copper Copper soil tests are low in a few area of the Plains. For most crops I like to see a copper (Cu) value of 0.20 ppm P. For a few crops like potatoes I try to raise the Cu soil test to 0.60 ppm Cu. Three pounds of Cu will raise the soil test 0.10 ppm Cu Cu rec. = ( ) X 3 = 2.4 lbs of Cu

31 Boron Boron is less soluble than some of the anions. But boron has a narrow safe range. Do not try to build B soil test. Boron should be applied when the B soil test is less than 0.25 ppm, except for cotton, peanuts and sugar beets that need 0.50 ppm B. B recommendation = One pound of B will raise the soil test 0.10 ppm B. Example: for wheat, corn, milo, etc. 1.5 (5 x 0.20) = ( ) = 0.5 lbs B

32 No Till Fertilizer Program It is best to knife in nitrogen Do not do a weed and feed program for N Phosphorus and other nutrients can be broadcast or placed in a band Second alternative for N is stream on UAN or broadcast urea Split application is necessary for sandy soils.

33 Liming Reaction

34 Nutrient Cycle? 1. Nutrients are removed from the land any time grain or forage is transported from the area. 2. How are the nutrients replaced? Higher yields the more nutrients that have to be replaced. 3. Carbon and some nitrogen comes from the air. 4. Other nutrients have to come from soil minerals, decomposition of organic matter, manures and fertilizer.

35 Lime Calcium and Magnesium 480 lbs of Ca per ton of 60 % ECC Wheat 9 lbs of Ca per ton of dry forage 2.8 lbs of Mg per ton of dry forage Turnips 66 lbs of Ca per ton of dry forage 7 lbs of Mg per ton of dry forage

36 Carbon/Organic Matter Soil Organic Matter Carbon and all plant nutrients 1 % OM in 8 inches of Soil is 24,000 lbs/a This Quantity of OM Holds About 1400 lbs of N and 200 lbs of S per Acre.

37 No Till Sulfur Deficiency Most of the Sulfur in the soil is held in the organic matter portion of the soil The idea is the build soil organic matter to improve soil quality and health and increase soil productivity. 100C : 10N : 1.4S

38 A/C Greenfix Blend Above Ground Biomass Test Results 10/11/2010 (4 reps) High Low Avg. Yld. T/A Nutrients in #/A C N P K Ca Mg S Zn Fe Mn C:N =16.6 Grass % Brassica % Legume %

39 Nutrient Uptake and Root Structure

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41 Factors Affecting Nutrient Uptake Oxygen Temperature Ion Interference

42 Soil Organic Matter Enhance crop productivity Build soil fertility Improve structure Build aggregate stability Increase nutrient retention Increase water holding capacity

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44 Soil Structure Retention & transport of water & nutrients Habitat for Microbes Reduced Soil Erosion

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46 Poor Soil Structure Prevents Water Movement Water Saturated Soil Air Space Moisture Soil Dry Soil

47 Rainfall Simulator

48 Water Penetration

49 No. 1 Environmental Enemy in Production Agriculture Intensive Tillage

50 Nutrient Balance and Carbon Sequestration. Net carbon sequestration requires other nutrients. N P Ca S C K Zn 7 10 units of C per unit of N units of C per unit of P Bo Mg units of C per unit of S Cl etc. Mn Balanced fertilization is needed for both crop uptake and carbon sequestration! Rattan Lal, 27 Jan., 2000

51 Carbon is a keystone in nutrient cycling! K N C P Ca Zn Cl Mg Soil carbon is the Keystone for all soil physical, chemical and biological processes and properties. S Mn Bo Management platform fertility, variety, irrigation, species, cover crop, manure, rotations, tillage, soil type, erosion, timing,