November 14, 2006

Nutrient Denial

Filed under: Accessability — shem kerr @ 8:45 am

Internal rates of return from intelligent application of nutrients to timber crops are typically in the range of 15 to 40%. Yet, comment from growers deride or pour scorn on the practice.

“We dont fertilize trees round here. Either they grow or they dont.”

What grudge does this grower have against his wallet? What bad things did it do to him? Or, is it some form of masochism, that if farming isnt hard enough already, then he has to make it even harder for himself?

“Humph, forests have grown for millions of years without growers applying fertilizer.”
Ok, all soils, including the particular ones on which this man is trying to grow timber, are naturally and perfectly balanced for optimal growth rate, tree form, and timber qualities from disparate species for the highest profit; also, silvicultural practices never interfere with the forest’s natural nutrient cycling pattern. Yeah, right.
“Well actually, it’s ok here, because my trees soak up the nutrient runoff from adjacent pasture, preventing it from entering the waterways.”
That’s very noble wanting to prevent eutrophication of water, still, he could be in trouble here. The likelihood is that if this runoff is the only nutrient addition, then nutrient imbalance will be worsened for the timber crop.
“This assertion that nutrition has anything whatsoever to do with tree health, form, or timber quality is nothing more than your pet theory.”
Basically, forest nutrition is so marginalized within the thinking of small growers, that discussion has degenerated close to personal attack.

Rather than being a silver bullet, nutrient management is one of an set of tools in a web of understanding. However, the silviculture researchers of some small growers come to conclusions divorced from any understanding of the relationships between tree physiology, nutrient balance, tree form, timber quality, and profitability. By omitting the central part of the tree’s story ( on how it lives, on how it works ) what these researchers are up to is anything but science. By studying smaller and smaller parts without reference to the whole, they have turned inward and shot themselves in the navel.

The stems in a timber crop will, up to harvest time, include probably 5 times the amount of nutrients as one crop of hay. However, given that the uptake is spread over the timber crop rotation, the crop is usually able to get sufficient without major grower inputs. The shorter the rotation, the more the crops take from the soil, and the more likely is the need for nutrient inputs. Even if the grower had to buy all of these nutrients, the costs would be in the hundreds of dollars – for a crop worth tens of thousands. Usually though, it is only one or 2 nutrient deficiencies that seriously limit growth, affect health, or timber output. It may be a single micro-nutrient deficiency that seriously affects the crop. In that case correction is usually low cost and highly profitable.

When it comes to pasture management, farmers value nutrient inputs. However, trees dont bellow or bleat; and farmers dont recognise the signs of malnitrition until it’s too late. Animals have legs, and can move to forage or find shelter. Trees are rooted to the spot. Why is it that in the minds of farmers that trees have an inferior status to grass or animals? No matter what so-called forestry scientists say on the subject, small growers dont see it the same way. There are cultural blocks. Forestry is on a slow trip out of the hunter-gatherer stage. Forests once were a seemingly inexhaustable supply of free or cheaply obtained timber. In some countries returns are still not attractive enough to encourage investment. The saying “money grows on trees” comes down to meaning trees just grow: there’s no point in finding a better way. In fact I was told, by the same very knowledgable farm forester who doesnt fertilize trees, not to worry about crop potential ( basal areas, timber properties or other factors), just grow the crop and someone will buy it. In other words, marketing is the bit at the harvesting end; not done in consultation with the customer at the front end of stand management planning before planting commences. ‘Woodlots’ have been seen as a way of dealing with erosion prone, weed infested or other sites that are not useful to other farming activities. Tomorrow it will be carbon sinks. Trees then tend to be planted on the most inaccessable infertile and hard sites, giving less crop growth, and making silviculture and harvesting more expensive. Given such attitudes and practices.and lack of commitment, growing trees as a timber crop will generally continue to not yield sufficiently to be a good investment for those small growers.


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