SHW 3002 ANIMAL AGRICULTURE1 NUTRIENT REQUIREMENTS OF PASTURES.

SHW 3002 ANIMAL AGRICULTURESHW 3002 ANIMAL AGRICULTURE 11

NUTRIENT REQUIREMENTS NUTRIENT REQUIREMENTS OF PASTURESOF PASTURES

Why pastures have to be fertilizedWhy pastures have to be fertilized

Nutrients are removed from soil by Nutrients are removed from soil by pasturespastures

Soil is not able to completely supply Soil is not able to completely supply the required nutrientsthe required nutrients

Nutrient uptake per year (kg/ha)Nutrient uptake per year (kg/ha)SpecieSpeciess

YieldYield

t/hat/haNN PP KK CaCa MgMg

Brachiaria Brachiaria ruziziensisruziziensis

32.932.9 333333 5454 442442 150150 7777

Pennisetum Pennisetum purpureumpurpureum 27.727.7 332332 7070 554554 105105 6969

Panicum Panicum maximummaximum

25.325.3 317317 4848 399399 163163 109109

Deficiency SymptomsDeficiency Symptoms

NITROGENNITROGEN : General chlorosis of : General chlorosis of leaves with older leaves first showing leaves with older leaves first showing symptomssymptoms

NITROGEN DEFICIENCYNITROGEN DEFICIENCY

Potato leaves:Potato leaves:

Left : normal green leaf Left : normal green leaf with sufficient nitrogen with sufficient nitrogen supplysupply

Right : nitrogen deficient Right : nitrogen deficient leaf, pale green and leaf, pale green and yellow tintedyellow tinted

Deficiency symptomsDeficiency symptoms

Phosphorus – Leaves become purple Phosphorus – Leaves become purple or red in the veins. Early symptoms, or red in the veins. Early symptoms, leaves dark green in colourleaves dark green in colour

PHOSPHORUS DEFICIENCYPHOSPHORUS DEFICIENCY

May develop purplish or May develop purplish or reddish colour on leavesreddish colour on leaves

Premature leaf lossPremature leaf loss

Poor root developmentPoor root development

Delayed maturityDelayed maturity

Decreased yieldDecreased yield

Rice plant under P-deficiency, stunted with limited tillers, narrow, short, erect and dirty dark green leaves.

Deficiency SymptomsDeficiency Symptoms

Potassium (K)Potassium (K) – yellow spots leaves – yellow spots leaves scorching on leaf margins and leaf scorching on leaf margins and leaf tips tips

K deficiency in maize

K deficiency in riceK deficiency in alfalfa

K deficiency in maize

Deficiency symptomsDeficiency symptoms

MagnesiumMagnesium – Interveinal chlorosis – Interveinal chlorosis and necrosis. Deficiency causes and necrosis. Deficiency causes hypomagnasaemia in animalshypomagnasaemia in animals

Lower leaf interveinal Lower leaf interveinal chlorosischlorosis in G in Gerbera.erbera.

Geranium - lower leaf Geranium - lower leaf interveinal chlorosis. interveinal chlorosis. Notice the initial Notice the initial (left) versus (left) versus advanced (right) advanced (right) interveinal chlorosis. interveinal chlorosis.

FertilizersFertilizers

N – urea (contains 46% N)N – urea (contains 46% N)

P – Triple Superphosphate (TSP) P – Triple Superphosphate (TSP) contains 21% Pcontains 21% P

Rock phosphate (about 15% P)Rock phosphate (about 15% P)

K – Muriate of Potash (contains 50% K – Muriate of Potash (contains 50% K)K)

Basal Fertilization Basal Fertilization

During Planting –During Planting –

N – 50 kg/haN – 50 kg/ha

P – 50 kg/haP – 50 kg/ha

K – 50 kg/haK – 50 kg/ha

How much fertilizer?How much fertilizer?

50 kg N = 100/46 x 50 kg urea50 kg N = 100/46 x 50 kg urea

50 kg P = 100/21 x 50 kg TSP50 kg P = 100/21 x 50 kg TSP

50 kg K = 100/50 x 50 kg MOP50 kg K = 100/50 x 50 kg MOP

Maintenance FertilizerMaintenance FertilizerPure grass pastures - grazedPure grass pastures - grazed

N = 200 to 400 kg/ha per yearN = 200 to 400 kg/ha per year– Applied 4-6 times per yearApplied 4-6 times per year

P = 40-80 kg/haP = 40-80 kg/ha

K = 75-100 kg/haK = 75-100 kg/ha– Applied 1-2 times a yearApplied 1-2 times a year

Maintenance FertilizerMaintenance FertilizerGrass Legume PastureGrass Legume Pasture

N = 0N = 0

P = 40 – 80 kg/haP = 40 – 80 kg/ha

K = 35 – 60 kg/haK = 35 – 60 kg/ha– Applied 1-2 times a yearApplied 1-2 times a year

MicronutrientsMicronutrients– 5-8 kg/ha Copper sulphate5-8 kg/ha Copper sulphate– 5-6 kg Zinc sulphate5-6 kg Zinc sulphate– 200 g/ha molybdenum200 g/ha molybdenum

Cut Fodder GrassesCut Fodder Grasses

N – 50 kg/ha (after every cut)N – 50 kg/ha (after every cut)

P – 40 kg/ha (after 3 cuts)P – 40 kg/ha (after 3 cuts)

K – 50 kg/ha (after 3 cuts)K – 50 kg/ha (after 3 cuts)

NITROGENNITROGEN

Importance of N in pasturesImportance of N in pastures

Needed in large quantities for Needed in large quantities for maximum growth – up to 800 kg/ha maximum growth – up to 800 kg/ha per yearper year

Most soils cannot supply the required Most soils cannot supply the required raterate

N from fertilizers are soluble and N from fertilizers are soluble and easily leachedeasily leached

N supply also affects protein contentN supply also affects protein content

N effects on dry matter yield

N effects on crude protein content

Sources of NSources of N

Organic matter in soilsOrganic matter in soils

N fertilizersN fertilizers

N fixation by legumesN fixation by legumes

N fixation by bacteria and algaeN fixation by bacteria and algae

In rain waterIn rain water

Nitrogen in SoilsNitrogen in Soils

Stored in Stored in organic matterorganic matter to depth of to depth of 90 cm from surface90 cm from surface

decomposition

Nitrate35 – 50 kg/ha per year

Biological N fixation (Bionif)Biological N fixation (Bionif)

Legumes as host in symbiotic Legumes as host in symbiotic association with association with RhizobiumRhizobium

Rhizobium forms nodules in rootsRhizobium forms nodules in roots

Effective nodules are large and pink Effective nodules are large and pink in colour (leghaemoglobin)in colour (leghaemoglobin)

Ineffective nodules are small in size Ineffective nodules are small in size and pale in colourand pale in colour

Biological N fixationBiological N fixation

RhizobiumRhizobium converts N from converts N from atmosphere into nitrite and nitrateatmosphere into nitrite and nitrate

RhizobiumRhizobium requires supply of requires supply of micronutrients such as Mo, Cu, B for micronutrients such as Mo, Cu, B for this processthis process

RhizobiumRhizobium is inhibited by presence of is inhibited by presence of nitrates in soilsnitrates in soils

Amount of N fixed by legumesAmount of N fixed by legumes

Varies with types of legumes and Varies with types of legumes and RhizobiumRhizobium strains strains

Temperate legumes (e.g. in NZ) – Temperate legumes (e.g. in NZ) – 280-400 kg N/ha per year280-400 kg N/ha per year

Good tropical legumes : 170 – 280 kg Good tropical legumes : 170 – 280 kg N/ha per yearN/ha per year

Moderate tropical legumes : 55-170 Moderate tropical legumes : 55-170 kg N/ha per yearkg N/ha per year

RhizobiumRhizobium inoculation inoculation

Inoculation necessary only when soils Inoculation necessary only when soils have never had legumes grown on ithave never had legumes grown on it

RhizobiumRhizobium is cultured in peat is cultured in peat

Seeds of legumes are mixed with Seeds of legumes are mixed with peat culture before sowingpeat culture before sowing

Use of sticker and pelleting with TSP Use of sticker and pelleting with TSP helps in inoculationhelps in inoculation

Recycling of NRecycling of N

75% of N75% of N ingested by animals are ingested by animals are returned through returned through urineurine, but 45% is , but 45% is lost through volatilization or leachinglost through volatilization or leaching

17% of N17% of N ingested by animals are ingested by animals are returned through returned through faecesfaeces and 6% lost and 6% lost through volatilization and leachingthrough volatilization and leaching

N CycleN Cycle

Transfer of N from legumes to Transfer of N from legumes to grassgrass

Direct transfer (amino acids from Direct transfer (amino acids from roots of legumes to grass)roots of legumes to grass)

Decomposition of roots and Decomposition of roots and rhizobium (1-5 kg N/ha per year)rhizobium (1-5 kg N/ha per year)

Decomposition of leaves and stems Decomposition of leaves and stems of legumesof legumes

Through grazing animals (85% of N is Through grazing animals (85% of N is returned)returned)

Problems in maintaining legume-Problems in maintaining legume-grass pasturesgrass pastures

Legumes are intolerant of heavy Legumes are intolerant of heavy grazinggrazing

Many pasture grasses dominate Many pasture grasses dominate legumes when soil fertility is highlegumes when soil fertility is high

Animals sometimes select for Animals sometimes select for legumeslegumes

Legumes are sensitive to nutrient Legumes are sensitive to nutrient deficienciesdeficiencies

Grass-legume vs Grass-NGrass-legume vs Grass-NLow costLow cost

Limited yieldLimited yield

High nutritive High nutritive qualityquality

Not tolerant to Not tolerant to heavy grazingheavy grazing

Not suitable for cut Not suitable for cut and carryand carry

High cost of High cost of fertilizerfertilizer

High yieldsHigh yields

Moderate nutritive Moderate nutritive qualityquality

Tolerant to heavy Tolerant to heavy grazinggrazing

Suitable for cut and Suitable for cut and carrycarry

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