Forage fertilization. Alex Rocateli

Transcription

1 Forage fertilization Alex Rocateli

2 Grazingland Types: Native pastures/rangelands Ecological processes Management: Prescribed Fire Grazing Stocking rate Herbicides Introduced pastures Technological Processes Management: Fertilization Grazing Fencing Stocking rate Herbicide

3 Pasture vs. Hay field Soil test Grazing fields: every fifth year (20 % every year) Hay fields: every third year (33% every year)

4 ph Importance of proper fertility

5 FORAGE YIELD ( 00) LBS/ACRE Soil acidity problem Effect of liming and nitrogen on ryegrass yields in an acidic soil APPLIED NITROGEN LBS/ACRE Lime not applied Lime applied

6 Importance of proper fertility P & K ph

7 Phosphorus and Potassium Amount applied based on: P index and K index provided by soil analysis. Critical p and K values for bermudagrass

8 Importance of proper fertility P & K N ph

9 Nitrogen Application based on: Location (yield potential) Response to N rate application NITROGEN Yield potential by OK region and N fertilization response of bermudagrass

10 Importance of proper fertility Secondary & micronutrients ph P & K N Based on: Soil testing Sufficiency program (Same approach as P&K)

11 Importance of proper fertility In-season cues P & K N Secondary & micronutrients ph

12 In-season cues Following the nature cues Cow pox How much?? Apply fertilizer if cow pox are present in pastures. It indicates N deficiency

13 In season Cues Green Seeker

14 Green seeker What is missing? Working on getting an improved model for bermudagrass.

15 Importance of proper fertility VRT In-season cues P & K N & S Secondary & micronutrients ph

16 Grid Soil Samples Composite sample ph 5.8 Buffer Index 6.9, target ph 6.8 Lime Rec 1 ton ac-1 ($30/ton) 101 acres $3030

17 Soil ph and Buffer Index Grid

18 VRT Lime VRT lime 32 tons on 24 $30/ton 960$ 1 ton/ac on 9 ac 1.5 ton/ac on 16 Over applied on 77 Under applied on 16

19 Importance of proper fertility VRT In-season cues WATER Secondary & micronutrients N & S P & K ph

20 Annual precipitation history in Oklahoma

21 Cumulative precipitation in Okemah, OK

22 Forage nutrient management Wet conditions Nutrient Losses Leaching (N,K) Denitrification (N) N 2 N 2 N 2 N 2 N 2 N 2 Sandy Loamy Clay K + NO 3 - NO 3 - NO 3 -

23 Pasture nutrient management Wet conditions Soil sampling Nutrient losses might be higher in a wet year More frequent and smaller amount applications Applied the nutrient according to plant need avoiding losses.

24 Pasture management Dry conditions Roots take up nutrients from the soil solution; therefore plant nutrient uptake will be severely reduce during drought periods Apply nutrients, specially Nitrogen when rain is detected in the forecast *N volatilization (urea)

25 SCENARIO 1 Planned earlier in the season: - Bermudagrass hay - Goal: 3 cuttings, 2 tons acre -1 per cut - First N application: 100 lbs acre -1 Evapotranspiration and Rainfall During Growing Season: - Only 1.5 ton acre -1 harvested at first cutting - The weather in April was very dry - After first cutting no water in soil - according to forecast Oklahoma Mesonet Date Hay Grass ET (inches) Rainfall (inches) Available soil water (inches) May May May May May May May First hay harvest Apply the 100 lbs N acre -1 for the second cutting?

26 SCENARIO 1 Evapotranspiration and Rainfall Oklahoma Mesonet Date Hay Grass ET (inches) Rainfall (inches) Available soil water (inches) Apply the 100 lbs N acre -1 for the second cutting? Considerations: 1. Soil water for plants (none, no N uptake) 2. Rainfall (none) May May May May May May May First hay harvest

27 SCENARIO 2 Planned earlier in the season: - Bermudagrass hay - Goal: 3 cuttings, 2 tons acre -1 per cut - First N application: 100 lbs acre -1 Evapotranspiration and Rainfall - SCENARIO 2 - Only 1.5 ton acre -1 harvested at first cutting - The weather in April was very dry, but rained on May 16 - After first cutting, 3 inches of water in soil - Rain in 3-4 days according to forecast Apply the 100 lbs N acre -1 for the second cutting? Oklahoma Mesonet Date Hay Grass ET (inches) Rainfall (inches) Total soil water (inches) May May May May May May May First hay harvest Rain Rain

28 Evapotranspiration and Rainfall Oklahoma Mesonet SCENARIO 2 Date Hay Grass ET (inches) Rainfall (inches) Available soil water (inches) Apply the 100 lbs N acre -1 for the second cutting? Considerations: 1. Soil water for plants (Yes, plants will take up N) 2. Rainfall (Yes) 3. First cut production (0.5 ton acre -1 lower than expected) (some N from first application in the soil) (second production < 2 tons acre -1 ) 4. N fertilizer price and application cost May May May May May May May First hay harvest Rain Rain

29 Questions? Contact information: Alexandre C. Rocateli Alex Office: (405) Fax: (405)