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Table of Actions

Actions have been scored for effectiveness, relative cost, and response using science and expert knowledge developed within the Our Land and Water National Science Challenge.

Sort contaminants by high to low for N (Nitrogen), P (Phosphorus), S (Sediment), and M (Microbes).

Effectiveness = kg of nutrient or sediment or coliform forming units retained or immobilised and categorised into Low (0-33%), Medium (34-66%) and High (67-100%).

Relative cost = Cost breakdowns are assessed as Low, Moderate, and High for each contaminant with in indicative cost in $/ha/yr. Nitrogen (Low <100, Moderate 101-366, and High >366 $/ha/yr); Phosphorus (Low <111, Moderate 112-476, and High >476 $/ha/yr); Sediment (Low <81, Moderate 82-169, and High >169 $/ha/yr); Microbes (Low <129, Moderate 130-192, and High >193 $/ha/yr).

Response rate = Fast - within a season, Moderate - within a year, and Slow - longer than a year.

The ratings for actions were assessed independently from the Physiographic Environment classification. Effectiveness of actions can be increased by matching the right actions to the landscape setting.

Strategy Description of function Effectiveness % Relative cost ($/ha/yr) Response rate Reaons for variability Factors limiting uptake Co-benefits Example references
Bridging stock stream crossings Avoid direct entry of faeces, urine and entrained hoof mud, and substrate disturbance during stream crossings. Low Low Mod Mod Low Mod Fast Fast Fast Highly dependent on stream length, width and number of crossings per farm. Too many crossings Avoiding stock losses in high flows. Davies‐Colley et al. 2004
Constructed wetlands Modification of landscape features such as depressions and gullies to form wetlands. Slow water movement encourages deposition of suspended sediment and entrained contaminants (e.g. P). High Low Mod Mod High Low Mod Fast Fast Wetland performance depends on intercepting the maximum amount of run-off from the catchment at the right flow rate. No suitable areas on farm (i.e. catchment lies outside of farm area). Flood attenuation, wildlife habitat and biodiversity McKergow et al. 2007
Natural seepage wetlands Natural seepage wetlands at the heads and sides of streams slow water movement through them and encourage the deposition of suspended sediment and entrained contaminants (e.g. P). High Low Mod Mod High High Fast Fast Fast Interception of run-off depends on landscape, hydrogeology and human modification. Price of permanent fencing ≫ temporary fencing. Flood attenuation, wildlife habitat and biodiversity Burns and Nguyen 2002, McKergow et al. 2007
Sediment traps and retention ponds In-stream traps and retention ponds allow coarse sized sediment and associated N and P to settle out. Low High Low High High Mod Fast Fast Fast Although design can be modified to maximise removal via settling, traps are ineffective at high flows when most sediment is transported May require resource consent Potential to buffer storm events and therefore potential downstream flooding. Hicks 1995, Clark et al. 2013
Stream fencing Preventing livestock access to stream, decreases stream bank damage (and sediment inputs via bank erosion) bed disturbance of sediments (and entrained E. coli, N and P) and stops the direct deposition of excreta into streams. High Low Mod Low Low Low Fast Fast Fast Gain is dependent on the area of the farm currently unfenced and stream density. Price of permanent fencing ≫ temporary fencing. Stream shading decreasing water temperature and light for periphyton and macrophyte growth. James et al. 2007, McDowell 2008, Muirhead and Monaghan 2012
Vegetated buffer strips Vegetated buffer strips work to decrease contaminant loss in surface runoff by a combination of filtration, deposition, and improving infiltration. Mod Mod High Mod Fast Fast Strip can become clogged with sediment and function poorly in areas that are often saturated due to limited infiltration or where surface runoff converges and breaks through strips. Land adjacent to stream may not be available or suitable for a buffer strip. Potential to stabilise stream banks. Smith 1989, Redding et al. 2008
Restricted grazing of winter forage crops Restricted grazing of a forage crop in winter to reduce deposition of excreta and surface erosion by grazing animals. High Mod Mod Mod High Low Fast Fast Fast Costs vary widely due to variations in soil type and climate, and on the frequency of use of a restricted grazing strategy. Must be accompanied by a stand-off area that has no connection to a waterway (e.g. runoff/effluent is captured). Decreased pasture damage and N2O emissions. Ledgard et al. 2006, McDowell et al. 2009
Greater effluent pond storage and deferred irrigation Effluent is stored in larger ponds allowing it to be applied to land when soil moisture deficit and physical conditions allow it to be adsorbed and not thus lost in runoff. Mod Mod Low Mod Low Mod Mod Mod Mod Depends on the number of cows, size of pond required, material and suitable location to build a pond. Inaccurate pond size can result in applications during wet periods and N and P losses. Differs with soil types and drainage status. The requirement for storage is dictated by local climate and if too wet may make practice unrealistic. Added water and carbon during summer and decreased (but unquantified) E. coli losses. Houlbrooke et al. 2008b
Low rate effluent application to land Coupling pond storage with low rates of effluent application can decrease N, P and E. coli loss by minimising the potential for surface runoff and sub-surface losses via preferential flow. Mod Mod Low Mod Low Mod Fast Fast Fast The requirement for solid separation (using low-rate sprinklers) and degree of existing infrastructure that is already suitable. Differences due to soil types and drainage status. Increased labour requirements compared to travelling irrigator. Added water and carbon during summer better matched to pasture growth. Houlbrooke et al. 2008b
Enhanced Pond Systems Covered Anaerobic Ponds to remove and digest organic suspended solids to methane-rich biogas for energy recovery. High Rate Algal Ponds remove N and P in harvest algae. Maturation Ponds also remove faecal contaminants as indicated by E. coli. High Mod High High High High Fast Fast Fast Removal efficiency varies seasonally so designed for winter performance specifications and have higher performance in summer. Requires substantial land area (10 to 40 m2/cow) Energy recovery / production. Fewer greenhouse gas emissions. Craggs et al. 2014
Restricted grazing and off pasture animal confinement systems Reduced direct deposition by grazing animals and surface erosion is coupled with a stand-off area to reduce losses during heavy rainfall. High Mod Low High High Low Mod Mod Mod Costs vary widely due to variations in soil type and climate, and on the frequency of use of a restricted grazing strategy. High capital and operational costs and increased management complexity; potential animal welfare and manure management issues due to the close proximity of animals. Decreased soil and pasture damage and N2O emissions. Ledgard et al. 2006, de Klein and Monaghan 2011, Christensen et al. 2012
Alternative wallowing Fencing off of existing connected wallows and the creation of a wallow that is not connected to a stream. Low High Mod High Low Low Fast Fast Fast Poor performance could occur if runoff from alternative wallow reaches stream in large storms. There must be an area close by that is suitable for an artificial wallow. Allowance for natural behaviour may decrease stress (unquantified). McDowell 2009
Preventing fence-line pacing Tree planting to provide shelter and maintaining sufficient feed to avoid stress when, for example, when feed is low or near calving. Low Low High High Mod Mod Planting, maintenance and effect of tree planting is subject to climatic influences (primarily wind direction). Supplying sufficient feed to avoid animal stress is dependent on the skill of the farm manager. Trees decrease stress and may have anthelmintic properties (if grazed). McDowell et al. 2006
Denitrification beds Large containers filled with woodchips that intercept drain flow and denitrify nitrate in water to nitrogen gas which is released to the atmosphere. High High Mod High cost when bioreactor was underloaded. True value much more likely to be at lower end when systems properly designed Appropriate hydrology needed - tile/sub-surface drained land or small surface drains. Might be integrated to support dissolved P removal Barkle 2006, Schipper et al. 2010
Precision agriculture Sensors and automation of irrigation and nutrient inputs optimises crop utilisation at fine scales. Mod Low Fast Effect improves with soil heterogeneity, past mismatches between nutrient inputs and requirements and farmer skill. Insufficient communication and training on benefits. Improved farm and herd management; improved crop reliability and quality; conservation of water. Hedley et al. 2010
Change animal type Animal type influences N leaching due to inherent differences in the spread of urinary N (the major source of N loss in grazed pastures). N leaching from sheep and deer is approximately half that from beef cows at the same level of feed intake. High Low Slow Highly variable over time due to changes in relative prices between cattle and sheep meat. Changing relative prices between animal types over time; possibly a need for a mix of animals on a farm; and better farm management skills and farm infrastructure (e.g. extent of fencing). This may also lead to decreased N2O emissions. However, a change to deer may lead to greater sediment and P loss. Haynes and Williams 1993, Hoogendoorn et al. 2011
Diuretic supplementation or N modifier Diuretics such as common salt generally result in increased water consumption by animals with an associated increase in the spread of urinary N by the animals. Low Low Fast Potential adaptation by the animal to supplementation or N-modifier leading to less efficacy of the strategy with time. Salt is more appropriate in well-structured soils for long-term use since excess sodium in soil can potentially lead to soil structure degradation. May also lead to decreased nitrous oxide and greenhouse gas emissions Ledgard et al. 2007
Improved N use efficiency Efficiency gains via: i) reduced use of N fertiliser on winter forage crops coming out of long term pasture; and ii) avoiding excessive N inputs to effluent blocks. Low Low Mod The ability to decrease N losses to water depends on (i) the existing level of farm intensity and N loss, and (ii) the management expertise to implement required changes in farm practices. Expertise is required to maximise harvested feed under a low input farming system, while an increase in per cow production (to allow a decrease in stocking rate) takes time as improved genetics is introduced into herds. Decrease emissions of greenhouse gases and an improvement in energy use Beukes et al. 2012, Gourley and Weaver 2012
Supplementary feeding with low-N feeds Lowering the protein concentration of supplementary feed to decrease N surplus and N excreted in urine and lost via subsurface flow. Low Low Mod Depends on source and price of feed and the efficiency with which it is fed to animals. Lack of facilities for feeding out supplementary feed and costs of introducing them; requirement for increased skills in feed utilisation; and increased risk, depending on milk or meat payout and feed prices May also lead to reduced N2O, but greater CO2 production in the production and feeding of the low-N feed sources. Clark et al. 2007, Beukes et al. 2012
Low water soluble P fertiliser Less fertiliser-P is lost in runoff due to the low water solubility of products such as reactive phosphate rock resulting in increased P use efficiency. Mod Low Mod Gain compared to highly water soluble P fertiliser is dependent on time of year that fertiliser is applied. Larger gains are evident where the coincidence of surface runoff soon after application is frequent. Soil pH < 6.0, rainfall > 800 mm. Also cannot be used for capital applications and must gradually replace maintenance highly-water soluble P applications at a rate of one-third per annum (i.e. 100% low water soluble P in year 3) Has a slight liming effect. McDowell et al. 2003a
Optimum soil test P concentration Matching soil Olsen P concentrations to pasture and forage crop requirements avoids enriched soil P concentrations that are more likely to lose more P in runoff compared to that at an agronomic optimum concentration. Low Low Slow-Fast Gain is dependent on soils being enriched beyond their optimum and method of decrease e.g. natural depletion = slow while cultivation = fast None None McDowell et al. 2003b
Tile drain amendments Use of P-sorbing Ca, Al and Fe materials as backfill for artificial drainage systems. High Low Fast Quantities of sorbing materials (e.g. Al, Fe and Ca). Coarse enough particle size of the material needs to maintain good flow and interaction with material Source may be far away and the cost of transport prohibitive Potential to decrease (via filtration) the loss of sediment and faecal bacteria (both unquantified). McDowell et al. 2008
Applying alum to forage cropland P-sorbing aluminium sulphate (alum) sprayed onto a winter forage crop just after grazing to prevent surface runoff losses of P. Mod Mod Fast May be ineffective in high rainfall environments where it may be washed from the soil. Few supplies and competing use as a water treatment additive None McDowell and Houlbrooke 2009
Applying alum to pasture P-sorbing aluminium sulphate (alum) sprayed onto pasture a week before grazing to prevent subsequent surface runoff losses of P. Mod Mod Fast May be ineffective in high rainfall environments where it may be washed from the soil. Few supplies and competing use as a water treatment additive None McDowell and Norris 2014, McDowell 2015
Red mud (bauxite) to land P-sorbing and caustic red mud (Al-oxide) incorporated into soil at rate of up to 20 Mg ha-1 to prevent P losses in runoff and leaching. High Mod Fast Increases soil pH which may increase P solubility if outside pH range 5.5-5.9. Few suppliers. If used for liming effect, grazing animals need to avoid treated area otherwise ingestion may impair rumen function. Alkaline and hence can be used instead of lime. Vlahos et al. 1989
Refurbishing and widening flood irrigation bays Water exiting flood irrigation bays as outwash represents about 20-50% of that applied. Re-contouring irrigation bays, and/or preventing outwash/wipe-off from accessing the stream network decreases P loss. High Mod Mod Inaccurate level resulting in flow (and outwash) faster than anticipated. Variation in the water supply rates. A move to spray irrigation is likely to be more cost-effective. More efficient use of flood irrigation water. Houlbrooke et al. 2008a
Dams and water recycling Recycling systems divert irrigation outwash for use in others part of the farm increases nutrient use efficiency. High Mod Mod Leakage from infrastructure A move to spray irrigation more cost-effective. More efficient use of flood irrigation water. Barlow et al. 2005
Soil conservation plan to plant trees Combination of retirement and pole planting on highly erodible land. Introduction of tree roots to soil regolith protects soil on steep slopes from mass movement erosion. Mod High Slow Benefit depends on severity of erosion and the number of years the trees take to glow None Decreased P inputs to waterways, improved shelter for animals. Hicks 1995
Benched headlands Constructed level bench that runs across the slope of a field. Suitable for use on cultivated soil where slopes are greater than 3 degrees. These encourage infiltration of water on the bench and reduce the slope length of water pathways. Mod Low Fast Depends on infiltration capacity of soil Management expertise Increased sustainability of cropping. Decreased P input (unquantified) to waterways. Basher 2013
Bunds Earthen barrier constructed along paddock edge to prevent water flowing onto or from field. Suitable for use on cropping land with slope greater than 3 degrees. Creates ponds of water at bottom of field where sediment settles out. High Mod Fast Depends on infiltration capacity of soil Management expertise Increased sustainability of cropping. Decreased P input (unquantified) to waterways. Barber 2014
Contour cultivation Cultivation along contours of cropping land with slopes greater than 3 degrees. Reduces the speed and eroding power of runoff water. Mod Low Fast Depends on infiltration capacity of soil and slope angle Education Increased sustainability of cropping. Decreased P input (unquantified) to waterways. Barber 2014
Contour drains Temporary drains that run across the slope of a field and into a permanent drain on the side of the field reduce the slope length of water pathways and thereby reduce the eroding power. Mod Low Fast Depends on density of drains Management expertise Increased sustainability of cropping. Decreased P input (unquantified) to waterways. Basher and Ross 2002
Cover crop Green manure or cover crop after harvesting of main crop is ploughed into the soil stabilising bare soil from erosion and improves water penetration and drainage. High Low Mod Depends on soil structure Willingness of manager to forgo short term gain for long term gain Increased sustainability of cropping. Basher 2013, Barber 2014
Minimum tillage Direct drilling of seed into stubble or pasture reduces the proportion of time that land is bare and erodible during the growing cycle. Low Low Mod Depends on the amount of time land is bare Management expertise. Could increase dissolved P losses. - Basher et al. 1997, Jarvie et al. 2017
Silt fence Material fastened to a wire fence for filtering out sediment from surface runoff. High High Fast Variability of material and contracting costs High cost Decreased P input (unquantified) to waterways. Barber 2014
Stubble mulching Stubble is mulched and left on field. Partial ground cover protects soil from erosion. Low Mod Mod Depends on the amount of partial ground cover Management expertise Decreased P input (unquantified) to waterways. Basher 2013
Wheel track dyking Series of closely-spaced indentations in wheel tracks created by tillage machinery. Slows surface runoff water down and settles suspended sediment. Mod Low Fast Depends on the proportion of runoff coming from compacted soil Management expertise Decreased P input (unquantified) to waterways. Barber 2014
Wheel track ripping Ripping of wheel tracks is suitable for use on cropping land after the use of heavy vehicles on cultivated soil. Ripping allows water to percolate into the soil rather than flow down the tracks. Mod Low Fast Depends on the proportion of runoff coming from compacted soil Management expertise Decreased P input (unquantified) to waterways. Barber 2014
Wind break crop Tall crop in paddock providing shelter for neighbouring cultivated paddock from wind erosion. Low Mod Mod Depends on value of wind break crop Management expertise Decreased P input (unquantified) to waterways. Basher 2013 McDowell and Sharpley 2009


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