Sweet sorghum [Sorghum bicolor (L.) Moench] is similar to grain sorghum with sugar-rich stalks. Being a water-use efficient crop, sweet sorghum has the potential to be a good alternative feedstock for ethanol production.
It is a multi-purpose crop which can be cultivated for simultaneous production of grain from its earhead as food and feed ingredients, sugary juice from its stalk for making syrup, jaggery, or ethanol, and bagasse and green foilage as an excellent fodder for animals, as organic fertilizer, or for paper manufacturing.
A study was conducted by the Mariano Marcos State University with the title “Commercial Production and Utilization of Sweet Sorghum (for Ethanol, Food, Feed and Forage)”.
Eight (8) promising sweet sorghum varieties came from ICRISAT and were used for multi-location tests. Study showed that of the eight sweet sorghum varieties, only five (5) showed adaptability to local conditions in MMSU.
- NTJ 2
- SPV 422
- ICSV 700
- ICSV 93046
- ICSR 93034
Adaptability of the top 5 Varieties
|Variety||Stripped Stalk Yield
Sugar by Brix’s
|2nd & 3rd
Adaptability of the top 5 Varieties per Region
- Region IV-A
- RCBD with 4 replications was used
- Basal fertilization of 14-14-14 at 800 g/20sqm
- Thinning done 10 – 12 DAP
- Side dressing with Urea at 180 grams/plot
- Hilling – up 30 DAP
- Observed armyworm and cutworm which were controlled with Hostathion
- Typhoon “FRANK” caused lodging with ICSV most affected
- Region V
- Highest stalk production was observed in SPV 422 (73 tons/ha) and lowest on ICSV 700 (35 tons/ha)
- Grain yield was highest on SPV 422 (9.55 t/ha) and lowest on NTJ 2 (3.87 t/ha)
- Sugar content was recorded using Atago refractometer. SPV 422 (18.62 brix) and ICSR 93034 (18.3 brix) and lowest on NTJ 2 (9.25 brix)
(% raw sugar,brix)
- Region VI
|NTJ 2||SPV 422||ICSV 700||ICSR 93034||ICSV 93046|
|Plant Stand (24 DAP)||1||1||1||1||1|
|No. of days to 50% Flowering||75.5||76.5||83.25||77.0||83.25|
|Plant Height, cm
(21 days after sowing)
|Plant Appearance Score||1||1||1||1||1|
|Plant Height, m (at harvest)||3.10||3.10||3.46||3.16||3.18|
|Stalk Yield, kg||8.42||8.37||7.33||9.04||7.00|
|Stripped Stalk Yield, kg||7.62||7.42||7.08||8.50||6.33|
|Stalk Jucie Yield, g||777.67||750.00||766.67||1,143.33||825.00|
|Stalk Juice Volume, mL||647||630||651||943||722|
|Stillage Yield, kg||6.08||5.96||5.71||6.71||5.81|
|Total Soluble Solids, Brix||12.40||10.27||13.57||10.90||13.57|
Good surface drainage is preferred although sweet sorghum can withstand long waterlogged condition; clay loam is preferred with soil acidity not lower than pH 6.
Two rotavations at a depth of 25-30 cm is desirable to attain a fine and good soil tilth. This is necessary to have a uniform germination because sweet sorghum seed are small as compared to corn.
Setting of furrow
Two planting seasons are possible for sweet sorghum. During the wet season, furrows are set 100 cm apart while the dry season planting are set 75 cm apart.
The recommended seeding rate is 5-8 kg per hectare to attain a population density of 130,000-150,000 plant ha. The seeds are drill-planted by hand or a planter can be used.
During the wet season planting, the furrows are set 10 cm deep. The seeds are drill planted at the bottom of the furrow and then spike tooth harrow is passed to cover the seeds to a depth of about 2-3 cm.
For the dry season planting, the furrows should be made at least 15-20 cm deep to be able to make use of more residual soil moisture. The seeds are set at the bottom of the furrows but these are not covered anymore if the soil is dry. The impact of irrigation water running through a flexible hose which is directed at the side of the furrow will cover the seeds. In cases where the soil is moist, the technique used during the wet season planting is followed.
For the 75 cm row spacing, maintain 10-11 plants per ha which is approximately 10 cm between plants with a population density of 130,000 plants
For the 100 cm spacing, 13 plants are maintained per meter of row or about 11 cm between plants with a population density of 150,000 plants per ha
Thinning should be done before hilling-up or side dressing the second fertilizer dose which is 14-21 days after emergence.
A fertilizer rate of 80-60-60 is generally recommended for a clay loam soil in both seasons.
The basal fertilizer is 30-30-30 or 215 kg of 14-14-14 per hectare. This is 21-22g/linear meter of row in the 100 cm spacing and 16g/m in the 75 cm spacing. The fertilizer is drilled at the bottom of the furrow before planting.
Side Dressing (21 days after planting)
If ammonium sulfate (21-0-0) is used:
The rate is 23-24g/m of row in the 100 cm spacing while 18g/m is applied in the 75 cm spacing.
If urea is used:
11-12g/m is side dressed in the 100 cm row spacing and 8-9g/m in the 75 cm spacing.
If the soil is dry, overhead irrigation should follow. Hilling up using a double-moldboard plow should is needed to cover the fertilizer and wet soil. The dry soil cover will serve as “soil mulch”.
Sweet sorghum is remarkably drought-resistant and resists months of dry weather until rains resume. Supplemental irrigation is rarely needed but sweet sorghum needs moisture for uniform seed germination, hence, overhead irrigation is recommended at planting when moisture is insufficient for germination. Each fertilizer application should be followed by irrigation in case there is no rain.
- Shoot FlyShoot fly attacks soon after germination up to 30 DAP. It is noted by dead hearts in seedlings and profuse tillering in affected plants. Apply Carbofuran 3G at 8-10 k/ha during planting applied at the bottom of the furrow.
- Stem borerStem borer affects at a later stage up to maturity. Carbofuran 3G at 8-10 k/ha could be applied on leaf whorls (2-3 granules/whorl) to prevent stem borer tunneling.
- StalksStalks may be harvested by hand, cut with a mower and picked up, or mechanically cut and squeezed in the field. The stalks are cut (similar to sugarcane) as close as possible to the ground leaving one node only. This node will be the sprouting point of the ratoon.
- Seed head and penduncleThese should be removed by hand after cutting the stalk down.
- Grain Crushing and Milling
- dry milling – comminution or grinding of big solid particles into smaller ones
- wet milling – soaking in water to form lactic acid; separates germ from kernel
- advantages of dry milling
- less capital investment in plant & equipment
- fewer control loops & simpler processing
- shorter time from construction to operation
- minimal loss of starch
- NOTE: old sugarcane crushers can be used
- Cooking process with enzymatic liquefaction
- gelatinization & dextrinization
- may be accomplished at 35% solids when using heat-stable a-amylase, but can be increased up to 38%
- high solids content results to:
- steam savings due to smaller mash & water volume to be heated
- lower a-amylase dosage due to increased residence time in slurry & liquefaction
- starch paste formation
- dissolution of starch into mash by steam cooking, above starch gelatinization temperature (68-74°C)
- marked by melting of starch crystals, loss of birefringence, & starch solubilization
- granules absorb large amount of water, swell to many times their original size, & open up enough for a-amylase to hydrolyze long chains into shorter dextrins
- breakdown of gelatinized starch into smaller fragments or dextrins by means of a- or ß-amylase or dilute acid
- action of a-amylase on gelatinized starch results in dramatic reduction of viscosity
- improves efficiency of the spiral or plate-and-frame heat exchangers used for cooling during saccharification or fermentation
- must be done immediately to prevent retrogradation or recrystallization of starch
- High temperature (120-150°) jet cookers with no enzyme addition
- Low temperature (105°C) jets with split enzyme dosage
- Low-temperature techniques (< 85°C)
- Slurry tanks above and below the gelatinization temperature
- Natural metabolic process that produces energy by breaking down carbohydrates (like sugars) in the absence of oxygen
- Facilitated/catalyzed by the action of enzymes present in microorganisms like yeasts
- End product is ethyl alcohol or lactic acid
- Energy is given off in the form of heat
- Alcoholic or ethanolic fermentation – most familiar type of fermentation
- Process in which a liquid or vapor mixture of two or more substances is separated into its component fractions of desired purity by the application or removal of heat
- Vapor of a boiling mixture will be richer with lower boiling point component
- When vapor is cooled, condensate will contain more of the volatile component
- Original mixture will contain more of the less volatile component
Dr. Heraldo Layaoen
National Team Leader for Sweet Sorghum
Mariano Marcos State University
Batac, Ilocos Norte
Dr. Ernesto del Rosario
College of Arts and Sciences
University of the Philippines Los Baños
Los Baños, Laguna
For further information, contact:
Dr. Heraldo L. Layaoen
Mr. Mario I. Remolacio
Mrs. Rosemarie G. Ramos
Mariano Marcos State University
Batac 2906 Ilocos Norte
Tel: (077) 792 2558
Dr. Heraldo Layaoen of MMSU is the overall coordinator of the projects, “Commercial Production and Utilization of Sweet Sorghum” and “Commercial Production and Utilization of Pigeon Pea.” MMSU serves as the model site. Interventions and project strategies will be replicated in the identified provinces of Ilocos Norte, Ilocos Sur, La Union, Isabela, Cagayan, Kalinga, Abra, Nueva Ecija, Tarlac, and Pampanga for the full implementation of the project. Photo from