1. Monitoring and Programme of Measures Results
Dr Jodie Whitehead
(ADAS)
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2. Overview The study areas Catchment characterisation Sampling programme
Mitigation measures
Key messages

3. What we are doing Trying to develop ‘best practice’
Understanding farming and interactions with water
farm practice data
soil and water measurements
Identify possible solutions
Work with farmers
Evaluate effectiveness: lessons learnt
Identify
issues
solutions
Implement
Monitor
effectiveness
Within the project we are trying to develop best agricultural practice
By understanding farming and interactions with water.
To help us with this we are collecting a comprehensive set of farm practice data along with soil and water measurements.
From this we have identified possible solutions to try and reduce diffuse pollution loads particularly nitrate levels.
This is being done in co-operation with farmers. Who are helping us to evaluate the mitigation methods and lessons learnt.

4. Study areas Key points: 650 km2 Arable/grassland Mix of soil types
No water protection zones
NVZ area
Catchment Sensitive Farming - priority catchments
This slide shows the 6 sub catchments within the project.
The 6 study areas cover approximately 650kn2 and are part of the larger From and Piddle catchments in Dorset.
The catchments are mainly arable mixed farmland on a variety of soil types.
The catchments are also covered by NVZ regulations and are a priority catchment under the catchment sensitive farming initiative.

5. Catchment characterisation
Farm audits
Farm Pollution Risk
Category
High
Medium
Low
The first step of the project was to characterise the catchments. This was done by undertaking initial farm audits, more detailed farm audits collecting farm data from the last 5 years and finally undertaking nutrient budgets for each of the farms.
The maps here show the results from the initial farm audits, where we were looking at the risk of diffuse pollution from each farm. Red is high risk, yellow medium and green low.
Risk was based on the catchment advisors opinion of the farm, whether nitrogen inputs were considered high or where farming practices would adversely effect nitrate leaching.
If we look at the catchment on your left we can see that the higher risk farms are at the bottom of the catchment.

6. Catchment characterisation
Nutrient budgets
From the initial farm audits and detailed farm audits farm gate nutrient balances were created for each farm.
The budget is helpful for the farmers as it also shows whether or not they could be using nutrients more efficiently on their farm.
The maps shown here show the nutrient surpluses for one sub catchment, the darker the colour the greater the surplus.
Its interesting to note that a similar pattern can be seen when compared to the initial farm audits suggesting that an experienced catchment advisor is crucial to catchment management.

7. Catchment Characterisation
Benchmarking nutrient budgets

8. Sampling programme Water quality/level sampling
Soil mineral N sampling
Porous pots
Routine soil sampling
Grain N sampling
Manure sampling
17 Boreholes
11 Wells
5 Springs
7 Stream Samples
Water level sampled every two weeks
Nitrate concentration every four weeks

9. Water quality results

10. Water quality results
Relationship between peak NO3 concentrations & water level/rainfall
Approximately 1 month lag time between rainfall & peak NO3 concentrations
Mitigation measures may have a positive affect on peak NO3 concentrations
But what about the high background NO3 levels in some boreholes??

11. Water quality results Average Nitrate N Surplus 109 mg l-1 67 kg ha-1

12. Soil Mineral N Results
Over the last 2 winters years we have been carrying out SMN sampling across the catchments both in the autumn and the spring.
Measured in spring, SMN can be a useful guide to the N fertiliser requirement of a crop.
Measured in the autumn, it is a good indicator of the amount of nitrate that can be leached in the winter.
The graph here shows the 2006/2007 data
Amounts varied greatly between fields in autumn
Amounts were larger than the average national NVZ monitoring samples.
Amounts differed between previous crops:
Amounts dropped substantially between autumn and spring,

13. Measures Based on initial farm audits Soil and fertiliser management
Ideas, feedback, discussion ….
Based on the initial farm audits results suggested that the best way to reduce nitrate loads from the farms was to aim our measures at soil and fertiliser management.
Measures were decided through feedback and discussion with the farmers and catchment advisers.

14. Six Measures Fertiliser recommendations Manure management
advice on rates (analysis)
advice on timing
Cover crops
Fertiliser spreader calibration
Spring manure application
N balance/N efficiency

15. Measure Uptake Measure % Uptake by Farmers Fertiliser recommendations81
Manure management plans & waste audits 52
Cover crops 19
Fertiliser spreader calibration 44
Moving from autumn to spring application for slurries & poultry manures 10
Use of on-farm N-efficiency 27
Out of the 74 farms targeted by the project 70% have agreed to participate against a target of 50%

16. Farmer feedback on measures
Fertiliser spreader calibration
Only small amount of fertiliser used on the farm so not worth it
Already calibrate the spreader every year
Just brought a new machine
Moving from autumn to spring application of manures
Not enough storage to cover the no application period
Cover crops
No spring crops in the rotation
Manure management plan and waste audit
No manures on the farm

17. Fertiliser recommendations and manure management
No large scale over supply of nitrogen
Some farmers applied more N than recommended
Main problem centred around a relatively few maize fields
Grass fields generally received less N than recommended under RB209
In general there was no large scale over-supply of nitrogen (as Fertiliser or manure) to crops in the catchments. Some farmers applied more N than recommended to a few of their arable crops. The main problem centered around a relatively few maize fields - where the N content of the manure applications was not taken into account when deciding on fertiliser N dressings. Where manures were applied to other arable crops, there was recognition of their nitrogen value. Grass fields generally received less N than would be recommended by the current version of RB209.

18. Cover Crops

19. Fertiliser spreader calibration – Why calibrate?
% CV
Spreader condition
Increase in N leached
<10
Excellent 4%
Respectable 6%
Poor – can be improved 8%
>20
Serious
13%
Free fertiliser spreader calibration was offered to all farmers within the project study areas during February 2007 and 2008
calibration process consisted of a full width tray test of the fertiliser to be spread along with a flow rate and application rate test.
Evenness is measured by the Coefficient of Variation or CV. The lower the CV value, the more even the spread. Uneven spread may be the result of machine wear and setting incorrect PTO speed or incorrect machine height. A respectable CV is between 10-15% (ideally less than 10%), At a CV of >20% visible striping might be seen in a field, resulting in economic losses.
Calculation of the effects of poor spreading suggest that, for cereal crops, a relative low CV of 15% will increase nitrate leaching by 8% compared with ‘perfect spreading’. This increases to approximately 13% at a CV of >20%. These results indicate that fertiliser spreader calibration is effective in reducing nitrate leaching.

20. Fertiliser spreader calibration - Results
2007
2008
% CV before calibration
% CV after calibration
Average 22 3 12 2
Median 8
Max 64 5 50 4
Min
0.3
So, in 2007 we calibrated 18 spreaders and in 2008 we did 17.
On average the CV’s improved by between 10 and 20%.
The greatest reductions were seen in 2007, mainly due to the spreaders being more out of calibration in 2007 as many of the machines hadn’t been calibrated regularly
The spreaders that were calibrated in both 007 and 2008 still required some calibration in 2008, showing the need for yearly spreader calibration.

21. Fertiliser spreader calibration - Example
Here we have an example of the spread pattern before and after calibration in 2007.
A visual improvement can be seen in the spread pattern.
The CV before calibration was 64% this was then reduced to 4% after calibration.
This was achieved through calibration and correction of the machines settings. One of the further recommendations of the test was to have the worn vanes replaced.
The same machine was submitted for calibration in 2008 with new vanes fitted it spread with a CV of 2%.
Results suggest that improved crop yield and benefits to the environment are just some of the money-saving pluses to come from a survey on calibrating spreaders.

22. What is N Efficiency?
N Efficiency is the proportion of imported N that is exported as ‘useful products’
Output
Input
X 100
Efficiency (%) =

23. Why is N efficiency useful?
Why both efficiency and farm gate balances?
47000 kg N
200ha
23000 kg N
Farm 1
Efficiency = 49%
Farm gate balance = 120kg N ha-1
32000 kg N
8000kg N
Farm 2
Efficiency = 25%
Efficiency shows how effectively N inputs are being used

24. N Efficiency Results

25. Economic analysis results
Type of measure
Net Cost
No. of farms relevant
Cost for the pilot area catchments (£m)
Fertiliser recommendations
-£3.72 per ha (benefit) 19
Manure management
-£9.3 per ha (benefit) 17
Cover crops
£68.8 per ha 18
0.45
Fertiliser spreader calibration
-£14.2 per ha (benefit)
N efficiency calculation
£600 per farm (£2.0 per ha)
0.40

26. Cost - benefit

27. Key Messages
Measures can help to reduce seasonal nitrate peaks in groundwater but high background levels may take years to decline
Evaluating the success of measures needs to be at a local scale (farm/field) instead of through the groundwater monitoring network
SMN and porous pot sampling
N efficiency and nutrient budgets
No single approach will achieve large reductions in N losses to the environment, but a range of smaller, cost effective N management measures may have a significant effect
The use of catchment advisors is essential, feedback from farmers has indicated that advice is a key element in tackling diffuse pollution
Farmers are keen to learn and use nutrients more efficiently on their farms
The value of WAgriCo is making sure that our experiences are used and built upon