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Soils Patterns and properties Relevance of soil Primary industries cover a large fraction of NZs land area first recipients of rainfall which off the soil to reach rivers and lakes The ability of the soil to act as a filtering agent is vital in maintaining the quality of freshwater bodies This abili...

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Soils Patterns and properties Relevance of soil  Primary industries cover a large fraction of NZs land area – first recipients of rainfall which infiltrates/runs off the soil to reach rivers and lakes  The ability of the soil to act as a filtering agent is vital in maintaining the quality of freshwater bodies  This ability is often compromised by a poor understanding of the types of soil on the farm  Nutrient losses (N,P) occur, waterways are contaminated  Soil – farms most important physical resource  First recipient of rainfall  Complex, high energy/surface area system where oxygen, water, nutrients, and organisms interact  Knowledge of parent material and formation processes gives: o Ability of soil to supply and accept nutrients (chemical properties) o Ability to withstand mechanical stress and allow movement of oxygen and water (physical properties) The environment of soil formation  Five key factors  Parent material o Strongly affects soil fertility  Climate o Physical weathering  Effects of climate – freezing, thawing, erosion result in size reduction (gravel  sand  silt  clay). Surface area increases, reactivity increases  Parent material redistribution – water transport, wind transport o Chemical weathering  pH and Eh (oxidation vs reduction) of developing soil, temperature, water flux  Results in secondary minerals with chemically active surfaces (Fe, Al, hydrous oxides)  Vegetation o Respiration of roots, plant residues, acidification o Decomposition of plant residues  earthworms, arthropods, fungi, bacteria o Chemically active organic matter (R-COOH, R-OH) o Polyphenols inhibit soil biota – low pH, deep litter layer  podzols  Relief or topography o Underlying strata are more likely to be exposed in steep areas o Microclimate effects on developing soil  Time o Soils take time and stability to develop  multiple transports, burials, weathering Allophanic soils  Very high P retention soils coincide with allophanic soil types

Agronomy Lecture 1: Growth 1. Discuss factors that govern the shape of a seasonal pasture growth curve 2. Draw a typical seasonal pattern for a pasture growth curve and indicate general changes moving from warm to cold or wet to dry climates Typical NZ dairy farm  Trace the flow of energy

Pasture grown

→ → Animal production Pasture eaten conversion utilisation

 14 tonnes dry matter per hectare per year  14000/365 = 38kg DM/ha/day  At 5 tonnes/year for a dairy cow  2.8 cows/ha Climatic factors controlling pasture production  Solar radiation (energy source)  Temperature (winter cold limits growth)  Rainfall/Soil factors (summer heat leads to moisture deficit)  Spring seed head growth  Soil fertility (pants need nutrients)  In general, low temperature limits pasture growth in winter and moisture deficit limits pasture growth in summer  Cold and dry (Otago)  Winter too cold for pasture growth and summer too dry  If irrigation water is available crops like Lucerne/alfalfa may be grown on regular pastures  Animals may graze higher altitudes in summer  Cold and Moist (Southland)  Winter growth rate low so animal feed requirements in winter need planning o E.g. forage crop planted in summer and feed carried forward  Summer rainfall = summer pasture growth o Often feed surplus  Cool summer conditions so pasture moisture demand reduced = increased forage energy values  Warm and dry (east coast north island)  High summer temperatures = summer drough o Uncertainty of summer grass growth Soil nutrient status  High soil fertility can triple pastoral production  Add P  Encourage clover  Fix nitrogen  Grow grass

Lecture 2: Supply and Demand 1. The concept that pastoral production systems are configured to match supply and demand as far as possible, both annually and seasonally 2. The influence of stocking rate and lambing/calving date decisions in setting the broad match of pasture supply to pasture demand on a property 3. The impact that farmer decisions about lambing or calving date optimisation may have on system performance 4. The interaction between regional environment (climate, soil, etc.) and farm system configuration and pressure points Feed supply and demand in a pasture system  For lowland NZ pastures 10-16 tonnes/DM/ha/day is fairly typical

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A winter feed deficit when pasture growth is inhibited by cold, often also a summer feed deficit arising from moisture deficit A late spring/early summer surplus, and a spring balance date when the system flips from deficit to surplus Animals used to be on farm all year, nowadays cows are often off farm in winter (May-July) Spring peak demand is usually closer to spring peak supply meaning less pasture surplus conserved for winter and/or summer deficit Any summer feed deficit is typically met by strategies such as irrigation, use of a summer forage crop or feed importation (palm kernel, maize silage) Too much grass as big a problem as too little grass (decline in feeding value when not grazed) Regional and within farm variation needs to be recognised and factored into planning

Changing stocking rate and lambing/calving date  Seasonal feed surpluses and feed deficits change their patterns when either the stocking rate or parturition date is changed  Simplistically, raising or lowering the stocking rate moves the animal demand curve vertically against the feed pasture supply curve, while moving the parturition date moves the animal demand curve horizontally against the feed supply curve  Increased stocking rate will increase winter deficit and decrease summer surplus  Later lambing/calving will make the balance date occur earlier in the season, reduce the feed deficit before balance date, and increase the feed surplus just after balance date  Also important

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Decisions such as culling ate on a dairy farm (cows sold in late lactation and not kept over winter can be made at short notice, for example in response to weather variation (drought))

Lecture 3: Rotation 1. Outline the use of rotation length to control intake in NZ farm systems 2. Provide understanding of research data dealing with impact of rotation length on a farm system Rotation length  Primarily intended to define a paddock-event’ so changes on a day-to-day basis  Rotation length is the grazing interval that would occur if today’s grazing management were maintained for a complete farm cycle  Calculated as whole farm area divided by area grazed today  Distinguish from grazing duration (number of days taken to complete a paddock grazing event)  Longer rotations require longer grazing durations when comparing two similar sized farms with a similar number of paddocks  Grazing Intensity  Defined as animal grazing days per ha obtained in a (rotational) grazing event o 

cows ×

days days ∨sheep × ha ha

 Can be thought of as the number of animals fed in one day from one hectare An easy way to calculate herbage consumption of animals

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DM DM kg ha animal ) =Animal intake( day day grazing intensity (animal × ) ha Herbage removed kg

Rotation length change  A longer rotation (increased grazing duration for individual paddocks) will leave less grass behind at the end of the grazing event, but because  The reduction in residual herbage mass is always proportionately less than the increase in grazing duration required to achieve it (so a longer grazing duration will not reduce the herbage length as much??), longer rotations with more herbage removed result in reduced daily herbage intakes for grazing animals  Used to grow more grass  Improve clover % in sward  Increased pasture growth  increased animal intake  so farmer decreases rotation length  Decreased pasture growth  decreased animal intake  so farmer increases rotation length  Use rotation length to  Impose control over animal intake  Help match pasture growth to animal demand  But grazing frequency should ideally also be linked to pasture growth rate, in order to maintain a good quality sward Seasonal considerations

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In winter, farmers use a long rotation length to ration feed which is in short supply and in this way surplus feed is stored in autumn in the form of increased herbage mass for release to animals in late winter Keeping animals, a day longer in a paddock:  Residual after grazing will be lower  Time to next grazing will be increased  Animal intake will be decreased  Future farm average cover will be increased In late spring or early summer farmers typically use a short rotation length to allow animals to eat their voluntary capacity and minimise accumulation of surplus herbage  Failure to control a feed surplus may result in loss of pasture quality and negative impacts for stock performance To be clear  A long rotation length is associated with a high grazing intensity; intake restriction is achieved through low herbage mass in the second half of the paddock grazing duration  The reverse is true for a short rotation length  The herbage disappearance is non-linear o Therefore, long rotations reduce intake – decreasing herbage disappearance slope with increasing days in paddock

Lecture 4: Grass Growth Segmental morphology of grasses  Tree branches grow from the tips whereas grass leaves have a cell division region at the base of the leaf, meaning that new leaf tissue is most often pushed up by the cell division at the leaf base  Older leaves die and decay at the base end  Have segmental morphology (segments are called phytomers)  Unique properties  Leaf growth from base (below grazing height)  Flexible pseudostem ok for treading  Leaf turnover and programmed death  Root growth from tip for soil penetration  Root turnover cycle ~3x longer than leaf cycle  Self-replacing  Motility over time o Shoots may colonise sward gaps  Pattern of growth in order  Apical meristem (growing point)  Elongating leaf  Mature leaves  Programmed dying (senescing) leaf  Tiller buds (axillary buds)  Daughter tiller  Roots – younger above, older below  Root development  Roots form on the phytomer soon after the leaf dies  Wheat and ryegrass have four sites – of which one to three usually develop

 Young roots can be seen on the phytomer one or two below the senescing leaf  Older roots about ten phytomers below the senescing leaf die off  Grazing  Grazing removes most leaves  After 3 leaves have formed (in ryegrass) little gained from grazing delay – an old leaf dies as a new leaf forms  A natural grazing interval determined by grass leaf appearance rate and number of live leaves per tiller (more or less species constant)  May or may not coincide with animal intake requirements Think tactically about grass  Understanding of leaf turnover is a key concept in optimising grazing management  Grazing interval (ryegrass long enough to develop 3 leaves)  But not so long as to allow significant leaf death/senescence  Other grass species have differing cycles White clover  Also has segmental morphology in which older segments are lost  Horizontally orientated stolons confers mobility  Annual cycle of stolon burial where earthworm activity is substantive Reproductive growth (seed-head formation) Flowering key points  Seasonal – triggered by increased day length, may be enhanced by cold exposure  30-100% of tillers in sward affected depending on species, may be over a shorted or more extended period  From a graziers perspective pasture growth rate is increased but pasture ME value is decreased when seed-heads are formed  Mature seed-heads are less palatable to grazing animals Controlling seed-heads by grazing  Longer rotation leaves paddock cleaner but reduces intake of animal  Shorter rotation leaves some seed head material uneaten but ensures higher intake and faster return time is also beneficial to seed head control (more likely to be eaten of younger)  Control of seed heads is important because It affects summer pasture quality and animal performance  Control may be achieved by  A high grazing intensity  Or a short return time  Option two works best

Lecture 5: Plant species and environment 1. Comment (superficially) on the historic conversion of forest (or other types of vegetation) to pasture in New Zealand 2. Outline two fundamental ecological concepts relevant to pasture husbandry a. Pasture species possess specific adaptations relevant to microenvironment colonisation b. Pasture production is determined more by the environment than the species present

Key points  Pasture sowings out of native vegetation pre to circa 1970 in multi-species swards, many of which remain as old pastures today  Current pasture renewal almost exclusively a ryegrass/white clover base mixture Key ecological principles in pasture husbandry  Plant species/microsite associations  Environment and productivity  Plant species effects are small compared to environmental effects  Environmental effects: o Temperature o Rainfall o Soil pH o Grazing frequency o intensity Habitat of carnivorous plants  Carnivorous plants are found in swamps where high water level and low oxygen levels inhibit conventional root function  Hypoxic conditions  Roots just for anchorage  Pitcher plants are found in areas of highly leached soil with a very low nutrient level Habitat for veld grass  Shade loving  Better copes with uptake of water or nutrients by tree  Displaces ryegrass under the oleander tree Key concepts  Changing species in a particular environment does not greatly change productivity (fine tuning option for seasonal emphasis)  Productivity generally determined by the environment, not he species  A species not suited to the environment will not persist

Lecture 6: Ryegrass Breeding 1. 2. 3. 4. 5. 6.

Can differentiate terms species and cultivar Can give key facts about ryegrass Are aware of cultivar development process Are able to list major germplasm sources in NZ Can explain the term perennial – Italian RG continuum Can list some common points of difference between commercial perennial ryegrass cultivars

Species and cultivar  Species  Botanical taxon with Latin name  Ryegrass and Tall fescue are two species  Cultivar  Commercial entity often legally protected by plant variety rights

 Effectively a sub-species commercially derived Ryegrass key facts  19th century settlers brought cold-adapted seed to a warmer climate (NZ)  Ryegrass range  Daily max temp 5˚C  Rainfall >750mm/year  High soil nutrient levels  Eastern lower rainfall regions of NZ marginal for ryegrass  Cocksfoot, tall fescue among others may be considered for planting as RG alternatives Cultivar development  Typically, this process takes 10-12 years Key germplasm sources in NZ  Old Hawkes Bay ecotype  Mangere ecotype  Spanish germplasm Perennial versus Italian  Ryegrass native to northern Europe adapted to winter snow and summer growth = perennial  Ryegrass adapted to Mediterranean region adapted to grow in winter and survive summer as seed (annual habit = Italian)  Ryegrass material originating from the UK tends to have a smaller % of shoots flowering and require winter cold exposure plus day length >12hours to flower, but it likely to be winter dormant with lower nutritive value  Increased persistence  Decreased nutritive value  Decreased winter growth  Ryegrass material originating from the Mediterranean basin tends to flower and die (high % of shoots) with day lengths >12hours (do not persist well through summer), but has good nutritive value and winter growth. So called Italian types may have had centuries of cultivation in other countries.  Decreased persistence  Increased nutritive value  Increased winter growth Ryegrass variety differentiation  Includes  Use of the Italian-perennial continuum  Different mix of the 3 main germplasm sources when breeding Methodology checklist Relevance Flowering date manipulation Early flowering often seen in lower rainfall environments. Later flowering varieties maintain high levels of leafy growth in late spring Tetraploidy Generally larger tillered with high nutritive value, show decreased persistence, dark green Selection for desirable traits e.g. selection for high ME for improved animal performance, improved N uptake from soil, high sugar content etc.

Fescue introgression High sugar content Endophyte strain

Tolerance to drought Winter effect, bred UK provides better utilisation in gut of N-containing compounds A fungus inside the plant – provides plant protection but some side effects for grazing animal

Flowering date manipulation  For animal performance, farmers are interested to prolong vegetative growth in spring (late flowering)  Also relevant for silage cropping (higher yield at similar feed quality)  Changing the flowering date moves the seasonal spring growth peak accordingly  Early spring growth may be desirable in summer-dry regions or where a farm has a strategic need for earlier spring feed  Flowering in a grass sward implies high herbage accumulation rate (kg DM/ha/day) but is associated with a fall in nutritive value  Farmers are interested in late flowering varieties because they can extend the period of high nutritive value spring forage growth into summer Ploidy level  Plant breeders can double plant chromosome numbers  For natural ryegrass 2n=14  A tetraploid would have 28 chromosomes  Tetraploids  Have larger shoot and seed size  Exhibit vigorous growth  Little more drought resistance  Often a little less persistent  Larger cell size so increased call content: cell wall so increased feed value Fescue introgression  Tall fescue is a natural hexaploid of meadow fescue, closely related to perennial ryegrass  Introgression aims to capture heat and drought tolerance genes from tall fescue into a ryegrass-type plant High sugar grass  Should increase animal retention of herbage N

Lecture 7: Endophyte 1. Explain what an endophyte is 2. Describe the life cycle of the endophyte 3. Know the names of five alkaloids (or alkaloid types) produced by endophytes (lolitrem, ergovaline, peramine, loline, janthitrems) and the significance of each of those chemicals Endophyte  A fungus, living within some grass plants  Symbiotic, not parasitic (the fungal mycelium grows between leaf cells and does not invade them)  Transmitted to the next plant generation within the seed and not the spores  Assists plant survival in warmer summer areas, but plants often spontaneously lose their endophyte in climates with cooler summers (UK)

Life cycle  Mycelium strands grow into leaves and new tillers from tissue near the growing plant  Can be isolated onto agar, where mycelium forms an amorphous mass  Mycelium grows up developing seed-head to infect aleurone layer of seed  Therefore, present in seedling at germination  Endophyte mycelium in leaf epidermis  N. lolii o Ryegrass  N. coenophialum o Tall fescue Alkaloid secondary metabolites of endophyte  Endophyte is fungus, alkaloid produced by fungus Lolitrem  Occurs in N. lolii, not N. coenophialum  Causes ryegrass staggers, but the picture is complex because the molecule has variants and there appears to be synergy between lolitrem and other compounds such as ergovaline  Endophyte strains with gene for lolitrem production not functional now available Peramine  Peramine synthesised by fungus is a feeding deterrent for a common insect pest, Argentine stem weevil  Tall fescue endophyte does not synthesis peramine but seems to achieve similar plant protection with lolines  Another ryegrass endophyte strain released synthesises janthitrem alkaloids Ergovaline  Higher levels in N. coenophialum, lower levels in N. lolii  A vasoconstrictor – reduces blood flow by causing artery walls to contract. Gangrene of feet and hooves in extreme cases, and/or internal tissue necrosis  Non-ergovaline-producing N. coenophialum strains now available Endophyte ‘Wild’ ryegrass N. lolii

Animal health issues Lolitrem

Insect p...