Advocates of organic production are convinced they have the answers, despite much research showing no consistent evidence that organic food is better quality, nor that its production has less impact on the environment than conventional methods.
This same debate is occurring in other countries and has recently been featured in the farming press in South Africa. The Albrecht system, or base cation saturation ratio (BCSR), promotes the concept of maximum plant growth occurring when an ‘ideal soil’ with a balanced ratio between exchangeable base cations (calcium 65%, magnesium 10% and potassium 5%) is achieved. The goal of the original research in the 1940s was to reduce luxury uptake of potassium in lucerne and Firman Bear and co-workers proposed the ‘ideal soil’.
At the same time, William Albrecht, professor of soils at the University of Missouri, suggested from his research in pots that plants require soils with high calcium saturation for optimum growth. However, when Albrecht’s doctoral research student Eugene McLean took the pot research to the field he couldn’t find an ‘ideal’ ratio, and concluded that “emphasis should be placed on providing sufficient, but not excessive, levels of each basic cation rather than trying to attain a favourable basic cation saturation ratio which evidently does not exist”.
A review of the Albrecht research by scientists at the University of Queensland, and published in the Soil Science Society of America Journal in 2007, reported that several of Albrecht’s experiments were fundamentally flawed, the research did not support the BCSR claims and that “the continued promotion of BCSR will result in inefficient use of resources in agriculture and horticulture”.
In the South African Farmers’ Weekly at the end of May, Dr Doug Edmeades (AgKnowledge) with colleagues from Stellenbosch University wrote that “the Albrecht system invariably results in substantial increases in input costs which do not translate into improved profitability”. This is because the BCSR results in recommendations for chemicals that are not needed while overlooking some that are. “A recent case in point was a recommendation for a high rate of lime to correct the calcium:magnesium ratio on high pH soils containing free lime.”
Proponents of the system do report increased yields, but “in the majority of cases yield increases are due to associated crop management practices”.
Scientists search constantly for ways to achieve greater productivity from the land, reduce impact on the environment and increase quality of product. Between 1900 and 2000, population increased from 1.7 billion to 6.1 billion and yields increased from 5.5 GJ/ha to 26.1 – a 379% increase. Between 1900 and 1950, the use of phosphate-based fertilisers increased yields from 5.5 to 9.6 GJ/ha. But the green revolution of the 1960s – a combination of short-strawed cultivars, irrigation, superphosphate, nitrogen, herbicides and pesticides – almost trebled yields from 9.6 to 26.1 GJ/ha. To feed the 6 billion population at the 1950 level without the above increase would have required a doubling of current land. To feed them at the current better state of nutrition would require even more.
Research has improved past production systems and shown efficient ways of progress. The sooner farmers start being rewarded for efficient production of high quality food – ie, meat and milk for least loss of carbon, nitrogen and phosphorus – the better. New Zealand as a whole would benefit.
• Jacqueline Rowarth is Professor of Agribusiness, The University of Waikato. Her attendance at the South African Large Herds Conference was supported by LIC.
