Companion planting and green manures: how they work

29 July 2021

Companion planting and green manures are common practices in agriculture that aim to establish a beneficial relationship between two plants, that is, they are able to enhance each other for growth or other important factors.

Want to know more? Read on to find out more!

What is crop partnership

Crop partnership, or companion planting, consists of sowing more than one plant species in the same plantation, in close proximity to each other. In this way, they can obtain different benefits while coexisting throughout their vegetative cycle. For the use of these associated crops, the ideal is to allocate a proportional plot of land to each one. However, be careful not to confuse a companion crop with a mixture of crops or mixed crops, as is the case, for example, with mixed cereals.

Crop association and its benefits

Associating two or more crops in the same plantation, as we have said, has numerous benefits, as this is the main objective of this practice: to ensure a somewhat symbiotic relationship between them. Here are some of the main benefits:

  • Better use of space. By combining different plants in the same soil, we maximise the available space. In addition, they can physically help each other: the tall plants shelter the short ones, generating a microclimate that is beneficial.
  • Protection against pests and diseases. By mixing different plants, their concentration is reduced, limiting the attacks or transmission of diseases. In addition, including aromatic flowers as companion plants can deter pests by attracting insects that act as natural predators.
  • Avoid weed growth. In this type of crop, the surface is usually covered, leaving no space for light or for weeds or weed growth.
  • Because they are two different crops, the production of biochemical compounds of one can positively, but also negatively, influence the other species. These properties make the crops more environmentally friendly and sustainable.
  • Accelerates growth. Often, combining one vegetable with another that provides certain micronutrients or organisms to the roots is beneficial in their life cycle, improving growth and even taste.

Companion planting: some examples

  • The three sisters technique was developed by Native Americans. It consists of planting beans and corn by shading the gourds while the gourds provide nitrogen to the soil. These tribes also grew beans alongside sunflowers, as the latter provided a structure for the former to climb.
  • Carnations are able to keep aphids and flies away, thus contributing to pest control. This is because of their smell and certain chemicals exuded by the roots, which can also attract ladybirds and wasps, among other insects, which are natural predators of smaller, more harmful insects.
  • Growing onions near carrots also keeps flies away from the tuber, which causes significant damage to the crop.

History of companion planting

Intercropping has been practised for centuries around the world. One of the earliest records is from China, which has been using azolla (water or floating fern) alongside rice since ancient times.

On the other side of the world, on the American continent, the natives also began to develop this type of practice, and although there are no records, the colonisers discovered in the 15th and 16th centuries that they had mastered it sufficiently to demonstrate a continuous and distant use over time. Some of the associations that remain today are theirs, such as the aforementioned three sisters, or the bean and sunflower association.

Facts such as these show that the association of crops has been with us for a long time, and has even taken on a renewed and leading role since the 1970s within organic horticulture for its natural and practical benefits.

What green manure is and how to use it in companion planting

Green manure is any plant that is grown in the soil and whose main purpose is to protect the soil and improve its conditions.

It is a very useful element for several reasons, such as its rapid growth, the amount of biomass it accumulates and the low cost involved. It is usually used for all types of crops, but in the case of associated crops, it must be taken into account that green manure must be sown in free areas and in areas where it does not enter into direct competition with plant species destined for trade or consumption.

Some types of green manure

Although any herbaceous plant can be used as green manure, there are some that have a greater presence in crops:

  • Leguminous plants: according to experts, they are the best green fertilisers thanks to their capacity for symbiosis with bacteria which, once buried, release nutrients to be absorbed by the roots of other crops.
  • Alfalfa: if temperatures are suitable, it can be used all year round.
  • White clover: a very popular variety because of its small size to cover the soil between crops.
  • Grasses, which are also important for human and animal consumption, such as oats, maize and barley.

What green manure is good for

Among all the benefits of green manure and the benefits it brings to other plants, the following stand out:

  • It increases the amount of organic matter and nutrients in the soil.
  • It prevents irrigation water from evaporating too quickly.
  • It slows soil erosion.
  • It reduces the attack of pests and the appearance of weeds.

Both crop association and green manure allow us to carry out sustainable agricultural practices that result in healthy and well-cared-for crops, thus producing healthier and more nutritious fruit. At Agromediterránea we are firmly committed to the use of this type of exercise, which has a direct impact on the excellent quality of all our products.

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