Challenges and Innovations in Fertiliser Technology and Spreading
Introduced ryegrass/clover pasture started to become the mainstay of the New Zealand economy following the decline in gold exports. The original soils, both of sedimentary and volcanic origin, were recognized as being phosphate (P) deficient early on. Application of phosphate rock had mixed success, partly because the large differences in agronomic efficiencies of different materials were not recognized at the time, as nor was the prevalence of sulphur (S) deficiency on all but coastal soils.
The commencement of single superphosphate (SSP) production at Ravensbourne near Dunedin in 1899 cured both problems with one hit. High-quality phosphate rocks were available through the British Phosphate commission from the likes of Nauru Island in the Pacific and Christmas Island in the Indian Ocean. Reaction with sulphuric acid produced a powdery product containing about 10% P as water-soluble monocalcium phosphate (MCP), and 12% S as calcium sulphate (gypsum).
The massive increases in pasture growth achieved with SSP lead to many more manufacturing plants being set up around New Zealand, some by private or publicly-owned companies, and some by farmer-owned cooperatives. Because of the high labour costs of spreading by hand, application was limited mainly to flat and rolling land, where bagged product could be spread manually from the back of moving trucks. Later, trucks fitted with bulk hoppers, drag chains or belts, and single or double spinning discs greatly reduced spreading costs.
However, this still left unrealized the production potential of the millions of hectares of steeper hill country. Interestingly, the idea of spreading SSP from aircraft was first mooted in the Wairarapa in the 1930s, as a means to encourage pasture recovery on slips. Successful trials were conducted discharging fertiliser and seed from bags, by hand through the window! Low payloads restricted wider use. Innovative if misguided attempts to improve payloads included jettisoning sealed bags of fertiliser and seed from the loading doors of larger aircraft. These were designed to burst on impact. Not a technique likely to result in even spreading, and potentially lethal to livestock!
Post World War II growth
The end of WWll brought with it dramatic changes. Key factors were the return home of many experienced and innovative pilots, and cheap war-surplus aircraft, such as the US Navy Grumman Avenger, with sufficient power to be fitted with fertiliser hoppers. Several multi-aircraft companies and cooperatives were established, including some that survive today. Larger twin-engined aircraft such as the Douglas Dakota were also used.
Driven by the need for airspreading steeper farms, many one-pilot businesses were set up using sturdy but light, manoeuvrable aircraft, that could take off from very short strips and be easily maintained, usually using hopper-fitted Tiger Moths or the purpose-built Auster. No other country had adopted airspreading like New Zealand had!
Helicopters also began to be used, but their very high relative operating costs limited their role in fertiliser to the application of liquid fertiliser sprays on high-value crops.
The massive increase in aerial topdressing in the 1950s transformed New Zealand’s lamb and wool production at a perfect time of high commodity prices. Innovation in fertiliser technology itself was limited to the introduction of semi-granulation and/or co-granulation with lime and serpentine to avoid potentially lethal bridging in aircraft hoppers. The incorporation of other nutrients, trace elements and herbicides became much more widely practiced, and S deficiency became understood and treated.
In fact, the S deficiency in our soils, compared to most countries where agronomic S requirements were met by ‘acid rain’ pollution, has kept SSP still the main fertiliser used to this day, whereas in most countries it has been totally supplanted by granular high-analysis bulk blends of DAP, MAP, urea and potash, and co-granulated NPK products.
The dominance of SSP here was aided by reliance on clover for nitrogen (N) fixation to maintain soil N fertility. This, plus the need to add S, reduced the attractiveness of DAP. The slow soil acidification induced by N fixation was countered by application of lime at heavy rates (typically 1-2 tonnes/ha) every few years.
From the mid-1950s, airspreading increasingly became the domain of the famous Fletcher. The first Lycoming-powered aircraft was imported from the USA in 1953. Manufacture later switched to New Zealand, and continuing power and payload upgrades, ultimately in the form of the larger-bodied, turbine-powered Cresco, kept this rear-hopper, front fuselage wheel design all-powerful in this country until the present day, although both these design features greatly limited demand for the aircraft in overseas markets.
Leading the way with experimenting with alternative aircraft designs and spreading technologies was the incredibly innovative Ray Patchett of Marlborough. Ray developed and patented new self-cleaning fertiliser-suspension booms for fixed-wing aircraft and helicopters, and fully automated, pilot-controlled hopper loading systems. He has become a committed supporter of the Australian-built ‘Fatman’ hopper-forward tail-dragging aircraft design, believing it to be the way forward for New Zealand.
Then along came the 1980s! Several factors combined to make this period a pivotal one for the fertiliser industry in New Zealand. These included the growth in fertiliser manufacturing research, the decline in the quality of SSP, government research with RPR and PAPR, and the downturn in world commodity prices and fertiliser use.
The growing interest in manufacturing alternative fertilisers
Unlike in the fields of agronomy, soil fertility and soil science, in which New Zealand has long been world class, we have traditionally had few chemistry-trained scientists involved in fertiliser technology, production and agronomic efficiency. The key reasons for this were the absolute dominance of SSP, and the extremely low usage of fertiliser N.
There were exceptions of course. Professor Keith Syers at Massey University set up the Fertilizer and Lime Research Centre (FLRC), which will hold its 25th annual fertilizer symposium in February 2012. Keith became heavily involved in RPR research.
Sunder Rajan was one of the very few MAF scientists who specialised in both making and trialling new fertilisers, particularly partially-acidulated reactive phosphate rocks, or PAPRs. John Watkinson was an excellent soil chemist who did some world-class work on selenium fertilisers, and on optimum particle sizes for elemental S and RPR.
Peter During, Ian Cornforth, Allan Sinclair, Mike O’Connor, Doug Edmeades and Long Nguyen were exceptionally good soil fertility experts who were involved in comparisons of different fertilisers and technologies, but were not personally involved in developing new products.
Outside the FLRC, the only research institute which had any real focus on fertiliser per se was the now-defunct Fertiliser Manufacturers Research Association or FMRA. This joint government-industry funded institute was located in Otara, Auckland and had a staff of 20 scientists and technicians. Although most of the FMRA’s activity involved the study of different phosphate rock options for SSP manufacture from a purely processing point of view, a few staff such as Andy Braithwaite and Roy Stephens did interesting laboratory and glasshouse work comparing different types of fertilisers, especially PAPRs. This work lead one of the smaller cooperatives, since taken over by Ravensdown, to temporally produce a phosphoric-PAPR at Napier in 1986/87.
The decline in quality of NZ-manufactured superphosphate
This relatively small involvement in fertiliser manufacturing research in New Zealand probably explains why a massive decline in the agronomic effectiveness of SSP during the 1970s took so long to be noticed. It was only by virtue of the existence of a long-term rates of SSP trial, commenced at Winchmore Irrigation Research Station by Russell Lobb in 1954 and fastidiously maintained by Don Rickard, that drew me to try to understand what was happening at a chemistry level.
It was clear that it was now taking double the previous quantities of SSP to maintain various yields relative to the maximum attainable. I concluded that this was largely a consequence of the change to using cheaper Christmas Island B and C grade rocks, containing high levels of iron and aluminium, to make SSP. Acidulation of this material lead to the formation of complex iron aluminium calcium phosphates of very dubious plant availability. This effect was exacerbated in those works where, in an effort to provide a more free-flowing product, serpentine rock was added before semi-granulation. The resulting partial acidulation of the serpentine made some magnesium plant-available, but left a significant proportion of the phosphate rock in the even less agronomically effective raw phosphate rock form.
Quin, I’m going to sue you for every cent you have…
MAF and “Government” analyst Mike Brown and I published our findings in the NZ Farmer magazine in late 1981. I was immediately ‘summoned’ to a meeting in Dunedin by Paul Sawyer, the intimidating CEO of Ravensdown, to ‘explain myself’. His conversation opener was to say that ‘Quin, I’m going to sue you for every cent you have’. I still clearly remember explaining to Paul that, being a young scientist with, at that stage, 4 children 5 and under, a mortgage and the 1972 Datsun 1600 I had driven down from Ashburton in, that particular course of action was unlikely to be worth his trouble. I don’t think Paul had experienced anyone taking the mickey before, and by the end of the meeting we had established some mutual respect. So two weeks later, Peter Elworthy (later Sir Peter), then Chairman of Ravensdown, visited Winchmore to hear directly what the trials were showing. Within a few months, Ravensdown had changed their phosphate rock source and were making an excellent SSP again.
Research with RPR and PAPR, and the “Maxicrop’ case
Promising results from field trials at Massey University and the Winchmore Irrigation Research Station lead to the MAF’s ‘National Series of RPR vs Superphosphate Trials’, which ran on 19 sites from 1981 intil 1986, and as a non-fertilised residual effectiveness comparison on some of the sites for a further 2 years. This series was probably the biggest fertiliser field trial project ever conducted in New Zealand, and enabled the situations where RPR could be successfully used for maintaining pastures in New Zealand – essentially a minimum rainfall and/or irrigation of 800mm, plus a soil pH of 6.0 or below – to be delineated. Phosphoric PAPR was shown to remove even these limitations. A subsequent ‘copy-cat’ Australian series, coordinated by Peter Sale from La Trobe University in Melbourne, produced very similar results.
The New Zealand trial results lead in 1987 to the formation by Fletcher Challenge – with a lot of push from the redoubtable Rod Russell – of the ‘Duraphos International’ company, to promote both RPR, and a PAPR made in Israel to the author’s specification. Competition to SSP had finally come to New Zealand!
At the other end of the scale, increasingly difficult times for farmers lead to a rash of ‘muck and mystery merchants’ making misleading claims such as Maxicrop’s infamous “3 pints will feed an acre” television advertisement. Statements by the legendary Professor ‘Tom’ Walker regarding it “being an expensive way to buy 44-gallon drums”, and MAF’s Doug Edmeades saying on Fair Go no less that “Maxicrop doesn’t work” lead to an $11million defamation case against MAF, which MAF won under the brilliant stewardship of QC Don Matheson, after a marathon, Commonwealth-record 12 months in court.
Downturn of the mid to late 1980s
A very promising start for Duraphos came to a crashing end in 1988 following the stockmarket crash and the subsequent decision by Fletcher’s to retrench to its ‘core activities’. The commodity price collapse that preceeded it, coupled with the removal of government subsidies on fertiliser, had resulted in a 50% reduction in fertiliser usage, making starting a new company not an activity for the faint-hearted.
But in 1989 Bert Quin and Grant McComb did just that. Quinphos Fertilisers, subsequently Summit-Quinphos after Sumitomo Corporation’s fertiliser division took a controlling shareholding in 1995, made steady growth year after year, in 2005 reaching 200,000 tonnes of RPR-based product, and 10% of the New Zealand fertiliser market on a nutrient basis, according to independent surveyor Nielsen. Proven lower P run-off losses with RPR, eventually incorporated by Dave Wheeler into AgResearch’s industry-funded ‘Overseer’ nutrient budgeting scheme, was becoming an increasingly important market advantage.
The sale of Summit-Quinphos by Sumitomo to SSP manufacturer Ballance, the inevitability of which had resulted in a change of management, and ultimately to the complete removal of the brandname, led to a steady decline in the promotion and use of RPR, but as it turns out in 2010 a young company Fertilizer New Zealand took over the mantle and started importing RPR itself.
Growth and intensification of dairy farming and increasing N use
The last decade has seen a truly meteoric rise in the amount of fertiliser N, principally as urea and to a lesser extent DAP, used on New Zealand dairy farms. Conversion of flatter sheep and beef farms, forestry and cropping land to dairy farms, and increasing intensification of existing dairy farming areas, has resulted in a massive swing away from reliance on N fixation by clover to the use of typically 200-300 kg of fertiliser N per hectare annually, consuming over 550,000 tonnes of urea annually in the process.
This growth in N use, and the increasing use of imported palm kernel as a supplementary feed, have lead to greatly increased N loadings on New Zealand’s soils, and to increased losses to the environment, both from fertiliser directly and from increasing losses from urine deposition. The resulting increasing eutrophication of New Zealand’s waterways, despite increasing restrictions of direct stock access and other ‘quick-fix’ physical measures, is an increasing threat both to the country’s actual environment and to how we are perceived by overseas markets.
New Thinking and New Technologies to Meet New Challenges
Environmental concerns and the growth of dairy farming are combining to make the 2010 decade the most important ever, in terms of the need for innovation. Fortunately, there are promising signs that fresh attitudes, thinking and technology are forcing their way to the fore.
Ravensdown and Ballance’s long-running and expensive legal fight over using whole-paddock application of nitrification inhibitors to reduce nitrous oxide gas and nitrate leaching losses from urine patches seems almost farcical, given the unimpressive environmental advantages and the slow rate of adoption of the expensive technology by farmers. Treating the patch directly from a urination-triggered tail-attached device may yet have its day.
Fertiliser placement, proof of placement and variable application rate technologies have all shown promise over the last decade, and will develop much further in the next, lead by innovative people such as Massey University’s Ian Yule.
Fluidised fertiliser technology offers considerable advantages, particularly in increasing the efficiency of urea, provided urease inhibitors are incorporated. This technology appears ideal for maximising the potential of plant growth stimulants such as gibberellic acid. The new “Futurespread” 40-meter swath suspension bucket for helicopters will bring the costs of helicopter application much closer to ground and fixed-wing costs, and as a result ease the cost of market entry for new players in the industry, as helicopters have multi-income streams.
Ray Patchett’s dream of a New Zealand-based turbine-engined redesign of the Australian ‘Fatman’ aircraft could reduce application costs by 30%, as well as finding a ready export market.
Incorporation of complexion agents, organic acids or polymeric organic acids with high-analysis P fertiliser application is likely to improve soil P efficiency and reduce P run-off losses. Young gun independent fertiliser researcher Peter Bishop is leading the way on this.
Watch this space.