Archive for the ‘water’ Category

Sustainable farming – what is it?

Wednesday, March 19th, 2014

Yesterday as a guest of Trevor and Anne-Marie Mills and the Western Port Catchment Landcare Network I attended a field day on the Mills’ dairy farm at Drouin South.

Amongst the principles of sustainable agriculture are that farming should:

– provide an amenable lifestyle for the farmer & family

– protect and enhance the productive capacity of the farm

– protect and nurture the natural environment and reduce environmental impacts

Judging by these criteria, the Mills have gone a long way to creating a sustainable farm. Much of this has been achieved by thinking ‘outside the square’ and often going against conventional thinking. For example T & A-M have fenced off and replanted many of the drainage areas and watercourses on the farm. Water is now piped to stock high up in each paddock. The result; less contamination of water, less nutrient runoff and cleaner water for the cows to drink.

The South Gippsland area was originally heavily forested and early accounts have detailed the diversity of wildlife that once existed. Now with areas on the farm returning to natural vegetation, some of the native animals are also returning. Happily these areas are often those that would be less productive and difficult to manage. The photos below taken from the same spot approx 5 years apart show the dramatic change around a natural waterway.

Before and after watercourse revegetation on the Mills Farm at Drouin South. By excluding stock from wet gullies significant improvements have been made to the quality of water flowing from the farm and as drinking water for stock. Approx 5 years between photos. Courtesy of T & A-M Mills and WPCLN.

Before and after watercourse revegetation on the Mills Farm at Drouin South. By excluding stock from wet gullies significant improvements have been made to the quality of water flowing from the farm and as drinking water for stock. Approx 5 years between photos. Courtesy of T & A-M Mills and WPCLN.

The WPCLN as part of their involvment in the property have been monitoring water quality and this has provided valuable feedback for farm planning.

On the farm management side T & A-M have adopted a rotational grazing system that takes advantage of the natural productivity of the soil and facilitates nutrient cycling whilst protecting against overgrazing and damage to pasture. The result, an increase in productivity which has meant that the herd size can be reduced whilst maintaining production.

I was especially interested to hear how Trevor had cut back on use of urea as a nitrogen fertilizer. This came about because he saw that the urea was favouring grass growth and supressing clovers. Now clovers are thriving and producing nitrogen naturally!

I think that soil testing still has a role to play on this farm. Particularly if it is done in a way that provides a better understanding of management effects on soil processes and the dynamics of nutrient movement around the property as well as off the property as natural losses and in farm products.

Judging by the attendance at the field day there is a lot of interest in sustainable farming and land management. The Mills farm is an excellent example for all to see that shows how productive farming can go hand in hand with protecting and enhancing environmental quality.

Farm water supply investigation

Saturday, January 25th, 2014

A preliminary investigation was carried out on the quality of water in two dams on a dairy farm in West Gippsland. The dams are a short distance apart in the same gully. The Upper dam is spring fed and can overflow into the Lower dam. The water was tested during summer. At that time the flow into the Upper dam had decreased and the water level was falling. The Lower dam was still fairly full.

The dams are in an elevated position and drain approximately 10 ha. The surrounding land is pasture.

Farm dam in West Gippsland. The Upper dam in this study. Water is pumped around the farm for drinking water for stock and also for washdown water in the dairy.

Farm dam in West Gippsland. The Upper dam in this study. Water is pumped around the farm for drinking water for stock.

There are many waterbirds on the dams – mainly ducks. Cows have access to both dams and commonly drink at the water’s edge. The water in both dams has a pale yellow-brown colour. There is significant attached bacterial – fungal mats clearly visible in shallow water.  One significant observation was that were no visible micro crustaceans.

Dam CO2 EC Turbidity Reactive C ORP*
ppm microS/cm FTU mg/L mV
Upper 18 289 11.5 0.5 207
elevated sl. elevated sl. cloudy moderate OK
Lower 5.8 738 3.5 0.5 205
moderate elevated clear moderate OK
* oxidation reduction potential

Some key findings are: Dissociated carbon dioxide was high in the Upper dam. The water is fairly clear in both dams with the Upper dam water just slightly cloudy. Overall salts as conductivity are elevated in the Lower dam. Both dams have oxidizing potential (a surrogate for oxygen level) within the desirable range.

Reactive or relatively fresh organic matter was estimated by permanganate digestion. In both dams reactive organic matter was in the moderately elevated range. Humic material in dams can be measured indirectly by UV absorbance. In both dams the UV absorbance was high, around 65%.

The pH of the Upper dam was 7.2 and pH of the Lower dam was 6.8. A pH buffer system analysis of the Upper dam gives a calculated pH of 6.7. This suggested the scenario of a falling pH (water becoming more acidic) as the carbon dioxide level rises. In this case the rise in carbon dioxide is being most likely caused by increasing organic matter decomposition. See organic matter figures below.

A pH buffer system analysis for the Lower dam gives theoretical pH of 7.84. This suggests that carbon dioxide level in this water is falling and this will cause the pH to slowly rise (the water will become more alkaline).

Farm dam in West Gippsland. This is the Lower dam in the study. Some physical and chemical factors show some improvement compared to the Upper dam. However there levels of the 3 key bacteria water quality indicator groups are twice the levels compared to the Upper dam.

Farm dam in West Gippsland. This is the Lower dam in the study. Some levels of physical and chemical factors are more favourable compared to the Upper dam. However the levels of 3 key bacteria water quality indicator groups are around twice the levels of the Upper dam.

Dam E. coli coliforms TC*
CFU’s / 100 ml CFU’s / 100 ml CFU’s / 100 ml
Upper 440 3317 53281
elevated** high moderate
Lower 960 7119 118274
elevated** elevated** sl. elevated
* aerobic plate count
** indicates contamination

For both dams the high  E coli level taken along with the high coliform levels indicate some fecal contamination of the water. Total aerobic bacteria level is approximately in the moderate range for exposed waters.

The main quality issue in both dams is elevated reactive organic matter levels and elevated E coli bacteria levels. There is some evidence that processes in the Lower dam are at least slowing deterioration of water quality. However on the negative side, levels of bacteria are significantly higher in the Lower dam.

Ideally in a study like this it would be useful to test the source water, in this case the spring water entering the dams. Unfortunately the spring was not accessible. There was also no other dam on the property to provide a comparison.

Effluent management on a dairy farm

Saturday, November 9th, 2013

For the last few weeks I’ve been visiting a dairy farm in West Gippsland to learn a bit more about how dairy farms work. It’s also an opportunity to apply some ideas about soil and water management in a practical context.

Cows can deposit around 8 – 10% of manure and urine output around the milking shed and yards. Manure and urine contains significant amounts of major nutrients including nitrogen, phosphorous and potassium.

On many farms this manure is often washed directly into specially contructed waste retention dams. A typical setup is a sedimentation dam sometimes followed by an aeration dam.

Sedimentation dam for dairy waste on a farm in West Gippsland. Water is washed into the dam from the milking shed and yards without treatment.

Sedimentation dam for dairy waste on a farm in West Gippsland. Water is washed into the dam from the milking shed and yards without treatment.

The picture shows a sedimentation dam on the WG farm. There is a thick crust of manure on top which means that conditions in the dam are most likely anaerobic. At this dam I didn’t want to get too close in case I became part of the waste system! Therefore I didn’t get a sample!

In an anaerobic dam the organic matter itself provides oxygen to help drive the other processes that eventually break down most of the organic matter into methane, hydrogen, carbon dioxide and ammonia. But the disadvantage of this method is that energy in the organic matter is lost (as methane) and importantly nitrogen is lost (as ammonia).

The overflow from the sedimentation dam on the farm enters a second aeration dam. What can we expect the water quality to be in this type of dam? There shouldn’t be much nitrogen but what other nutrients will be present?

Dairy farm aeration dam in West Gippsland. Water flows into this dam from an uphill sediantation dam that takes waste directly from the dairy.

Dairy farm aeration dam in West Gippsland. Water flows into this dam from an uphill sedimentation dam that takes waste directly from the dairy.

The aeration dam is just below the sedimentation dam. The overflow pipe can be seen in the picture. The water has a brown colour and a slightly unpleasant smell. Here are some water quality tests done in the Apps Labs lab: Dissociated carbon dioxide 13.5 ppm (elevated); Turbidity (unfiltered) 57 FTU (high); Turbidity filtered (0.45 micron) 19.8 FTU (still high); pH 7.1 (very slightly on the alkaline side); UV absorbance 99.2% (very high dissolved humic materials); Conductivity 1459 microS/cm (elevated salts); redox potential (ORP) -44.7 mV (anaerobic, and that’s at the surface).

Nitrate and nitrite were checked using screening tests. Both were at low levels or absent. That’s expected anyway because nitrates usually don’t exist in low oxygen conditions and nitrites usually form from nitrates under reducing conditions. Phosphate was checked using two different test kits. One showed phosphate over 30 ppm. The other showed phosphate as 43 ppm. Both these levels are very high.

There may be significantly more phosphate present in the two dams than the amount measured as some is likely to be held in the sediments.

What about nitrogen? Ammonia – nitrogen in the aeration dam was 0.44 ppm. This is higher than normally found in natural waters but is not excessive. At pH 7 around 0.4% of this nitrogen can be expected to be in the ammonia form as opposed to the ammonium form. This is not good for water life because the ammonia form is harmful. In general as water becomes more alkaline, an increasing amount of any total ammonia nitrogen present is likely to be in the ammonia form. This same amount of ammonia nitrogen, is roughly equivalent to 2 ppm nitrogen as nitrate. This is slightly elevated for natural waters so the nitrogen in the ammonia form probably doesn’t account for all the nitrogen in the original manure entering the two dams.

What is the best way to use dairy effluent to capture maximum nutrient value?

The following web resource provides detailed figures on tests done on dairy effluent dams and suggests way to reuse the nutrients in the effluent:

DPI Victoria 2013, Using dairy effluent as a fertilizer. Downloaded from http://www.dpi.vic.gov.au/agriculture/dairy/pastures-management/fertilising-dairy-pastures/chapter-13, November 2013.

My tank drinking water smells, what can I do?

Monday, December 31st, 2012

One of the frequent problems seen in water tanks is smelly water. This can occur in above and below ground tanks and includes rain water tanks. People often describe the smell of their water as musty, decaying or like ammonia or rotten eggs. It can be just a little bit off-putting or in some cases can be very unpleasant. In any case its hard to drink and wash in smelly water.

The ammonia or rotten egg smell is a give away for anaerobic conditions. In other words poorly aerated water.  The first test to do when investigating smelly tank water is a redox test. Redox or oxidation reduction potential is an indicator of oxygenation and unlike oxygen level tests redox can also show very anaerobic conditions.

Tests from one underground tank with smelly water showed that redox was 145 mV just below the water surface. Generally redox in the 200 – 250 mV range is commonly seen and acceptable for drinking water. Below 0 mV is definitely not good. So 145 mV was a little low but not too bad. However at the kitchen tap where water is drawn from deep in the tank the redox was -58 mV. Now that is bad! It indicates anaerobic water. This water had an unpleasant ‘eggy’ smell.

testing being carried out on a below ground concrete rain water tank. The tank is dug into a slope with no barrier to stop runoff running onto the tank.

Testing being carried out on a below ground concrete rain water tank. The tank is dug into a slope and risks contamination because the tank is level with the ground on the uphill side.

Checklist for smelly tanks:

  • is there runoff entering the tank?
  • have you been on holidays or have you just bought the property?
  • do the downpipes from the roof go underground then come back up before the tank?

What can be done about smelly water? If the smell can be traced to anaerobic conditions the simplest thing to do is direct the stream from a garden hose back into the tank. Just ripple the water and try to get a slow circulating movement happening in the water.  There’s no need to do anything too drastic like emptying the tank or throwing in handfulls of chlorine. All you need to do is get oxygen back into the water to reverse the reactions that created the smells in the first place. As a safeguard think about installing a cartridge water filter, one that has an activated carbon cartridge. That will help to remove some of the smells and will be good insurance against any future contamination. The Basic Water Quality Test from Apps Laboratories is designed to test water quality factors and can be used to trouble shoot water quality problems. Apps Labs also supplies rural and farm water filters.

Water pollution case study

Wednesday, February 16th, 2011

Contamination of waters by organic matter including manures is a type of water pollution. Excessive organic matter load in water is likely to cause a number of changes including:

Higher turbidity
High decomposition rate leading to elevated carbon dioxide and lowered oxygen,
Undesirable intermediate products of decompostion including nitrite and ammonia.
Elevated nutrient levels
Elevated dissolved organic matter
Elevated bacteria levels in general and specifically E coli if manures are present

The owner of this dam on a property north of Melbourne noticed an unpleasant smell coming from the dam. The water was also very discoloured.

Farm dam polluted by runoff. The owner has already fenced off the water to exclude stock.

Farm dam polluted by runoff. The owner has fenced off the water to exclude stock. But what is the source of the contamination?

Here are the test results for this dam: pH 6.8, ORP 217 mV (low end of desirable range), turbidity 624 FTU (very turbid), UV absorbance 40% at 1 : 25 dilution (very high), ammonia + ammonium 12.4 mg/L (high), carbon dioxide (dissociated fraction) 25.6 ppm (high), nitrate 8.9 mg/L (slightly elevated), nitrite 0.16 mg/L (any nitrite is undesirable), phosphate 16.9 mg/L (very high), E coli 13,100 CFU’s / 100 mls (very high), aerobic plate count 2,067,000 CFU’s / 100 mls (high).The indications are that there is an organic matter contamination problem – because of the E coli, probably from manure.

Here are the results from the drain in the foreground of the photo: pH 6.9, ORP -33 mV (very low, indicates low or depleted oxygen)), turbidity 976 FTU (very high levels of semi suspended particles), UV absorption 53% (high, at 1 : 25 dilution), ammonia 26.3 mg/L (high), carbon dioxide 42 ppm, nitrate and nitrite both 0, phosphate 27.3 mg/L (very high), E coli 14,900 CFU’s / 100 ml, aerobic plate count 1,553,000 CFU’s / 100 ml.

My brief interpretation: Decomposition in the runoff water is producing ammonia and carbon dioxide. As the water reaches the dam oxygenation levels increase slightly allowing some nitrate to be produced. However there is not enough oxygen to convert all the nitrogen decomposition products to nitrate hence there is some nitrite detectable in the water.

Investigating water quality

Saturday, January 22nd, 2011

Water quality standards like the Australian Drinking Water Guidelines often set the upper limit for contaminants like metals and organic chemicals. The Guidelines mention dozens if not hundreds of potential contaminants. But in many cases it is not clear at what level a particular chemical becomes a health hazard. For example it will depend on how much water is consumed over a given period and whether the contaminant has short or longer term effects. Arsenic is a contaminant that is thought to have longer term effects which are hard to quantify.

Dam near the Howqua River

This farm dam is in a fairly isolated location near Mansfield Victoria. The first step towards good quality dam water is to maintain a good vegetation cover in the catchment area.

Sometimes a customer wants a quick assessment of water quality. For example ‘is it safe to swim in a particular water body’? Its impossible to go through all the potential contaminants that might be present. Here are the results for a recent test. E coli 0, coliforms 0, aerobic plate count 141,000 (all CFU’s / 100 mls), pH 9, ORP 257 mV, dissolved organic carbon (as UVA) 12.5 ppm, EC 19.5 miliS/cm, turbidity 0 FTU. Would you swim in this water? The bacteria all tested absent or low, the oxidizing potential was within the acceptable range and the water was very clear. Its possible to find natural waters with at least one of those factors at the same level. But in the same sample the values for pH, DOC and EC sound alarm bells! Oddly enough the turbidity value (very clear water) in this case possibly indicated a problem because natural waters usually have some turbidity. The question went back to the customer, ‘Was there any obvious reason that they knew about for the unusual test results?’ It turned out that the water was from an artificial lake near an industrial area. Therefore the recommendation was that it would not be prudent to swim in that water.

Water quality indicators

Sunday, January 10th, 2010
Waterhole on a drying creek in Central Victoria

A waterhole on a drying creek in Central Victoria The water is very discoloured and has an earthy smell with abundant protozoans and a few algae The ORP value (oxygenation) has dropped to the low side of the desirable range.

At Apps Laboratories we measure a range of factors in water samples.  Some like dissolved metals can be compared directly to the Australian Water Quality  Guidelines. Others like salinity indicate what the water can be used for for example depending on the salt tolerance of irrigated crops. More often we want to give the landowner an idea of what is wrong with the water; an indicator of  ‘health’ or quality.

This gives a better understanding of management of the water or possible treatments. Here is what we found in a recent dam water sample. The water has a smell like compost and was discoloured green by algae. A quick check of ORP level showed very low oxygenation. High ammonia (unionized form) confirmed that there was probably high organic contamination of the water and that under low oxygen conditions some was being converted to ammonia. We also didn’t find any nitrates but this was expected because of the low oxygen. UVA absorbance was very high further suggesting high levels of organics in the water. The water also had elevated salts and a calculated significant sodium hazard.

Very high densities of algae usually indicate high nutrient inputs. The fact that we found some phosphate was a bit worrying as algae usually use up all the phosphate as they grow. Perhaps a check on the water coming into the dam would be recommended. The water was also very alkaline (pH 9.2). Algal blooms remove carbon dioxide especially during the day and send the pH upwards. At night the pH should return to more normal levels. There were two unusual characteristics of this water; the pH stayed high overnight and there was higher than expected alkalinity.  Some of this water is waste water from a food processing plant.

Overall the ‘quality’ was low and several problems were indicated both in the source water and in the stored water.

Boosted reverse osmosis filter for farms

Friday, August 21st, 2009

One of the problems with many homes in rural areas is that there is not enough pressure from pressure pumps to run a reverse osmosis filter system. Reverse osmosis filters work by pushing water against a very fine membrane. Only a proportion of the water, usually 1/4 to 1/3 gets through, leaving behind most salts and other contaminants.  The rest of the water with the contaminants goes to waste.

A boosted RO system for rural homes.

A boosted RO system for rural homes.

RO systems are designed to remove a large proportion of most contaminants from water including salts and chemicals. The result is very clean water. RO works more efficiently with reasonably clean water like rain water tank or spring water.

The picture is of a boosted RO I made up. It is in the lab and produces rinsing water for the lab and also drinking water for the house. Output is about 108 l/d. It uses a 24 gpd membrane. 50 gpd membranes are also commonly used. The prefilter is just a 1 micron sediment cartridge. The second cartridge is a 1 micron carbon block cartridge. This cartridge is designed to reduce tastes, smells and protozoan pathogens. Here are some results for the lab RO system.

Before filter After filter
DOC* by UVA 254 nm 2.1 ppm 0
Conductivity 87 microS/cm 7.4 microS/cm

* DOC = Dissolved Organic Carbon. DOC is directly proportional to UVA at 254 nm for most waters. Here an estimate of DOC is made based on an approximate relationship derived from published data from a variety of waters.

There are no detectable dissolved organics getting through and the salts level has been significantly reduced. RO membranes can also reduce bacteria in the water but I haven’t tested bacteria reduction yet.

For a range of water filters to suit both town and country applications see Water Doctor water filters.

ORP in water – what does it mean?

Sunday, July 5th, 2009

Recently a couple of bore water samples came through the lab. By coincidence although they came from very different locations they had some distinct similarities. These were elevated dissociated carbon dioxide, elevated soluble iron and elevated manganese. But they both had another similarity – low ORP or redox value. The sample with the highest metal levels had an ORP of around 110 mV. In the other the ORP was around 160 mV. I usually expect ORP levels of between 200 – 400 mV in good quality water.

ORP is a measure of oxidizing capacity. A low ORP especially below 0 indicates reducing conditions. In the sample above with the lowest ORP I aerated the water with an aquarium pump for 5 hrs but could only get the ORP to around 300 mV. After that it slipped back to around 200 mV. What an ORP probe measures is the average effect of usually many different redox reactions pulling the mV value up and down. Oxygen supply is thought to mainly influence higher ORP values but lower values are created by reduction of oxygen supplying species (molecules / substances) such as sulphate and oxides of metals like iron and manganese.

For more detail on why measuring redox is important please see pH and ORP in water.

What’s in water?

Saturday, June 13th, 2009

Water testing is a little bit like problem solving. Most people want to know if there are any underlying issues that may affect their water quality. For example if there are higher than expected numbers of bacteria, if there are dissolved metals present or if there is any contamination from organic chemicals. Most test results are ‘indicators’ and go towards characterising water quality. They also give some ideas about both water treatment, for example by using water filters or, often more importantly water supply management.

There are a lot of things that can possibly be in water: algae and microorganisms, organic chemicals, metals, different salts and dissolved gases. But water is not a static system – it is a living (usually) system that has its own properties. One of the most useful tests I do in the lab is to measure carbon dioxide. Specifically its the dissociated fraction that is part of the pH buffer system. By also measuring alkalinity its possible to calculate a theoretical pH. Now when that’s compared to the actual pH some inferences can be made about factors that are affecting water quality. Something similar is done in medicine where analysis of the pH buffer system can indicate if a persons illness is affecting or originating from kidneys or lungs.