Biochar and Specific Organic Fertilizer for Post-Mining Reclamation Treatment

Mining activities are not just digging, loading and transporting, but environmental sustainability is also an important thing that must be considered. Even post-reclamation has become an obligation for mining companies with severe sanctions if neglected. Environmental damage due to mining if left unchecked will become a serious environmental problem such as natural disasters, and become a bad legacy for future generations. This means that post-mining reclamation must be carried out properly or adequately so that the negative impact on the environment can be minimized or even eliminated. Reclamation planning and implementation needs to be done well so that the reclamation goals can be achieved.

Low fertility on post-mining land is indeed a separate problem for revegetating the land. When a mining company has good management of overburden (OB) and top soil so that it can be returned (backfill) to the former mining pit (void) as before, the decline in soil fertility can be minimized. But if the management is bad, the fertility of the soil will drop drastically or be severely damaged so that in these conditions certain treatments need to be carried out to restore, improve or increase the fertility of the soil. The condition of land that has low fertility or is like barren land is almost the same as sandy land. In general, coastal sandy land has the following characteristics: sandy soil texture (90%), granular soil structure, loose consistency, low nutrient content, low soil ability to store nutrients, very fast permeability, drainage and infiltration, porous (majority with mesopores and macropores, and less of micropores), low water holding capacity, low soil ability to support plant growth and relatively high salt content or is a marginal land for agriculture or plant cultivation, so the treatment approach on sandy land with post-mining land is an effort effective approach.

Agriculture or cultivation of sandy land can be done for both seasonal and annual crops, the same goes for post-mining land. Factors of effectiveness and efficiency need to be done to get optimal results such as the type of nutrient and its amount, water requirement and so on. Conditioning the land so that it can hold water and nutrients must be done so that the added fertilizer can be utilized properly. Minimum input so that production costs can be reduced or economic factors are other important things. With post-mining land areas that can reach thousands of hectares, the input in the form of quality fertilizer is a must. In addition to inorganic fertilizers as macro elements, organic fertilizers as a provider of micro elements also need to be added. Specific organic fertilizer according to land conditions and plant needs can be made for this purpose. The use of compost with volumes ranging from 20-30 tons/hectare can be significantly reduced by using this specific organic fertilizer.

Sandy soils generally have high P and K content. The function of organic matter, in this case manure, can stimulate the availability of P nutrients that have accumulated in the sandy soil in the form of total P, so that available P becomes greater. With the availability of P, the available K is also greater, because P interacts with K. Amelioration technology to increase soil fertility is needed. Amelioration itself is an effort to improve soil fertility through the addition of certain materials. Amelioran is a substance that can increase soil fertility by improving physical and chemical conditions. Biochar as a soil amendment will be effective for this purpose, even when compared to other soil amendments, biochar has many advantages, one of which is being able to last or not decompose in the soil for hundreds of years. While increasing the efficiency of using biochar is by designing slow release fertilizer (SRF) so that the release of fertilizer is according to plant needs or can be used by plants optimally.

Plants are composed of 92 elements, but only 16 are essential for their growth and development. Of the 16 elements, elements C, H, and O are obtained from air and water (in the form of CO2 and H2O), while 13 other essential mineral elements are obtained from the soil and are generally classified as "nutrients". There are 6 macro nutrients namely N, P, K, S, Ca and Mg. These macro elements are needed by plants in large quantities with a critical content (value) between 2 – 30 g/kg dry weight of plants. These macro nutrients are divided into two, namely primary nutrients (N, P, K) and secondary nutrients (S, Ca, Mg). Primary nutrients are provided in the form of all types of plants and all types of soil. Meanwhile, secondary nutrients are only for certain types of plants and certain types of soil. While micro nutrients consist of 7 elements consisting of 5 elements which are metals namely Fe, Mn, Zn, Cu and Mo, and 2 non-metallic elements namely Cl and B. The need for micro nutrients is relatively small ranging from 0.3 – 50 mg/kg dry plant weight. The combination of macro fertilizers and specific organic fertilizers will maximize plant growth.

Biochar and N2O Emission in Agriculture

Urea Plant

The world's production of urea fertilizer in 2020 will reach around 181 million tons and this type of urea fertilizer is the most widely used. In practice, the use of urea fertilizer is mostly inefficient, so it is wasted and pollutes the environment. It is estimated that the level of loss of urea and pollution to the environment, in use reaches around 40% or 72.4 million tonnes globally. Efforts to improve fertilization efficiency can be done by modifying it to become a slow release fertilizer (SRF), one of which is highly recommended, namely biochar, as a slow release agent, read more details here. In addition, the use of urea causes N2O emissions. N2O (nitrogen monoxide) is a greenhouse gas and air pollutant, N2O is a dangerous gas because it has a stronger effect about 300 times per unit weight than CO2 in a span of 100 years. In air, N2O reacts with oxygen atoms to form NO, and NO then breaks down ozone.

Urea is one of the conventional fertilizers commonly used in agriculture. Urea has a main content in the form of nitrogen which is absorbed by plants in the form of ammonium (NH4+) and nitrate (NO3−). Loss of nitrogen in the fertilizer occurs due to evaporation as ammonia (NH3), immobilization in the pores of the soil or washed by water, both rainwater and irrigation water. In addition to economic losses, environmental pollution due to excess nitrogen also causes a number of negative effects. Nitrogen from urea can also be lost due to complete denitrification of nitrates to produce nitrogen gas (N2) or through incomplete nitrate denitrification to produce nitrogen monoxide (NO) and nitrous oxide (N2O) gases, which evaporate from the soil. Nitrate, nitrogen monoxide (NO) and nitrous oxide (N2O) gases contribute to environmental problems. Nitrates are harmful substances that cause water pollution. Excess concentration of nitrate in drinking water is harmful to health, especially in infants and pregnant women.

Meanwhile, nitrous oxide (N2O) has now become the largest ozone depleting substance emitted in the 21st century. The main source of global nitrous oxide (N2O) emissions is nitrogen-based fertilizers, especially urea fertilizer. The presence of N2O in the lowest region of the atmosphere (troposphere) can cause a greenhouse effect or global warming because N2O traps infrared radiation emitted from the earth's surface and then warms the atmosphere. In addition, N2O can migrate up into the stratosphere where it reacts with oxygen atoms to produce some nitric oxide (NO). Then, the depletion of the ozone layer occurs because NO reacts with stratospheric ozone (O3) to form NO2 and O2. Furthermore, NO2 reacts with O to form NO again. The depletion of the ozone layer increases the amount of UV rays from the sun that reach the earth's surface.

Biochar application has been suggested as a strategy to reduce nitrous oxide (N2O) emissions from agricultural soils while increasing soil carbon (C) stocks, especially in tropical areas. Climate change, especially temperature increase, will affect soil environmental conditions and thereby directly affect soil N2O volume. Related to climate issues, there are two aspects of the role of biochar, namely as a carbon sequestration / carbon sink and reducing nitrous oxide (N2O) emissions, while related to agriculture, namely increasing soil fertility and increasing the productivity of agricultural products. The multi-benefit application of biochar is predicted to become a trend in the bioeconomy era, when the aspects of sustainability, food adequacy and as a climate solution become a complete package in one action.

The effort to minimize the use of urea fertilizer is by modifying it to become a slow release fertilizer with biochar as the slow release agent. The use of excess doses of urea apart from damaging the environment is also a waste. The use of urea can still be used to a certain extent, namely that all of the urea can be absorbed by plants with minimal loss or environmental pollution. When all the nutrients/fertilizer nutrients can be completely absorbed by the plants, it means that there is no residue in the soil, so that damage or environmental pollution can be minimized even avoided. The residue, especially in the long term, will cause severe soil damage. Slow release with close to the rate of absorption of nutrients by plants is a condition that is pursued or NUE (nutrient use efficiency) as much as possible. The technique of modifying urea fertilizer into SRF is the key.
 

The Urgency of Biochar to Improve Soil Fertility in Palm Oil Plantations Amid High Crude Palm Oil (CPO) Prices

The high selling price of CPO, thus providing a large profit so that it can cover production costs, certainly does not last forever. The success of FFB production in palm oil plantations is one of the keys to the success of CPO production. The success of FFB production is related to the success of the plantation and the highest cost component in palm oil plantations is the cost of fertilizer. The high need for palm oil fertilizer for each palm tree reaches around 10 kg annually and this fertilizer is non-subsidized. Fertilizer as one of the components in the CPO production cost chain is easy to buy if the price of CPO is high or there is a big profit. But solely relying on the current high CPO price for the palm oil business operations is certainly a mistake.

And the fact is that in 2019 the price of CPO has fallen and the palm oil industry has suffered losses or almost no profit at all. The fact is that when there is a decline in CPO prices it also raises concerns for Indonesia because the palm oil industry has many strategic roles both economically, socially and environmentally. It was noted that CPO prices have continued to decline every month since 2018 compared to prices of CPO at 2017. This downward trend has touched world CPO prices since 2015. The CPO price was recorded at $448/ton in November 2018. Even though the world CPO price in 2018 2016 and 2017 averaged over $700/ton. On average, CPO prices decreased by 15-16 percent compared to 2017. Exports of CPO to Indonesian traditional markets, namely the European Union and India in 2018 also decreased compared to 2017.

And it's not impossible that this will happen again. Such as past experience in the form of accusations of an issue from the European Union Parliament which aims to prevent palm oil from Indonesia from dominating the European market, so that CPO exports decrease, a trade war that can occur at any time. While the excuses used are about deforestation, child labor practices and utilizing customary forests. This certainly should be a valuable lesson. The only way PTPN holding can work around this is by downstreaming CPO products (CPO derivatives), namely by creating an oleochemical industry. If the CPO price drops, the majority of CPO will be brought to downstream products. If the downstream product margins are not good, the majority is just CPO. Production flexibility is a strategy that makes the palm oil industry "immune" to crises. The majority of their products, both CPO and its derivatives, are for export. But downstreaming the palm oil industry is also not an easy and cheap thing that not all palm oil companies can do.

Biochar to improve soil fertility, increase fertilization efficiency so as to increase FFB productivity is the best solution. With the increase in FFB productivity, CPO production will automatically increase so that efforts to extensification through deforestation can be avoided. In fact, in addition to global CPO prices which can drop at any time, fertilizer prices can also increase at any time. This further encourages the biochar application efforts. The use of biochar in palm oil plantations is also a climate effort for carbon sequestration (carbon sink) or a negative carbon scenario to reduce CO2 concentrations in the atmosphere, so that this can generate additional income in the form of carbon credits, which have a higher value. Another factor is that in the palm oil industry or CPO production, only 10% of vegetable oil produced and 90% are biomass, while this amount of biomass has great potential as a raw material for biochar production.

And because organizationally the palm oil company is divided into a plantation division and a CPO mill division, so to facilitate operation the biochar production can be a separate business unit but still within the same company or it could be with another party. And for example empty fruit bunches (EFB) as raw material for biochar whose position is in the mill while the application of the biochar is in the plantation land. In addition to the benefits mentioned above, the production of biochar is also an effort to deal with biomass waste and produce energy that can be used for the production of CPO or in the mill. And when the CPO price drops but the production costs are low because the use of fertilizer in the plantations can be suppressed but the FFB productivity remains high, the losses experienced are also less.