Company: International Coffee Farms
Author: Valentina Pedrotti
Location: Boquete, Chiriquí. Panama
Date: 16 January 2019

 

Introduction

Coffee production is a complex and highly demanding activity including not just the coffee processing but the management of all the sub products obtained in the mill. Once the coffee cherry gets into the wet mill, it undergoes a series of processes that removes the pulp and the mucilage from the seed, to finally obtain the parchment ready to be sun dried or machine-dried. Both the coffee pulp and mucilage represent more or less 60% of the total wet weight of the fruit. It means, that for every 100 lbs. of coffee cherries, there is 60 lbs. of organic material that cannot be used directly on the farms due to environmental implications.

Under this scenario, the coffee industry has been looking for alternatives to manage all these volumes of sub product in a profitable and beneficial way. Traditionally, the coffee pulp has been used as fertilizers, livestock feed, or even as a source of biogas (ICO, 2005). More recently, the vermicomposting has been implemented as another strategy to manage sub products. This is a biotechnology that manages the intensive breeding of earthworms in specialized beds aiming to transform fresh organic substrate into a more suitable material for plants. This bio-oxidation promoted by microorganisms and earthworms produce humus and leachate as final products. Both can be use on the farms.

The aim of this study was to characterize the humus and leachate produced in the vermicomposting system from coffee pulp, in terms of chemical and microbiological components. Additionally, the effect of the foliar and edaphic application of leachate in two-year-old trees was determined, in terms of plagiotropic and orthotropic growth.

 

Objectives

  • Characterize the chemical and microbiological composition of the two main sub-products obtained in the vermicomposting of coffee pulp: Humus and leachate.
  • Foliar and edaphic leachate application on Catuai young coffee plants every 21 days during 6 months of the rainy season.
  • Assess the effect on the plagiotropic and orthotropic growth of leachate applications.

 

Methodology

Experimental setup/Vermicomposting

 

Coffee pulp collection methods

The coffee pulp for experimentation was obtained from the mill of International Coffee Farms Corporation, located in Boquete, Panama, from different farms: Cuatro Caminos, Loma de los Cedros, La India, Horqueta 1, mainly from the varietal Catuai.

Experimental setup/ Vermicomposting

The experiment was performed in a brick tank measuring 7,3 m length x 0,93 m breadth x 0,70 m depth with an empty space at the bottom allowing the leachate produced by worms percolate and be collected. A 10 cm layer of partially composted coffee pulp (from two weeks) was used as source of food for the worms. In the beds, around 2 kilograms of the worm Eisenia foetida were inoculated. The humidity was maintained by periodical sprinkling of water. The perforated mesh that covers the entire structure, allowed the air circulation. Every two weeks, the worms were fed with partially composted pulp.

Once the bed reached its maximum capacity, the worms were harvested using traps with fresh food. The leachate was collected every 5 days and stored in a tank located under shade and ambient temperature (around 25°C).

Three humus samples in different areas of the bed were taken for chemical and microbiological analysis. And three leachate samples were collected as well in sterile containers. All the samples were brought immediately to the lab for chemical and microbiological analysis.

1.Leachate and humus sample for the lab.

Experimental area.

The experiment took place in Loma de los Cedros coffee farm, in Boquete, Chiriqui District, Panama. This is a shaded commercial coffee farm located at 1,550 m.a.l.s. Within the farm, 228 m2 of experimental area was delimited, considering a buffer area to isolate the experiment with the rest of the farm.

The foliar and edaphic application of the leachate started in May, one month previous the rainy season starts until complete 6 months of application. Six different treatments were applied plus one control (table 1). For each treatment, a population of 10 trees was assigned. With a distance of 1 meter per tree and 3 meters between treatments. The total experimental population was 60 trees and 10 control.

Leachate application.

Around 200ml of leachate at different concentrations was applied via foliar and edaphic using a spray pump every 21 days.

4.Leachate application

The orthotropic and plagiotropic development was assessed and monitored by counting the number of new branches growing from the main stem and the number of nodes. The starting point was identified in each tree, allowing to monitor the development throughout the six months on the same part of the tree. The diameter of the stem as well as the altitude was measured monthly.

Leac: vermicomposting leachate, Fert: Regular fertilization program managed at International Coffee Farms: 2 application of Nitro Ca and Hidrocomplex (1 oz/ application) plus two applications of Humiteck (100 cc/ application). Control: Plants with only the regular fertilization program managed at International Coffee Farms.

Statistical analysis.

All the chemical and microbiological data are the arithmetic means of 3 replicates. The physical data measured on coffee trees are the arithmetic means of 6 trees and the statistical analysis of this parameter was carried out through an Independent Variance Analysis.

 

Results

Potential phytotoxicity of fresh coffee pulp.

Fresh coffee pulp has a negative impact on the germination rate and development of a plant, that is closely related to the concentration of it in the final substrate. The higher the concentration of fresh pulp in a substrate is, less probability of germination a plant has. In cases where 100% of fresh pulp was used as a substrate, the germination rate was less than 13%, reaching levels of 0% of germination (table 2).

Results obtained from the three coffee pulp samples obtained in the vermicomposting system. Analysis done at Centro de Investigación Agronómica CIA. Costa Rica University 21/03/18.

Results obtained from the three coffee pulp samples obtained in the vermicomposting system. Analysis done at Centro de Investigación Agronómica CIA. Costa Rica University 21/03/18.

Analysis of the radicle system shows the same behavior as the germination test (refer to table 3). The radicle cannot develop in a substrate with high fresh pulp concentration.

Fresh coffee pulp is an organic unstable product, in terms that it continues the decomposition after being applied on the soil. Due to the high oxygen demand to carry out the aerobic decomposition, it can lead to the reduction of this element and sudden death of beneficial aerobic bacteria in the soil. Besides, its excessive amount of tannins and phenols can cause the inhibition of root growth ( Velmourougane & Kurian , 2011). This is an indirect response of the potential phytotoxicity of fresh pulp on plant development and the main reason why placing large amounts of fresh pulp in a small area can cause problems to the trees.

 

Chemical characterization of the leachate and humus

The chemical composition obtained in the chemical analysis of the humus and the leachate samples shows that both products can be used as a complementary source of nutrients but not as a fertilizer substitute. As it is shown in the table 4, the contribution of micro and macronutrients is low and cannot be compared with a regular fertilizer.

Because their nutrient contents are very low, large volumes of humus would be required to make significant contributions of nutrients to the crops. As an example, if we need to apply 100 Kg/ha of Nitrogen, we will have to incorporate about 6,400 kg/ha of humus. In terms of logistics and availability of this product, it is not something manageable on any coffee farm.

However, the benefits of implementing leachate and humus in a coffee plantation are from other nature. The chemical results show that the humus obtained from the decomposition of the pulp is an excellent source of organic matter for the soils (%C 26.02). The incorporation of humus on the farms, will improve the concentration of organic matter into the soil and, therefore, improving the cation exchange and the availability of micro and microelements for the coffee trees. The pH value of both, is around 9, which result beneficial in soils were the pH is low. This is something very common to find in coffee producing countries with high rainy seasons.

It is important to mention that both, humus and leachate, have high concentrations of Fe, especially the humus. Therefore, the application of both products should be done with caution, and it is recommended to do a soil analysis on the farm prior to application.

Other benefit of the implementation of such sub products obtained from the vermicomposting of coffee pulp is the incorporation of micro fauna into the soils that improves the microbiological activity on the farm. The microbiological analysis shows that samples of humus and the leachate obtained in the vermicomposting system, contain important populations of Actinomycetes, Fungi, Yeasts and Nitrogen Fixers. Each of these group of organism has a beneficial function. Besides, there are no dangerous bacteria such as E. coli and Salmonella in any of the samples assessed.

Actinomycetes are gram-positive aerobic bacteria responsible for the earthy smell of fresh soil, but must important, for its role in the cycling of complex organic molecules such as cellulose. This improves the availability of nutrients for plants (Bhatti, Haq. , & Bhat, 2017). Lactobacillus is another interesting group of bacteria that works as a probiotic also on the soil. These bacteria allow the slow release of nutrients of the rhizosphere to be absorbed by the plants (Kang, 2016).

Soil yeast population are usually affected negatively by common agricultural practices such as chemical disease control. While healthy soils with organic matter usually have higher yields of yeast colony (Botha, 2006).

Today, many farmers are looking to take palliative measures to improve the concentration of these microorganisms in the soil. Some studies have shown that adding brewer’s yeast to conventional crops such as tomato and sugarcane can enhance the N and P status of plants altering their growth and biomass. It means that yeast can potentially improve crop growth and nutrients supply ( Lonhienne, Mason, Ragan, Schmidt, & Paungfoo-Lonhienne, 2014). The application of humus and leachate can be another option to increase soil yeast.

 

Physical effect of the application of leachate on young coffee Catuai trees

Treatments were separated into two categories: leachate application plus regular fertilization program and only leachate application. Among them, different concentrations were used.

These analysis are the result of the average value of 6 trees, based on a Normal distribution and an Independent Analysis of Variance. (a) shows no statistical differences with control. (b) shows statistical differences with the control. The description of each treatment is defined in table 1.

According to the statistical analysis, the treatment 1:20 leachate plus fertilization has a better result compared to the control treatment. In average, during 6 months of monitoring, one more pair of leaf has grown compared with the rest of the treatments and the control. It represents a significant increment in the coffee fruits production per tree.

The same effect has been recognized on the orthotropic growth. In this case, two treatments show statistical increments compared to the control, these are: 1:20 leachate plus fertilization and 1:40 leachate plus fertilization.

These analysis are the result of the average value of 6 trees, based on a Normal distribution and an Independent Analysis of Variance. (a) shows no statistical differences with control. (b) shows statistical differences with the control. The description of each treatment is defined in table 1.

Finally, the change of altitude of the coffee trees during 6 months of application with the treatment 1:20 leachate plus fertilization is statistically different from the control. Again, this concentration of leachate allows the best results in three physical variables that are related to production yields and health plant.

These analysis are the result of the average value of 6 trees, based on a Normal distribution and an Independent Analysis of Variance. (a) shows no statistical differences with control. (b) shows statistical differences with the control. The description of each treatment is defined in table 1.

These results are a second proof that leachate by itself is not recommended to be used as fertilizer substitute. In general terms, the best results appear when there is a combination of both, and the most efficient treatment in terms of volume and final result is the 1:20 leachate concentration plus a fertilization treatment. This for young trees.

In all the physical analysis assessed during the experiment, the application of only leachate (regardless the concentration it was applied), shows no statistical differences with the control population.

In this study, we objectively could identify the advantages and limitation of the application of processed sub products obtained from the vermicomposting of coffee pulp, such as the leachate. The result shows that leachate can be an improver of the fertilization programs on a farm and a soil enhancer in terms of adding new microbiota on the soil. However, it is not recommended as a substitute of a regular fertilizer.

Nowadays, there is a dangerous concept or idea where all the products considered natural and or organic are healthy. However, depending on the concentration of a products, anything can be dangerous or poisoning. This happens with humus and leachate as well. The high amount of Fe can be considered one of their main limitation, and the main reason why a farmer should know in advance its Fe concentration in the soil before applying these types of products.

 

Importance and interest to the membership of the SCA.

Sustainable actions need to be implemented in each stage of the coffee industry, if we consider developing this market for a longer time. However, it is necessary to promote actions that are proven to be better options than the conventional ones. Otherwise, we can naively fall into a false sustainability.

Members of SCA, specially producers, can use this information as a reference in the management of sub products at their farms. Besides, it is well known that Environment Regulation in terms of sub products management are everyday more demanding in producing countries. Therefore, these kinds of technologies will be considered more and more not just and extra activity on the farm, but a vital activity within the coffee processing system. Real proven sustainable options are what the coffee industry is demanding in order to follow this path.


References

Lonhienne, T., Mason, M., Ragan, M., Schmidt, S., & Paungfoo-Lonhienne, C. (2014). Yeast as a Biofertilizer Alters Plant Growth and Morphology. cropscience, Vol 54.

Velmourougane, k., & Kurian , R. (2011). Chemical and microbiological changes during vermicomposting of coffee pulp using exotic (Eudrilus eugeniae) and native earthworm (Perionyx ceylanesis) species. Biodegradation, 22:497–507.

Bhatti, A., Haq. , A., & Bhat, A. (2017). Actinomycetes benefaction role in soil and plant health. Microbial Pathogenesis, Vol 111. Pages 458-467.

ICO. (2005). Posibles usos alternativos de los residuos y subproductos del café. ICO, 1967/05.

Kang, A. (2016). Understanding Lactobacillus Role in Modern Agriculture Practice. Research & Reviews: Journal of Ecology and Environmental Sciences.

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