shw 3002 animal agriculture1 nutrient requirements of pastures
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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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