Ruy Anaya de la Rosa (B4SS), Gerard Cornelissen (Norwegian Geotechnical Institute, NGI), Erlend Sørmo (NGI), and Ludovica Silvani (NGI) conducted training workshops in biochar production in the two B4SS project areas in Indonesia in July 2017.

In Lampung, South Sumatra, we met with our local partners, Jubi and Bu Neneng (Indonesian Soil Research Institute, ISRI) who explained us the progress made in the B4SS project so far, including the baseline survey, field trials at ISRI’s research station and the preparation for training the farmers to produce biochar in Kon Tiki kilns during this trip. Then, we went to the house of the leading farmer to meet the beneficiaries of the B4SS project in South Sumatra. Farmers were advised to dig a Kon Tiki soil pit and dry feedstock for producing biochar with low emissions. When we arrived at the demonstration site, we noticed that the soil pit they made was relatively big with a diameter of about 3m and depth of about 1.2m. The farmers that were most active in biochar production said that the Kon Tiki soil pit was too big for them to operate safely.

The feedstock that the farmers saved for producing biochar was corncobs. They said that they dried the corncobs under the sunlight and stored them in bags prior to our visit. However, we chopped some corncobs in half and noticed that the core was moist and spongy, and therefore the pyrolysis process in the Kon Tiki kiln was initially smoky. We explained them that it is important to dry and store the feedstock appropriately because otherwise the pyrolysis process in Kon Tiki kilns will be slow and smoky. Although most farmers did not seem to be very worried about the smoke, they showed concern about the longer time they need to produce biochar with wet feedstock than with dry feedstock. Hence, some farmers spread the corncobs on a plastic blanket laid on the concrete floor to allow them to dry under the sunlight, whereas others went to their farms to collect dry cassava stems, which they typically pile up and burn in the fields. They realised that adding dry cassava stems to the wet corncobs in the Kon Tiki soil pit reduce smoke and accelerate biochar production. We noted that it is important to understand the local perceptions about drying feedstock in order to provide informed advice.

After the production process was finished, the NGI team demonstrated hot enrichment of biochar in a drum, where they dissolved NPK fertiliser in water and added some of the hot biochar that was just produced in the Kon Tiki kiln. Hot enrichment of biochar allows the nutrients in the chemical fertilisers to go into the expanded pores of the hot biochar faster than cold enrichment. However, some farmers said that they would prefer to do cold enrichment of biochar, even if it takes longer to “charge” the biochar with nutrients, because hot enrichment in a drum requires collective work and the biochar is too hot to move comfortably with a shovel into the drum. Moreover, they would need a mask to cope with the black dust arising from the drum when the hot biochar gets in contact with the water. At the end of the day, we all enjoyed learning about biochar production from each other.

The next day, we went to ISRI’s research station to see the demonstration site where the effects of two treatments of biochar made from cacao shells + NPK fertiliser on maize yield are compared with those of NPK fertiliser alone, NPK fertiliser + lime, and NPK fertiliser + ash made from the same amount of feedstock as the biochar. The results show that the (unwashed) biochar applied at a rate of 15 t/ha provides the highest effect on plant growth. At the site, the NGI team took samples of the maize roots split in half and took photographs to conduct a shovelomics study. It was clear that the roots of the maize plants treated with biochar were bigger and more abundant than those of the plants treated with NPK only or lime. In the afternoon, three farmers invited us to see their fields where they will use biochar to grow cassava, maize and rice.

In Lamongan, East Java, we met with the 10 participant farmers. Bu Neneng explained them the potential of biochar to improve soil functions and the activities of the B4SS project. We also heard about farmers’ common practices, concerns and challenges to grow mainly maize and, to a lesser extent, peanuts. Based on NGI’s biochar research work in Zambia, Gerard said that a significant amount of biochar is removed from the soil together with the roots of the peanut plants during harvest, and therefore biochar would need to be reapplied to that soil the following season. After hearing this, farmers suggested to only try biochar to grow maize in their fields. We then conducted a similar training workshop in biochar production in Kon Tiki kilns as the one we did in South Sumatra, and farmers here also thought that hot enrichment of biochar in a drum barrel is a lot of work.

This was another week of intense B4SS work, which would not have been possible without Jubi’s and Neneng’s assistance and leadership in coordinating the farmers, students and ISRI’s staff who were also very helpful and eager to learn about producing and using biochar for sustainable land management. Special thanks go to the NGI team that has been very important in promoting biochar in Indonesia. Terima kasih!