From hand weeding to glyphosate, not so many years have passed. It was during the second half of the 20th century when man used chemical products ( herbicides ) to control… rather… an exaggerated eradication attempt of the weed species that compete with the crops of interest. But is this view of weeds correct?
DO WEEDS EVER CONTRIBUTE SOMETHING?
Many variables are involved in an agrosystem. This we have already talked about on more occasions and I think I remember that one of thelas is the microfauna of the soil; that microfauna that we must take care of and maintain at all costs for a good balance of the soil. A bit similar happens with weed herbs. It is evident that they have to be controlled, which is very different from the term eradicate that I mentioned in the previous paragraph. In themselves, although they are called “bad”, they also contribute to the mechanical stabilization of the soil (prevent erosion) since their powerful roots hold the soil. Other times, depending on the species and density, they can favor suitable conditions for many beneficial soil microorganisms in the development of crops.
WHAT DOES A WEED REPRESENT IN THE AGRONOMIC WORLD?
A word. PRODUCTIVITY . It is, after the weather, one of the most important causes of productivity loss worldwide. They compete directly with crops and, luckily or unfortunately, (rather the latter), they tend to be stronger and more powerful than plants of agronomic interest. We have to realize that they are very adapted to the environment in which we plant, they have a high rusticity, and a bestial reproductive capacity (otherwise they would not be weeds). If, in addition to this, we provide them with nutrients in the form of fertilizer that is primarily for our cultivation, we have an invasive cocktail that is difficult to control.
THE PERSISTENCE OF HERBICIDES IN THE SOIL
It is one of the problems associated with the use of some herbicides. It does not happen with all, not even with the vast majority, but it is true that there are some active principles of some herbicides that can affect crops whose characteristics are within the spectrum of action of the herbicide from the preceding crop. Normally, in commercial products, it is perfectly advised what periods to leave for depending on which crops after the application of the product.
IS A HERBICIDE REALLY NECESSARY?
It all depends on the objective of our cultivation and its size.
Actually, where the productivity value falls in considerable numbers, they tend to be legume and cereal crops in large-scale monocultures. In horticultural crops, although they can also compete with crops, their impact is usually less acute. They still have it.
Let’s imagine a small garden in which we get about 18 kg of product (whatever it is) and that if it had not been for the weeds we could have obtained 20 kg. We have had minor losses, since 2kg up and down means practically nothing to us. A total of 10% losses is not that bad either and then we hoisted our achievement saying what a marvel of an orchard that without pesticides and herbicides we have achieved some lustrous vegetables!
Extrapolate that to a field of 100 ha where the economic benefit, after depreciation of machinery, products, labor, taxes, blah blah blah blah, is 5% of what is billed if all goes well. Boom! Does the perspective change right? Not only do we have no profit, but we may also have to put money in. So do we use herbicide or not? Well, in some cases it is necessary but a balance must be found between alternative tillage techniques for a more restrained use of them in case of having to use them.
It is not at all realistic, in a developed country, to think that current agriculture, as it is thought, can be economically viable without using a single gram of herbicide. To achieve this “ecological ideal”, we must first start by questioning our economic model, our model of life and food (more than 1/3 of what is produced is thrown away), but that is another issue that we leave in the inkwell … or on the keyboard in this case. What it should do is tend to its minimum use , combined with cultural farming techniques.
WHAT ARE THESE ALTERNATIVES TO COMPLEMENT OR REDUCE THE USE OF HERBICIDES?
There are many ways to supplement the use of herbicides (if necessary) to drastically reduce their use and even, depending on what occasions to do without it. Here we mention some of them and their articles developed suitably.
Expensive but effective method in hot latitudes (southern Spain) where, after irrigation to moisten the soil, it is covered with a transparent plastic during the summer months, achieving temperatures above 40ºC that reduce the viability of the seeds present in soil. It is not effective for all crops or in cold areas. It is usually used in greenhouse or irrigated crops where the productions are very high per hectare and it compensates the investment. Here we leave you a complete article on solarization .
CROP ROTATIONS AND ALTERNATIVES
It is one of the most effective non-chemical methods that exist because there is a competing flora associated with each type of crop and it is one of the few methods that demonstrates its effectiveness regardless of the type of crop (cereal, horticultural, irrigated, rainfed …)
There are many crop rotations between non-competitive species (carrots, onion) with other more competitive species (potato) to break the cycle of the weeds present. We’ve already talked at length about rotations in these two articles:
Whether from organic products, minerals (stones, ashes …) or plastics, they greatly limit the germination and growth of seeds once we have our crop minimally developed. Another article we leave you on the padding to expand the information of this system.
This is another world in which agricultural research invests a lot in knowing what is the best planting density to obtain the highest yield in the same space. It is difficult to play with the planting densities and it is difficult to demonstrate if a higher density causes a decrease in weeds due to a greater coverage of the cultivated species that prevents the emergence of some of its competing herbs. There are studies that show that it is and others that it does not. Here we have disparity of opinions.
And after this dissertation on the use of herbicides, we will answer the initial question. Herbicides in our garden yes or no? Absolutely not. In our home gardens, idle, in the city or in the village, the answer is no. The hand weeding, increasing planting densities, padded … all these techniques are more than enough to ensure production more than plentiful and a final feeling of our products satisfying the garden year after year.
Anyway, here we leave you extended and interesting information about different types of herbicides and their uses.