Thursday, 29 June 2017 14:55

Where will all those inputs end up?

Written by  Adam Duker
Effluent loss to waterways is a major risk to water quality. Effluent loss to waterways is a major risk to water quality.

Why is it important to reduce sediment, phosphorus and E. coli losses from winter grazed paddocks?

On dairy farms there is potential for large losses of sediment, phosphorus and faecal microorganisms, which may impact water quality in streams and rivers.

The effects can be addressed by good environmental management practices (GMP) onfarm. These will reduce your environmental and business risk and result in a more sustainable farm and healthier environment.

There are expectations from our consumers and our communities to farm in an environmentally responsible manner and being able to say and prove “I farm to good management practice standards” is important.

Nutrients

Nutrients come from multiple sources on farm such as fertiliser, effluent, nitrogen fixation, supplementary feed and irrigation water. Having a good understanding of where nutrients come from and go to on your farm means you will be able to make better decisions, e.g. about purchasing and applying fertiliser.

Applying the right amount of fertiliser in the right place at the right time will ensure the best possible response and return on investment and will minimise the risk of losses to water.

Effluent

Effluent loss to waterways is a major risk to water quality because of the nutrients and faecal bacteria it contains. All milk companies require effluent systems to be fit for purpose and be able to achieve 365-day compliance with the rules.

Ensuring effluent is applied to pastures and crops, at the appropriate depth, rates and times, reduces the risk of nutrient loss through leaching and runoff and maximises the value of effluent in terms of nutrient uptake.

Having sufficient effluent storage will allow you to store effluent when soil or weather conditions do not suit application.

Waterways

Keeping stock out of waterways ensures stock stay safe and waterways healthy. Stock, when in waterways, deposit dung and urine which increases nutrient and faecal bacteria levels in the water.

The stock also cause erosion and disturb stream banks and beds. Stock exclusion is among the best ways to improve water quality. Sediment, faecal bacteria and phosphorus can also enter waterways by overland flow. The use of buffer strips and riparian planting not only reduces overland flow of nutrients and sediment, it also provides shade and habitat for aquatic life.

Irrigation

Water is arguably the most important resource on farm, even more so on irrigated farms. Often there is limited water available and significant costs may be associated with pumping it around the farm. Water taken for farming is removed from the natural cycle and may reduce stream flows or groundwater levels.

Ensuring water is not wasted will save money and benefit the environment. A well-designed irrigation system is easier to manage and more reliable. Managing well is key to ensuring the system operates efficiently and that water is applied at the right depth across the farm. This will result in more even pasture growth and easier pasture management.

Sediment

Land, and more specifically the soils, are fundamental to a productive dairy farm.

Management practices which result in pugging, compaction, extended periods of bare soil and grazing unsuitable land will result in top soil damage, erosion and loss of production. Sediment can be a limiting factor to water quality as it discolours the water and silts up stream beds, thus damaging the aquatic habitat.

Nutrients, most notably phosphorus attached to the sediment, can cause undesirable plant and algal growth which also harms aquatic life. Sediment accumulation has downstream impacts on rivers, estuaries and harbours.

Storage Infrastructure and waste

Feed and fertiliser are costly and a major source of nutrients in the farm system.

Make sure you are getting maximum value from your spending by ensuring storage and loading are done correctly to avoid wastage and reduce the chances of any nutrients entering and contaminating waterways.

Waste, including farm waste, household waste and dead stock, poses the risk of contamination of waterways, groundwater and land. Appropriate management reduces this risk.

Winter grazing of crops

Winter grazing of dairy stock on forage crops can account for a large proportion of annual sediment losses from the whole farm system.

It has the potential for large losses of sediment, phosphorus and faecal microorganisms, which may impact water quality in streams and rivers.

Soil damage and reduced production are additional concerns. Compaction and pugging can seal the soil surface, increasing sediment and nutrient loss.

How can you minimise nutrient and sediment losses when grazing winter crops?

- Strategic grazing management can cost-effectively reduce runoff and sediment loss

- Protect critical source areas (CSAs) which are the areas that contribute to the greatest losses, i.e. gullies, swales and damp areas

- Select winter grazing paddocks that will minimise nutrient and sediment losses

- Consider soil, slope, moisture and stock management before sowing a paddock

- If possible, avoid cultivation and stock grazing in critical source areas

- Graze least risky areas of paddock first and graze towards more risky areas

- Start grazing at the top of a slope and move downhill.

• Adam Duker is a catchment engagement leader at DairyNZ. He gave this presentation at DairyNZ Farmers Forum in Taranaki.

 

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