Crop rotation in organic farming is a vital practice that maintains soil nutrients, suppresses weeds, and controls pests. To sustain soil health, crops such as legumes, which improves soil fertility, are rotated with cereals, which exploit the soil. Egyptian clover, a leguminous crop, is widely used to fix nitrogen into the soil and nourish it.
Crop rotation has very ancient roots. Historians tell us that Romans already started using this technique. From the Middle Age to the 18th century farmers in Europe made use of a three-year rotation including a fallow year. Then, at the beginning of the 18th century, Jethro Tull, the English pioneer of modern agriculture, introduced a four-year rotation and developed horse-drawn seed drills and hoes, starting the agricultural revolution. Today, one-year, two-year, three-year, or four-year rotations with crops belonging to different botanical families are implemented in accordance to European Union and regional regulations. Among the annual soil-improving crops, KALI decided to use the “Maremma” variety of the Egyptian clover (Trifolium alexandrinum) in our einkorn and spelt fields. This is a very plastic species that offers farmers a lot of flexibility both in sowing and harvesting management. Already present in ancient Egypt and Syria, this crop is common in the Mediterranean region, in Northern Europe during the warmer seasons and in the southern United States. Dr. Oriana Porfiri, agronomist and one of the leading international experts in the field, has kindly agreed to talk with us about the main characteristics and benefits of the Egyptian clover.
What is the role of the Egyptian clover in organic farming?
Egyptian clover belongs to the botanical family of leguminous crops, which play a key role in soil fertilization. In fact, nitrogen-fixing symbiotic bacteria present in its root nodules can fix atmospheric nitrogen making it available for other plants. Egyptian clover is an annual crop, which can also grow wild. It is sown and harvested within a year, similarly to wheat, as opposed to other related species such as the red clover or the Persian clover, which are perennial and can be harvested for several years after one initial sowing. Egyptian clover is best sown in autumn or late winter. Once the plants have grown, they can be used to make fodder, to produce seeds, or as green manure. The decision on the use of this crop depends on the organization of the farm: if you have livestock on the farm you will use it to make forage or you can harvest it and sell it on the market. However, since Egyptian clover is not in great demand, companies usually prefer to make seeds instead of forage. The third possible way is using the clover as green manure. After sowing, the plants are grown until the beginning of flowering. Then they are chopped and buried in the ground. Green manure is essential for soil fertility, especially in organic farming where the use of fertilizers is strictly limited.
Are there many varieties of Egyptian clover?
There are several varieties or biotypes of Egyptian clover. They have different biological characteristics, size and ability of re-growing. There is a register of these varieties, which is filed with the Italian Ministry of Agriculture. New biotypes are registered and evaluated after several tests. Each variety is owned by a person who has created it. It is similar to a copyright, a property right, such as when you patent a shoe, or a dress, or a machine. When a company decides to grow clover for producing seed, as in your case, it must work together with a seed company. In fact, the seed must be certified and this process can only be done by a licensed seed company. There are different biotypes: there is an early variety, a late variety, a lower variety, a higher variety. In short, they differ from each other for some characteristics. However, there are not so many selection criteria for clover because the differences are not so striking. The most critical characteristic on which you can base your choice is the precocity. If a farmer has very short rotation cycles and he is sowing very late, then he should choose varieties that grow earlier. Another element of differentiation is the color of the seed. However, it does not play such a big role for a farmer whether a seed is perfectly yellow, yellowish, or completely purple. The color is only an element of characterization of the variety as the color of hair in humans.
What problems can arise from clover cultivation?
When we cultivate something, we create a system that is somehow weaker than a wild system. This principle, which applies to agriculture in general, is crucial in organic or biodynamic agriculture. A cultivated system is more delicate. This said, clover does not present so many problems. Regarding weed control in organic farming, a first approach is the use of the harrow. Harrowing could help remove weeds after the clover plants have developed roots and have emerged from the soil. However, this practice is more often used to allow clover plants to breathe and to facilitate their recovery rather than for weed control. A second approach to weed control is cutting the plants, i.e., using a machine that completely cuts the vegetation of both clover and weeds. Since the Egyptian clover re-grows very fast, it usually manages to recover and stop the growth of weeds. The cutting must be done at the right time. This means that clover plants can only be cut before they have started producing flower buttons and if the weather conditions can allow a re-growth. If, for example, the clover is cut in the second half of June and from then on we are in the middle of summer with high temperatures and no rain, this clover will not grow again. In this case, the farmer has stopped not only the weeds but also the development of clover.
Therefore, similar to all agronomic interventions, it is necessary to evaluate these interventions based on the conditions of the crop and of the weather. When sowing clover in autumn, the chances of cutting it are higher because the crop will have the whole winter to grow. When sowing in late winter or spring, there will be less chances to cut it because the crop will have a shorter cycle, i.e., less months to develop.
Which pests can damage clover crops?
Fungi such as powdery mildew and botrytis are among the pests that can frequently target clover plants. These diseases attack the clover stem causing its blackening and, in case of particularly humid conditions, also its necrosis. The stem loses its firmness and the plants crash on the ground. In case of fungal attack, farmers can cut the plants to eliminate their superficial part, to ventilate them and move them. Also harrowing in the phase of regrowth can be useful in organic farming. Insects can also damage clover crops, eating the flowers, or attacking the plants at the time of setting. But, in this case, interventions are very rare.
Clover has a very limited environmental impact. Even in conventional agriculture it is grown almost without the use of chemicals. Most of the companies usually choose to grow clover for environmental reasons. The advantage of clover is that it is a very plastic crop and can adapt quite well. Even if it suffers a pest attack, it will produce a little less seeds but it can still be harvested and the production is not totally compromised.
The Egyptian clover in a nutshell?
The Egyptian clover is among the "simplest" and fastest soil-improving crops. It is a very plastic annual species that can be sown in autumn or late winter. Finally, it can be used for producing fodder, seeds, or as green manure.