Water

Ok, after talking a lot about soil, rocks and agriculture, let’s talk a little bit about water.

I guess it’s not unknown that even though water is abundant, the water that we can drink is quire rare. If 97,5% of Earth’s water resides in the oceans and is too salty to drink or use to water crops, than it lasts only 2,5% of the type considered fresh, which is water with few dissolved salts. Since most fresh water is tied up in calaciers, icecaps, and underground aquifers, just over 1 part in 10,000 of Earth’s water is easily accessible for human use.

Water constantly moves via the hydrologic cycle and, as it moves, it redistributes heat, erodes mountain ranges, builds river deltas, maintains organisms and ecosystems, shapes civilizations, and gives rise to political conflicts.

The freshwater ecosystems are rich in life, and they are:

• Rivers and streams – water from rain, snowmelt,or springs runs downhill and converges where the land dips lowest, forming streams, creeks, or brooks. These water-courses merge into rivers;

• Lakes and ponds – bodies of open standing water. Their physical conditions and the types of life within them vary with depth and the distance from shore.

• Marshes, swamps, and bogs – systems that combine elements of fresh water and dry land. They’re also called wetlands, and are very rich and productive.

Groundwater is very important to the hydrologic cycle because the precipitation that reach Earth’s land surface and does not evaporate, flow into waterways, or get taken up by organisms infiltrates the surface. Most percolates downward through the soil to become groundwater.

Groundwater is contained within aquifers, porous, spongelike formations of rock, sand, or gravel that hold water. The world’s largest known aquifer is the Ogallala Aquifer, which underlines the Great Plains beneath eight US states from South Dakota to Texas. However, overpumping for irrigation has reduced this aquifer’s volume by nearly 10% so far -a volume equal to 18 years’worth of the entire flow of the Coloado River.

Unfortunatelly for us, different regions of the world possess vastly different amounts of groundwater, surface water, and precipitation. However, people are not distributed across the globe in accordance with water availability. Canada, for instance, has 20 times more water per citizan than does China; the Amazon River carries 15% of the world’s runoff, but its watershed holds less than half a percent of the world’s population. Many countries like Pakistan, Iran and Egypt face water shortages.

Because fresh water is distributed unevenly in time and space, it became necessary to erect  dams to store water, so that it may be distributed when needed. In India, monsoon storms can dump half of a region’s annual rain in just a few hours. Northwest China receivs three-fifths of its annual precipitation during 3 months, when crops do not need it.

We divert and deplete surface wter to suit our needs. Water from rivers, streams, lakes and ponds are diverted to homes, cities, and farm fields. The Colorado River’s water, for instance, is heavily diverted and utilized, in a way that after all the diversions comprised, just a trickle makes its way to the Gulf of California. There are some days when water does not reach the Gulf at all. This flow reduction has altered drastically the river and its once rich delta; plant communities were modified and populations of fish and aquatic invertebrates where wipped out, devastating fisheries.

We are depleting groundwater more than surface water because most aquifers recharge very slowly. Most groundwater use goes toward agriculure. We withdraw 70% more water for irrigation today than in 1960, and since then, the amount of land under irrigation has doubled. Expansion of irrigated agriculture has kept pace with population growth. Irrigation can more than double crop yields by allowing farmers to apply water when and where it is needed. Still, most irrigation remains inefficient, and overirrigatin leads to waterlogging and salinization.

Worldwide today, 15-35% of irrigation withdrawals are thought to be unsustainable, and like Ogallala, many aquifers are being drained as water is “mined” at rates faster than it is recharged. As aquifers are depleted, water tables drop. Groundwater becomes more difficult and expensive to extract, and eventually it may run out. To make the situation even worse, when groundwater is overpumped in coastal areas, salt water can intrude into aquifers, making water undrinkable; and as aquifers lose water, the land surface aboe may subside, that’s the reason why cities from Venice to Bangkok to Mexico City are slowly sinking, while streets buckle, buildings flood, and pipes break.

Still, there are some solutions to depletion of fresh water:

• To address the depletion, we can aim either to increase supply or to reduce demand, lowering demand is more difficult politically but will likely be necessary in the long term;
• To increase supply in a giver area, people have transported water through pipes and aqueducts from areas where it is more plentiful or accessible. In many instances, water-poor regions have forcibly appopriated water from commmunities too weak to keep it for themselves. Los Angeles, for instance, grew by using water it appropriated from the Owens Valley, Mono Lake, and other rural regions of California. Becaouse of that, these area’s environments are desertified, crating dustbowls and devastating local economies.
• Desalination  also may help. The process of “making” fresh water by removing salt from seawater or other water of marginal quality. However, desalination is expensve, requires large inputs of fossil fuel energy, and generates concentrated salty waste. Over 7,500 desalination facilities are operating worldwide. Most are in the Middle East, where water is scarce and oil is cheap.
• To decrease demand farmers can improve efficiency by lining irrigation canals to prevent leaks, leveling fields to minimize runoff, and adopting efficient irrigation methods.
• Choosing crops to match the land and climate in which they are being farmed can save huge amounts of water. Crops that require a great deal of water are cotton, rice and alfalfa are often planted in arid areas with government-subsidized irrigation. In this way, the true cost of water is not part of the cost of growing the crop.

Genetic modified organisms

The genetic modification of organisms started with the green revolution, when it was necessary to modernize agriculture to increase food production. The GMOs promise to increase nutrition and the efficiency of agriculture while lessening impacts on the planet’s environmental system. However, they also may pose risks that are not yet well understood, and this concern has given rise to protests around the globe from consumer advocates, small farmers, environmental activists, and opponents of big business.

The genetic modification of crops and livestock is one type of genetic engineering, a process whereby scientists manipulate an organism’s genetic material in the laboratory by adding, deleting, or changing segments of its DNA. GMOs are organisms that have been genetically engineered using recombinant DNA, genetic material patched together from the DNA of different organisms. In this process, scientists break up DNA from multiple organisms and then splice segments together, placing genes that produce certain proteins and code for certain desirable traits -like rapid growth, disease and pest resistance, or higher nutritional content – into the genomes of organisms lacking those traits. An organism that contains DNA from another species is called a transgenic organism, and the genes that have moved between them are called transgenes. To se an animation of the transgenic mouse, click here.

Genetic alteration of plants and animals by humans is not something very new. Mendel was actually the first one. However, there is a difference between Mendel’s GMOs, selective breedings, and the ones from genetic engineering, and it lays is on the technique:

• Selective breeding mixes genes from individuals of the same or similar species, while with recombinant DNA technology, scientists mix genes of organisms as different as viruses and crops, or spiders and goats.
• Selective breeding deals with whole organisms living in the field, and genetic engineering involves lab experiments; it deals with genetic material apart from the organism.
• While traditional breeding selects from among combinations of genes that come together on their own, genetic engineering creates the novel combinations directly.
• Traditional breeding changes organisms through the process of selection, while genetic engineering is more akin to the process of mutation.

The impacts of GM crops are many, however, there is no study or research yet to prove them, nevertheless, some of these consequences have been already seen in some places. Eitherway, the concerns are:

• That the new foods might be dangerous for people to eat, since the transgenics are a mix of genes of different species. Apparently speaking, transgenical food is the same, however, genetically speaking, they’re different from eachother despite the fact that the genes of the transgenes are the same in all transgenic. That happens because the place on the transgenics DNA where the intruders gene is put is not aways the same. The genetic engineering haven’t found a way to do that yet. Therefore, the consequences that these new DNA combinations might cause to our organisms are still unknown;
• That pests would evolve resistance to the supercrops and become “superpests”;
• That the transgenes would be transferred from crops to other plants and turn them into “superwheeds”;
• That the pesticides (insecticides, herbicides, and fungicides) used become stronger and stronger to fight pests, and pollute the water, the air, and the soil.
• That transgenes might ruin the integrity of native ancestral races of crops;
• That the transgenics monocultures might reduced biodiversity, because many fewer wild organisms are able to live in monocultures;
• That natural seeds might disappear, substituted by GM;
• That food supply might be dominated by a few large agrobiotech corporations that develop GM technologies. Those corporations would be Monsanto, Syngenta, Bayer CropScience, Dow, DuPont, and BASF;
• Much of the research into the safety of GM organisms is funded, overseen, or conducted by the corporations that stand to profit in their transgenic crops are approved by regulators.

Knowing about the possibilities of these problems, critics argue that we should procced with caution, adopting the precautionary principle, the idea that one should not undertake a new action until the ramifications of that action are well understood. In a few words, we could think of GM as a medicine, a medicine that might “cure” all our problems. However, if we look at the side effects on it’s package leaflet, well… they’re pretty bad…

People of different cultures have reacted differently to GM. European consumers have expressed widespread unease about possible risks of GM technologies, so their governments demand that GM food is labeled as such. In the US, however, consumers have accepted the crops approved by US agencies, and they don’t realize how much of their food contains GM products. Yet, there are still many things to be studied and thought… that’s polemic that has to be discussed.

Green Revolution

Green revolution is the introduction of industrialized agriculture to the developing world in the mid- and late- 20th century and it allowed the production of greater quantity and quality of food. This industrialization became necessary because people realized that farmers could not keep cultivating more land to increase crop output, than, agricultural scientists devised methods and technologies to increase crop output per unit area of existing cultivated land.

This new agriculture uses synthetic fertilizers and chemical pesticides; special types of grains that are more resistant to wind and diseases and produces high yields -transgenics; and heavy equipment powered by fossil fuels.

These developments had mixed effects on the environment. The use of already-cultivated land reduced pressure to convert additional natural land for new cultivation. As a matter of fact, between 1961 and 2003, food production rose 150%, population rose 100%, and the area converted for agriculture increased only 10%. Therefore, the green revolution prevented some degree of deforestation and habitat conversion when many countries were experiencing their fastest population growth rates.

However, there also are many negative sides that we must pay attention to:

• The intensive application of water, fossil fuel, innorganic fertilizers, and synthetic pesticides worsened pollution, and soil problems like erosion, salinization, and desertification;
• As monocultures made planting and harvesting more efficient, the increased output reduced biodiversity, because many fewer wild organisms are able to live in monocultures than in native habitats or amid tratitional small-scale polycultures;

• When all plants in a field are genetically similar as in monoculture, all are equally susceptible to viral diseases, fungal pathogens, or insect pests that can spread quickly from plant to plant. Therefore monocultures bring some risks of cataqstrophic failure;
• Many yields are declining in some regions because of the decline in soil quality from the heavy use of fertilizers, pesticides, and irrigation.

Green revolution and population

It is really important to understand the reason why the green revolution happened.

The transfer of technology to the developing world that marked the green revolution began in the 1940s, when US agricultural scientist Norman Borlaug introduced Mexico’s farmers to a specially bred type of wheat that produced large seed heads, was short in stature to resist wind, was resistant to diseases, and produced high yields. Within two decades of planting and harvesting this specially bred crop, Mexico tripled its wheat production and began exporting wheat. After this huge success, the wheat was taken to India and Pakistan, and soon, many developing countries were doubling, tripling, or quadrupling their crop yields using selectively bred strains of wheat, rice and corn, among others.

In the 1960s, India’s population, for instance, was skyrocketing and it’s traditional agriculture was not producing enough food to support the growth. By adopting green revolution agriculture, India sidestepped mass starvation. In the years since intensifying its agriculture, India has added several hundred million more people and continues to suffer widespread poverty and hunger.

Still, because of the huge problems brought by the green revolution, we can’t think of it as the solution of our food supplies problem. In fact, Borlaug  called his green revolution methods “a temporary success in man’s war against hunger and deprivation”.

Impacts of Agriculture

Agriculture is the practice of raising crops and livestock for human use and consumption. It always  and it’s impacts on global environment have increased when Green Revolution began, around 1945. It’s environmental effects include:

• Alterations of the Earth’s hydrologic cycle;
• Increased levels of atmospheric greenhouse gases;
• Decreased biodiversity;
• Accelerated rates of soil erosion;
• Rapid spread of eutrophication in freshwater and marine ecosystems.

You can read more about these consequences here.

The human population has grown and so have the amount of land and resources given to agriculture, which currently covers 38% of Earth’s land surface. Most of our food and fiber are obtained from cropland, land used to raise plants for human use; and rangeland or pasture, which is land used for grazing livestock. The large-scale mechanization and fossil fuel combustion enabled farmers to replace horses and oxen with faster and more powerful means of working with crops and livestock. This was the agricultural revolution, and it allowed the increase of food production by intensifying irrigation; introduction of synthetic fertilizers; and the use of chemical pesticides reduced competition from weeds and herbivory by crop pests.

Modern industrialized agriculture enabled us to feed more people at a very high ecological price. Industrial agriculture can remove forests; destroy wetlands; turn grasslands to deserts; diminish biodiversity; encourage invasive species; pollute soil; air and water with toxic chemicals; and allow fertile soil to be blown and washed away.

Even though we  have more food to feed more people, political obstacles and inefficiencies in distribution makes 850 milion people in developing countries without enough to eat. In adition, although human population growth has sloewd, we can still expect our numbers to swell to 9 bilion by the middle of this century. Therefore, the kind of word we’ll live in then will depend on choices make now, and knowing  how to make food supply sustainable , maintaining healthy soil, water and biodiversity is one of them. Agricultural scientists and policymakers pursue a goal of food security, the guarantee of an adequate and reliable food supply available to all people at all times.

There are some farming techniques that can reduce the impacts of conventional cultivation on soils. Those are:

• Crop rotation – the type of crop grown in a field is alternated from one season or year to the next. This method can return nutrients to the soil, break cycles of disease associated with continous cropping, minimize erosion that might come from letting fielts lie fallow, and reduce insect pests, because if an insect is adapted to feed and lay eggs on one crop, planting a different type of crop will leave its offspring with nothing to eat. The crop rotation works if one of the rotated crops are legumes, because they have specialized bacteria on their roots, responsible for fixing nitrogen, revitalizing soil that the previous crop had partially depleated of nutrients;

• Contour farming - cultivation on slopes, even though water might erode the soil more easily. Farmers plow furrows sideways across a hillside, perpendicular to its slope and follow the natural contour of the land to help prevent formation of gullies;

• Terracing – the most effective method for preventing erosion, terracing consists on making levels platforms to contain water from irrigation and precipitation. It transforms slopes into series of steps like a staircase, enabling farmers to cultivate hilly land without losing huge amounts of soil to water erosion;

• Intercropping – also minimize erosion because it consist on planting different types of crops in alternating bands or other spatially mixed arrangements. Intercropping provides more ground cover and reduces vulnerability to insects and disease;

• Shelterbelts or windbreaks- used to reduce erosion from wind. Consists on the plantation of rows of trees or other tall, perenial plant along the edges or fields to slow the wind;

• No-till farming – a tractor pulls a “no-till drill” that cuts furrows through the topsoil and crop residue, drops seeds into the furrow, and closes it over the seeds. A dose of fertilizer might be added to the soil along with the seed.