Wednesday, June 22, 2011

Water, oil and phosphate

As published in March 2011 Grower
Dan Bloomer, LandWISE
Farmers are under constant pressure from the community. You hear and see it in the media everyday. “Cut food prices!” “Stop sucking our rivers dry!” “Produce more food!”
We hear of fully allocated water, peak oil, peak phosphate, and rising populations with higher and higher expectations (no observable peak there yet). So what can anyone do?
The last few generations have seen massive increases in agricultural productivity. Often attributed to increased fertiliser, chemical sprays and irrigation, it is often portrayed as negative.  But increased productivity is also the result of increased efficiency and learning compounding on learning. Efficient farmers produce more crop per hectare, more crop per litre of water, per litre of oil, per kilogram of phosphate. So they eke out those finite resources to give more people better nutrition.
Water, oil and phosphate are finite resources. Being more efficient doesn’t make any more. But it gives time to come up with the next great plan. And that’s what we must do with urgency.
Let’s think for a minute about those three farm inputs.
In the case of oil (energy), we ultimately need substitutes. Alternative energy options that may suit cities are not practical on farm. So agriculture is seen as a high priority area for remaining oil supplies (after the military).
Our immediate task is to increase efficiency until viable agricultural energy alternatives are developed. In the medium term, bio-fuel economics will give “Grow your own” new meaning. But more paddocks set aside for tractor feed means less for human feed. Even in the long term, energy efficiency must be a very high priority.
For crop production, the major efficiency gains farmers can have right now come from reduced cultivation. Avoid compaction, cultivate less, improve soil and require less cultivation. A positive spiral up the slippery slope.
Phosphate and water don’t have substitutes. Efficient use and recycling are essential.
Phosphate is lost in eroding soil and in our farm effluent and urban waste streams. It goes to sea. It takes millennia to return to land in mineable quantities, if we don’t remove the fish stocks in the meantime.
The Taupo urban treatment system applies waste to soil and produces stock feed, so the nutrients are rapidly returned to the agricultural system. We need the rest of the country (world) to follow suit. On farm, we need to minimise phosphate use and avoid excess soil levels. And we need to stop soil erosion and loss of effluent.  Water largely recycles itself and New Zealand has a very fortunate short cycling period. We do need to capture rainfall (free irrigation) and retain water in the landscape. That means strategic use of water storage including farm and community dams. On farm, it also means keeping soils in top condition to allow infiltration and store as much water as possible, and still ensure suitable drainage.
Our other main duty is looking after water quality, keeping nutrients levels suitable for stable ecosystems. We need to keep farm nutrients on the farm for growth. The cost of external nutrients is increasing. Soil is a resource we must retain. So there are multiple drivers for keeping soil and nutrients away from waterways.
Soil is the linking theme throughout this article. Too often we draw down on this natural capital for short term gain. It is the base farm resource and biggest capital investment. It is central to all we do and deserves as much care, repair and maintenance as any asset.

No comments:

Post a Comment