Devised for industrialized farms, precision agriculture now has the potential to increase the yields of smaller acreage farms.
Precision agriculture is closely associated with technology and its application to large-scale farms in developed countries. GPS-equipped sensors on tractors, for example, enable farmers to measure and respond to soil variability across vast tracts of land, and dispense the right amounts of fertilizer and water exactly where it's needed.
About 500 million small-scale farms provide more than 80% of the food consumed in large parts of the developing world, and these farmers and their families also make up most of the world's undernourished people.
For many years, this was widely seen as irrelevant to small-scale farmers in developing countries. How much variability can there be on a two hectare plot? And how could poor farmers afford the technology? But there's a growing body of research now to support the idea that small-scale farmers can benefit from precision agriculture. One of the reasons for this is greater awareness of how much variability can exist in even the tiniest plot of land.
Raj Khosla, professor of precision agriculture at Colorado State University, confirmed this in a 2012 study of how the nitrogen in the soil of seven farms in China ranging from 1.5 to 7 hectares (3.7 to 17.3 acres) in size correlated with wheat yields.
"We saw the same scale of variability that I would see here in Colorado," he says. "There was variability of 1.5 tonnes of wheat per hectare to five tonnes, with strong spatial correlation. Where yields were higher, plants were removing more nutrients. We've seen variability on less than a third of a hectare of land."
About 500 million small-scale farms provide more than 80% of the food consumed in large parts of the developing world, and these farmers and their families also make up most of the world's undernourished people. If precision agriculture is relevant to small farms, the next question is how to transfer it to that context.
The technology which has driven Devised for industrialized farms, precision agriculture now has the potential to increase the yields of smaller acreage farms. in the global north is becoming more widely accessible. For example, a new handheld device known as the GreenSeeker can be used to measure the health and nitrogen status of plants, enabling farmers to make more precise assessments of fertiliser requirements.
"The GreenSeeker is based on the relationship between the light reflectance in the red and near infrared spectrum of a plant, and the nitrogen status of that plant," says Bruno Gérard, director of the Global Conservation Agriculture Program at the International Maize and Wheat Improvement Center (CIMMYT).
"It is now used by extension services in the Yaqui valley in Mexico to recommend nitrogen application on wheat. In other parts of the world such as Ethiopia and South Asia, CIMMYT scientists are also evaluating the use of GreenSeeker. Better use of nitrogen fertiliser not only increases profitability but also reduces groundwater pollution."
The GreenSeeker costs about $500 (£297), making it relatively affordable though still expensive for many small-scale farmers. Khosla suggests enterprising farmers may find ways round this once they see the potential benefits.
In Uttar Pradesh, India, Tata Chemicals carried out a trial with a farmer on his two-acre plot to see how precision levelling improved his spring wheat yields under flood irrigation. Traditionally, farmers in that region use a wooden plank hooked to an ox to level fields, an imperfect technique that leaves water unevenly distributed.
"A small precision leveller tractor with GPS was used to level half of the land," says Khosla. "The traditionally levelled field yielded 800kg, while the precision levelled field produced 2.25 tonnes, almost 300% more. That farmer then applied for a microfinance loan to buy his own precision leveller, and is charging a fee to neighbouring farms to level them."
At the same time, precision agriculture does not necessarily depend on technology. For the past decade, the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) has been promoting micro-dosing of fertilizer to resource-poor farmers in sub-Saharan Africa. This means using only 8-10kg of nitrogen per hectare, approximately a fifth of the recommended application rates, but applying it precisely to the roots three to four weeks after planting.
There is no technology involved. In Niger, farmers commonly use Coca-Cola bottle caps to measure the dose. But the precision means farmers get good results, even using much less than the recommended amount.
"The basis for the micro-dosing rate was that resource-poor farmers are likely to adopt lower rates because they are more affordable," says Kizito Mazvimavi, head of ICRISAT's impact assessment office. "Although higher rates are known to give higher yields, the marginal returns to investment when using lower fertilizer rates are much better."
In Zimbabwe, ICRISAT has recorded yield increases of 30-50% among farmers adopting the technique. With evidence that precision agriculture techniques can work, the challenge is creating appropriate enabling environments to encourage take-up.
In a low-tech setting this may depend on knowledge transfer, which ICRISAT has done by training extension workers and NGOs, and by providing factsheets to farmers. ICRISAT has also persuaded the Zimbabwe Fertiliser Company to supply products in smaller 10kg formats. Other support mechanisms, such as microfinance services, might also encourage more farmers to invest in low or medium-cost technologies.
It may seem a big leap from precision agriculture's roots in large-scale, highly-resourced farms to the opposite end of the spectrum, but researchers and development actors increasingly recognise that the ideas are highly transferable.
"We've already proven that it is scale-independent," says Khosla. "So it's about replicating the same principles: using the right inputs, the right timing, in the right amount, and employing techniques and human labour together to make that happen in small-scale environments."