Saturday, 25 January 2014

Just-Add-Water Experiment - Update

On 4th January 2014 we kicked off our 'Just Add Water Experiment' which we described in our blogsite post dated 6th January 2014. Here's a link. In the comments section of that post you will find updates describing watering events, daily temperatures, rainfall events and a few other bits and pieces.

It's now 19 days since we kicked things off and we felt it time to share photos taken today showing what's happening at the site.

The photo below was taken outside but adjacent to the site i.e. not watered aside from natural rainfall. Stock are able to access this section of land. If you enlarge the image and look very closely you will be able to see some very slight green grass growth ... just a few plants:

The photo below was taken inside the watering area of the site. Stock are able to access this section of land. If you expand the image and look closely you will see many green plants but only minimal leaf area due to the grazing impact.

The photo below was taken inside the watering area of the site and inside the stock exclusion area. You will see many plants and most have a reasonable amount of green leaf area. We expect to see rapid growth in the coming weeks.

At this point it is fair to say that considerable seed germination has occurred on the watered area.

Remote Power Supply Performance During Serious Heat

Our maximum daily temperature during the past fortnight has been as follows:
12th January: 42 degrees C, 13th January: 40, 14th January 40, 15th January: 42, 16th January: 44, 17th January: 43, 18th January: 45.5, 19th January: 42, 20th January: 40, 21st January: 38, 22nd January: 38, 23rd January: 35, 24th January: 25 (17 mm rainfall received during the course of the day), 25th January: 30

9 days of temperatures of 40 degrees or more is quite an extended hot spell. It has given us quite an opportunity to see how both we and our set-up handle the heat.

A few years ago we installed what our research suggested was the most energy efficient reverse cycle refrigerated air conditioner manufactured by Mitsubishi Industrial, model number SRK71ZEA-S1. A photo of the external inverter unit is below:

Our original intention was to install an evaporative air cooler but we opted for an air conditioner on advice from many that the former are of little use during high humidity periods. The latter does require considerably more power to run and was not in the calculations for our remote power system. It and the stock water pump are by far and away the two major power use items during summer. The latter is getting more use than normal presently due to the 'Just Add Water Experiment' we kicked off on 6th January.

Our house is not large by any means and during the renovations we did our best to insulate both the roof cavity and walls where we replaced the old plasterboard.

So here are some observations and learnings during the recent hot spell:

  • We both seem to be a bit better at handling heat than the 'average Joe-blow', which might be genetic or physiological
  • Our house insulation combined with fan use is such that we are comfortable inside in temperatures up to about 35 degrees
  • Solar panel performance deteriorates in temperatures above about 35 degrees C. On days below that our solar panels will harvest up to 19 kilowatt hours on a clear day, and when it is above 40 degrees about 17 kilowatt hours is the best we can hope for
  • The inverter we use that converts battery stored direct current to 240 volts AC recently 'chucked a serious huff' during temperatures above 40 degrees while the back-up generator was running.
  • The air conditioner doesn't draw much power when external temperatures are up to about 35 degrees, uses more up to 40 degrees, and heaps more when it is above 40 degrees.
  • We've found that the most appropriate internal temperature setting for us with our air conditioner unit is 28 degrees. The internal unit is near the ceiling so that actual temperature at 'living' height is well below 28 degrees
  • We've found that on above 40 degree days it works well to run the back-up generator for an hour in the morning and another hour in the evening. We see the cost of running the generator as the price of comfort during extremes.
  • We'd need to double the capacity of our solar panels to capture enough natural energy to cater for above 40 degree days. This is not cost justifiable as the reality is that there are not that many days during the year when temperatures are above 40 degrees.
  • On days when the maximum temperature exceeds 40 degrees we run the air conditioner from around 12.00 pm through to 9.00 pm.

Thursday, 9 January 2014

Upgrading Some Tree Guards

Our livestock are by nature pretty handy at consuming the leaf matter on Kurrajong Trees across the farm. This is not an issue with established trees but is for those we planted some years ago to become paddock trees. The addition of cattle to our enterprise mix also means that being taller than sheep they are easily able to get over the top of the guards we installed ... at the time just to protect the plants from sheep.

We've decided to upgrade the tree guards around young Kurrajong Trees in paddocks that have below what we think is the desirable number of paddock trees, especially in the Spring Paddock, Airstrip Paddock and Duck Dam Paddock. The photo below shows one of the Kurrajong trees in the Spring Paddock with the old guard still in place.

It would be great to be able to upgrade the guards on all of the trees we've planted as paddock trees but the materials are a bit on the pricey side.

The photo below shows the same tree in the Spring Paddock with a new guard in place. Height is 1.8 metres constructed out of sheep yard mesh. Hopefully this will do the trick!

Monday, 6 January 2014

Just-Add-Water Experiment


Our last decent rainfall event was in mid-September 2013 at 36 mm; so things here on Ochre Arch are ‘crisp’ and the long term forecast suggests little rain until autumn or beyond.

The quality of our bore water supply is first class, both in terms of mineralisation (or lack of it) and lack of impurities (zero chance of hose fitting blockages). The marginal supply cost is low at around $0.50 per kilolitre and marginal on-farm pumping cost is next to zero provided we don’t need to draw on the back-up diesel generator i.e. power source is from our solar and wind turbine sources. We are not stocked to capacity and thus are not using our full daily bore water scheme supply allocation.

It’s been a while since we kicked off a new on-farm experiment. They are one of the best ways to learn.

Experiment Description

We've installed a high flow water sprinkler well out from fence-lines in the Airstrip Paddock and will observe vegetation change over time from the soil (under the range of the sprinkler) being kept constantly damp from regular evening watering events using our surplus water scheme supply.

Current Soil Surface Condition

The photo below shows the soil surface condition at the site.


We recently purchased the following parts and assembled a water sprinkler (parts listed from the ‘top down’ in terms of the final assembly):
  • 20 mm brass two-nozzle impact sprinkler. This was the highest capacity sprinkler the supplier had on hand. We wanted to be able to apply the maximum water over the greatest area in the shortest period of time.
  • 3/4 inch BSP threaded plastic socket
  • 900 mm 3/4 inch BSP threaded pipe riser. The riser needed to be at least this high to keep it clear of the sheep.
  • 3/4 inch BSP threaded elbow
  • 3/4 inch to 18 mm Neta brass fitting. Our hoses are 18 mm rather than the 12 mm standard, allowing for higher volume flows.

Here's a photo of the brass nozzle on the top of the riser.

Estimating Water Flow Rate

When the assembly was complete we attached it to a hose near the house connected to the bore water supply hydrant. The spray nozzle was placed in an empty 20 litre bucket and the hose turned on full pressure. We timed to see how long it took to fill the bucket with water. The pressure was such that initially water flowed out of the bucket. After things settled we calculated bucket fill time at 25 seconds giving a flow rate of 0.8 litres per second.

Our initial thinking was that we’d run the sprinkler in the paddock long enough to disperse 1,000 litres. Based on the above figures this would take a tad over 20 minutes.

Installing the Sprinkler

We chose to set the sprinkler up in the Airstrip Paddock with water sourced from the hydrant on the fence between the holding yard for both our sheep and cattle yards and the Airstrip Paddock. Site location factors included being within close proximity to the house (we can see the site from under the covered area to the east of the house), on pasture that has been reasonably heavily grazed and in a paddock that we set stock with both pet sheep and our rams. Whatever grows will be a good source of protein for these livestock through to the end of summer.

Using one of our 18 mm hoses as the connector and distance setter we selected a spot equidistant from two fence-lines such that it would not be possible for the water to land on fence-lines i.e. all growth will be within the Airstrip Paddock. In the interest of simplicity a shortened star post was hit into the ground at the desired location and the new assembly attached.

Here's a photo of the riser in place, with the nozzle on top.

Stock Exclusion Area

Using two panels of weldmesh we constructed and put in place under the estimated drip line a circular fenced area. The diameter is approximately 3.6 metres giving an area of approximately 10.2 square metres. Having this in place will allow us to observe vegetation growth without the sheep having access, although other herbivores such as kangaroos and rabbits may gain access.

The photo below shows the stock exclusion area with the sprinkler 'doing its thing'.

First watering

At a tad after 7.30 pm on Saturday 4 January 2014 we turned the water supply to the sprinkler on. There was a brisk breeze blowing which meant that the water spray up wind was not nearly as far as it was downwind. The sprinkler worked extremely well.

After 20 minutes when in theory about 1,000 litres of water had been dispersed the top of the soil under the sprinkler was damp but our impression was that it would not be sufficient to get much growth happening. Consequently we decided to run the sprinkler for a full hour, making 3,000 litres dispersed. The soil surface was very damp (but no mud).

Watering close to sunset should mean we reduce the evaporation from the site, or certainly in comparison to what might occur if we did the watering during the middle of the day.

Area Watered
Once the watering was complete we were then able to calculate the total area watered. We simply walked across the wet area from drip-line to drip line twice at perpendicular angles. From this we estimated that the diameter of the wet area was 22 metres or slightly more than the length of a standard cricket pitch. Using a web-based calculator ( the approximate area watered was 380 square metres or 3.8 % of a hectare.

Water Applied per Square Metre

3,000 litres of water spread evenly over 380 square metres equates to roughly 8 mm water falling per square metre (sought-of comparable to 8 mm rainfall). Using the generally accepted guide that every mm rainfall produces 10 mm soil profile moisture this means that roughly 8 cm of soil profile moisture would have been created. Most of the ‘action’ in the soil happens in the top 4 inches or 100 mm, so we are pretty happy with our first watering. Using the foregoing it means that we will be applying roughly 1 mm water over the area each 7.5 minutes.

Second Watering
On 5th January 2014 we again watered the area for one hour. Our intent is to repeat this at around the same time each day for at least 2 weeks regardless of any natural rainfall.

Moisture Profile Check
At 4.00 pm on Monday 6th January 2014 we dug into the soil within the drip line to see what the moisture penetration was so far. The top 100 mm was damp, and dry below this depth. Daily watering for one hour should be sufficient to stimulate plant growth. One point to note: the temperature on 4th through 6th January 2014 has not been extreme but the wind has been strong.

Cost of the Experiment
The total cost of the materials used in the experiment is around $100. Daily water cost will be about $1.50.

Reporting Outcomes
We will make periodic posts showing any material change on the site.

Thursday, 2 January 2014

Review of 2013 Rainfall

Our impression was that 2013 was, overall, a dry year. With 2014 upon us it is a good opportunity to check the data and do a brief analysis of the 2013 rainfall results to see what actually happened.

Some context:

  • The summer of 2012/3 was particularly dry
  • The previous two summers were very wet
  • Our long term average rainfall is around 600 mm per annum, spread evenly over each month (50 mm per month)
  • We tend to have more rainfall event days during the cooler months, but higher falls per event during the hotter months
  • 2006 was one of the driest on record at a total of about 265 mm
To the 2013 figures:
  • Total rainfall received was 385 mm. This is roughly 2/3rds of the long term average.
  • Thus overall 2013 WAS a dry year
  • Total for the summer months was  31.5 mm (average 10.5 per month) ... dry
  • Total for autumn was 114.5 mm (average 38 per month) ... dry
  • Total for winter was 169 mm (average 56.3 per month) ... a tad above average
  • Total for spring was 70 mm (average 23.3 per month) ... dry
If we define a significant rainfall event as one where we receive 25 mm or more (half the monthly long term average figure) then:
  • There were (only) 4 significant rainfall events during 2013
  • They were: 70 mm on 1 March, 42.5 mm on 2 June, 28 mm on 19-20 July, and 36.5 mm on 16-18 September
  • The year was one where rainfall was predominant during the cooler months
  • A pretty good year for those growing winter crops
  • Not so bright for us graziers