|June 1, 2004:
The bewildering array of crop productivity products
out there is badly in need of rigorous, systematic comparative
evaluation. A small, and unfortunately flawed, start has
been made by Oregon State University researchers on one
crop in one location, evaluating 15 products.
The researchers found that there were no significant
differences between any of the treatments, including
The plant productivity products were: humic acid products,
Norwegian kelp concentrate, a nitrogen fixing bacteria,
plant growth regulators (cytokinen and ammonium zinc
acetate), and various organic fertilizers.
The products of nine companies were evaluated in 15
treatments in an onion crop. Each treatment generally
consisted of a combination of products from one company.
The products were too numerous to list here.
According to the researchers, humic acids in the humic
acid products were far below the 75 kg / ha rate recommended
in humic acid research. With the exception of one product
at 31.4 kg / ha, the others averaged less than 5 kg
/ ha. To attain the recommended 75 kg / ha, some of
the humic acid products would cost over $1000 / ha.
The only foliar-applied humic acid product supplied
humic acid at only 1/10th of the recommended foliar
rate of 0.5 kg / ha.
For micronutrients, with the exception of one product,
all of the foliar-applied products supplied micronutrients
at far below the recommended rates.
The nitrogen fixing bacteria inoculant didn’t
give results because all of the plots were fertilized
with nitrogen fertilizer.
Kelp extracts had no effect on yield or size classification
of the onions.
While this research is helpful in giving some perspective
on plant productivity products, there are a number of
deficiencies in the work. The most glaring is that no
consideration was given to sensory quality or for shelf-life.
Lots of anecdotal evidence, and some research, suggests
that kelp products have an effect on sensory quality
and shelf-life of fruit and vegetable crops.
Many plant productivity products improve yields where
crops are stressed – either by disease, insect
attack, difficult soils etc. The onion crop in this
research was grown under optimum conditions.
As far as the “active ingredients” being
far below the recommended rates, well, this may or may
not be relevant. It is like doing a chemical analysis
on a biological inoculant and saying that the NPK levels
are far below those recommended. The ingredients might
be synergistic with each other in small amounts.
However, it does seem that the humic acid products
were coming up awfully low on humic acids. We need more
research to be done to answer these questions.
It should also be taken into consideration that organic
crops may react differently to these products than conventionally
grown crops do. Organic crops are much more underpinned
by biological processes, which may respond quite differently
to these products.
The same kind of research as this needs to be done
on at least another 100-200 products, on dozens of crops,
in different regions, in different conditions of stress.
Feibert, E. et al. 2003. Nonconventional additives
leave onion yield and quality unchanged. HortScience
Don Lotter has a Ph.D. in agroecology and has worked
in sustainable agricultural development in North America,
Latin America, and Africa over the past 25 years. He
can be contacted via his website www.donlotter.com