The invisible resource

At the University of New South Wales, we are developing the design of a new satellite. It will have a very unusual capability: it can measure how much moisture is in the first few centimeters of soil. 

When one wishes to account for water resources, the list of assets includes lakes, rivers, streams, reservoirs, and the underground water table. But the additional water to be found in the soils, right at the surface, is a highly significant resource as well. In Australia, for example, a calculation shows that there is as much water in the uppermost layer of Australia’s soils as in all her lakes, rivers and reservoirs. It is also the most crucial to plant life—this is the water that plants actually absorb.

The importance of this invisible resource to the environment cannot be overstated. In addition to the obvious importance to farming, moisture in the soil has many other far-reaching impacts. 

• Soil moisture drives the weather. High moisture in a soil heated by the sun will increase the chance of cloud formation.
• It is a critical factor in determining wind erosion, the source of the huge dust storms that plague Australia and some other nations. Advance warning of dust storm conditions will help protect persons with respiratory conditions.  Knowledge of soil moisture can improve the success of ground cover planting programs for dust mitigation.
• Soil moisture is critical for minimizing water erosion of soils, by watering the plants that stabilize the soils against erosion.
• Knowledge of trends in soil moisture is a key to effective land use planning. Long term changes to soil moisture can force unwanted change; awareness of soil moisture trends can allow for orderly transitions and protect livelihoods. Today, most land use planning maps are static and outdated; real-time knowledge of soil moisture can make advisories more responsive.
• Soil moisture is the key to the health of sensitive ecologies, including wetlands, forests and iconic sites. The effectiveness of water diversion for ecological health and restoration is highly dependent upon the existing soil moisture levels.
• It is critical for broad acre farming and grazing. Soil moisture determines, for instance, how long a grazier may use a particular paddock before having to move her cattle.
• Soil moisture is a key driver for “tipping points” in agricultural settings. If moisture falls below a certain level, a farm may simply crash and be unrecoverable. Only weeds will remain.
• Soil moisture determines the success of carbon storage initiatives. Carbon stored in the root zones is not volatile, so it represents a permanent form of storage. To use this storage technique effectively, water must be conserved in the root zone.

In a subsequent post, I'll discuss why this resource must be measured from space, and what is involved in the process. 

Vertical farming: how big an impact?

Vertical farming is basically the use of the third dimension to increase the effective density of planted area. The idea has been around for millennia, and the term itself for a century .

VF solves two problems faced by conventional agriculture in the Century of Scarcity: it is stingy with land, and with water.

Recent advocates for vertical farming have been Ken Yeang and Dickson Despommier. The latter's approach is featured in this futuristic video . I have worked with the inventor of contour crafting, also featured in the video, to propose its use in very simple structures for VF like this "GroWall" structure:

Unfortunately, buildings cost more than dirt. Hence there is always a question of whether vertical farming is economically viable. In the "40 Point Plan" video, the argument is made that economies of scale will eventually make VF affordable.

I was skeptical until I came across actual vertical farming going on in Singapore . As you can see in the CNN clip, the approach is similar to Despommier's in several respects.

Singapore is the perfect place for VF. It has the highest population density in the world, and absolutely no room for agriculture. Every calorie is imported, except perhaps for fish. Singapore's wealth means that somewhat higher prices can be charged for locally grown food (although in my own trip to Singapore, I found food prices quite reasonable). The extra expenses associated with VF might be offset by the savings in importation costs--and the carbon from the transportation as well. Singapore also has several high-technology water purification projects underway, which should be exploited by the VF effort.

Having a viable VF enterprise going in a wealthy place like Singapore will lead to improvements in the technique over time. Affordability will increase, and VF will expand to less wealthy areas.

And that's important. The UN Food and Agriculture Organization has estimated a need for120 million additional hectares for farming by 2050, even with projected increases in productivity. Conventional arable land is actually shrinking, due to erosion and urban growth. To create such a vast new amount of farmland, there's really only one place it can happen: the earth's rain forests (since agriculture also requires water). That would be devastating to the climate, and to species diversity.

Can VF scale up to make a dent in this 120 million hectare increase? It seems unlikely on its face. More feasible, perhaps, would be to use VF in a targeted way, to supplement some calorie-adequate diets with foods rich in certain nutrients or micronutrients. Another exciting idea would be to combine VF with solar desalination of brackish water--such as that going on in the fantastic Sundrop Farms project here in Australia that I've blogged about earlier.

Both the Singapore VF installation and the Sundrop Farms results have shown economic viability. Now, the next hurdle is for them to show scalability to keep up with humanity's skyrocketing food needs.