BMP testingWild, invasive and medicinal plantssingle study (5 samples)

Four o'clock flower leaves — BMP: 5 studies, weighted mean 325 m³ CH₄/t VS

The leaves of the marvel of Peru (Mirabilis jalapa) are the biomass of an ornamental plant and tropical weed, studied in different size-reduction fractions with a very consistent result.

rating: good CH₄ ≈ 52 % (estimate)

Published 21 November 2025Updated 29 October 20263 min readFeedstockData Editorial Team

Photo JDP90 (Joydeep) / Wikimedia Commons, licence CC BY-SA 3.0, source file; changes: cropping

Weighted mean: 325m³ CH₄/t VS
Range: 290–341m³ CH₄/t VS
Records: 5single study (5 samples)
Publications: 1source
Temperatures: 37 °Cof the test

Methane in biogas

≈51–54% CH₄

Medium methane content · ≈ 5.2 kWh/m³ of biogas

estimate from the substrate type The collected studies contain no measurement. The interval follows from the approximate composition (carbohydrate-dominated (no protein or fat characteristics)) and the yields of compound groups according to FNR.

How we calculate it and what the zones mean

Rating for biogas plants

good — editorial rating for biogas plantsStable, usually accepted without a fee

Potential per tonne of fresh matter: high (89 m³ CH₄/t); no particular threats to stability. Handling costs: fibres, floating layer.

Why? Rating factors

Potential per tonne +2

+2potential 89 m³ CH₄/t fresh matter (BMP 325 × DM 31.2 % × VS 87.8 %)

Process stability 0

0no factors

Handling and costs −0.5

−0.5fibres, floating layer — shredding and intensive mixing

Total points: 1.5 · thresholds: ≥ 2.5 very good, ≥ 1 good, below — neutral; negative with cumulative process risk.

Editorial rating per the methodology · confidence of the rating: low · excluding market prices

Add to the co-digestion calculator CSV data

BMP curves from 5 studies

Weighted mean Individual records

Dashed lines are a model curve (first-order kinetics, B(t) = B₀·(1 − e^−kt)); the end point comes from the publication. All curves are model curves.

Cumulative methane production over the test [m³ CH₄/t VS]. The thick line is the weighted mean of all records (325); dots mark the end values given in the publications. Point at the chart to read values; click a legend item to hide or show a record.

Records and sources

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Source	BMP m³ CH₄/t VS	Temperature	Sample	Curve
Sharma et al. (1988) · 1 DOI	290	37 °C · mesophilic	Mirabilis · pretreatment: Material were first dried in the sun and then in an oven at 90oC	end point (model curve)
Sharma et al. (1988) · 2 DOI	327	37 °C · mesophilic	Mirabilis · pretreatment: Material were first dried in the sun and then in an oven at 90oC	end point (model curve)
Sharma et al. (1988) · 3 DOI	329	37 °C · mesophilic	Mirabilis · pretreatment: Material were first dried in the sun and then in an oven at 90oC	end point (model curve)
Sharma et al. (1988) · 4 DOI	339	37 °C · mesophilic	Mirabilis · pretreatment: Material were first dried in the sun and then in an oven at 90oC	end point (model curve)
Sharma et al. (1988) · 5 DOI	341	37 °C · mesophilic	Mirabilis · pretreatment: Material were first dried in the sun and then in an oven at 90oC	end point (model curve)
Weighted mean	325	arithmetic mean 325, SD 21

Typical composition

Dry matter (DM): 31.2% (range 31.2–31.2)
Volatile solids (VS): 87.8 % DM (range 87.8–87.8)
C/N ratio: 21.2

Median and range of the determinations reported in the publications behind this substrate's BMP records (read from: CROPGEN D4); dry matter: 1 determination, volatile solids: 1 determination. DM from a single determination – indicative value.

Sources: Sharma et al. (1988).

The composition of the raw material varies between batches — for plant calculations use an analysis of your own sample. The calculator inserts typical values automatically.

Process properties

seasonal
fibrous
variable composition
editorial classification

Low confidence: the description is based on general characteristics of the substrate group, not on studies of this material. Treat it as a hint to be verified.

Advantages

Methane potential in the database: weighted mean 325 m³ CH₄/t VS (median 329; range 290-341; 5 records from 1 source).

Drawbacks and risks

The records relate to different particle sizes (Sharma 1988): the result depends strongly on shredding, not on the plant.

Dosing

No dose data; only a small addition to a green feed after a BMP test. Low-confidence data.

Introduce gradually, starting with a small dose and monitoring the process (e.g. FOS/TAC, pH, gas composition).

Practical requirements

Shred: shredding increases the surface available for degradation and speeds it up, but does not necessarily raise the final gas yield (FNR 2010, Ch. 3 “Triturado”).

Sources of the process data

The co-digestion calculator will assess a specific mixture containing this substrate.

What it is and where it comes from

The marvel of Peru (Mirabilis jalapa) is a perennial of the Nyctaginaceae family, native to South America, grown as an ornamental plant and in places naturalised. In Poland it is grown as an annual in gardens, but it has no productive significance. In the biogas literature it is one of the species studied as biomass of wild-growing plants and weeds in tropical regions, where it grows luxuriantly without inputs.

Properties relevant to digestion

The leaves have a high moisture content and contain protein, soluble sugars and fibre (cellulose, hemicellulose), and little lignin. The plant contains secondary compounds, including betalains, trigonelline and saponins, the effect of which on digestion at typical shares is not well documented. A higher protein content provides nitrogen, so the C/N ratio is moderate. Hydrolysis is rapid, and fresh mass spoils quickly. Older leaves are more fibrous than young ones.

How to read the spread of results

The dataset contains several records from a single study in which the leaves were tested in different size-reduction fractions (mesophilic, 37 °C). The results are very close to one another, which indicates that within this range size reduction had little effect on the final result, but this is a single study and a single batch of material. The result is also affected by the age of the leaves, the time of harvest, the method of sample preparation and the inoculum.

In biogas plant practice

Marvel of Peru leaves can supplement the feed in tropical installations, together with manure, after size reduction. Their advantage is the lack of competition with food crops and ease of procurement. Storage requires prompt use or ensiling. Because the plant can be invasive, its deliberate cultivation or spread is not advisable. For Poland the data are of comparative significance.

It is also worth stressing that values from a single study are not sufficient for designing an installation: verification on local biomass is required, because the composition of the leaves depends on the soil, fertilisation and the season, and in a temperate climate the plant would grow differently and have a different dry matter content.

A further matter is the content of the tuberous roots, which in this plant contain toxic compounds; studies on leaves do not describe their behaviour in the digester, so the roots should not be equated with the leaves.

Methodology in brief

BMP is the amount of methane obtained from volatile solids (VS) in a batch test, given in m³ CH₄ per tonne of VS (numerically the same as NmL CH₄/g VS in the publications) and converted to normal conditions (0 °C, 101.325 kPa). The weighted mean gives each publication a total weight of 1, split equally between its results for the substrate — a paper testing twenty varieties does not outweigh a paper with a single sample. In inter-laboratory programmes the unit is the laboratory (total weight 1), and within it the weight of a test grows with the number of bottles (replicates). Results after pretreatment (e.g. thermal, chemical, enzymatic) are shown separately and are not included in the mean.

Solid lines are curves measured in the tests. Where a publication gives only the final result, we draw a first-order kinetic model, B(t) = B₀·(1 − e^−kt): only the end point comes from the publication, and the shape of the curve serves purely as visualisation — do not read the production on a particular day from it. For this substrate k = 0.134 d⁻¹ was assumed (median of rate constants k reported in the sources and/or fitted to the mean measured curves).

The statistics describe the spread of published results — a descriptive compilation, not a meta-analysis or a guarantee of plant yield.

Full methodology and correction policy

Bibliography

Sharma, S.K.; Mishra, I.; Sharma, M.; Saini, J. (1988). Effect of particle size on biogas generation from biomass residues. Biomass 17(4), 251–263. DOI: 10.1016/0144-4565(88)90107-2 DOI

All sources of the site: bibliography.