We present to your attention another study on the possibilities of producing biogas from amaranth. This data was published in 2009 during an event called the Bavaria Biogas Forum. Two specialists from Germany worked on the report – Dr. Mandy Fritz and Dr. Catherine Deiglmayr.
In her work she examined in detail the features and possibilities of using amaranth as a biogas substrate. We give you an adapted version of the report with explanations and an extended description – this makes the text more understandable to a wide audience.
Amaranth (Amaranthus cruentus L.) is an annual herb with erect panicled, blood-red inflorescences. The flowers of amaranth crimson small, actinomorphic, same-sex, collected in large complex inflorescences. The plant is home to the Andean Highlands of Bolivia, Peru and Chile.
Amaranth, like maize, sorghum or miscanthus, refers to plants with C4 photosynthesis.
Help from Wikipedia. C4 is a carbon binding pathway characteristic of higher plants, the first product of which is four-carbon oxaloacetic acid, and not three-carbon 3-phosphoglyceric acid, like most plants with ordinary C3 photosynthesis.
This type of photosynthesis is more effective than C3, inherent in crops such as sugar beets, potatoes and some others.
Like sorghum, amaranth has a high thermal need and is very sensitive to frost. Amaranth, thanks to its valuable protein composition and high content of beneficial minerals, has long been a product, fell in love with supporters of a healthy balanced diet. Culture refers to psevdoslakami. In recent years, the possibility of using amaranth for biogas production has also been actively discussed.
However, as noted by German researchers, the test results show that amaranth in the climatic conditions of Bavaria cannot be used in this way. Since the cool temperate climate leads to late maturation of the culture, and the dry matter content is not so high.
However, despite these problems, below are recommendations for the use of amaranth, as well as the results of previous studies.
Amaranth is a very modest culture, which is demanding on air temperature. The warmer the better. However, there are no other special requirements. The best cultivation option is arable land without weeds.
Soil and Seed Preparation
Due to the low grain mass (0.8 g), amaranth should be properly prepared for sowing. According to German researchers, the preparation of amaranth seeds should be carried out similarly to the preparation of sugar beet seeds.
Technique and features of sowing
Since amaranth is extremely sensitive to frost, seeding is not recommended before the end of April / beginning of May. The distance between rows depends on the characteristics of sowing, as well as on how exactly weed control is planned. For example, if in the future the corresponding equipment will be used, the distance between the rows directly depends on this technology.
With a planting density of up to 50 plants per square meter, the seeding rate is 500 grams of seeds per hectare of sown area. Germination rate is about 80%.
Features of crop rotation
Since amaranth is not associated with any of the common crops, it has no special requirements for crop rotation.
Plant Care and Protection
Amaranth shoots develop slowly, and therefore the plant is extremely sensitive to weeds. To combat them, it is not recommended to use herbicides. The only good way to eliminate weeds is the mechanical method – that is, weeding, either manually or using specialized equipment.
It is necessary to carry out one or two weeding until the plants reach a height of 5-10 centimeters. Other plant protection measures are usually not necessary.
Fertilization and fertilizer
Fertilization should usually be held back so as not to cause vegetative growth. For good development, sprouts can be applied to each hectare of sown area:
- 80 to 100 kilograms of sodium;
- up to 50 kilograms of P2O5 – nitrogen-phosphorus fertilizer;
- up to 100 kilograms of K2O – crystalline potassium.
It is also good to use pet manure
Harvesting begins in early October (we recall, we are talking about the lands of Germany). To do this, use a special grinder. However, to avoid losses is almost impossible.
Productivity and qualitative composition, methane yield
Optimal conditions for the growth of amaranth — nitrogen fertilization, good soil temperature and ambient air — were created on the test plots. 150 tons of green mass per hectare of arable area was collected. However, in reality, the yield is likely to decrease by 20-30%, since in nature there will be no such conditions as in the experimental area.
The calculated methane yield is 270 Nl CH4 / kg oTM. The fermentation test at the Institute of Agricultural Engineering and Livestock Bavarian State Institute of Agriculture methane yield was 280 Nl CH4 / kg oTM. The theoretical yield of methane is less than 2500 cubic meters.
The ability to harvest a second crop
Amaranth is not able to give a secondary crop due to its slow development cycle.
German researchers concluded that, in general, amaranth is not recommended for use as a biogas substrate, because the yield level is not so great, in their opinion, and the maturation of the plant is too slow.
However, we focus your attention on the fact that this work was published back in 2009. At that time, active research on amaranth, as a substance capable of activating the production of biogas, was still ongoing. And in previous articles we wrote about the results obtained confirming the effectiveness of amaranth phytomass in the production of biogas.