Friday, March 7, 2008

Of Salinization and Agricultural Land Mismanagement

Despite the 5,000 year –or so – history of agriculture, does our contemporary agricultural community take heed on the lessons learned from the past on the causes of agricultural topsoil salinization?

By: Ringo Bones and Vanessa Uy

The serious – though preventable – problem of agricultural topsoil salinization is as old as the practice of agriculture itself, it seems like we at the present are not trying as hard as we should in preventing such problems. Especially by ignoring on what we had learned in the past about the phenomena of salinization and doing it in our peril. Is the problem still relevant in 2008 given we had learned so much before?

The Girsu Documents of southern Iran, which dates back 4,300 years, showed accounts on the progressive salinization of cultivated lands. The documents mentioned how the rich farmlands of Mesopotamia, in what is now Iraq, were ruined by irrigating them using the brackish water from the Tigris and Euphrates rivers. Wheat was once cultivated on a large scale but by 2,400 BC farmers turned to barley, which is more salt tolerant, as an alternative crop. Seasonal floods, which raised the water table, increasingly salted the topsoil. By 2,000 BC, even barley began to fail. Eventually the land was abandoned and the water table dropped, leaving a salt saturated desert where no crops can grow.

Typical of the alluvial plains of Mesopotamia and the rest of the Middle East, as in any dry area, there is relatively prodigious amount of salt in the ground because rain water, or even water in the surface soil, evaporates before the salty minerals has a chance to leach out. Therefore, any rise in the water table will lift up the salty water up to the surface soil. Seasonal floods, which cover large areas with standing water, can also cause such a rise. Our “start up” farming methods of centuries past has actively created such a situation in arid regions for centuries by digging a number of irrigation canals which continually silt up and overflow onto the surrounding land. Furthermore, in very hot and arid lands, the thirsty soil can actually suck up salty water from below via capillary action during the long, dry spells.

Despite the great havoc wreaked on the land before we learned better agricultural management, there is still hope that some areas – seemingly beyond salvation – may yet be brought back to full productivity via proper irrigation. A cause for hope is the fact that in most arid regions, rain has not yet leached the valuable surface minerals from the topsoil. At the same time, however, there is a concern that conventional irrigation methods will raise the water table and in doing so bring increasing amounts of harmful salt to the fertile surface through capillary action.

Years ago, a program was tried in Afghanistan (this was before the Soviet invasion and the subsequent Taliban takeovers) to combat and reverse salinization by flushing the fields with water to wash out the crystallized salt. And also deep drainage ditches were dug to assure that the water table stays below a safe minimum. Additionally, tamarisk trees were also planted. Tamarisk trees are salt tolerant plants and are being used to restore Afghan soil and these trees also sop up excess water thus guarding against further salinization.

The agricultural regions surrounding the Aral Sea and the Aral Sea itself was also a relatively recent victim of agricultural farmland mismanagement. Several rivers that fed the Aral Sea were diverted by the then Soviet Union to cotton fields used in the large scale production of nitrocellulose or guncotton (smokeless powder) to beef up the nation’s Cold War era arsenal. It was only in the last couple of years or so that existing programs were seriously involved in restoring the Aral Sea and the surrounding communities. Like the International Aral Sea Rehabilitation Fund – have shown favorable progress. But their work won’t be easy because the agricultural lands surrounding the Aral Sea not only suffer from salinization, but also contaminated with toxic pesticide residue left over from the chemically intensive Soviet era agricultural methods.

Jatropha: Kick Starting Terraforming Technology?

With Jatropha’s ability to thrive in arid regions and it’s ability to stabilize and even reverse the effects of desertification. Will Jatropha cultivation be a baby – step towards the development of knowledge to be used in terraforming technology?

By: Vanessa Uy

With global warming now increasing the rate of desertification that’s poised to ruin the croplands of relatively arid developing nations. Even a “recently developed” country like China is loosing 54 billion yuan annually to desertification. In short, do we have to resort to a technology that only exists in science fiction literature in order to save humanity and our environment? But before delving any deeper, let us examine existing ideas in current use or will be used in making a certain piece of land suitable for farming and or returning it to its more naturally bio diverse state.

The concept of land reclamation is broadly defined by two distinct practices. One of which involves creating new land from the sea or riverbeds. Recently the most famous example is the one’s being demonstrated in the coastal region of Dubai, UAE – namely Palm Jumeirah or “The Palm Island” as the project is widely known in the West. The other practice of land reclamation involves restoring an area to a more natural state usually when an open pit mine is resealed, the topsoil returned so that the area can either be farmed or turned into an arboretum. Or recovering the chemical pollutants / contaminants from the topsoil and groundwater. Or reversing the effects of salination to make the land useable again. The last two are currently used to rehabilitate agricultural lands in the Aral Sea region, which was rendered useless due to irrigation and agricultural mismanagement that resulted in desertification compounded by salination and excessive amounts of pesticide contamination.

Did you know that even in dry climates, a typical virgin / undisturbed land is able to support considerable vegetation if not disturbed (the woodlands found in the Israel – Lebanon border for example). The roots of trees and plants secure the soil and hold water, thus preserving the area from erosion. But poorly managed cultivation / farming practices of the plains and timber cutting on the slopes removes roots and expose the land to wind and water erosion, which flushes away deposits of gravel from the lower slopes down to the plain. Further overcultivation destroys the productivity of the plains. Which is now set aside for grazing by herds of cattle. Agricultural activities of the area are forced to move up to the low slopes, where the hazard of rapid soil erosion of the topsoil is much greater. The ensuing loss of fertility of the steeper hillsides caused by topsoil runoff renders the area useless for further cultivation, and cattle grazing move up to the slopes, accelerating the process of erosion by constant grazing. If further “destruction” of the already barren landscape is left unchecked especially when there is no longer enough to browse for cattle. The area is then turned over to sheep and goats to be stripped clean. This results in the total desolation of a once fertile landscape and this stage is marked by the disappearance of all the topsoil and large sections of bedrock are exposed on the hill and plain. The resulting dusty land can no longer support life and could enlarge in area during times of scant or nonexistent rainfall. Thus accelerating the spread of desertification, like the one currently happening in China that’s costing the Beijing Government 54 billion yuan annually from farming revenue losses.

The man-made desertification described previously is now threatening to affect small villages in the South Sumatra region of Indonesia were the Palm Oil industry, driven by the bio-fuel boom, resorted to slash and burn methods of agriculture. Even ancestral lands of marginal economic value in the South Sumatra region are now starting to be affected by the hastily planned Palm Oil plantation expansion whose “green credentials” have recently been found of dubious value to say the least.

In evaluating the available solutions to halt the spread of desertification, Large scale Jatropha cultivation is probably one of the best – if not the best – way of stabilizing and even stopping the spread of desertification because Jatropha is not a genetically modified organism. Remember our bad experiences with genetically modified organisms back in the late 1990’s when Monsanto made a large scale trial cultivation of their genetically modified soybean crop. The genetically modified soybean was said to be pest and weed resistant, but quite a large number of people developed allergies when they consumed Monsanto’s genetically modified soybean.

Using Jatropha to make desertificated land arable can be compared that to the concept of terraforming. Terraforming as a concept is a staple in science fiction stories where an alien planet’s environment is made to be more hospitable to humans by using technology like large bio - reactors filled with genetically engineered blue-green algae to make the atmosphere breathable to humans. By turning excess atmospheric carbon dioxide into oxygen like the oft shown planned terraforming of the planet Venus and Mars. Desert environments are somewhat hostile to us humans especially if you take into account that you can’t grow any food crops there. As large scale Jatropha cultivation continues as a pioneering species, the leaves being shed as the plants continue to grow plus the waste pulp from bio-fuel production can be used as an organic fertilizer thus steadily increasing the fertility of the arid lands in which the Jatropha are planted. When it comes to the growing concern about increasing carbon dioxide in our atmosphere threatening the stability of our climate, large scale Jatropha plantations can also serve as a “carbon sink”. Jatropha can do this by absorbing carbon dioxide in the atmosphere and depositing it into the plant’s own cellular structure as carbohydrates, sugars, and cellulose where it no longer contributes to the increased greenhouse effect. This is like hitting to birds with one stone since the increased carbon dioxide in our atmosphere is primarily responsible for the increased trend in desertification. This project could be the first step in making terraforming a practical environmental engineering reality, not just an esoteric / recondite intellectual exercise in science fiction novels.