The Importance of SRF (Slow Release Fertilizer) With Biochar in Palm Oil Plantations

Biochar is not a fertilizer so even the nutrient content in biochar can be ignored. Even though there are a number of biochars that contain certain nutrients, this is a special matter and really depends on the raw materials used. Biochar is a soil amendment that functions to improve soil properties such as soil structure including increasing soil porosity/soil friability so that roots can penetrate deeper, soil aeration, water availability, shortening the age of harvest, inhibiting the development of plant pests and retaining nutrients and reducing soil acidity. Compared to other soil amendments which have weaknesses, including the need for large and continuous amounts because they decompose quickly, have the potential to negatively affect the climate, and introduce disease-causing microbes/pests, biochar has many advantages, including the volume required is not large enough, not continuous and able to survive in the soil (helps conserve carbon in the soil) is not decomposed for hundreds or even thousands of years. The above makes biochar can function to improve soil fertility and climate solutions (carbon sequestration / carbon sink) or an action to increase organic matter on agricultural land or plantations and mitigate the effects of climate change. 

Even so, biochar can be used to make fertilizer, namely slow release fertilizer (SRF). SRF is a fertilizer whose release is regulated to provide maximum growth effect or SRF is designed or modified fertilizer for controlled fertilization according to plant needs so as to provide increased use efficiency and at the same time increase yield or harvest. This is motivated by the low efficiency of fertilization so that even more is wasted than is utilized or low NUE (nutrient use efficiency). The function of biochar in SRF is as a slow release agent in the fertilizer because it has a porous structure. In making SRF, several methods can be used, including increasing the size (granulation, pellets, etc.), smoothing the surface of the fertilizer, mixing it with other materials that are difficult to dissolve (slow-release agent) and covering the fertilizer with certain materials so that the release of the fertilizer becomes slow (coating). The use of SRF is becoming popular to save fertilizer consumption, increase yields and minimize environmental pollution. 

Soil fertility is a complex trait or condition that must be kept optimal, especially regarding this fertilization. The component of soil fertility itself includes a number of things, namely the depth of the soil solum, soil structure, nutrient content, storage capacity, humus content, number and activity of soil microorganisms, and the content of toxic elements. Productive soils with high soil fertility, both naturally and/or due to human actions, are mainly due to the following characteristics: nutrients in the soil are mobile and easy to obtain, the ability of the soil to convert fertilizer into easily available forms, the ability of the soil to store nutrients dissolved in groundwater from the leaching process, the ability of the soil to provide a natural balance of nutrient supplies for plants, the ability of the soil to store and provide water for plants, the ability to maintain good soil aeration to ensure the availability of oxygen for roots, and the ability of the soil to bind (fix) nutrients and convert them into forms available to plants. Soil fertility must guarantee high, consistent and sustainable production.  

An understanding of the nutrient composition of fertilizer and its release mechanism will help make strategic plans to slow down the release of the fertilizer at a certain level. Compared to conventional fertilizers slow release fertilizer (SRF) has a very slow release speed which can be tens of times slower so that fertilization efficiency increases significantly. It is estimated that more than 50% of fertilizer is wasted due to various reasons including evaporation, immobilization in the soil and leaching due to water, for example due to rain or irrigation. This inefficiency of fertilization is not only detrimental from an economic aspect as well as the environment, namely making the soil acidic, killing soil microbes, and water-soluble fertilizers that can poison water that may be consumed by humans and animals.

Currently, developing countries use more than 60 million tons of fertilizer per year, while according to the Food Agriculture Organization (FAO) world fertilizer consumption reached 190.4 million tons in 2015. With this low level of efficiency, can be imagined how much fertilizer is wasted useless and only pollute the environment. Regarding SRF, the dose of biochar use must also be measured properly because the use of biochar that exceeds the dose will be useless. This is due to the hydrophobic nature of biochar, so that the excess dose does not or only a little can release the fertilizer slowly.

A number of parameters to be observed for administering biochar as SRF are the amount of FFB (fresh fruit bunch) production and its quality (yield of CPO, and its FFA content), continuity of fruiting throughout the year, and the level of uniformity of fruit maturity in one bunch. And it turns out that the use of biochar gave significant positive results, namely FFB production increased by more than 20%, fruit maturity uniformity was almost 100%, CPO yield was more than 25%, and FFA was only 2-5%. With the high production of FFB and the yield of CPO, the intensification of palm oil plantations should have been carried out rather than the extensification that was suspected of being an attempt to convert forest functions or deforestation which tends to receive negative attention from various parties. For more details, read here. There are still many things that can be optimized so that the palm oil industry is efficient, environmentally friendly and sustainable.

Tens of millions of tons of empty fruit bunches (EFB) at the palm oil mills are potential raw material for biochar production as well as tens of millions of hectares of oil palm plantations that can be used for biochar applications. In addition to overcoming the problem of biomass waste, biochar production also produces energy that can be used for the palm oil mill itself, in more detail, please read here. Compared to the production of fuel pellets from empty fruit bunches (EFB pellets) and the production of electricity from empty fruit bunches, the production of biochar has many advantages and advantages both economically and environmentally. In the end, modifying the fertilizer according to the use of the biochar will significantly increase the nutrient use efficiency (NUE) in the fertilizer, ensuring the effective circulation of nutrients and mitigating climate change with carbon sequestration.