1.5 - Describe the environmental impact of primary production management 11 Ag/Hort

Unit Overview

Over-Cultivation Describe the circumstances of over-cultivation? break up of soil to a particle size less than crumb size What is its impact on the environment? Destroys soil structure Fine soil is easily eroded by wind Soil compaction causes poor aeration/drainage

Solving The Over Cultivation Problems Minimum tillage – use herbicides to kill weeds, minimal cultivation to control weeds and reduce soil structure damage, direct sowing of seeds into uncultivated seed bed Add lots of organic matter to decrease loss of soil structure Quickly re-establish plant cover to reduce soil erosion. Plant roots hold soil together Cover bare ground with a mulch to reduce soil erosion

Disposal of Animal Manures Describe the circumstances of the disposal of animal manures. Animal manure from dairy farm milking sheds or piggeries can be: sprayed onto paddocks, placed into settling ponds (best) What is its impact on the environment? The effluent is rich in Nitrogen Spraying effluent onto paddocks can contaminate soil water The effluent can leach through the topsoil and enter the groundwater used for drinking water OR drain into waterways which will then be rich in nutrients

Solving the Effluent Disposal Problems Put effluent into settling ponds. Once settled then apply the liquid to paddocks Monitor the water status of the soil to avoid runoff

Indiscriminate Use of Chemicals Describe the circumstances of the use of chemicals. Chemicals can be used to kill insects, plants, diseases What is its negative impact on the environment? Chemicals can harm other organisms eg plants, humans, animals, natural enemies of the pest Chemical residues can be left in the soil Chemicals in the soil can wash into waterways and harm fish Pests can become resistant to the chemicals, and no longer be killed Spray drift harms non-targeted organisms

Solving the Indiscriminate Use of Chemicals problems Use of Integrated Pest Management (IPM) to reduce the use of chemicals Use environmentally friendly organic sprays instead of more toxic conventional sprays Use biological control to manage pests ‘naturally’

Indiscriminate Fertiliser Application Describe the circumstances of fertiliser application. Fertiliser is added to soil to improve plant health or growth Indiscriminate means fertiliser is applied without care What is its impact on the environment? Heavy applications of fertiliser increase the chances of fertiliser runoff Fertilisers feed nuisance plants (weeds) and algae in waterways Algae and nuisance plants affect stream life and drains, making water unpleasant for swimming and drinking

Solving the Indiscriminate Fertiliser Application Problems Correct application timing depending on the weather and time of year to minimise leaching Reduced rates of fertiliser applied to the land which requires good monitoring of soil nutrient status Changing the type of fertiliser from a fine material to pelletised fertiliser that will not be too easily leached away Apply away from waterways so they do not become nutrient rich

Burning Waste Describe the circumstances of burning waste. Burning is a method of disposing of plant stubble, hedge trimmings, fallen trees, tree stumps, rubbish What is its impact on the environment? Burning creates smoke, ash, carbon dioxide which pollutes the air Other dangerous chemicals can be released when rubbish is burnt, which can harm people and animals Loss of control of the fire leads to damage of non-targeted plants, habitats, animals

Solving the Burning of Waste Problems Compost plant material and use as a fertiliser or soil conditioner Chip plant material and use as a mulch

High Density Sheep Grazing Describe the circumstances of high density sheep grazing. Pasture is grazed at a high density during rotational grazing Sheep graze close to the soil surface leaving only a little plant cover What is its impact on the environment? Increases the risk of erosion by killing pasture plants and so increasing the exposure of soil Increased erosion causes water to be murky and affects plant life Poor water clarity makes water unsafe for swimming

Solving the High Density Sheep Grazing Problems Reduce stock numbers so there are fewer animals grazing the same area Move stock faster so less intensive grazing occurs Change the type of pasture to one that can tolerate harsher conditions Increase plant health by fertilising the soil. This will allow more animals to graze the same area because the feed supply will be increased

Use of Compost Describe the circumstances of the use of compost. Decomposition of organic waste material What is its positive impact on the environment? When added to soil, micro-organisms breakdown organic matter, improving the soil structure (ie aeration, drainage, water holding ability) Nutrients are added to soil so nutrients from another environment are not imported Organic matter is broken down by micro-organisms releasing nutrients for plant uptake, requiring less mining of fertilisers Nutrients are re-cycled

Treatment and Recycling of Effluent Describe the circumstances of the treatment and recycling of effluent. How, what, when, where, why What is its impact on the environment?

Biological Control Of Insects Describe the circumstances of the biological control of insects. The natural enemy of a pest is used to kill the pest What is its positive impact on the environment? It does not kill other organisms A lot of chemicals are not needed to control the pest

Crop Rotation Describe the circumstances of crop rotation. What is its positive impact on the environment? Write an answer involving Fertiliser Write an answer involving Pesticides

Use of Resistant/Tolerant plants Describe the circumstances of resistant or tolerant plants. What is its positive impact on the environment?

Pest Monitoring Describe the circumstances of pest monitoring. This involves observing and recording pest numbers What is its positive impact on the environment? Spraying occurs when the pest population reaches a particular level, reducing excessive quantities of chemicals entering the environment

Use of Riparian Strips Describe the circumstances of riparian strips. These are strips of land either side of a waterway that are fenced off. The strips are planted with shrubs and trees What are there positive impact on the environment? Stock don’t enter the waterway and excrete /urinate in it so water quality is improved The plant roots bind the soil, reducing erosion Fertiliser is not applied to this area so less fertiliser runs off into the waterway

The End of the Year