Saving on Nitrogen Costs with Forages. Brie Menjoulet Agronomy Specialist

Transcription

1 Saving on Nitrogen Costs with Forages Brie Menjoulet Agronomy Specialist

2 Reducing Nitrogen Costs What are your options? 1) Incorporation of legumes Potential for increased yield N-costs reduced or eliminated 2) Reduced N-inputs Lacking an essential nutrient

3 Law of the Minimum: It only takes one scarce nutrient or one other limiting factor to affect plant growth and vigor!

4 Reducing Nitrogen Costs What are your options? 1) Incorporation of legumes Potential for increased yield N-costs reduced or eliminated 2) Reduced N-inputs Creates the possibility for: Yield loss Stand thinning Increase in weed populations Decreased forage quality

5 Complex cycle! Nitrogen (N)

6 N 2 O NO N 2 N 2 O N 2 NO 3 - NO NO 2 - NO 3 - NH 4 + & NO 3 - NO 3 - NH 4 + NO 2 -

7 Nitrogen (N) Complex cycle! Forms in soil change frequently Soil moisture level, organic fraction, temperature We usually don t soil test for N levels Little attraction to clays and organic matter Primary uptake forms: Nitrate-Nitrogen NO - 3 Ammonium-Nitrogen NH + 4 Application timing and rate makes a difference

8 Grass Pastures and Hay Fields Split nitrogen applications Spring & fall Fertilize when the plant can respond Surface urea applications Volatilization No more than 120 lb/acre/year Endophyte reaction High N application rates increase endophyte

9 N Application on Orchardgrass 0 lb N 50 lb N 100 lb N 150 lb N

10 Legumes ~ 80% of atmosphere is N-gas (N 2 ) Nodules are home to nitrogen-fixing bacteria Bacteria convert N 2 to NH 3 Most fixed N goes to host plant ~ 20% N goes to surrounding plants They will save you $$$$$$ Dilution and lessening of fescue endophyte

11 White Clovers White Small, intermediate and large Common white- Dutch and Louisiana Ladino Large white Pilgrim, Merit, Regal and Tillman Low fiber, high protein digestibility, heavy N-fixer, easy to establish Bloat When seeding with grass = ½ to 1 lb/acre Overseeding = 1 to 2 lb/acre

12 Red Clovers Early and late flowering Medium red clovers 2 to 3 cutting re-growth potential Kenland and Kenstar varieties Resistant and long-lived Need fall rest period Bloat Common varieties should be bought locally When seeding with grass 8 lb/acre Fall/winter establishment is better Spring grass control necessary Overseeding = 10 to 12 lb/acre

13 Legumes Dry matter yields of tall fescue-red clover vs tall fescue with N fertilizer (Lexington, KY, 2-yr average) Treatments Tall fescue-red clover 6 lb seed/a Tall fescue + nitrogen Yield, lb/a 11,100 0 lb N/A lb N/A lb N/A 9900 Adapted from Southern Forages

14 Legumes Adapted from Utah State University Yield response without legumes: Price of N application is not worth the minimal yield response 20 to 30% legumes provide sufficient N for grasses

15 Nutrient Needs/Removal (Hay) The greater the yield, the greater the fertilizer need Nutrients must be replaced to sustain yield Synthetic and/or organic fertilizers

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17 Nutrient Replacement Fertilizer costs based on removal for cool-season grass hay Nutrient Fertilizer ($/lb) Removal Rate (lb/ton) Nutrient Value per Ton Nutrient Value per Acre (3 ton) Urea Ammonium Nitrate Phosphorus (DAP) Potash Total nutrient value: $58.80/ton of hay harvested

18 Nitrogen Fixation by Legumes Legume N Fixed (lb/a/yr) Alfalfa Red Clover Ladino Clover Annual Lespedeza Adapted from Southern Forages At $0.60/lb for ammonium nitrate: Legumes fix between $30 and $150 of N/A/yr

19 Nutrient Replacement Fertilizer costs based on removal for clover/grass hay Nutrient Fertilizer ($/lb) Removal Rate (lb/ton) Nutrient Value per Ton Total costs: $31.80/ton with legumes as the N source Nutrient Value per Acre (3 ton) Urea Ammonium Nitrate Phosphorus (DAP) Potash

20 Legume Establishment Considerations

21 Minimum Nutrient Needs

22 Liming For cool-season grass: 5.5 to 7.0 For most legumes: 6.0 to 7.5 Limit application to 2 to 3 ton/acre/year The poor man s fertilizer

23 Liming for Efficient Fertilizer Use ph (salt) Percent Percent Nutrient Nutrient Availability Availability Nitrogen % Phosphorus % Potassium %

24 Take Home Points: Nitrogen is not easily retained in the soil and should be added just before times of greatest need Forgoing nutrient applications has consequences Split N applications More efficient Use legumes to reduce and eliminate N Weed control should be considered prior to overseeding Get to know your soil Take soil tests