Original source: Timac AGRO
Patricia Giraldo and Antonio Vallejo, professors at ETSIAAB, highlight the importance of efficient fertilisation and the choice of resistant varieties to face the challenges of climate change in agriculture. Adverse weather events, especially drought, have caused alterations in the crop cycle that affect production. The question is: what tools do we have to adapt to these changes and become less polluting? The use of fertilisers is essential, as is opening up to new varieties.
The alternation of long periods of drought, high temperatures, as well as the irregularity and new seasonality of rainfall are some of the consequences of climate change that are affecting agriculture and causing new trends in crops. “The most worrying phenomenon is drought,” says Patricia Giraldo, professor at the Polytechnic University of Madrid in the Department of Biotechnology-Plant Biology at the School of Agricultural, Food and Biosystems Engineering (ETSIAAB).
As a result, the flowering and ripening seasons are altered, there are more virulent episodes of water and heat stress in plants, unexpected pests…
In short, we are witnessing a scenario of uncertainty for the farmers that affects crop yields. And the question is: are there tools that allow them to adapt and anticipate the new situation and, at the same time, pollute less to mitigate its effects?
“The truth is that the increase in food production does not mean an increase in arable land, so if we grow crops in worse conditions we will necessarily have to optimise the process, bearing in mind that there is an ever-increasing need for food,” says Giraldo.
The only way to mitigate the consequences of climate change in agriculture and reduce the carbon footprint is to take a “multidisciplinary approach to the problem, applying efficient fertilisation, a selection of varieties that are more resistant to climate change, different management strategies, irrigation optimisation, initiatives for soil recovery with organic matter and microorganisms, sensors that tell us how and when to fertilise and irrigate…”, says Patricia Giraldo. “By combining all these variables, we will achieve greater crop profitability and also pollute less, which is known as climate-smart agriculture,” she points out.
In short, it is a question of opting for new, better adapted varieties, making the best use of fertiliser, as well as using the most appropriate management techniques.
The power of efficient fertilisation
“The first thing to achieve is the maximum output of fertilisers by the plant, to avoid, as far as possible, contaminating aquifers and preventing them from reaching the atmosphere in the form of polluting gases,” Patricia Giraldo points out. For this reason, the expert advocates the use of new generation solutions that are more intelligent and efficient.
An important part of the carbon footprint associated with the use of fertilisers, both organic and mineral, is due to N2O, which is produced by two microbiological processes in the soil: nitrification and denitrification. Taking this into account, “the reduction of emissions of this gas will favour the reduction of the carbon footprint associated with these crops”, says Antonio Vallejo, professor and lecturer in the Department of Chemistry and Food Technology, also at the ETSIAAB.
In his opinion, the best way to mitigate emissions is to adapt management practices, especially nitrogen fertilisation and water, to the characteristics of the crops. The idea is to increase nitrogen use efficiency through the 4R strategies: right dose (right rate), right nitrogen source (right source), right location of the fertiliser (right place) and right moment of application (right time), in other words, to go for “precision fertilisation, adjusted to the needs of the crop”, he says.
In this sense, there are various tools available, such as nitrification inhibitors, or strategies such as the distribution of the dose during the crop cycle or fertigation injection that guarantees the immediate incorporation of the fertiliser.
With regard to nitrification inhibitors, the expert affirms that “they will be used in the future”, but points out that their use will be conditional on the residual effect they produce. He also predicts that biological inhibitors of natural origin that are not obtained through synthesis, such as those based on substances secreted by plant roots, which partially inhibit nitrification, will be promoted. However, he warns that this biological mechanism has only been described in certain crops. “Ideally, they should be applied in sufficient quantities to inhibit the growth of nitrifying populations for weeks… but to date there are no commercial products with this capacity,” he regrets.
As for controlled-release fertilisers – soluble fertilisers coated with an insoluble substance that prevents their release, and those with low solubility – the expert states that “they have demonstrated efficiency in the use of nitrogen and therefore also in the reduction of losses through leaching, which has been less in terms of reducing emissions into the atmosphere. The key to these fertilisers is the need to synchronise the release of nutrients well with plant demand,” he stresses. If this is achieved, they will have done their job.
Finally, Patricia Giraldo also discusses the use of biostimulants and their contribution to crop development: “With effects such as increasing the root system, these products allow the plant to make better use of natural resources, which translates into a better response to water stress and a reduction in fertiliser units,” she says. As a consequence, there is more biomass development and an increase in associated carbon fixation.
More resistant varieties
Another key to tackling climate change is to use varieties that are more resistant to unfavourable climatic conditions, especially drought. “Right now we are researching traditional varieties – which are not cultivated today – but which are more adaptable than the current ones because they preserve a lot of genetic variability that has been lost over time,” says Patricia Giraldo. And she adds: “Although the current varieties are more productive, nothing assures us that in a few years they will be able to respond to the phenomena of climate change”. “In the end, even if they do not produce as much in optimal circumstances, if they are capable of guaranteeing a more stable production in the face of unusual phenomena – for example, a heat wave in April or May when the cereals are filling with grain – they are preferable, at least we avoid losing the harvest,” she points out.
For this reason, the challenge now is to ensure that, as well as adapting to weather changes, “these recovered traditional varieties remain as productive and profitable as the current ones”.
“We are going to have to decide according to changing conditions because what happens if the farmer is growing varieties that need cold before flowering and suddenly the temperatures rise? He will either have to consider changing location, change varieties of the same crop (from winter to spring) or change crops,” he stresses.
Thus, it is clear that efficient fertilisers, such as inhibitors or controlled-release fertilisers based on low solubility or technologies adapted to plant demand, have an impact on reducing emissions. At the same time, by allowing a lower use of fertiliser units, they are decisive for a higher profitability of the crop. Similarly, the use of more resistant varieties is emerging as another of the challenges for the agriculture of the future.
