Agricultural Science Notes - Grassland Management and Conservation

Introduction / Uses of Grass

• Grassland is essential for agriculture, serving two primary purposes:
  • Providing grazing and immediate nutrition for livestock during the summer.
  • Being harvested for winter nutrition.
• Livestock enterprises raising cattle or sheep heavily rely on grass for productivity.
• Managing grass is crucial for peak productivity, similar to managing crops like barley or potatoes.
• Farmers must carefully plan pasture management to balance grazing and conservation needs.
• Monitoring grass growth allows farmers to budget their grass effectively.
• Ensuring each pasture is grazed to its maximum potential prevents grass wastage.
• Good grassland management is critical for farm efficiency.
• Closing pastures in late summer is essential for recovery and spring grazing.
• Figure 1 illustrates the annual grass growth curve, showing the impact of drought on grass availability.

Livestock Units

• Understanding grass budgeting requires knowing pasture production and animal consumption.
• Grass production can be estimated based on pasture size, growth curves, and real-time monitoring.
• Animal consumption varies by type, sex, and age, simplified using "Livestock Units" (LU).
• LU measures the amount of livestock grazing in a pasture and quantifies green herbage needed.
• LU also helps calculate winter fodder needs.
• A dairy cow has an LU value of 1.0, serving as the standard.
• A bull has an LU higher than 1.0, while a sheep has an LU significantly less than 1.0.
• Key figures to remember:
  • One LU requires 12 tonnes of herbage per year (one tonne per month).
  • One dairy/suckler cow = 1.0 LU
  • Cattle 1-2 years = 0.6 LU
  • Cattle <1 year = 0.4 LU
  • Sheep = 0.15 LU
• Example LU Calculation:
  • Farm with 75 Dairy cows, 22 sheep, 12 cattle <1 year:
  • Calculation: $(75 \times 1.0) + (22 \times 0.15) + (12 \times 0.4) = 83.1$ LU
  • Herbage needed per year: $83.1 \text{ LU} \times 12 = 997.2$ tonnes

Grassland Management – Grazing Systems

• The grazing system involves moving livestock to maximize grass use and pasture recovery.
• Rotational systems provide consistent fresh grazing and pasture rest.
• Pastures need approximately 3 weeks to regrow after grazing.
• Students must know examples of grazing systems and how they combine with management options like leader-follower systems.
• Access to water is critical in all grazing systems.
• Rotational grazing helps break the lifecycle of endoparasites.

Rotational Grazing

• Animals are moved around during the grazing season.
• Areas are allowed to recover between rotations.
• Rotation can be between entire fields or sections of a large field.

Block Grazing

• Large fields divided into smaller blocks grazed independently.
• Animals remain on each block for a week or more.
• Suitable for part-time farmers due to reduced labor.
• Advantages:
  • Cheaper due to reduced fencing and labor costs.
• Disadvantages:
  • Less efficient than paddock or strip grazing, leading to more grass wastage.

Strip Grazing

• Fields divided into long, narrow strips providing 24 hours of grass.
• Electric fences define strips and are moved daily.
• Back fence prevents animals from trampling previously grazed strips.
• Mobile water source or "run-back" pathway to trough is necessary.
• Advantages:
  • Fresh grass is always available, and no grass is wasted.
  • Pasture can recover without animals returning.
• Disadvantages:
  • Labor-intensive due to daily fence and water source movement.
  • Fixed water sources pose a challenge.

Paddock Grazing

• Available space divided into equal-sized paddocks, each containing one day's grazing.
• Requires at least 21 paddocks for 21-day recovery periods.
• Fencing can be electric or fixed (though fixed is expensive).
• Multiple paddocks can share a water source.
• Advantages:
  • Fresh grass always available, and no grass is wasted.
  • Potential for silage production from excess grass.
  • Paddocks allowed to recover between rotations.
• Disadvantages:
  • Expensive to set up due to fencing and water source requirements.
  • Requires significant management and attention.
  • Small paddocks are difficult to cut for silage.

Set Stocking

• No division of pasture; animals turned out at a set rate per unit area.
• Often used on large, rough, or hard-to-access areas.
• Advantages:
  • Cheap, with no need for expensive fences or mobile water sources.
  • Low labor and maintenance requirements.
  • Minimized poaching and density issues.
• Disadvantages:
  • Inefficient grass usage; animals may be selective.
  • Good grass may be trampled and ruined.
  • Ungrazed grass becomes stemmy and unpalatable.
  • Constant exposure to pests and diseases.

Zero Grazing

• Animals do not graze on pasture; grass is cut and brought to them.
• Also called ex-situ grazing; useful when animals are housed year-round.
• Catch crops can also be used for zero grazing.
• Advantages:
  • No poaching or compaction of land.
  • Energy saved on movement leads to higher LWG and milk yields.
  • Distance from yard not an issue.
  • Water sources and fencing not required in the field.
• Disadvantages:
  • Extremely labor-intensive.
  • Costly in terms of labor and diesel.

Complementary Grazing Systems

• Animal management systems used alongside rotational systems.
• These systems work in combination with other grazing systems, not instead of them.

Creep Grazing

• Used when young animals graze with adults.
• Paddock subdivided to give young animals access to fresh grass adults can't reach.
• Gate too small for adults allows access to fresh grass.
• Young animals can move freely back and forth.
• Advantages:
  • Young animals can suckle longer.
  • Access to fresh grass for weight gain.
  • Additional concentrate rations (creep feed) can be provided exclusively to young animals.
  • Avoids disease and parasite build-up in young animals.
• Disadvantages:
  • High costs of mobile fencing and water sources.
  • Labor-intensive if combined with strip grazing.

Leader-Follower Grazing

• Extension of a rotational system.
• Young and older animals are in separate paddocks for the whole rotation.
• Young animals graze first, followed by older animals.
• Advantages:
  • Freshest grass provided to youngest animals for growth.
  • Avoids disease and parasites in young animals.
  • Increased grass usage as older animals graze what young animals leave.
• Disadvantages:
  • Same as rotational systems.
  • Costly with mobile fencing and water sources.
  • Labor-intensive with daily animal and fence movement.

Mixed Grazing

• Cattle and sheep grazed together on the same pasture.
• Do not graze sheep and goats together (same endoparasites).
• Takes advantage of differences in grazing habits and parasite types.
• Advantages:
  • No grass wasted as sheep are less selective than cattle.
  • Reduces internal parasite numbers in each species.
  • Production of each animal type increased by 10-15%.
  • Increased tillering of grass due to close cropping by sheep.
• Disadvantages:
  • Lower density of each animal type.
  • Same disadvantages as the rotation system (cost and labor).

Extended Grazing

• Extends grazing period into winter (December to March).
• Reduces the carbon footprint of the enterprise.
• Grazing land closed off from July to allow grass build-up.
• Advantages:
  • Reduces the need for winter housing and feeding increases profit margins.
  • Reduces need for silage and concentrates reducing dependence on market prices.
  • Makes the enterprise more sustainable, and reduces carbon footprint.
• Disadvantages:
  • Poorer grass quality in autumn and winter may affect LWG.
  • Weather can make land unusable (flooding or poaching).
  • Reduces pasture available for normal grazing later in the year.
  • Can decrease ryegrass proportion and increase annual meadow grass.

Grassland Management – Fertilising Grassland

• Grassland requires careful maintenance and fertilization like tillage fields.
• Nitrogen is especially needed when intensively grazed.
• Nitrates directives must be followed when applying nitrogen.
• Manure deposited during grazing must be considered in the nitrogen budget.
• One dairy cow (1 LU) produces 85kg of nitrogen per year.
• Nitrogen requirements are reduced with clover present.
• Fertilizer application should always follow soil testing and soil index results.
• The table shows maximum nitrogen contributed by livestock at different stocking rates.
• Generally, the maximum application is 170kg per hectare per year (2 LU per hectare).
• Additional nitrogen is the difference between livestock N and maximum N.
• At 2LU/ha, maximum additional nitrogen would be around 36kg.

Phosphorus

• Additional fertilizers should be applied only after soil tests, and only if a soil is deficient in a particular nutrient.
• Phosphorus application depends on Soil Index; no additional P needed at index 4.
• Phosphorus needed will depend on the stocking rate.
• At the highest stocking rate (211-250 kg/ha/yr) and assuming the lowest soil index (1) the maximum amount of P applied would be 39kg/ha.
• If the grass is being cut for silage with no grazing, then at the poorest index (1) the max P is 40kg/ha before the first cut, and 10kg/ha before the second cut.

Indirect Impacts of Grassland Management

• Goal: optimize grass production and quality for year-round livestock feeding.
• Management actions maximize grass production, quality, and efficient use.
• Grassland management impacts livestock and wildlife.

Impacts of Grassland Management on Livestock

• Reduces disease and endoparasites.
• Rotational grazing breaks the lifecycle of endoparasites.
• Disease is minimized when animals avoid grazing around dung.
• Mixed grazing results in higher growth rates for both sheep and cattle.
• Creep grazing allows calves access to their mothers for suckling.

Impacts of Grassland Management on Wildlife

• Use of pesticides and herbicides affects pollinators.
• Excess nitrogen fertilizers decrease soil invertebrate diversity.
• Run-off from fertilizer causes eutrophication.
• Diversifying grazing swards benefits pollinators and insects.
• Ploughing and reseeding decrease biodiversity if old pasture is replaced with a new ley.
• Ploughing has a negative impact on soil structure and soil invertebrates.
• High stocking rates result in high nitrogen and soil compaction, which is bad for biodiversity.
• Semi-natural and rough grazing have the highest bird and butterfly diversity.
• Closely cropped grass dramatically decreases the number of invertebrates found; spiders need a taller stem length.

Grassland Management – Health and Safety

• Health and safety considerations are paramount.
• Consider the Hazard, Risk, and Precautions.

Working with Livestock

• Hazards: livestock (cattle or sheep).
• Risks: being kicked, trampled, crushed, bitten, injured by horns.
• Precautions:
  • Ensure an escape route.
  • Handlers should be capable and experienced.
  • Be aware of cattle behavior.
  • Cows in heat are unpredictable.
  • Mothers with young are protective.
  • Don’t put a bull in a field with public access.
  • Do not isolate or corner an animal away from the herd.
  • Inspect and maintain fencing.
  • Gate locks and latches should be operational and checked frequently.
  • External fencing should be stock-proof.
  • Have a plan for moving animals.
  • Be calm and avoid panicking animals.
  • Ensure only one option for cattle movement.

Working with Fertilisers

• Hazard: Fertilizers themselves.
• Risks: irritation/burning of skin and eyes, inflammation of respiratory system; fire hazard.
• Precautions:
  • Agrochemicals should always be fully labelled.
  • Chemical storage should be correct and specific to each chemical.
  • Persons handling chemicals should wear suitable PPE.
  • Use automated chemical sprayers where possible.
  • Ensure all parts of the sprayer are clean and well maintained before use.
  • Store bags of fertiliser at least 10m from drains and waterways.
  • Do not mix types of fertiliser in the same storage space.
  • Do not store fertilisers with combustible materials, or near heat sources / sources of ignition.

Working with Machinery

• Hazard: Vehicles and machinery.
• Risks: being crushed, struck, pinned; entanglement in PTO; injury by moving parts.
• Precautions:
  • Check machinery is in good working order.
  • Ensure all operators and drivers are trained.
  • Park on flat, solid ground; lower machinery.
  • Use caution around the PTO shaft.

Electric Fencing

• Risks: shocks and entanglement.
• Precautions:
  • NEVER use barbed wire for electric fencing.
  • Never work near live fencing in an enclosed space.
  • Never try to crawl under live fencing.

Conservation of Grass

• Conservation refers to storing grass for future use, especially as winter feed.
• Conserving grass as hay or silage is relatively cheap.
• Two main methods: fermentation (silage) and dehydration (hay).

Conservation of Grass as Silage

• Process of conserving grass as silage is called “ensiling”.

How and When to Cut the Grass for Silage Production:

• The weather: Needs to be good weather, not windy or wet
• The heading date of the grass: Early = May, late = June. This will determine the peak productivity
• Aiming for the peak digestibility: This is the peak DMD of the grass (around 75% at the heading out day, then declines after that).
• Aiming for peak carbohydrate level: Carbohydrates are needed for the fermentation process, so we want to maximise the carbohydrate content at cutting

Maximising Carbohydrate Content:

• Cut at peak vegetative growth
• Do not cut soon after rain
• Let the grass wilt on the field after cutting
• Cut grass in the afternoon
• Use additives

Additives

• Acids aid preservation and lower pH.
• Sugars increase carbohydrate concentration.
• Enzymes break down grass fibers.
• Bacterial inoculants speed up fermentation.

Biochemistry of Silage Production:

• Grass is preserved by acid from fermentation of carbohydrates.
• Anaerobic bacteria produce acid.
• Oxygen must be removed.
• Rolling and sealing removes oxygen.
• Bales must be carefully wrapped, silage pits carefully covered; oxygen causes rotting.

Silage Quality Comparison:

• High Quality:
  • High sugar content.
  • Lactobacillus bacteria.
  • Lactic acid.
  • Palatable and digestible.
• Low Quality:
  • Low sugar content.
  • Clostridium bacteria.
  • Butyric acid.
  • Unpalatable and low nutrient.

Silage Production Methods:

• Bale Silage versus Pit Silage

Pit Silage:

• Grass is cut and wilted.
• Collected with forage harvester and brought to the silage pit.
• Silage pit structure: a 3-sided concrete structure with a concrete base.
• Machinery is used to roll grass to force out oxygen.
• Heavy-duty plastic sheeting is used to seal the surface to prevent oxygen getting in, and it is often held down with old tires.
• Advantages:
  • Less plastic used.
  • Large amounts can be stored in one place.
• Disadvantages:
  • Entire pile can rot if covering fails.
  • Must be used once uncovered.
  • Not suitable for small farms.

Bale Silage:

• Grass is cut, wilted, and baled as round bales.
• Bales immediately wrapped in multiple layers of plastic.
• Black plastic is most common.
• Care must be taken when moving and stacking the bales to ensure that there are no holes made in the plastic.
• Bales should be stacked carefully.
• Popular option on smaller farms.
• Advantages:
  • Any excess bales can be sold.
  • Lower spoilage.
  • More nutritious due to lower DM loss.
  • Baling is less expensive, and there are low transport costs
  • Reduces effluent if the bales are wrapped correctly
• Disadvantages:
  • Higher cost per unit of silage.
  • More plastic waste.
  • More labor intensive to feed out

Environmental Impacts of Silage Production:

• More environmental impacts than hay.

Effluent:

• Waste liquid produced in the early stages of ensiling.
• Contains high levels of nutrients and nitric acid.
• It is very polluting if it gets into watercourses because of high levels of nutrients and nitric acid
• Silage pits must have secure storage.
• Greater effluent risk from round bales.
• Effluent can be diluted and used as a fertilizer.

Plastic:

• Significant waste plastic generated.
• Recycle silage wrapping when possible.
• Select more recyclable wrap or biodegradable options.

Quality Assessment:

• High carbohydrate content.
• Acid for preserving grass.
• Lactobacillus fermentation, not Clostridium.
• Overly wet or slimy silage is a sign of Clostridium.

Conservation of Grass as Hay

• Less detailed than silage production.
• About 20% of grass in Ireland is conserved as hay.
• Heavily reliant on good weather for drying.
• Equipment similar to silage production.
• Mower conditioner cuts and makes swathes.
• Baler makes round or square bales.
• Rotary tedder aerates swathes.
• No effluent is produced, and no plastic is required.

How and When to Cut:

• Done when DMD is highest (May or June).
• Needs prolonged good weather (grass needs to dry out to only about 20% moisture).
• Grass should not be grazed for 6 weeks prior to hay cutting

How Hay is Preserved:

• Preserved by dehydration.
• Haylage is intermediate between hay and silage.

Haylage:

• Grass left to dry for a few days (60% moisture).
• Bales wrapped in plastic.
• Conserved through fermentation and acids.
• Lactic acid from Lactobacillus preserves the grass

Machinery Used in Grass Conservation

• Students should be able to identify machinery from images.

Mower Conditioner

• Cuts grass.
• Pushes grass through rollers for drying.

Rotary Tedder

• Shakes up swathes for faster drying.
• Used in hay production only.

The Baler

• Makes square bales for hay, round bales for silage.
• Silage bales are wrapped.

Forage Harvester

• Picks up swathes and drops grass into a trailer.
• Used for pit silage.

Storage of Conserved Grass

• Serious risks associated with storage.
• Correct storage mitigates accidents.

The Silage Pit:

• Hazards: overturning machinery.
• Precautions:
  • Never overfill.
  • Slope sides at a safe angle.
  • Place rails on sunken pits.
  • Never go under the cover (suffocation risk due to oxygen used up during fermentation).

Hay and Silage Bales:

• Surface should be level, smooth, and well-draining.
• Stacks should be away from power lines.
• Remove bales from the upper row first.
• Monitor remaining bales.
• Round bales should be stored on their flat ends.
• Square bales should be stacked using an interlocking pattern.
• The height of the stack should not exceed 1.5 times the width of the base.

Conservation of Grass – Health and Safety

Working on the Silage Pit:

• Hazards: Silage pit, steep slopes.
• Risks: being crushed, falling, suffocating.
• Precautions:
  • Do not overfill the pit.
  • Slope sides at 45 degrees or less.
  • Mark edges clearly.
  • Never go underneath the silage cover.

Working With Machinery:

• See “machinery” in the grassland management H+S section.

Harvesting:

• Harvest time sees peak in farm fatalities due to a limited time-window creates pressure on farmers.
• Tractors, harvesters and farm vehicles pose a significant risk.
• There are a high number of accidents associated with the improper storage, handling, and transport of bales.
• Precautions:
  • All farm workers should take adequate breaks for food and rest.
  • Safety guidelines for working with machinery must be carefully followed
  • Extra care must be taken to ensure vehicles are legal and roadworthy if there is a need to use public roads to access different pastures for harvest.

Working with Bales:

• Hazard: Bales.
• Risks: being crushed, falling, being rolled over, crushed by bale handling equipment.
• Precautions:
  • Never climb on stacks.
  • Stacks should be stable.
  • Store on a level surface
  • If stacking is necessary, round bales should be stacked on the rounded side, to a max of 3 bales high.
  • Never take bales from the middle or bottom layers.