Can we grow corn and import less?

With global warming, drought and less rain, feed resources are becoming increasingly scarce. Nearly one-third of livestock needs are imported in the form of ingredients used to produce concentrates (corn, soy and barley). We produce more than 2.3 million tons of concentrate feed each year, of which 60% is for poultry and 40% for ruminants. We import more than 1 million tons of corn and 650,000 tons of soy each year. During droughts, imports are even greater to make up for feed shortages.

The pros and cons of corn

Maize has been cultivated for thousands of years and is a staple food for many populations in South America. Maize was the first cultivated cereal in the world, ahead of wheat and rice. Cultivation conditions vary from continent to continent. It is suitable for both small-scale farming and intensive, ultra-mechanized cultivation.
It is used primarily in animal feed in the form of grain corn or silage. In human food, it is used to make gluten-free semolina, starch and to extract edible oil. Some varieties are used to make popcorn, while others provide canned corn that is often used in salads. It can be fermented to produce alcohol, bioethanol or biogas.Among its disadvantages, we can first mention its high water requirement, especially during the flowering period (around and after), when the need is greatest. Any lack of supply will lead to a significant drop in crop yields. Corn prefers fertile, deep, fine-textured, well-drained soil. Soil rich in humus, well fertilized, preferably organic. Excessive temperatures (> 50°C) slow down corn growth.

Growing corn requires specialized equipment, from planters to harvesters. Despite its high resistance, weed control and the use of specific pesticides are essential to obtain an interesting performance.

The most interesting varieties are usually hybrids or even genetically modified varieties that are resistant to herbicides and pests. This crop requires the import of the necessary seeds every year. Depending on the weight of 1,000 seeds and the planned density (80 to 100,000 plants/ha), 40 to 50 kg of seeds are needed per hectare.

Corn planting development prospects

In Tunisia, maize cultivation is currently of secondary importance, negligible and almost non-existent. Large-scale, intensive cultivation of maize could in principle produce greens that can be used directly for animals or preserved in the form of silage, as well as grains needed to produce concentrated feed for poultry and cattle.

Until now, maize cultivation has been rarely considered in Tunisia, mainly because of its high water requirement, especially since maize is a summer plant and water resources are limited. Logically, with global warming and increasing water scarcity, we cannot imagine developing a crop that consumes too much water.For some time now, there has been increasing talk about the vast water resources of southern Tunisia, with some advocating the development of the deposit, which is very important for agriculture and the production of food products that Tunisia desperately needs. In fact, studies have shown the existence of two deep groundwater levels in the south (the North Saharan Aquifer System or SASS). These two aquifers, shared with Algeria and Libya, represent actual water reserves covering an area of ​​1 million square kilometres and an estimated 60 trillion cubic metres. Tunisia benefits from 8% of the continental plan, or 542 million cubic metres.³/year accounts for 24.3% of the reserves. Algeria is allowed to mine 1.328 billion cubic meters³/year, Libya 340 million cubic meters /year. Unfortunately, these reserves take thousands of years to form, but in Tunisia these aquifers appear to be non-renewable or even rarely renewable.

This year, some farmers, in cooperation with the National Institute of Field Crops (Ingc), have conducted trials of durum wheat cultivation in the Dhehiba region of Tataouine. The results appear to be encouraging, with satisfactory yields, given the difficult growing conditions. This experience will be extended to Medenine and Kebili next year. Ingc Director General Jarahi said (press May 15, 2024) 430,000 hectares of durum wheat may be planted in the south. In fact, the question is not whether wheat or corn can be grown in the desert. The answer has long been known that both plants prefer hot, dry climates and can produce excellent yields. The problem is knowing how to provide them with enough high-quality water to achieve satisfactory and profitable performance.

In Algeria, at the end of the last century, the state undertook to develop large-scale cereal cultivation in the middle of the desert by exploiting groundwater and using giant pivot ramps for irrigation. Large-scale production of wheat and corn (silage and grain) has been going on for several years. Given the importance of this experiment, we quickly came to the following first conclusions.

Overview of the Algerian Experience

To encourage investors, the state must strongly support investors and encourage them to come and settle in the Sahara. The scope of this support includes facilitating land acquisition, infrastructure construction (deep water surveys, roads, power grids, etc.) and providing the necessary inputs, while ensuring the elimination of all production. Priority is given to the cultivation of cereals, wheat is harvested in June, followed by corn, which is harvested in November-December and is harvested as silage, wrapped in large plastic bags or as grain. The yields seem interesting: up to 70-80 tons of wheat/hectare, 40-50 tons of corn silage or 90 tons of grain. A huge, impressive green circle just appeared in the middle of the desert, which is undergoing extraordinary mutations, radical changes and intense dynamics. Huge mobile pivots dump water from the depths, and large machines (tractors, combine harvesters, giant semi-trailers for transporting wheat) cultivate the fragile desert soil all year round.

Although these results seem promising, this mode of operation poses many problems, especially those of sustainability, especially the non-renewability of resources and soil salinization. “mining”.In addition, the very high cost of production, lack of access to spare parts and equipment maintenance, difficulties in the supply of fertilizers and other inputs, the distance from consumption and processing centers, the absence of roads, the difficulty of finding labor in the central Sahara Desert… All these difficulties make groundwater extraction difficult and unprofitable, despite strong support from the state.

Pivot irrigation results in high evaporation in desert environments, which, in conjunction with high evapotranspiration from plants, significantly increases crop water requirements. Although water salinity is variable, the accumulation of salts, especially in the absence of rainfall for leaching, can make soils infertile and force farmers to frequently relocate crops. In addition, desert soils are inherently sandy, poor in organic matter, and have very low microbial activity.

Finally, intensive farming is difficult to carry out in the extreme climatic conditions of the Sahara Desert, and the animals selected have a very low tolerance to high temperatures and heat stress. The corn silage produced on these farms must be transported to the north for use in livestock pastures, and the manure is brought back to improve soil quality. This logistics is very expensive and is a significant source of carbon dioxide (CO², a major greenhouse gas).

Use SASS water with caution

The groundwater in southern Tunisia has been moderately exploited so far. With global warming and insufficient rainfall, the number of uncontrolled well drillings continues to increase. In some places, they are overexploited, causing the water table to drop, salinization and the drying up of many water points.

The development of SASS water resources poses many problems and must be done with great caution and adequate research. The aim is to draw conclusions from the Algerian experience and see the medium and long term effects of the “mining” exploitation of an unsustainable resource (groundwater) in a desert, a fragile and vulnerable natural environment and very specific socio-economic conditions.Existing technical solutions include using solar energy for pumping and electricity, desalinating brackish irrigation water to avoid the accumulation of salt in the soil, using sludge from water treatment plants and organic farming and agro-food waste in oases to enrich organic matter, direct sowing to protect the soil, using water-saving systems such as obvious dripping or even burying, smart computer-controlled irrigation systems, and judicious selection of varieties that are resistant to heat stress and less demanding of water.

Although the one-time yields of intensive crops such as wheat and maize are very attractive, large-scale cultivation must be carried out in a well-researched manner and with a coherent strategy. The newly established South and Sahara Development Office and research organizations such as the Institute for Research in Arid Areas (IRA Medenine) must be strongly involved in this strategy aimed at utilizing the vital water. Ensure the sustainability of this resource and the protection of soils, the environment and the Saharan ecosystem.

Ultimately, although very attractive, maize cultivation in Tunisia could not develop and remained marginal due to its very high water requirements, especially since it is a summer crop that requires large amounts of irrigation water.

In the North, water resources continue to decrease and the Ministry of Agriculture has banned summer market gardening to meet the population’s drinking water needs. Dam reserves are at minimum levels, rationing and water cuts are frequent. Southern waters must be used with caution. The Algerian model is unsustainable, uneconomical and dangerous in the medium and long term. Nevertheless, it is also justified from the perspective of national security and sovereignty, given the unstable global political and economic environment. Existing solutions can exploit research and currently available technological possibilities to develop part of our deep waters in a smart and rational way. Reusing recycled water from wastewater treatment plants for corn production is also a good alternative and a rational use of our available water resources.

Rida Belgawi