Sources and pathways for nutrients and to water and means of intervening CSG 14th August 2014 This presentation is an introduction to the sources and pathways of nutrients and microbes into water and some of the interventions available to reduce the loss. This information will assist in your understanding of the relationship between land and water.

Presentation format Sources , Pathways and Variability Targeting interventions Whatawhata case We will outline sources, pathways and interventions and then we will take some time to look in detail at the work undertaken at Whatawhata research centre

Water Quality What is Water Quality? A variable, often defined by communities, but good quality may be water that is safely drinkable, swimmable and fishable, supports cultural values and healthy ecosystems. The three main issues affecting water quality in rural settings are: Suspended sediments: that smother the beds of rivers and estuaries Nutrients (nitrogen, phosphorus): that encourage excess plant growth, algal blooms Faecal microbes: that affect human, and often animal, health. A recap on how we define water quality and why the focus on the four contaminates

On Farm Nitrogen cycling and losses Values are kg N/ha/year Milk Meat 65 250 75 dung urine Feed N Fertiliser N 20 120 N fixation 2 60 ammonia 370 35 NO3 35 leaching N2 O 5 Urea - N Organic NH 4 rapid slow This demonstrates cycling of nutrients within a dairy cow system. It shows the inputs and outputs and the biological processes in the animal, plant soil interaction. Note the low level of nutrient leaving the system via leaching compared to the levels through out the cycle. In a paddock, nutrients and sediment are perceived as a resource promoting plant productivity, but downstream they can become pollutants. 3

Nitrogen cycling and losses Meat Wool 15 Values are kg N/ha/year Fertiliser N 20 N2 fixation 60 urine 125 200 dung 60 N2O, N2 5 ammonia 15 NH4 NO3 Organic - N Urea slow A ‘typical’ N cycle for a sheep & beef farm shows low conversion of N cycling into product and a large amount of N excreted in urine which represents a major source of N loss. rapid leaching 15

Sources

On Farm Sources of N Nitrogen (1) urine patches, (2) fertiliser, (3) effluent irrigation, (4) clover N-fixation, (5) rain/atmosphere 4 A major N input to the system comes from the urine of livestock. There is also a background level of nitrogen entering the system through biological nitrogen fixation from legumes. Fertiliser N and the N present in effluent 1 2 3

Sources of nitrogen entering streams in the Waikato region This demonstrates the contribution of different land use to N entering streams in the Waikato. Niwa data

Farm Sources of P Phosphorus (1) fertiliser, (2) soil erosion, (3) animal excreta/effluent irrigation P attaches to soil particles and is introduced to the system through phosphate fertiliser. It is present in livestock excreta and effluent irrigation 1 2 3

Sources of phosphorus entering streams in the Waikato region This demonstrates the contribution of different land use to P entering streams in the Waikato Niwa data

Farm Sources of Sediment (1) grazed pasture, (2) stream bank/bed erosion, (3) animal excreta, (4) animal tracks, (5) unpaved roading 1,2 3 4 5 Sediment leaving hill land can accumulate in stream banks and be moved through the system after storm events. Sediment also accumulates on flat surfaces where it may be deposited after storm events

Faecal microbes what are they? Rotavirus faecal microbes viruses bacteria protozoa Indicator: enteroviruses, phages Pathogens: human enteroviruses and adenoviruses, noroviruses, rotaviruses, hepatitis A Indicator: E. coli Pathogens: E. coli, Campylobacter, Salmonella Indicator: Clostridium perfringens spores Pathogens: Giardia, Cryptosporidium Campylobacter Crytosporidium Faecal microbes is a generic term that covers: virus; bacteria and protozoa all of which impact on human health. Indicator species are used in monitoring to act as a proxy for a range of these microbes.

Sources of Faecal Microbes 1 (1) grazed pasture, (2) effluent irrigation, (3) wild and feral animals, (4) livestock in, or close to, waterways, (5) laneways connected to drains 2 4 5 Animals and birds are a source of microbes into water 3

Critical source areas 80% of losses come from 20% of area pathway Critical source area Within a landscape 80% of losses may come from around 20% of the area the 20% is therefore noted as a critical source area where interventions can be targeted

Illustrating CSA These pictures illustrate what a critical source area could look like.

Pathways The driving force behind contaminant transfer from land to waterbodies is water, because it provides the energy and the carrier for contaminant movement.

Location where a water quality objective/ limit The Challenge….Managing contaminant movement to waterways Once a contaminant is generated from its source it travels through different pathways before it reaches a water body. Location where a water quality objective/ limit has been set

The Water Cycle This is a schematic of the water cycle processes and shows the pathways that contaminants travel through.

Attenuation Attenuation is the permanent loss or temporary storage of nutrients, sediment or microbes during the transport process between where they are generated (i.e., in the paddock) and where they impact on water quality (i.e., a downstream water body, such as a lake). It is important to understand the concept of attenuation as it acts as a natural intervention resulting in a reduction of concentration of nutrient entering receiving waters

Attenuation Generic attenuation processes include flow attenuation, deposition, microbial transformations, vegetation assimilation and other physical and biogeochemical processes.

Attenuation These processes can alter pollutant concentrations and loads by: (i) decreasing the mean concentration or load, (ii) decreasing variability of concentration or load, (iii) increasing the total

Time Lags Hydrological and biogeochemical processes that result in long residence times of nutrient and sediment pools in catchments, stream channels and lakes and reservoirs. Such time lags, sometimes referred to as legacies, reflect the fact that the land-cover conversion and nutrient and sediment pollution may have occurred for decades to centuries prior to what you see today. The concept of Lag is another important one as what you see today may be the result of land use decades before and when interventions are put in place it may be several decades before you see the improvement because of the lag.

Variability in time (Dairy monitor catchments) This slide demonstrates the lag in observed improvement to interventions put in place in 1996 Lag in response of suspended sediments (SS) and total phosphorus (TP) to improved stock exclusion and reduced pond discharge in 1996

Variability through space and time Consequences for what and where This then takes us on to another concept, that of variability

Variability and land use types None Sheep Mixed Deer Dairy Arable Variability and land use types Different land use types result in different contaminant losses adding further spatial variability The wide range of losses within a land use is due to: climate soil type topography management Infers much gain can be made Different land use types result in different contaminant losses adding further spatial variability and the information shows that there are gains to be made through changes in land use

Variability in performance Farm nutrient efficiency and N losses to waterways Room for improvement to low leaching levels Waikato Indicates that there is room for improvement on those farms that are currently leaching over 40kg of N/ha/year

Targeting interventions; what are they? An instrument (e.g. a sensor) A system (e.g. climate forecasting) A farm management practice (e.g. time of application of N fertiliser) A product A catchment intervention (e.g. Riparian margins) Infrastructure (e.g. Irrigation scheme) Included also are enablers of technologies such as decision support tools e.g. Crop calculator There are a range of intervention types that can be used to reduce concentrations of contaminants

Farm Scale

Good Management Practice But how much when you’re farming well? Good Management Practice is a term used a lot. The land and water forum note that farmers can be expected to at a minimum implement good practice however what that is and what it means when applied are not well understood or agreed on. Also it is not necessarily the case that application of good management practice by all farms will meet any community derived limit for water quality Good Management Practice Numeric catchment limits for nutrients

Good Management Practice Examples: • Whole farm (map, plan, skills) • Land (erosion control, ground cover) • Plant (fertiliser use, irrigation, crop residues) • Animal (effluent, grazing) • Other (waste, agrichemicals)

Nitrogen Interventions: Cost-effectiveness Low Impact (0-10%) Medium Impact (10-30%) High Impact (>30%) High Cost Restricted grazing Enhanced waste water treatment systems Winter housing and manure management Medium Cost Supplementary feeding, low N diet High sugar grass Improved irrigation, farming practice Greater root activity Lipids or ionophores High tannins DCD North Island Duration control grazing Environmental forecasting BioChar Soil processes, new products & formulations (commercial) Ryegrass N use efficiency Constructed and managed wetlands, denitrification systems DCD South Island Match land to agricultural use Diuretic supplementation or N modifier Low N pasture Change Animal Type Optimal fertiliser management Effluent management Gain in nutrient efficiencies by nutrient management, farm systems approach, overseer, Precision agriculture -targeted mitigation high N areas Optimise timing of pasture grazing / feed to lower N in diet Groundwater assimilative capacity Examples of the cost benefit of applying interventions for reducing N leaching Low cost

Improve Production Efficiency: e.g. N Improved production efficiency of N can be achieved with higher genetic gain animals, better pastures and efficient use of artificial N, optimizing stocking rates and use of animal shelter e.g.: Scenario Profit ($/ha) Production (kg MS/ha N loss (kg N/ha) Baseline Canterbury dairy farm (modelled) 2000 1500 40 Current breeding worth & better N management 2150 1600 35 High breeding worth, low stocking rate & better N management 2450 1750 20 High breeding worth, high stocking rate & better N management 2500 We should also take into consideration productivity gains within the farm system as improving efficiency can also retain nutrients within the product part of the farm system

Phosphorus Interventions: Cost-effectiveness Low Impact (0-10%) Medium Impact (10-30%) High Impact (>30%) High Cost Buffer strips Natural and constructed wetlands Aluminium sulphate to pasture / cropland Sorbents in and near streams Irrigation water use and recycling Medium Cost Effluent pond storage / low rate application Tile drain Restricted grazing Stream fencing Low Cost Fertiliser management - Optimize soil P, low water soluble P fertiliser Examples of cost benefit for P interventions

Precision Farming Technology Options and Timeline Tools developed that provide real-time monitoring to match the supply of water & nutrients with crop demand to maximise productivity: 2013 Crop calculators Water & irrigation management tools Variable rate irrigation 2016 New crop calculators developed (e.g. onions, kiwifruit) Advanced climate and weather forecasting Advanced irrigation scheduling Decision support tools must also be taken into consideration when thinking about interventions and we have some examples here of the use of increasing efficiency through precision application

Next generation dairy farms P 21 II Waikato: Higher genetic merit cows, lower stocking rate, lower replacement rate, off-paddock periods in autumn/winter, reduced N fertiliser inputs and improved dietary balance The Pastoral 21 mark 2 programme is funded by the Ministry for Business Innovation and Employment (MBIE) and primary sector partners. It is designing farm systems for future use that focus on the animal, plant and soil.

Catchment Scale

Buffers & contaminants Filtering surface runoff RIPARIAN ZONE LIVESTOCK STREAM RIPARIAN ZONE LIVESTOCK STREAM Filtering subsurface flow Stream bank stabilisation RIPARIAN ZONE LIVESTOCK STREAM RIPARIAN ZONE LIVESTOCK STREAM Setback This illustrates the pathways within a catchment and where to plant buffer strips

Performance comparison Riparian fencing Subsurface flow filtering Grass filter strips 0 10 30 50 100 % low medium high sediment phosphorus nitrogen Seepage wetlands This slide demonstrates the efficacy of buffers

Waiokura WQ trends 2001/08 More milk from catchment AND Parameter Trend Reasons Sediment 40% Riparian management Faecal bacteria Fewer Pond discharges Nitrate N 14% More cows/Increased N fertiliser use Total P 30% Fewer pond discharges Less P fertiliser used Waiokura was one od the dairy catchment and shows the impact of buffers on reducing contaminants More milk from catchment AND environmental expectations being met

Catchment Interventions: Cost-effectiveness Low Impact (0-10%) Medium Impact (10-30%) High Impact (>30%) High Cost Constructed wetland and managed natural wetlands Improved waste water treatment technologies Medium Cost Catchment-wide riparian management Storm-flow mitigation Low Cost Riparian management guidelines Environmental forecasting, detailed time and space Critical source area mapping and targeted controls Cost-benefits of some of the catchment interventions

Ambulance at the bottom of the cliff- Catchment Restoration interventions Sediment capping Lake Okaro (30 ha) modified zeolite application c. $75,000 p.a. over 3 years Phosphorus inactivation Lake Rotorua alum dosing $1M p.a. Dredging Expensive although costs will vary considerably depending on circumstances Oxygenation/destratification Destratification trial in lake Rotoehu (790 ha): $524,000 Hypolimnetic withdrawal Limited application so far in NZ but proven to be “low cost” in Europe and USA. Weed harvesting Hornwort harvesting in Lake Rotoehu (790 ha): $52,800 p.a. $22/kg N and $165/kg P Diversions Ohau Channel wall in Lake Rotoiti (124 ha): $10 million This slide demonstrates the huge cost to try and restore water quality

Whatawhata Case Whatawhata Case