How Sensors and Science Are Improving Farming in the Desert

According to globalagriculture.org, agriculture is consuming the Earth’s available fresh water at a surprising rate: 70% of “blue water” from watercourses and groundwater is used for agriculture, the organization reports – three times the level used 50 years ago. The demand is expected to increase by 19% in the next 30 years because of irrigational needs for farmers.

Advances in technology and the science behind growing crops (whether corn, soybeans, fruit, or vegetables) can enable consistently good yields, despite climate conditions that might otherwise seem daunting to farmers and growers.

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In an area of Spain with perhaps the most inhospitable farming conditions in all of Europe, research has been conducted into the use of both sensors and soil surfactants. Testing has not only led to better understanding of irrigation management, but how to amend soil to actually reduce the demand for irrigation in the region.

The lessons learned in Spain are applicable globally, to ensure that the continually increasing demand for water is matched with correspondingly higher yields to feed the world.

The Rise of Precision Agriculture

Sensors and mapping technology allow farmers to maximize yields with minimal resources. Referred to as precision agriculture, the technology has also begun to be referred to as “smart” agriculture with the advent of Global Positioning System (GPS) capability for civilian use.

With this technology, farmers have been able to map crop fields more accurately than ever before, which in turn enables monitoring of field conditions for application of fertilizer and weed treatments to match the specific needs of plants. Early precision agriculture users have benefited from crop monitoring to obtain optimal fertilizer and pH correction recommendations.

As a refresher, there are four general categories of sensing technologies being employed in commercial farming:

Location sensors, which use GPS satellite signals to determine latitude, longitude, and altitude of farmland.

Optical sensors, which use light to measure soil properties. The sensors measure different frequencies of light reflectance and can help analyze clay, organic matter, and moisture levels in soil.

Electrochemical sensors, which detect specific ions in the soil to provide information on pH and soil nutrient levels.

Mechanical sensors, which measure the compaction of soil. Tensiometers, a popular type of mechanical sensor for irrigation planning, detect the force used by the roots in water absorption.

It is the work using comparatively inexpensive tensiometer-based mechanical sensors in particular that is leading to some of the greatest advances in both irrigation management and crop output.

Irrigation and Soil Treatment in Europe’s Only Desert

Almeria is an arid area in the badlands of southeastern Spain, near the Desierto de Tabernas, which is often called “mainland Europe’s only desert.” Almeria is also the home of the largest concentration of greenhouses in the world, growing vegetable crops including tomato, pepper, melon, cucumber, eggplant and zucchini.

Because of the harsh conditions, optimal water use in Almeria demands exacting irrigation and water techniques. Drip irrigation has improved how farmers there use water efficiently, but management has still largely been based on farmers’ practical experience, with little scientific support for the protocols being used.

The University of Almeria and the Estacion Eperimental “Las Palmerillas” have been conducting research into the use of soil moisture sensors for irrigation management in the area. Tensiometers are used as a reference to evaluate and develop protocols for irrigation management. The tensiometers measure the moisture content of the soil and trigger irrigation via a double line drip tape spaced approximately every four feet.

The researchers continuously monitor these sensors to identify periods of over- and under-irrigation. Local farmers now have a way to calibrate their irrigation strategies according to soil condition and crop conditions. Better control of irrigation has led to better cost control, minimized water waste, and optimized rootzone water levels.

But irrigation strategies are not enough to improve farming, without also considering soil amendment.

Local water in this farming community has a high level of salinity (above 4000mS/cm). Irrigation also demands complicated water treatment, requiring the water to be run through a reverse osmosis system. This understandably increases the cost of water considerably by the time it reaches the crop.

To manage the cost of water irrigation now more scientifically calculated using tensiometers, one of group of growers in Almeria also undertook a test of soil surfactants to determine to what degree application might reduce the amount of water while maintaining crop quality and yield.

In the spring of 2014, farmers ran tests on approximately 5 acres of a commercial melon crop in the region. The trial involved soil surfactant applied at specific intervals:

  • 32 oz per acre after planting
  • 16 oz per acre two weeks after planting
  • 16 oz per acre four weeks after planting

After just four weeks following this carefully controlled program, tensiometer readings detected sufficient moisture levels. At that point, irrigation on the treated area was stopped for nine days. Irrigation intervals thereafter were reduced from 1.5 hours per day to 20 minutes per day.

The farmers participating in the program found that from that point until harvest, crop growth required only 20 minutes of irrigation per day, reducing what was required to grow the crop.

Similar results (that is, the ability to reduce the time and amount of irrigation with the use of soil surfactants) have been observed in other parts of the world, including the United States. Areas where water availability is a factor (the Ogallala Aquifer, or parts of California, for example) or regions that have to pay for water – or where increased energy costs are a factor – have benefited from the use of these tools to manage water use.

The Combination for Reduced Water Consumption and Improved Yields

Modern technology can assist with irrigation, as moisture sensors and tensiometers enable growers to monitor and manage moisture levels. While these advancements can help assess soil conditions, they are not sufficient to maintain and increase yields.

Changing climatic conditions, as well as the natural conditions in growing areas worldwide, affect the quality of water used for irrigation in farming and the capacity of soil to make use of that water. Monitoring can provide an understanding of water conditions and better manage its use, but it must go hand-in-hand with appropriate strategies to better condition the soil to accept irrigation.

A combination of sensors and monitors is the right first step to help farmers evaluate moisture levels, salinity, fertilizer requirements, and more. From there, soil amendments and applications such as soil surfactants can improve the use of water in farming, to improve yield while sparing the overuse of water in a time of increasing global demand for the resource.