Effective use of drip irrigation technologies for for Westwood provides results

We followed Neil Mill from Westwood Central NSW during a recent farm walk to look at how he is managing to produce results with drip irrigation.

Neil lives and farms the ‘Westwood’ aggregation approximately 20km north west of Narromine in Central West NSW

Neil operates mixed cropping farm with a combination of dryland and irrigated winter crops, in a normal year Neil irrigates summer crops from 2 bores and the Budda Lake Scheme supply. In 2009 he planted 100ha of cotton and retained sufficient water for 40ha of young citrus. Usually with schemes operating he would plant approximately 500ha of summer crops.

Water situation

The farm comprises of 5300Ml of Budda Lake Scheme license, of which there is no allocation for 2009, and 2 bores with 400Ml of license each, these bores both yield 4.2Ml/day, and pump into 2 x 400Ml storages.  The storages reticulate via channels to both drip blocks.

Neil’s main objective is to produce efficient sustainable yields therefore Neil focus is on improving soil conditions and maximizing water use efficiency.  Generally he likes to implement 100% rotation with his cropping cycle.

Why did Neil decide on drip?

He says cotton is grown on Westwood under drip in 2 blocks, one is an early block of 37ha that is approximately 20years old (still operating very effectively, replaced tape once, and 3 controllers), and the other block is a new system installed in 2008. 
Neil says drip was chosen in both cases for the following reasons:

1. Better as a system to manage variable soil types.
2. When relying on groundwater, easier to manage small volumes of water available.
3. Highest water use efficiency.
4. The technology is tried and proven.
5. Manipulation of a crop is far easier with drip providing better control of water and nutrients.
6. Drip technology offers huge potential for improvement in yields and water use efficiency, i.e. bales / Ml with improvement in management practices.

What is the drip irrigation configuration?

The new block comprises of 20 ha of sub surface drip irrigation designed in 2 shifts. Each shift applies 1.2mm/hour and has drip laterals spaced 2m apart. The emitters are 1.05l/h @ 0.45m spacing; the tape is Netafim Ozline with a 25mm ID.

What are Neil's experiences with the drip blocks compared to your flood irrigation blocks?

• Soil type is 65% grey heavy loam (self mulching) with the remainder a lighter variable red soil, drip overcomes this variability evening crop performance.   
• Fertilizer: The main difference was with the application of N, the flood block got most of it’s N up front in total 240units applied.  The drip block had its N applied through the Fertigation system throughout the season totaling only 120units.
• Labor: There was a significant labour saving on the drip block, one man easily managed it including Fertigation, whilst there was no data collected the labour component on the drip system is estimated to be at least halved compared to the flood.  
• Water use – Significant difference was documented (see table below), the difference is attributed to the ability of the drip system to take advantage of summer storms, and light rain fall, the crop utilised these falls due to 50%-60% of the growing area under drip remaining dry allowing rain fall to be stored in the ground. The crop was also germinated on rainfall moisture, this is very important on 2m beds, as in a dry year up to  1.5 – 2.0Ml can be used getting the crop out of the ground, Neil estimates that 8/10 years in his 20 years experience with drip he successfully germinated his crops on moisture from rainfall.
• From energy usage prospective better rainfall utilization has also greatly reduces the operating costs. Neill believes that combination of climatic conditions, rainfall and warm summers that are not too hot and variable soil types made drip irrigation an easy choice for him. Neill has also pointed out that drip did not suit all applications and farming systems.

Yield Water Use 2009 Cotton season:

How did the Cotton crop perform on 3 mg?

The crop showed little signs of stress throughout the season, with timely rainfall and constant moisture monitoring with Aquaspy capacitance probes using sensors down to 1.0m; he was able to keep a close eye on the crop.  The peak application rate applied throughout the season was 6 hours per shift or 7.2mm/day. Moisture probes that log information and can be interrogated with a high frequency irrigation are essential in scheduling water application and maximising efficiency. Achieving high water use efficiency, also leads to high efficiency in the area of fertilizer usage, labour, and return on your water asset.  With the changing climatic conditions experienced in the Macquarie Valley over the past few years, drip has enabled me to make better use of smaller amounts of water.

Neil is happy with 2m row spacing, and his new block of 20ha was very inexpensive to install as the pump and mainline were paid for by the citrus installation, this allows night time hours to be productively used to irrigate the cotton.  2m row spacing also saves approx $1000 per ha. Combined in his case these facts made drip in Cotton economically attractive.

The field was close to the citrus, close to power, not suitable for flood, and close to water distribution channels, so it all made sense.  

Neil's concern was the inability to deal with compaction after the drip was installed; there is no mechanical means of treating compaction.  Neill believes that with better crop rotations and better technology with harvesting and farming equipment (bigger, wider wheels, traction control etc) compaction can be better managed and minimized.

Weed control was better with drip as placement of water discouraged weed growth.

In summary: Neill states that the choice of drip was easy for him, he has been happy with his original block for many years, and very impressed with the new block, he made special mention of the improvements over that time in the area of controllers (running the system, Fertigation and overall user friendliness of Netafim controllers), and the effective run lengths in tape, meaning less in field infrastructure. Neil is very happy with his 2009 results, but believes that with improvements in management greater results are possible.


Neil Mill farm walk March 2009.