Sweet super sorghum - yield data for the ICRISAT hybrid

Earlier we referred to how the India based International Crops Research Institute for the Semi-Arid tropics (ICRISAT) has been focusing on the development of a sweet sorghum hybrid for the production of ethanol (previous post).

The ICRISAT improves crops suited for cultivation by some of the world's poorest people, those who live in drought-prone regions of the globe, such as the Sahel, Norht-East Africa, or the Rajasthan desert. The institute's aim is to help raise these people's farm income, food security and environmental protection through the development of improved and diversified cultivars, eco-friendly and cost-effective pest management practices, efficient seed supply systems, and commercialization of diversified and alternative uses of crop produce.

Its plant breeding experiments with sweet sorghum (Sorghum bicolor (L.) Moench) resulted in a cultivar that is relatively drought tolerant, needs comparatively small amounts of water and yields high amounts of easily extractable sugar that can be used as a feedstock for ethanol production. Like sugar cane, the sugars are contained in the plant's canes. After it has been extracted, the biomass residues can be used as a solid biofuel in power (co)generation plants, or later as a feedstock for next generation biofuels. Alternatively, it makes for a good animal feed.

ICRISAT tested the new hybrid - called SSH 104 - first in Andhra Pradesh, with so much success that the plant was immediately patented. The institute then took it to the Philippines, where a vast region of land was identified as suitable. It is from these field trials, carried out in collaboration with the Mariano Marcos State University (MMSU) in Batac, Ilocos Norte, that we now have the first (comparative) data on the yields and economics of the plant. Dr. Heraldo L. Layaoen, crop scientist for the program shows they are impressive indeed:

• Average yield: In the MMSU study, the average yield was 110 tons per hectare of sweet sorghum cane stalk for two cropping seasons in eight months (one main crop followed by one ratoon crop.) Ratoon is the outgrowth after the main stalk has been cut.
• Sugar content: the MMSU studies have shown that sugarcane has up to 14 percent sugar content while sweet sorghum has 23 percent.
• Cropping season: one hectare planted with sweet sorghum will yield 95-125 tons after a planting season of 100-115 days, compared to sugar cane's 65-90 tons per hectare with a longer crop season of 300-330 days.
• Water requirements: sweet sorghum adapts well to drought and will not compete much for fresh water, needing only about 175 cubic meters per crop, which is just one-fourth of sugarcane's 700 cubic meters water need per crop.
• Commercial viability: the study estimates the net income for two cropping seasons with sweet sorghum to range from 65,000-72,000 pesos per hectare (€1000-1150 / US$1300-1500), comparing favorably to sugarcane and most other commonly grown crops
  
• Ethanol potential: at an extraction and processing rate similar to that of sugar cane and an average yield of 110 tons/hectare, using first generation bioconversion technologies, an ethanol yield of around 10,000 liters/hectare (1070 gallons/acre) can be expected
  

These results have prompted the Philippine Agriculture Secretary Arthur C. Yap to recognize sweet sorghum as a strategic crop, after ICRISAT director General William D. Dar urged the country to include the plant in the government's list of priority commodities for research and development:
bioenergy :: biofuels :: energy :: sustainability :: sugar cane :: sweet sorghum :: sugar :: ethanol :: biomass :: plant breeding :: ICRISAT ::

"The commercialization and massive planting of sorghum augurs well for our country," Dr. Dar, who is a Filipino himself, said.

Currently, sugarcane is the main crop tapped by the government for a gasoline-ethanol blend. But according to Dr. Layaoen, the trials showed that compared with sugarcane, sweet sorghum may actually be a better source of fuel.

The fact that sweet sorghum has slightly higher biomass yields than sugar cane, and that its stems have a higher sugar content, make the cost of producing a liter of ethanol from sweet sorghum lower than that from sugarcane molasses.

Agriculture Secretary Arthur C. Yap said he now considers sweet sorghum to be a "plant of life", citing different reaons: for one, from its stalk can be squeezed the precious sugar-rich juice suited for ethanol production. For another, the silage after the extraction of juice is rich in micronutrients and minerals that can be used as forage for animals.

Aside from ethanol, sweet sorghum can also be made into other food products such as syrup, jaggery (a kind of molasses), "basi" wine, flour, cookies, cakes and pop sorghum kernels (like popcorn). "It has far higher protein and vitamin content than honey," Dr. Layaoen points out.

Implications for the global biofuel economy
We can only begin to imagine the potential of sweet sorghum as a crop that drives the carbohydrate economy of the future. Its high yields and its low water requirements make it suitable for production in vast zones of the globe where sugarcane would not thrive. Poor farming communities in the semi-arid areas of the tropics and the subtropics stand to benefit massively from the sorghum opportunity.

Like sugarcane, the plant can be harvested mechanically, even though production costs remain low even when grown and harvested by smallholders. The fact that the bagasse, the residues which remain after the sugar has been extracted, makes for a good forage for animals, means the crop can be integrated in farms that produce both food, fiber, fuel and feed. This flexibility in itself is important for small farmers, as it allows them to hedge risks and switch between markets relatively easily.

Most importantly, unlike oil palm, the crop explicitly does not grow in rainforest zones, making its chance to be part of a genuinely sustainable biofuel economy all the more likely.

Sorghum is one of the five top cereal crops in the world, along with wheat, oats, corn, and barley. Currently, it is grown in over 66 countries. About 90 percent of the area planted to sorghum is located in developing countries, mainly in Africa and Asia, where low-income farmers grow the grain variety generally for food. In the Philippines, the use of sorghum as a whole is very limited since rice and corn have been recognized as important human energy sources. But this will now change.

Picture: Sweet sorghum hybrid SSH 104, field trial in Andhra Pradesh. Credit: ICRISAT.

More information:
ICRISAT: Biofuel Crops: Power to the Poor - Sept. 2006.
Davao Sun Star: Sorghum another source of biofuel - Feb. 21, 2007.