Get better yield of cassava?

Get cassava yield

get cassava yield

Variety name of Cassava

Cassava (Manihot esculenta) or Tapioca (also called kahoy, tapioca-root, manioc, yuca, balinghoy, mogo, mandioca,kamoteng and manioc root) is a major staple food in the developing world. It is one of the most drought tolerant crops, capable of growing on marginal soils 1,2,3, tolerances for some insect and diseases and it can be growth in soil pH 5-6. Nigeria is the world’s largest producer of cassava while Thailand is the largest exporting country of dried cassava (largest cultivation areas in Thailand are Northeastern and eastern part).

The sharp increase in imported fossil fuel prices have become a matter of economic stability, and the Thai economy has been directly affected. Hence, the Thai government declared the ethanol production policy. Producing ethanol allows commodities prices to increase. The most popular cash crops are usually used as ethanol raw material in Thailand, namely cassava, sugarcane and molasses4. Also, Thai government has promoted policy of bio-diesel production by using palm oil as raw material. They target to produce 1 million liter of ethanol per day in 2006 and expected to reach 3 million liter per day in 2011 which require a lot of cassava to be raw material.

Thai cassava roadmap

Thai Department of Agriculture has pronounced cassava roadmap in order to increase production yield from 3.2 MT per rai in 2006 (20 MT per ha) to be 5 MT per rai in 2007 (31.25 MT per ha) or about 36% increased in a year. Therefore, farmers need to know the suitable practice to achieve that target and be able to supply for starch and ethanol industries in Thailand under limitation of cultivated area.

Most researches and journals indicate that the best practice to get better yield of cassava is applying chemical and organic fertilizer together which usage rate adjust base on soil condition. Cassava is a potential crop that yield can be increased if farmers apply the right practice, unfortunately, most farmers do not realize about farm management practice including land condition, as a result they cannot get the better yield as they expected.

Farmers can increase production yield to be higher than 5 MT per rai (31.25 MT per ha), be environment friendly, maintain soil fertility as sustainable way with the same investment.

There are 4 rules, NOT to do;

1. Do not cultivate cassava in alkali soil (pH > 7) farmers should grow other plants in this soil condition instead of cassava such as maize and sugarcane due to alkali soil is very hard to improve.

Why? Cassava cannot absorb macro nutrients such as Nitrogen, phosphorus and some micronutrients such as Manganese, Boron, Copper and Zinc because these nutrients are fixed in soil elements (alkali presence Na+ ion and it is more mobile and has a smaller electric charge than Ca++ so that the thickness of the diffuse adsorption zone increases as more sodium is present causing nutrients locked in soil). While Cassava cannot absorb adequate nutrients especially micro nutrients, it shows symptom such as chlorophyll lacking (cause to insufficiency of photosynthesis); green pale leaves or yellow leaves as well as tuber does not get enough nutrients that causing lower yield.

2. Do not cultivate cassava in flood area or in clay soil (bad water circulation) because it can cause tuber rot disease. In addition, sometimes farmers do early harvest of immature cassava because of rainfall that cause of lower yield.

3. Do not use only chemical fertilizer because soil would be not balance in term of chemical, physical and biological properties if using only chemical fertilizer for long time. In case of soil losing its balancing famers must use organic fertilizer together with chemical fertilizer since major property of organic fertilizer is improving soil structure and allow plants absorb nutrients efficiency, as a result farmers get better yield.

Suranai et al., (1999) pointed that using 500 kg of chicken manure with 50 kg of chemical fertilizer per rai (1 rai = 0.16 ha) can get highest yield of cassava tuber (Variety Rayong 72, age 12 months) up to 9,780 kg per rai while Wanlee et al., (2006) planted 4 cassava varieties in same soil condition, they applied cow manure 500 kg per rai in first year and applied only 50 kg of chemical fertilizer formula 32-16-32 (or 16 kg of N, 8 kg of P and 16 kg of K) per rai (1 rai = 0.16 ha) in the second year. As a result, Cassava varieties Rayong 5, Rayong 72, Rayong 9 and Kasetsart 50 have production yield as 8149, 10079, 7659 and 8764 kg per rai and have starch content as 26%, 25.2%, 32.6%, 28.9% respectively when plant age 12 months.

4. Do not harvest immature cassava (age < 12 months) because it is growing stage, it does not gain great tuber weight (small tuber) effect to lower production yield. Cassava should be harvested when age 12 months; big root and high starch content. Also, should not harvest cassava age more than 18 months because tuber be smaller and starch content be decreased.

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