Healthy farms, healthy fish

Transcript

Plant steep areas

Don’t watch the farm go down the drain! Planting up steep slopes, gullies and stream banks will reduce soil erosion¹⁰ off the farm and keep silt out of the water. Many native freshwater fish cannot tolerate water that has been muddied by excess sedimentation¹¹.

Steep areas on farms are often unproductive. There is ongoing work being done to investigate how to control erosion on these marginal sites while also increasing productivity, such as Mānuka plantation research for medical-grade honey.

Acknowledgement: Showdown Productions

Prevent algal blooms

Healthy water means healthy stock. This means preventing excess nutrients¹² from leaching or running off into waterways. Excess nutrients from fertilisers and effluent coupled with hot weather¹³ and unshaded streams fuels eutrophication¹⁴ and algal blooms¹⁵ that can be fatal to humans, dogs and livestock. Prevent algae¹⁶ growth by fencing and planting waterways to cool the water. Where fencing is impractical, install drinking troughs and shade at the top of the paddock to encourage stock away from swamps and streams.

Dr Ross Monaghan

Nutrient¹⁷ leaching¹⁸ is an environmental issue for two reasons. The first is too much nitrate¹⁹ getting into our groundwater²⁰ aquifers that are used for drinking water supplies. High concentrations of nitrate in drinking water that’s used for making infant formula poses a risk to young infants because they can’t process that nitrate that we as adults can. So we want to make sure that the drinking water we provide has a concentration that the World Health Organisation recommends is less than about 10 milligrams of N per litre²¹.

The second aspect that is coming to attention more frequently in New Zealand and abroad is the problem of eutrophication. Eutrophication is a term that describes the nuisance growth of weed and algae in surface waters²², in streams and estuaries²³. That process is really driven by two nutrients – nitrogen²⁴ and phosphorous. So nitrate that leaves this farm ends up in a lake or an estuary²⁵. If it arrives with phosphorous, together, that’s quite a fertile combination that will promote that nuisance weed and algal²⁶ growth. And the growth can have lots of undesirable effects in terms of how we might be able to use that water for recreational purposes, and habitat²⁷ value, choking out all the other wildlife that can occur.

Winter is a high-risk period for nitrogen leaching because of at least two reasons. The main one is that it’s the time of year when we have a lot of surplus rainfall arriving and thus a lot of drainage and transport of any nitrogen that’s sitting in the soil, potentially available for leaching, and secondly, it’s a time of year when plant uptake is quite low, so particularly if you’ve got a relatively bare paddock, for example, a forage²⁸ crop²⁹ paddock that’s been recently grazed, there’s a lot of nitrogen that’s being returned to that paddock in the form of urine but very little plant uptake until temperatures warm up in the following spring. So those two factors cause winter to be a high-risk leaching loss period of the year.

Acknowledgements: © University of Waikato with additional materials courtesy of Dr Ross Monaghan/AgResearch; Juliet Milne/Otago Regional Council; and Tamara Douglas.

Plant wet areas

Boggy seepages, peat bogs and springs on the farm are an important source of water for streams, especially during dry summer months. These wetland areas are also important for filtering out excess nutrients before they can reach other waterways. Instead of draining, fence and plant with native sedges, toetoe and harakeke³⁰ so they form a buffer zone to absorb and slow down run-off³¹ after heavy rain.

Acknowledgement: University of Waikato

Care for drains

Don’t drain away the farm profits. Fencing and planting drains helps to shade out weeds and keeps silt out, reducing the number of times they need digging out. Less maintenance saves time and money.

Acknowledgement: Ross Henry, 123RF Ltd

Reduce nitrogen

Go easy on the nitrogen. Nitrogen sources on the farm are animal effluent deposits or fertiliser³² application. When nitrogen levels on the farm exceed what the pasture and plants can take up, the excess often ends up in waterways. Further, it can be converted to nitrous oxide³³ (N₂O) – a greenhouse gas³⁴ that contributes to the greenhouse effect, which is a driver in climate change³⁵.

Managing nitrogen on the farm is good farm practice. Farmers can do this in a variety of ways, from planting nitrogen-fixing crops to employing nutrient budgeting tools. Retiring eroding steep hills and boggy areas will also help reduce the amount of nitrogen running off or leaching into waterways. Read more about nutrient management on the farm, or use our interactive to learn more about the Terrestrial nitrogen cycle.

The recent government report Our Fresh Water 2017 confirms that nitrates and nitrogen levels are increasing in our waterways.

Dr Ross Monaghan

Some of the farm management practices that are most commonly employed to minimise the risk of nitrogen loss are to make sure that you don’t apply too much nitrogen per application or too much in any one year. We make sure that farm dairy effluent we’re collecting back in the milking parlour is well managed, so it’s returned to land at a low rate. Something that can help reduce direct losses of urine near to streams is just to prevent stock from urinating directly into those riparian zones³⁶.

Another strategy involves being careful about when urine is deposited back to pastures. Where we can have animals under cover or on a stand-off where we capture the urine and we store it through the risky winter period and return it to land in the following spring, we can reduce nitrate leaching³⁷ losses quite considerably.

One important strategy for helping to manage the nitrogen problem is the way we look after riparian and wetland³⁸ areas. Wetlands³⁹ are really important parts of our landscape that act as filters for some of the run-off, particularly for filtering out nitrogen that’s passing through wetlands. So it’s really important that we protect the wetlands that we have remaining and reinstall some that have been drained and are perhaps overgrazed and to make sure that we don’t allow stock to graze those riparian zones and either cause treading damage or excrete urine or dung directly into the waterways.

Urine is very high in nitrogen, and in the case of dung, it’s quite enriched with phosphorous and faecal⁴⁰ bacteria⁴¹. Phosphorous contributes to that eutrophication issue, and faecal material can carry with it zoonotic microorganisms⁴² that can make us sick, so we want to avoid that risk altogether as best we can. The main way is just to put up a fence.

The Overseer® tool is a nutrient budgeting model that has been developed with input from other universities and CRIs. It’s a tool to help just guide nutrient management, and particularly inputs of fertiliser, but also to make sure that we don’t double up on fertility from effluents as well as from fertiliser. And increasingly, that tool is being used as a calculator to determine, for example, the nitrogen footprints to either water or to atmosphere⁴³ from different types of farming activity and different types of landscapes and soils and climates. That tool is going to be essential to allow us to explore ways by which farmers can look at their budget and say, “OK, how can I maximise my nutrient efficiency, how can I minimise my losses, and how can I get the most bang for my buck in terms of purchasing fertiliser?”

Acknowledgements: © University of Waikato, with additional materials courtesy of Dr Ross Monaghan/AgResearch and McDonald’s Lime.

Fence stock out

Stock can damage stream edges, and the direct depositing of their faeces⁴⁴ (poo) and urine into the water dirties the water and adds to the rising nitrogen levels. Native fish need good stream banks for hiding in and laying eggs, and they’re also intolerant of dirty water.

For farmers, hauling cows out of swamps and waterways on a miserable winter night is no fun. A good dairy cow can be valued at $1,500, so losing them is expensive.

Farmers all around the country are realising good environmental practices, such as fencing off waterways, makes good business sense and is good farm practice too.

Acknowledgement: University of Waikato

Fish-friendly culverts

Fish passage is critical for our native species. Many need to be able to migrate in order to complete their life cycle.

Look at the culverts on the farm and identify culvert crossings that work well for fish and those that don’t. Fix those that aren’t working by adding ramps and/or baffles.

When looking to install new culverts, make sure these are fish friendly too!

Cheri van Schravendijk-Goodman

The problem with culverts in tributaries⁴⁵ are that they disconnect habitat from the main stem of the river. A culvert is a big pipe, often used for helping with drainage of land, but the problem with the culverts is they tend to sit kind of this high off the surface of the water or maybe a bit closer depending on what the river’s doing. Now our whitebait – species like kōkopu⁴⁶ and that – they can climb but they can’t jump. They’re not superfish.

Fish ramps and baffles are infrastructure⁴⁷ that we’re going to hopefully retrofit⁴⁸ to these culverts and floodgates to improve connectivity between the river and the tributary⁴⁹, because kōkopu and kōaro like to get up into those tributaries, probably īnanga⁵⁰ as well, and they perhaps could be where they’re spawning⁵¹, so we want to make the passage as smooth as possible without impacting on the actual adjacent land use, you know, because the culverts and that do perform a function. Often it could be related to human safety, particularly the floodgates. We don’t want to make it difficult for humans and nature to co-exist.

Rock ramps or a fish ramp is a way for reconnecting those tributaries that have these barriers like these culverts and floodgates.

The techniques that have been applied by NIWA is using rocks embedded into concrete ramps. Our fish are really good climbers, our galaxiids, and so you try and create a way to help them get up to that culvert. It also provides a rest spot for the fish.

A baffle is a rocky substrate⁵² or a brick or something inside the culvert, and again that’s about giving the fish something to climb up on to and to rest.

Culverts create a really unnatural system. Normally, when these tributaries come down, their flow would be slowed down by twists and turns and rocks and stuff. Culverts are just one straight smooth system, so the water velocity⁵³ can get really, really fast and hard. By putting baffles in there, you’re not only giving an opportunity for these fish to be able to climb up the incline of those culverts but also giving them a bit of a place to rest and be protected sometimes when they’re tired.

Acknowledgements: © University of Waikato with third-party materials courtesy of Cheri van Schravendijk-Goodman, Dr Bruno David (WRC) and Dr Cindy Baker/NIWA. Certain photos in this video are the copyrighted property of 123RF Limited, their contributors or licensed partners and are being used with permission under licence. These images and/or photos may not be copied or downloaded without permission from 123RF Limited. The Waikato Tainui College for Research and Development acknowledges the financial support given by the Waikato River Cleanup Trust Fund, which is administered by the Waikato River Authority. The Waikato River Cleanup Trust does not necessarily endorse or support the content of the publication in any way.