History of aerial topdressing in New Zealand: Encyclopedia II - History of aerial topdressing in New Zealand - Origins

History of aerial topdressing in New Zealand - Origins

History of aerial topdressing in New Zealand - Other Aerial Applications

The first known aerial application of agricultural materials was by John Chaytor, who in 1906 spread seed over a swamped valley floor in Wairoa, New Zealand, using a hot air balloon with mobile tethers.

The first known use of a heavier than air machine occured on 3 August 1921 when as the result of advocacy by Dr Coad, a USAAC Curtiss JN4 Jenny piloted by John MacReady was used to spread lead arsenate to kill catalpha sphinx caterpillars near Troy, Ohio in the United States. The first commercial operations were attempted in 1924 and use of insecticide and fungicide for crop dusting slowly spread in the Americas and to a lesser extent other nations. Crop dusting poisons enjoyed a boom after World War II until the environmental impact of widespread use became clear, particularly after the publishing of Rachel Carson's Silent Spring.

The topdressing of fertiliser by air took substantially longer to be developed.

History of aerial topdressing in New Zealand - Early Suggestions

Initial interest in New Zealand concentrated on seed sowing, however much of new Zealand's central North Island farm land, given to returned servicemen after World War I, had proven deficient in trace minerals such as cobalt, copper and selenium, forceing difficult topdressing by hand in rough contry, or abandoning the land for forestry and the possibility of using aircraft soon occured.

Spreading Superphosphate by agricultural aircraft was independantly suggested by two New Zealanders, John Lambert of Hunterville and Len Daniell of Wairere in 1926. There was some publicity when in 1936 Hawkes Bay farmer Harold McHardy used a de Havilland Gypsy Moth to sow clover seed on his own land. This lead the Soil Conservation and Rivers Control Council to decide to fund aerial sowing and topdressing trials to prevent erosion in 1937, but little progress was made, despite strong advocacy by Doug Campbell.

At that time it was illegal for anything to dropped from an aircraft, which dissuaded several advocates who felt a law change was needed before experiments could begin. In fact news of early experiments was spread by an article was a published by a government pilot for the Ministry of Works who simply took the risk of publishing an article showing he broke the law.

History of aerial topdressing in New Zealand - Alan Pritchard

Alan Pritchard pilot for the New Zealand Public Works Department, recalls the idea of spreaing seed occured to him as he was flying E Madden of the Ministry of Works in a Moth, sharing grapes and throwing the seeds out of the open cockpits. A few months later, he was prevented from conducting an aerial survey in Northland when the Ministry's Miles Whitney Straight ZK AFH was grounded by bad weather. A supervisor J L Harrison, complained Pritchard was holding back men needed to sow lupin seed. Pritchard suggested that the sowing the seed by air. Burrying the hatchet, Harrison and Pritchard spent that evenining experimenting with methods of dispersal, before settling on sewing a sack onto a peice of down pipe. The following morning, 8 March, Pritchard flew over Ninety Mile Beach while Harrison, on his signal, held the down pipe out a window and emptied the sack. They then landed and examined the spread of the seeds. It was found a distribution of 1 seed per square foot was obtained from a height of 100 - 150 feet. On Monday 10 March, they sowed 375 acres, using 2lb/acre (instead of the 5lb/acre used when sowing by hand). The pair returned to examine the site at 2 weeks, 1 month and 2 years, at all points the aerially sown land was indistinguishable from that sown by hand. After the outbreak of World War II, he had the good fortune to retain the use of ZK AFH, when most ofter aircraft were impressed for war time service.

Pritchard wrote up the experiment in the NZ Journal of Agriculture (vol 70 p117-120). This came to the attention of the Minister Bob Semple, who Pritchard occasionally flew as a VIP. Semple asked how Pitchard had obtained permission. Pritchard admitted he hadn't, and had "cribbed' back the time in the ZK AFH's logbooks by extending the time of other flights. Semple encourraged Pritchard to continue, adding "Don't let anyone catch you, and if they do, send them to me". Pritchard conducted various trials between 1939 and 1943, at some point during which he added fertiliser to the seeds.

As a result in 1945 the Department of Agriculture estimated aerial topdressing would cost about £4 per ton of fertiliser (on a basis of 2 cwt per acre), which was economic, (in actual fact, this price turned out to be a significant overestimate). Pritchard now found an ally, who could officially sanction further trials.

History of aerial topdressing in New Zealand - Doug Campbell

Doug Campbell had been suggesting the spread of both seed and fertiliser for erosion control and adding trace minerals since the 1930s. Immediately after the war, he obtained permission to build a sheet metal hopper for ZK AFH to test the spread of blue stone crystals. In 1946 the first pure topdressing flight was conducted. Mixtures fo bluestone crystals, sulphate of ammonia, slaked lime and carbon black were used. The lack of a lid for the hopper initially resulted in irritating dust spreading through the aircraft in turbulence, in cold wet conditions it was necessary to heat the hopper to prevent the fertiliser coagulating, while in dry conditions the powder tended to dispirse in the wond before reaching the ground. Never the less in July Campbell arranged for ZK AFH to topdress 1,100 acres of a copper deficient farm. In August 1947 trials with cobalt sulphate in liquid form were conducted on the farm of KM Hickson near Taumaranui, with a horseback mounted radio used to convey results to the pilot. It was soon suggested that cobaltised superphosphate would be easier to spread although it was felt a speciaised aircraft would be needed to do this.

Campbell published his research in the New Zealand Journal of Science and Technology Volume X 1948 as “Some observations on Top dressing in New Zealand”.

Convinced by the trials, Campbell formed the co-ordinating and advisory committee on Aerial Topdressing with representatives from the Ministry of Public Works, Department of Agriculture, Department of Air, DSIR and Soil Conservation council. At the committee's first meeting on 27 November 1947 it resolved to ask the RNZAF for assistance.

History of aerial topdressing in New Zealand - The Royal New Zealand Air Force trials

The RNZAF between the second world war and the cold war, the RNZAF was a large and competent organisation without a lot of work to do. It responded enthusiastically to Campbell's suggestion, initially proposing to use Tiger Moth and DC3 aircraft, but concerns about corrosion lead them to use "expendable" war surplus Grumman Avengers.

Experiments were resumed on 5 September 1948 using the Witney Straight and three Grumman Avengers; the Royal New Zealand Air Force put superphosphate in a converted long range fuel tank in Avenger NZ2504 and dropped it over the concrete runway at Ohakea. (NZ2504 is now preserved in the Royal New Zealand Air Force Museum).

The superphosphate was too powdery but a more granular form was found before final trials measuring distribution pattern of spread by air on September 16. The results were considered very promising. Trials proceeded to hill country at Te Mata near Raglan, and were extended to three other sites.

For 1949 a Research and Development flight was formed under Stan Quill equipped with the three Avengers and a DC3, while instructions were sent to england to modify 2 Miles Aerovans on the production line to carry 1 ton hoppers. The 1948 fuel tank was replaced by a hopper with sides angled at 60 degrees and a vibrating rod to losen the superphosphate. Large scale topdressing started on 14 March 1949 spreading clover-super mix. The "Topdress III" trials culminated on 21 May 1949, with a demonstration drop on eleven different properties close to Masterton in front of large numbers of farmers and press. These trials were calculated to have spread 2.5 cwt/acre at at an all up cost of 15/- despite the use of inapproprately over powered combat aircraft. Further public displays were given to cabinet ministers on 30 August at Johnsonville, on 9 September at Ohakea and at a September 17 Airforce day airshow. As these trials were a resounding success, in addition to the Aerovans, 12 RNZAF Bristol Freighters, then under construction were modified to take Superphosphate hoppers.

Following the successful RNZAF trials, in 1950 farmers groups lobbied the government to have the RNZAF provide subsidised topdressing with the Bristol freighters and even advocated using giant Handley Page Hastings. But by this time, government work was being overtaken by private enterprise as in ex-airforce pilots bought kiwi built De Havilland Tiger Moth biplanes cheaply, placed a hopper in the front seat and went into business flying from the paddocks of any farmer willing to pay. The RNZAF was waking up to the "Communist threat" and preferred to concentrate upon defence and the government reluctant to spend money or interfere with the increasing number of commerical operators.

Adapted from the Wikipedia article "Origins", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki