Increasing production with fast flow border check irrigation

Take home messages:

• Irrigate with a time of 1 to 3 hours per bay.
• Planting the crop at the right time is essential.
• Monitor soil moisture.
• Timing of nitrogen fertiliser application is very important.

Background

From small areas of fast flow irrigation on annual pastures on my Goulburn Valley dairy farm, I had already recognised the potential increase in yield by getting the water on quickly. I would have expanded fast flow irrigation on my farm during the 1990's but because I could not get a big enough or consistent enough delivery, I put expansion on hold. Added to that, at the time the hardware (outlets) was not developed enough, and the automation was not sophisticated enough.

I decided to try fast flow irrigation again when the Goulburn Murray Water Irrigation District was upgraded and delivery of 25 ML/day was possible. Also, the hardware and software required to deliver the water became available and I took advantage of the Commonwealth On-Farm Modernisation Program, delivered through Goulburn-Broken Catchment Authority.

The soil type on my farm is mainly Lemnos Loam (a clay loam).

Methodology

From 2011 to 2013 we installed 75 Padman PE 600 mm outlets (Box type with MC Pipes 600mm rubber joined going under the channel bank). Forty-nine of these were automated with Rubicon FarmConnect.

These were used to irrigate summer crops of maize, millet and lucerne, and some annual pasture from autumn to spring.

Four moisture meters were installed at the same time, one in each of these crop types.

Most of the paddocks these outlets were put into were lasered (some previously and some newly done). Generally the slope is between 700:1 and 750:1. This is not as important as it used to be because fast flow irrigation eliminates water lying around in puddles on flatter ground.

Since the initial installations I have installed a total of about 120 PE 600 outlets. The majority of these are on annual pasture (Shaftal clover and ryegrass). I have also increased the area sown to crops such as maize and lucerne, and some is on perennial pasture.

To date we have not increased the number of automated outlets but we are in the process of doing this now.

Results

Maize

Fast flow irrigation has had excellent results. My preferred watering duration is 1 to 2.5 hours per bay. I have some bays that are longer and take three hours, and I believe they are a little too long in my soil.

I am applying 100ml water, and in less than two hours after watering, there is no water still lying on the surface of the paddock. (I could apply up to 125ml per watering and this would slightly increase the time between irrigations, but the timing for this has not worked out for me this year, and it is also probably influenced by the soil type.)

I pre-irrigate (fast flow), then deep rip (at least 30cm), then apply pre-emergent spray, and then sow all in one week. In Goulburn Valley, I believe it is critical to sow by the 12th November.

The sowing rate is 90,000 seeds per hectare.

I prefer to get my crop 1 m high before the first irrigation. This is because:

• it will not get a growth check due to the watering, and
• any grass seeds left on the ground will be shaded out by the canopy, and therefore, will not affect the crop.

Fertiliser application: 100kg/Ha DAP at sowing, then urea applied in the first and second irrigations (180kg/Ha applied in the water after the outlet), then again on the fifth irrigation (50kg/Ha).

We have averaged 26 tonne DM/ha over the last three seasons.

The key to this is the ease of management due to good layout. I would not even attempt growing maize if the layout is not good. This is because you need to produce at least 16 tonne/Ha to break even. I think 30 t/Ha is the potential, anything above 22 t/ha is good. Over the last few seasons, my contractors tell me that the regional average has been 16t/Ha.

Looking around this year (2015), I think the average crop in our district looks much better as better methods are being adopted.

Lucerne

No prewatering.

Sown in August into a fine seed bed to take advantage of the higher chance of rain to strike the crop. If it does not rain within 2 to 3 weeks of sowing, irrigation is necessary.

Before we graze the crop, we mow 6-8 hours before the cows go in. We make sure that at grazing there is enough moisture for the canopy to grow back before the next irrigation to prevent weed seeds from striking.

Watering time is two hours or less, and the bays dry off quickly, leading to an extended life of the plant because it is not frequently waterlogged.

Lucerne is fertilised with 100kg single superphosphate/Ha annually prior to sowing. We aim for an Olsen P of about 40.

I believe the benefit of fast flow irrigation on lucerne is:

• it is easier to manage, and
• the plant is healthier.

Annual Pasture

No pre-watering and weeds are kept in control over summer.

Some paddocks will have speed discs, or grader if necessary. 100 kg single superphosphate prior to sowing. Lime is applied approximately every ten years.

Direct drill sowing with Baker Boot – 15kg annual ryegrass, 4kg Shaftal clover/Ha.

First watering is only applied after the maximum daytime temperatures are below 28 degrees C. First watering is slower than later waterings (e.g. 15 ML/day), otherwise the paddock dries out too quickly and the small seedlings do not survive.

Second and subsequent watering is applied as fast as possible (e.g. 25 ML/Day).

Annual pasture cut for silage in 2014: 1000 tonne DM from 200Ha (five tonne DM/ Ha) and excellent quality.

I believe that the biggest advantage of fast flow irrigation on annual pasture is that a large area of pasture can be watered in a short time. This allows much greater control in timing of grazing and harvesting (e.g. if silage harvesters can cut 80 Ha/day, then you need to be able to water 80Ha/day so that it is ready at the right time and the harvesters can keep cutting and stacking). I do green chopped pit silage and get contractors in to mow, rake, chop and roll the pit. We cover it with plastic. This is of great economic advantage in my operation.

Conclusion

The combination of a good irrigation system to deliver a fast, constant flow, together with automation, allows me to deliver irrigation to my crops using best practice, and gives me a better lifestyle (less time irrigating). I believe it has also allowed me to double my production of dry matter per ML water used, as well as producing better quality fodder.

Contact Details

Russell Pell
Dairy Farmer, Wyuna
0429 438 389
crpell1@bigpond.com