By mid-2011, world population clocks tell us there will be 7 billion people on earth; that’s 7,000,000,000 chemical engines that require a minimum of 2,000 calories a day in food to stave off starvation.

The caloric value for our digestive system of rice and wheat, the basic starches for most of us, is around 340 per 100g. If we only ate cereals to meet our daily caloric needs, men would consume 290 kg and women 214 kg in a year.

So we need 1.76 million each day if we were all vegetarians. Of course, many of us enjoy meat. The efficiency of energy transfer from plant to livestock means that we need about three times the plant calories to provide animal protein.

Round up some numbers and ratios for carnivores and each and every day agricultural land should produce the equivalent of 3 million metric tons of usable grain; over a billion tons each year.

Suppose 7 billion was the peak and the population was stable for a while. Sustaining food production would become more difficult each year because nutrient depletion, soil degradation, desertification, and irrigation water shortages are spreading across much of our productive land. Demographers suggest that world population growth will slow, but not until the total number reaches between 9 and 12 billion souls. Then the numbers may drop again over time to perhaps 6 billion by the end of the millennium.

The challenge for this generation is planning to overcome this population hump without starving.

Imagine the disputes we will have if food supplies run out. Our history is one of war and conquest whose proximate cause might be the desires of selfish empire builders, but ultimately it is about land, natural resources and growing enough food.

It would also be sensible to overcome the hump without stripping the earth of its ability to support life.

This challenge is real. Finding enough food is a daily truth for many in the developing world, but food production requires solutions from everyone, even those of us who are well-nourished.

So what can be done?

One solution is to continue throwing technology at the problem. For some time now, farmers have used artificial fertilizers, genetics, and irrigation methods developed by scientists to avoid declining yields. These agronomic efforts have produced spectacular short-term results, particularly the green revolution of the 1970s.

In recent times more high technology has been added to the mix. Today we can see crops in laser-leveled fields with computer-managed irrigation to synchronize with plant water demand and fertilizers precisely applied from hoppers triggered by integrated GPS systems linked to yield maps. This is the ultimate high input system and can work extremely well where the soil is suitable for precise management of nutrient input and output. The Dutch have been especially good at perfecting these systems.

This intensive approach to agriculture suits us well. We really like the technological solution that decreases direct human effort and increases both the quantity and reliability of returns, even though the initial investment is prohibitive for subsistence systems.

High-tech agribusiness also fits well into our economies. It generates profitable products and uses many suppliers and service providers to distribute the economic benefits in the market.

Given all these benefits, one option seems attractive and we must implement it, especially where soils, climate and management capacity are suitable.

But technology is not a universal solution.

Most agriculture is low-input and relies on nature to deliver production mostly without help. Providing technological solutions to farmland managed with little or no external input will be difficult because farmers who rely on natural soil regeneration have no alternative. They lack the resources to do otherwise. However, these lands must also constantly produce to support the growing human population.

The solution on these lands is to help nature achieve natural regeneration and efficient nutrient recycling. This means helping the soil to regenerate its natural fertility.

Maintaining production in low-input agriculture has been the holy grail of agricultural development work for many decades. Under the guise of ‘sustainable land management’ organisations, from the FAO and the World Bank to local organic cooperatives, they have sought ways to achieve sustainability.

What has been lost in many of the larger schemes is the simplicity of the sustainable solution. All it requires are practices that sequester carbon in the soil.

So how are we going to produce enough food?

We will have to apply technology where we can. Science will help and we cannot be too picky about issues like genetic modification.

However, the intelligent application of technology is essential. It cannot work everywhere and it is unwise to create large tracts of monoculture crops, even if they are managed by computers. Nature has a bad habit of replacing similarity with diversity. And in this case by diversity, read pests and diseases.

However, the big solution will be to put the carbon back in the soil where it has been depleted and also improve soil carbon levels where we can.

Soil maintained for optimal carbon levels retains and exchanges nutrients efficiently, has a good structure that supports plants and allows roots to develop, and retains moisture but also drains. In short, soil carbon promotes plant growth.

The initial solution to growing enough food on low-input land is to use carbon markets to reward farmers who store carbon in the soil. Paying farmers to grow carbon will help reduce greenhouse gas emissions and even sequester some CO2 from the atmosphere in the soil. Greenhouse gas emitters can buy the greenhouse credit created by low-input farmers.

In the end though a greenhouse benefit is not the real value of the investment; the true return is growing enough food.