Beyond the Sip. We are glad to start introducing you to coffee from several points of view, particularly from the Agricultural-Biological coffee scope.
With these series of articles, we will take you on a journey to have a better understanding of coffee practices in the agricultural world. We will be talking about soil fertility and how coffee plants grow and which factors can affect its development and the quality of the coffee bean, building a bridge between the Terroir and your daily cup of coffee.
Today you’re going to learn how certain agricultural practices affect the environment as well as the biological dynamics between soil, water and plants. As a fact, we need to understand that every agricultural activity has an environmental impact, at several degrees of intensity.
According to the international year of the soils 2015’s edition, a report of an international group of FAO scientists (Food and Agriculture Organization) mentioned that 33% of the world’s soils are moderated or highly degraded by erosion, deforestation or chemical pollution.
This means that the sustainability in agricultural practices, rural communities’ quality of life, and also the availability of producing enough food for the world’s consumption are all on increasing risk.
As a field technician, during my field’s visits, I’ve learned a lot from farmers and while talking with them, it is common to heard comments like:
– “When I was a child, my grandfather used to get a lot of sacks of coffee and corn, the soil was really fertile”
– “The weather in this area used to be colder… And now it’s too hot!”
– “I’ve noticed there is no much rain as years ago and I have to use more fertilizer on the soil now”
What are the sources of the progressive environmental changes conditions through time that the farmers are talking about?
Well, I can point out two main reasons, demographic growth and monocropping systems:
Demographic Growth refers to the increment of population and expansion of urban centers, increasing the demand for resources, and replacing already existing agricultural land with urbanism.
Due to the lack of green spaces and coverture of soil with concrete, the local temperature rises, the overall air and ground humidity decrease. According to Huang et al., 2019 (Environmental Research Letters 14) It is expected that globally urban land will expand by 78% – 171% between 2015 and 2050, meaning a significant boosting heat risk over cities, towns, and its surroundings.
Monocropping systems may have a higher yield and simpler management and harvesting labors, especially through the use of machinery; however, they tend to have a greater demand for agricultural inputs and cause higher pressure over soil than poly cropping systems.
Short cycle crops as tomato, potato, corn, wheat and plenty others are normally used on monocropping systems, which after the harvest leaves the soil’s surface completely exposed to wind and sun, resulting in the progressive removal of the organic matter and the further loss of water retention, infiltration capacity and loss of nutrients (KETCHESON, 1980).
Landscape affected by burns and deforestation, it can be seem that places without trees become arid during warm seasons. Alarming decrease of water supply for nearby populations.
As we can imagine, the processes of degradation of soils are faster than the processes on which it is formed; but do we really understand what the soil is and how they are created in the first place?
Soil
Soil is basically the outer layer of Eath’s crust as a result of thousands of years of degradation of rocks by the action of the wind, water, and biological activity. As plants were adapting progressively to the environment also they were having less dependency on aquatic resources like seas, rivers or lakes.
However, plants managed to start their journey into the continental territories to spread through rocks surfaces as Moss and Lichens (composite organism from Algae family) that through a very slow process were releasing minerals from rocks, turning it into smaller particles and producing a friendlier substrate where other plants were able of settle.(bigger ones)
“Lichens” are the colonizers of dry and hard surfaces, they are not parasites of trees.
Over time, the rocky landscape was turned into green surfaces, accumulating layers and layers of organic matter; starting a progressive succession of ecosystems that nourished themselves from the remains of the previous one. The combination of the organic matter alongside the particles originated from sedimentation, were creating a ground with proper characteristics (texture, water retention or water filtration, air) which gave sustenance to forests, jungle, and fields and therefore agricultural practices.
Regarding the size of the particles of the soil and its permeability to water, it behaves similar to the pass of water through grounded coffee, if it’s made too coarse, the water pass by too quickly as sandy soils but if it’s particles are finer than the water would need longer time to pass to lower layers, as compacted clay soils, similar to those found in tropical countries.
Commonly we can find the called OXISOLS SOILS which main characteristics are compact, clayish, rich on Bauxite ( soft rock rich in Aluminium) and Quartz providing the soil with a hard consistency which makes it hard for water retention and filtration, that is a low-quality soil for agricultural practices.
Pass of water through the soil has similar “behaviour” to water passing throughout grounded coffee.
After a while you may be wondering, how is it possible to find vast jungles and tropical forests in the Amazonas region, Congo, or deep mountain forest where the coffee farming occurs? Most soils in tropics are Oxisoils, vegetation sustains itself over thin layers of organic matter. Once the forest is removed, the organic matter layer quickly disappears.
These mountains and rainforests ecosystems, sustain themselves over a thin layer of organic matter that took ages to be created, centuries or millennia of accumulation of fallen leaves, decaying trees, and other organic materials, that quickly goes away after a couple of years exposed to the consequences of indiscriminate deforestation and agricultural practices. Insects, fungi and bacteria increase to play a huge role in the recycling process of organic matter and soil formation
Farmers use chemical fertilizers to nourish their plantation; nutrients taken by the plants shall be restored. The excessive use of Ammonia (nitrogen source) and other chemical fertilizers, may affect ionic balance in the soil and for instance, the availability for plants to take other nutrients.
Nutrients must be added to the soil to compensate those that were taken by the crops during their development. The excessive use of Fertilizers affects the chemical soil composition, bringing the appearance of a certain phenomenon known as Acidification and Alkalinisation of the soil, terms related to pH: negative logarithm (base 10) of the activity of hydronium ions (H+), in a solution (Slessarev et al,. 2016).
Nutrients must be added to the soil to compensate those that were taken by the crops during their development. The excessive use of Fertilizers affects the chemical soil composition, bringing the appearance of a certain phenomenon known as Acidification and Alkalinisation of the soil, terms related to pH: negative logarithm (base 10) of the activity of hydronium ions (H+), in a solution (Slessarev et al,. 2016).
The pH is measured in a scale that goes from 1 to 14; acid soils have a pH below 7 and alkaline soils have a pH above 7. There are naturally acidic or alkaline soils around the world, making some soils more suitable for agriculture than others, and through the application of fertilizers the soil’s pH can be extremely changed many times.
The Acidification causes pH to go below 3,5 making it difficult for the plants to have access soils nutrients like Phosphorus Ions, Magnesium and Calcium, while alkalization occurs when pH gets over 9, causing hydric stress to roots.
FAO, already has made warnings about the increasing amount of agricultural land that has been affected by both phenomena.
Another fact to consider is the type of system crop used, Monocropping or Poly-cropping and its intended duration on the field also has a great impact on soil and water retention. Regarding duration, there are three types of crops:
● Short cycle: Characterized by fast-growing plants that require high supervision and amount of inputs (water and nutrients), lasting around 4 months at the field before harvest, after which the soil shall be prepared again. Example: beans, tomato, corn, wheat.
Preparation of soil for potato crop, soil is frequently exposed to sun and wind between crop cycles, having more erosion rate than soils from coffee plantations or forest.
● Medium cycle: crops that require around 8 months or a little more, before being harvested. Example: Sugarcane, cassava, pineapple.
● Long cycle: plantations that are intended to last several years at the field. Example: coffee, banana, avocado, coffee, eucalypt.
The rate of erosion and other parameters can vary among these types of crops, being the soil of short cycles the ones that tend to hold more moisture, organic matter and beneficial microbial activity in comparison to the other two. In a similar way, land with an already established forest has less vulnerability to erosion and water deficit than land under agricultural practices; overall the microclimatic conditions vary among natural and agricultural systems.
In this picture, we can observe different types of vegetation. We could perceive that the erosion rate of a soil is affected by the degree of human intervention for agriculture and the inclination of the land, we can imagine as well that the amount organic matter and soil moisture is higher in land covered by trees and diverse vegetation than land with only grass or intensive cropping. Picture taken in “La Pedregosa”, Vìa Sabaneta. Trujillo, Venezuela. 2019.
Example: To illustrate this, imagine yourself walking through a forest with tall trees during the dry period in a tropical country; despite the season you may feel fresh and humid air under the trees, then as you leave the forest and pass through a coffee or banana plantation you start to feel more solar radiation but still feeling moisture under the shadow of the leaves.
However, at the end of the plantation, you would find yourself facing a grassland with full exposition to sunlight and your body quickly starts to sweat more due to the heat and the need for water is increasing.
Something similar happens to the plants, according to its environmental conditions, the evapotranspiration rate changes, the mechanism on which plants release water vapor through the leaves for heat regulation on their leaf surface. Plants shall take enough water from the soil to compensate for the evapotranspiration rate, otherwise, the plants may enter under water stress and further damage to its tissues.
Solutions?
Farmers could deal with water stress by installing irrigation systems but requires an investment that plenty of farmers in developing countries can’t afford or they lack enough water to cover the full demand of their crops frequently, being vulnerable to drought.
Nevertheless, farmers could make use of polycropping systems to guard themselves at certain degree against extended periods of drought, trying to reduce input intake but decreasing also productivity; not all short-cycle crops are easily subjected under polycropping systems, for instance, farmers shall evaluate until certain degree they extend monocropping according to their available resources and the capacity of the land and region to sustain them.
Coffee plantation, full sunlight. Ground level “weeds” can be used as protection against erosion in fruit plantations. There is no competition between these type of weeds and coffee plants for sunlight or nutrients.
In the case of coffee plantations, particularly Arabica species, mostly grown on mountain regions can be found a long native forest in polycropping systems, meaning that it is a crop that undergoes considerable low pressure over land, once has been established, being considered as a proper crop for preservation strategies.
However, due to certain circumstances like the spread of Coffee leaf rust (CLR-ROYA), Broca (COFFEE BORER BEETLE) or the dropped of coffee prices have caused on several occasions the movement of farmers from coffee cultivation to short-cycle crops and its following negative potential impact over soil and water resources.
How can we reduce this tendency?
We could deal with the problem from several angles, from improving the quality of living for the farmer household to improving access to education to rural communities and promoting environmental policies.
There are several environmental options over the table. One of them may facilitate access to alternatives to the usage of wood as combustible for cooking; giving the fact that it is common among rural communities worldwide, also contributing to increasing the rate of deforestation and even respiratory problems due to the smoke.
Materials such as coffee hulls, pellets, clay ovens or electrical kitchens have been proposed and have shown good results to deal with the problem but more work needs to be done through campaigns to spread their usage and facilitate investments.
Inside Job Coffee, as your portal to coffee farming, we are concerned and at the same time want to get our dear readers involved in such a necessary journey in the benefits of the farmers and coffee cultivation. We invite you to follow our campaigns and our coming articles.
Bibliography
● J. W. KETCHESO. 1980. Long-range effects of intensive cultivation and monoculture on the quality of southern Ontario soils. Department of Land Resource Science, University of Guelph, Guelph, Ontario
● Slessarev, E. W.; Lin, Y.; Bingham, N. L.; Johnson, J. E.; Dai, Y.; Schimel, J. P.; Chadwick, O. A. (21 November 2016). ”Water balance creates a threshold in soil pH at the global scale” (PDF). Nature. 540 (7634): 567–569. doi:10.1038/nature20139. PMID 27871089.
Author: Eduardo Matos Santiago
Biologist- Agronomist at Inside Job Coffee
Masters in Economy and Science in Coffee
