Topdressing Trials

How it all began – Wairarapa Times-Age 31 January 1998

In 1948, it was proposed that topdressing trials be carried out, with the Royal New Zealand Air Force supplying the aircraft.

Seven tons of “hard-to-get” superphosphate were obtained from the New Plymouth fertiliser works and costs and spreading methods were looked at.

A Tiger Moth was initially selected to do the spreading, but because of a small payload it was decided to use a Douglas D-47 B Dakota (DC3).

This decision was changed again because the corrosive effects of fertiliser weren’t known and the DC3 was an expensive machine. So a Grumman Avenger was eventually used.

On September 10, 1948, the first hopper of a Grumman Avenger was filled with a ton of superphosphate for a ground load test. On September 15, the hopper was given its first flight test and fertiliser dropped over Ohakea Air Force Base.

The official trial was held the next day and after some fine tuning it was successful enough for on-farm trials to start.

These were conducted near Hamilton on October 12. The field trials proved aerial topdressing was practicable.

In March 1949, more trials were conducted near Ohakea and after the success of these the organisers were asked by Len Daniell, who farmed near Alfredton, for large scale tests to prove that aerial topdressing was the answer for hill-country farmers.

A 1000-acre trial was organised in Wairarapa and this led to the beginning of “Operation Topdress III”, the name taken after the earlier on-farm trials were dubbed I and II.

Thirteen properties with different terrain, soil, pasture and management were selected for the trials – but the one thing they all had in common was a shortage of manpower to spread fertiliser by hand.

At the end of April 1949 most of the topdressing team left Ohakea for Masterton in a road convoy made up of a station wagon, car, a one-ton truck, jeep, fuel tanker and radio van. Later that day a DC3 Dakota flew in more supplies and one of the two Grumman Avengers arrived.

People for the trials booked into hotels for a two-week stay.

On May 3, 1949, the first load of fertiliser was ready to be spread. But at the point of take-off, the plane’s undercarriage retracted.

The plane skidded across the aerodrome and the propeller bent. The full hopper was forced to the end of the plane, causing a three-hour delay in flying.

The specially-built hopper was written off which was considered a greater setback than the loss of the plane.

Later the same day the first of three successful fertiliser drops were made on the Wardell Estate at Te Whiti.

The spare Grumman Avenger was flown to Masterton, but on May 4 one of the hoppers didn’t open and it took two hours to cure the problem.

On May 5, a full aerial topdressing programme was carried out. Ten tons of super were spread over Hugh Morrison’s Awatoitoi Station, watched by a huge crowd of spectators. This was the first public display of aerial topdressing.

The two Grumman Avengers were organised so that while one was spreading fertiliser on the farm, the other was waiting at Masterton for the hopper to be filled.

That same day 10 tons were dropped on Len Daniell’s Wairere property.

May 9 saw an attempt to drop lime over Wairere but the hoppers wouldn’t open because the lime didn’t crumble and lumps stopped the sliding strip from moving forward into the sowing position.

Three weeks after the convoy arrived in Masterton, Operation Topdress III was completed.

It included the spreading of 125 tons of superphosphate and 12 tons of lime over 440.6ha, with the planes flying for 59 hours 10 minutes at an average of about 26 minutes a flight.

Mr Daniell is reported as saying after the trials that when large multi-purpose planes were available a new era in the development of the economy would begin.

Unfortunately, once the air force trials were finished, farmers couldn’t find aircraft to finish the job started so continued sowing fertiliser with sleds, packhorses and men.

After the trials farmers knew aerial topdressing was possible, but there wasn’t very much interest in Wairarapa.

Len Daniell, one of the first campaigners for aerial topdressing, felt the air force was the only organisation for the job. When Federated Farmers representatives met government representatives they were given an assurance that only one Bristol Freighter from the air force would be fitted out for the job.

Pat Boyle and Malcolm Forsyth, instructors at the Wairarapa and Ruahine Aero Club at the time, decided to begin a flying school specialising in advanced flying skills.

Accompanied by aircraft engineer Tom Withey, they went to Wellington to discuss their plan with the director of Civil Aviation. He was impressed with their ideas but suggested they were more suited to aerial topdressing.

So Air Contracts Ltd was formed and on February 23, 1950, a Tiger Moth was brought for the job of aerial topdressing. Mr Withey also bought a “Moth” and it was this aircraft that was ready for topdressing with a hopper on April 14, 1950.

The first aerial topdressing order for Wairarapa came from Hugh Morrison of Blairlogie Station who wanted 100 tons spread.

That first order was spread on a slightly- eroded hill face and flying was shared by pilots Pat Boyle and Malcolm Forsyth.

On the second day of spreading, the Tiger Moth hit two fences on take-off, causing damage to the propeller, a wing, and ripping off the undercarriage.

By the end of 1950, Air Contracts Ltd had expanded to own four Tiger Moths, and employed two extra pilots.

Wind directions were originally taken from smoke made by burning empty fertiliser bags, but in the summer months farmers weren’t so keen on lighting fires.

It turned out that smoke didn’t give reliable wind directions, so a portable wind sock was made.

The shock was made from a large number of nappies sewn together and worked perfectly.

By 1951, Air Contracts had six pilots, all flying Tiger Moths. They were paid £750 a year.
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