Thursday, June 04, 2009

Is there a role for agriculturalists in soil research?

Here's a lesson: Unsound science looks like sound science if you don't know what you are looking at... Science can produce inaccurate results if the methodology adopted to simulate farming practices is unrealistic. For instance, in 2003 (just 6 years ago) The Australian Journal of Experimental Science published a scientific paper titled "Effects of Grazing and Management on Herbiage Mass..." 2003, 43, 892-905. They were trying to test the claims of Holistic Management and Grazing For Profit's grazing management systems that they produce more vegetation than conventional grazing. Practitioners of these grazing techniques will tell you that it can take approximately 7 years for the full impact of grazing management to kick in with any dramatic results, unaided. It seems that the soil biology has to reach a critical mass. As well, anything less that 35-55 paddocks defeats the purpose because rest (or freedom from grazing) is the key variable in vegetation growth. Animal impact - bunching them up so that they graze the paddock evenly, disturb the topsoil and fertilise it with their dung and urine - is a key part of the system, which is why such a time controlled grazier would graze 25-50 sheep per hectare for the period of grazing, which is in many case less than a week or two weeks. Table 1. compares how the simulation of the land management technique was designed for the experiment with reality of how that technique is practiced.

Naturally the researchers concluded that there was no effect on herbiage mass from rotational grazing. Therefore, they concluded 'recipes' (exotic grazing management systems) don't work. One alternative explanation that they did not consider was that they were not good rotational graziers. And had they been aware of what was necessary to make such a system work, perhaps they would have produced a more useful research result. As it is, this piece of research adds little to the knowledge base, but it was given the status of 'scientific fact' by virtue of its publication and no doubt used by extension officers and district agronomists to knock rotational grazing systems which are taught by the organisations mentioned above which engage their students in a mentoring relationship, which means they no longer rely on the extension staff for advice. They also promote a low-chemical/low artificial fertilizer regime which most extension officers would not have encountered in their training and would therefore be uncomfortable with.
But had practitioners been part of the research team and allowed to have input on the methodology, the findings might be more useful. The Evergraze project has 4 landholders consulting to the research team, I believe. Even then it has a 4 paddock and a 20 paddock rotation. The phenomenon of scientists being unable to verify what farmers on the ground are finding was demonstrated in a paper called Production-Oriented Conservative-Impact Grazing Management. It was prepared for a WA Department of Agriculture workshop in 2002, by Ben Norton. He points out that the majority of published research studies of rotational grazing find that continuous grazing is better than or comparable to rotational grazing in terms of either animal or plant production. Yet “Hundreds of graziers on three continents claim that their livestock production has increased by half or doubled or even tripled following the implementation of rotational grazing…” The answer to the conundrum lies in the methodology adopted by the scientists: the research trials employed only 16 paddocks or less in the rotation. A typical real-life rotational cell will have 40 to 80 paddocks, the high numbers affecting the amount of time animals are intensively grazing each paddock and the amount of time the paddocks have to recover.

Someone should tell them....