There is only one planet earth. It is 71% water and 29% land, though large areas are uninhabitable deserts, mountains, lakes, and permafrost. A little over 50 million square kilometers is farmland, not all of which is capable of supporting crops. As the world’s population races towards 9.7 billion, farmers need to double our food supply in the next 30 years. Historically, growing more food was as simple as clearing more forests for farming, but we now understand the catastrophic impact of deforestation. In the 20th century we industrialized yields with technology, but we now know how some of these impact the soil negatively. Today’s added challenge is climate change, shifting and shrinking where crops can be grown. Farmable land could be halved by 2050 and every time the temperature rises one-degree Celsius, wheat yields could fall by 6%, rice by 3%, and maize by 7%. To increase food production to feed the future world we will need to find ways to farm poorer land in harsher climates—and do it sustainably.
Billions of acres of farmland have been abandoned because of soil degradation. However, proactive restoration programs could return 400 million acres to agriculture, producing an extra 9.5 billion tons of food by 2050. One of the oldest and simplest ways to restore exhausted farmland is to leave it fallow. It’s a lengthy process, but it can be improved by more active management including replanting native species of grasses, bushes, and trees. In parts of the Sudan, seedlings are provided free to farmers who plant them just before they abandon a plot. The farmers nurture them and graze animals in their shade, the manure adding nutrients to the soil. Similarly, legumes such as soybeans contain bacteria in their root nodules that capture nitrogen from the atmosphere and fix it in the soil. Planted as cover crops, legumes not only restore soil fertility but also protect against wind and water erosion, weeds, and moisture loss—all supporting the soil’s rehabilitation.
Pollution is a growing problem, with China categorizing 19% of its agricultural soil as polluted. However, some contaminants can be removed without using chemicals. Aeration and composting with micro-organisms are effective over time, while genetically modified organisms and some plants actively reduce toxicity—willow shrub effectively extracts the pollutant cadmium. Such processes are lengthy and expensive, but they have successfully turned polluted wasteland into productive farmland in Mali and Mauritania. Similarly, salt pollution is widespread in arid areas, frustrating and preventing crop growth. But the land can be restored to farming through specialist drainage systems, leaching with water, or even planting switch grass or dwarf saltwort that can thrive in salty conditions.
Every year an area half the size of Britain turns to desert, but new ways to farm these hostile landscapes are being developed. One is the Sahara Forest Project that uses solar power to desalinate brackish water for irrigation and power salt-water cooled greenhouses, where vegetables can grow all year round. The desalinated water is recovered to revegetate surrounding areas. Another innovative scheme mixes sand with nano-particles of clay to transform desert into fertile agricultural land in a few hours—though it remains prohibitively expensive for most. More viable for arid regions is planting trees to provide shade, maintain soil structure, and hold the rain where it falls, revitalizing dry soils. In the Middle East, lines of trees form shelterbelts that not only prevent desertification but also reduce wind velocity and improve the microclimate, increasing crop yields by as much as 50%.
Restorative techniques such as agroforestry and water harvesting are often combined together, sometimes on a huge scale such as the Great Green Wall and Sahel Initiative. This is breathing new life into barren and degraded landscapes across more than 20 dryland countries around the Sahara. In drought-stricken Niger, the farmer-managed natural regeneration program (FMNR) has seen 280 million new trees planted on seven million hectares of farmland, slowing desertification, improving soil quality, and increasing annual cereal production. FMNR has proved so successful it is spreading rapidly through Africa and into Asia.
While rising temperatures are usually a problem, in Canada it is making millions of frigid acres farmable. In the vast prairies of central Canada, thawing could increase arable land by more than 25%—one stretch between Ontario and Quebec will bring an area the size of Belgium into agricultural production. Elsewhere, greenhouses can help regulate the environment, in both cold and hot climates. In India, extended drought, heatwaves, and unpredictable rainfall reduces yields by up to 13%, so some farmers are turning to greenhouses built of breathable aluminum-coated cloth netting. These not only protect crops from torrential rains but also reflect sunlight to moderate internal temperatures. Fitted with highly efficient drip irrigation systems, these greenhouses yield five to eight times more than surrounding fields.
Another innovative idea is tapping into the world’s abundant supply of seawater to irrigate arid land. Until recently, desalination was too expensive and energy-heavy for widescale irrigation, costing around $3 per cubic meter. But technological advances, such as reverse osmosis that traps salt particles in thin membranes, have seen desalination deployed with particular success in Israel. Here, the use of desalinated water has increased from 32% to 80%, achieving an output of 785 million cubic yards of freshwater per year—around 20% used for farming.
Mankind has long been selectively growing certain strains of plants to improve productivity and create crops that are more able to thrive in more adverse weather conditions and poorer soils. Now there is the possibility of cutting soil out of the agricultural equation entirely through hydroponics that grow crops in nutrient rich solutions. This not only overcomes the problems of soil quality and climate, it can be employed anywhere and produces more than 50 times the yield of traditional methods. If it could be scaled up economically, hydroponics could go a very long way towards delivering the future food security needed for a population of close to ten billion, and it is perhaps the ultimate expression of how we can farm our unfarmable land.
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