The NZ economy based on farming, and tourists coming to see landscapes such as this...Trouble is as farms have become more intensive, if they are not managed carefully, we could end up with our waterways looking like this...
Also, 48% of NZ ghg emissions come from ag. agriculture to be included in our emissions trading scheme from 2015. How can new zealand dairy farmers continue to farm profitably under increasing pressure to reduce the impacts on the environment?
Today I’m going to present some modelling work we did with dairy farm systems aimed at increasing the efficiency of milk production so as to make it more profitable and reduce environmental impacts. Give some background: intensification of dairy farming in NZ what is causing our major environmental issues on farmStrategies we modelled to prevent this. How strategies affected milk production, profit, GHG, nitrate leaching, Look at these effects under a range of climatic conditions experienced in the Waikato region of NZ.
NZ dairying based on cows grazing ryegrass and white-clover based pastures all year round, with average of 10% of diet as supplements either bought in or made on the farm.
We have increased the amount of feed eaten per hectare by increased utilisation of pasture, increased use of nitrogen fertiliser to grow more pasture, and increased use of supplements purchased from off the farm.
As a result, Milk production increase by 130% since 1990. Although that is great for our dairy industry, it is putting increasing pressure on our environment.
How does intensification of dairying cause environmental problems?We’ve seen more fertiliser go on to grow more pasture, and more cows go on to eat this....But, the more cows we have, the more methane is produced, and also the more urine, causing very concentrated patches of nitrogen on pastures. In wet conditions, nitrogen particularly from urine, but also from fertiliser, can be leached through the soil into ground water, as nitrate, which reduces water quality. And, nitrous oxide, a potent greenhouse gas can be produced from urine and fertiliser.
Lots of research looking at single strategies to reduce either nitrate leaching or greenhouse gas emissions on farm. Options include less animals, which could lead to less milk produced, but if this is combined with using more efficient animals that convert more of their feed in to milk, and have good reproductive performance, can reduce animal replacement rates, so less young stock required..3. Also, if time on pasture reduced at risk times, less urine patches and therefore less N loss.4.Low N feed supplements lower urinary N conc5. Less N lost from system by leaching and nitrous oxide production if use less N fert and nitrification inhibitor.Most of these been tested in isolation, and have some effect, but we modelled them all together and looked at the combined effects.
Modelled dairy farm in the Waikato region. We modelled a base farm, which represents the average farm in this region, and an efficient farm, which stacks up all of these technologies for improving efficiency and reducing the environmental footprint.First we reduced stocking rates from 3.0 to 2.6 cows/ha, but to ensure good pasture utilisation is maintained, this was combined with higher genetic merit cows, which have a high intake capacity, high production, and good fertility and health. This allowed for replacement rates to be lowered from 23 to 17%. The efficient farm was also changed from an entirely pasture-based system, to one where maize grain was bought in and fed during feed deficits. (in mid to late lactation. This increases the production of each cow, and using a low N feed means lower nitrogen concentration in urine).The final 3 strategies focus on reducing nutrient loss and improving nitrogen use efficiency. On the baseline farm, cows are on pasture throughout lactation, but in the efficient farm cows are on a loafing pad 12 hours per day in the last 2 months of lactation and the effluent collected. Therefore, nutrients can be spread back on pasture evenly, reducing N losses. The effluent area is increased from 20 to 24% of the farm area on the efficient farm. Nitrogen fertiliser is applied to the remainder of the milking platform for each system, at 180 kg N/ha for the base farm and 50 kg /ha/yr for the efficient farm. A nitrification inhibitor was also applied to pasture in autumn and winter on the efficient farm to reduce N losses.
The Waikato region, which we modelled here has average rainfall 1100 mm/year, reasonably even distribution but can be dry in summer, with temperate climate .Productivity of farms in Waikato relies heavily on summer rainfall, if we get enough then get good pasture growth, so cows have more to eat, produce more milk or use less supplements therefore more profit, but higher intakes can also lead to more methane produced.If we get too much rain in winter, the soils become saturated, and you get nitrous oxide production and nitrate leaching.We wanted to model how the base and efficient farm varied under a range of Waikato climates.We modelled 3 years that represented low, average and high production in the Waikato. These years had annual rainfalls of ....., respectively. Most of the variability was due to differences in summer rainfall, as shown in the next slide.
This slide shows summer monthly rainfall for each year modelled. 2003/04 in dark blue very wet in february, bad flooding in some parts of nz.2004/05, medium blue, average summer, 2007/08 in light blue, where we had a drought.
Results..Pasture produced on milk platform, t DM/ha/year.. av approx 15 t, but varies by approx. 5 t across the 3 years in both base and efficient farm.Efficient system always slightly lower than for base farm, as less N fertiliser use.
Total feed intake on milking platform varied from 12 to 13 t DM/ha across farm systems and years. More consistent on efficient farm because flexibility of using maize grain when feed supply low, ranging from 8% of diet in dry year to 1% of diet in wet year.
Milk production measured in MS (fat + protein yield). Efficient farm in red, consistently higher production than base farm despite fewer cows. This due to higher production per cow. Less variability in production on efficient farm due to ability to buy in feed when needed.
Operating profit. This is the profit before take out money for debt servicing. This is based on the same financial model each year, with a milk price of $6.10/kg MS. Profitability was consistently greater on the efficient farm, due to higher milk production and lower costs associated with having fewer cows (reduce per cow costs). Profit was greatest in the wet year for both farms, due to higher pasture production.
t CO2 eq/ha/yr. From milking platform and support area with replacement animals.Little variability between years, as main factor is no. of animals.Methane emissions were reduced by 15-19% for efficient system.
This includes methane from WFM and nitrous oxide and CO2 from OVERSEER model. Climate little effect, efficient system reduced total GHG by av of 25%, and emissions per kg milk solids by 27-32%.
This includes N losses from the milking platform and support area. (maize area info in paper).Dramatic decrease in leaching for efficient system, being 30 to 50% lower than for the base farm across years. (This is the combined effect of less animals, more capture of N off loafing pad, and use of nitrification inhibitor and less N fert. )We also see a large climatic effect here, with leaching higher from urine produced in the dry year. This is because of low pasture growtht that year, so you get less N taken up by plants, and a wet winter the following year.
Increasing efficiency of farm systems by using a combination of technologies including fewer but more efficient animals, low N feed supplements and management and technology to reduce N losses can improve both economic and environmental performance of pasture based dairy farms.We showed that although slightly less pasture was grown, milk production increased by.... profit... GHG.... N leaching.....Efficient system was consistently more profitable and better for the environment across all climate scenarios. The impact of climate on these responses was small for GHG, but large for profit and N leaching. However, the feasibility of these management strategies would vary between farms and responses would vary in different regions.
Dairy farm systems for good economic and environmental performance. Vicki Burggraaf
DAIRY FARM SYSTEMS FOR GOOD ECONOMIC AND ENVIRONMENTAL PERFORMANCE VICKI BURGGRAAF1 IRIS VOGELER1 PIERRE BEUKES2 DAVE CLARK2 1 AGRESEARCH LTD 2 DAIRYNZ
48% NZ GREENHOUSE GASHow can we farm profitably with a low environmental footprint?
OVERVIEWModel dairy farm with increased efficiency1. Dairy intensification in NZ2. Causes of environmental issues3. Strategies to reduce negative impacts4. Model effects on production, profit, GHG, N leaching5. Effects of year to year climate variability
DAIRY INTENSIFICATIONSince 1990:• 78% increase in dairy land area• 20% increase in SR (cows/ha)• 85% increase in total no. cows
DAIRY INTENSIFICATIONSince 1990:• 78% increase in dairy land area• 20% increase in SR (cows/ha)• 85% increase in total no. cowsIncreased feed intake per hectare• Pasture utilisation• Increased use of nitrogen fertiliser• Increased use of bought-in supplements
DAIRY INTENSIFICATIONSince 1990:• 78% increase in dairy land area• 20% increase in SR (cows/ha)• 85% increase in total no. cowsIncreased feed intake per hectare• Pasture utilisation• Increased use of nitrogen fertiliser• Increased use of bought-in supplements MILK PRODUCTION INCREASED 130%
PROBLEMS OF INTENSIFICATIONMore cows and high N feed: More N fertiliser: methane nitrous oxide N fert URINE nitrate leached
REDUCING THE IMPACT 1. Fewer animals 2. Efficient animals 3. Stand-off pasture – less nutrient loss 4. Low N feed supplements 5. Less N fert use, nitrification inhibitor Small effects in isolationSTACKED TECHNOLOGIES
MODELLED DAIRY FARMSPARAMETER BASE FARM EFFICIENT FARMStocking rate (cows/ha) 3.0 2.6Cow genetic merit (BW) 60 120Replacement rate 23% 17%Feed Pasture Pasture + maize grainStand off pasture No YesEffluent area 20 24(% of farm)N fertiliser area 180 kg N/ha 50 kg N/ha/yr + nitrification inhibitor
WAIKATO CLIMATE EFFECTS• Rainfall 1100 mm, temperate climate• Summer rain: more pasture → milk, profit• Winter rain: nitrate leaching, nitrous oxide• Base vs efficient farm: Low Medium High production Dry Average Wet summer 945 mm 1056 mm 1197 mm rain/yr
WAIKATO SUMMER RAINFALL 250 2003/04 200 2004/05 2007/08 150mm 100 50 0 Dec Jan Feb Mar
MODELLING FRAMEWORK•Management WHOLE FARM MODEL•Daily climate Pasture production Grain fed Milk production Profit •Management •Annual rainfall Methane Urinary N APSIM OVERSEER Nitrate leaching Total GHG
PASTURE PRODUCTION 20 Base Efficientt DM/ha/year 15 10 5 0 Dry Average Wet
TOTAL FEED INTAKE 8% 4% 1% maize grain 14 12t DM/ha/year 10 8 Base 6 Efficient 4 2 0 Dry Average Wet
MILK PRODUCTION 1400 1200 1000kg MS/ha 800 Base 600 Efficient 400 200 0 Dry Average Wet
OPERATING PROFIT 4500 4000 Base 3500 Efficient 3000 2500$/ha 2000 1500 1000 500 0 Dry Average Wet
METHANE EMISSIONS 8t CO2 eq/ha/yr 6 4 Base Efficient 2 0 Dry Average Wet
TOTAL GHG EMISSIONS 12 10t CO2 eq/ha/yr 8 6 Base 4 Efficient 2 0 Dry Average Wet
N LEACHING 80 Base 70 Efficientkg N/ha/year 60 50 40 30 20 10 0 Dry Average Wet
CONCLUSIONSEfficient farm systems: •Milk production ↑ 8-17% •Profitability ↑ 18-80% •GHG ↓ 23-27% •N leaching ↓ 30-50%Impact of climate: •Efficient always best •Variability high for leaching, profit