Cassava Production Guide for Beginners
Cassava can be a long term plant, from six months to two years depending upon the use it is intended for. Although this grows anywhere that the soil is loose and not water logging, and rich, farmers do not care much for it. Many are still unaware that besides being second to rice among crops, cassava is valuable in industry. From cassava, alcohol, glucose, solvents explosives, animal feed, fertilizers, energy and others are derived.
There are many kinds of cassava that are well adapted to our climate, but only four of these are common because of their low hydrocyanic acid content. There are Golden Yellow, Katabang, Macan and Brasil. Two others used in the manufacture of starch are the Hawaiian 5 and Java Brown. The Mandioca Sao Pedro Preto is not edible because of its high poison content.
* Cassava may be planted at any season, but it is better if the soil is always wet in the first 4-5 weeks after planting.
* The stem to be planted must be from a matured plant, about a year old, 25 cm long with 5-7 nodes from the bottom stem. The thickness of the stem must not be smaller than half of the fattest part of the stem from where it is cut. If the stem is smaller than this, it will not have much nutrient content with which to start the new plant, so the roots and growths will be small.
* Cut the stem crosswise with a sharp bolo. Avoid bruises and breaks, and plant within the week when the stems are cut.
* The stems to be planted can last up to 10 days if these are wrapped in a wet cloth or sack and placed in any airy and shady place. If it is not possible to plant immediately, these will still grow within a month if it is sprayed with any of the following before storage: Orthocide or Daconil, Manzate, Dithane, Demosan, Brassicol, Visigran, or Agallol.
* It should be stored in a shady, humid or cool place with temperature between 20-30°C.
Like any land preparation for planting, plow the land to remove weeds and grasses. Let it stand for a week to allow the remaining weeds to grow, then plow again. Let it stand for another week and plow for the third time.
Make hills about 75 cm apart from one another, depending on the kind to be planted.With the help of a pointed stick, make a hole about 18 cm deep in each hill where the stems are to be planted, one in each hole. Plant early in the morning or late afternoons during summer or any time when the sun is cool.
Three methods of planting cassava
a. horizontal — during summer so that the plant will be kept moist.
b. vertical — during rainy days so that it will not rot if constantly wet.
c. slanting — between the two seasons mentioned.
In planting, unless the stem is horizontal, bury 3/4 of the stem in the soil, and cover the 1/4 with 10 cm fine soil.
After a month, other short term crops may be planted in between the cassava plants. But if the other plants will be as high as the cassava as they grow, they can be planted at the same time.
When applying fetilizers for a second time, hill up around the plants, as in corn fertilizing. Cassava needs watering, especially in the first two months of its growth, when the root crop is beginning to grow.
As much as possible, the soil where the cassava is to be planted should be analyzed at the Bureau of Soils. However, if this is not possible, the following may be used:
+100+120 NPK mix or about 222 kg urea 45-0-0
500 kg solophos (0-20-0)
200 kg muriate of potash (0-0-60)
Apply half of the N.P.K. on planting and the remaining half about two months afterwards.
Always remove the weeds, but when the plants are two months old, don’t till any more because the growing roots (fruits) could be hurt. About three months after planting, gramoxone herbicide could be used to control weeds.
Malathion or Servin may be sprayed on insects pests, but the bigger enemies are the rats and pigs. To control the yellowing and eventual falling of leaves, spray demothoate 3 spoons for every (kerosene) can of water, or follow the
instructions on the label.
Spray every 2-4 weeks. But the best measure against insect pests are the natural pesticides like the mixture of wild pepper, makabuhay and the like.
Cassava may be harvested 10-14 months after planting. Try first a few roots’. If the rest of the crops don’t grow any more, then it is time to harvest. Plow the field or carefully pull up the crops manually. Cassava is sold fresh or dried as flakes. Wash well, peel and shred, then dry.
Harvest and Storage of Cassava
Cassava is ready for harvest from six to seven months after planting. This is sweet if harvested at the right age, but premature, it is tasteless and rots easily. When over mature, it will have harbored mold (bukbok) and/or will be eaten by pests, and the fibers will be tough.
* Don’t harvest just after a rain or when the soil is wet. The crops will rot easily and it will be difficult to clean off the soil around it.
* If the soil is compact, loosen it first with a pointed wooden stick, not metal, so as not to bruise, or hurt the crop.
* Pull up the whole plant gently, with all its root crop. Don’t drag so as not to bruise, which will cause the start of rotting.
* In separating the crop from the stem, don’t just break it off. Use a sharp knife for cutting closest to the stem.
* Don’t leave the crops exposed under the sun but in the shade.
* Separate the small ones from the large ones, and the damage from the undamaged or unhurt. Cook soon those with damage or bruises as these will be the first to rot, or use the damaged crops and the small ones as animal feed. The good ones and matured may be stored or sold.
There are two easy of storing cassava that enables it to last 3-4 months. This is by keeping them in a hole in the ground, or by storing the crops in a wooden box. In transporting the crops from the field to the storage place, put them in a firm container (like a basket not sack) so as to avoid bruises that will eventually cause rotting.
A. Storage in the Ground
* In an elevated and shady place, where one side is lower than the other and does not log water, dig a hole about 30-40 cm deep, one meter long (or depending on the amount of crops to be stored), and about one meter wide. This can contain about 75 kilos of crops. Digging should be downward. At the end of the down end, make a canal about 20 cm wide crosswise and deeper by about 7 cm than the big hole, where the water will run when it rains.
* Arrange the mature crops and without bruises in the hole.
* Cover with soil (better if sand) every layer.
* If sand is not available, clay may be used, but not very wet, because this will hasten the rotting of the stored crops.
B. Storage in a Wooden Box
* The storage box must be made of wood, about one-half meter wide, 60 cm long and 30 cm high. This can accommodate about 20 kg of cassava packed in sand or wood shavings. The box must have its own cover.
* Fill the bottom of the box with 3 cm thick moist (not wet) sand or wood shavings.
* Arrange the crops one beside the other and cover with moist sand or wood shavings.
* After each layer of crops, cover with sand or shavings.
* Cover the last layer with about 8-9 cm thick of same before putting on the lid.
* Store the box with cassava in a cool and dry place.
* Do not place directly on the ground, and stack up alternately so as to allow circulation of air between them.
This manner of storage will keep the crops up to 3 months.
When is cassava poisonous?
There are two kinds of cassava: the sweet and the bitter kinds. The ordinary kind sold in the market is the sweet kind, and the one made into laundry starch is the bitter kind.
The manner of planting, whether horizontal or upside down has nothing to do with its poison. Cassava naturally contains hydrocyanic acid, which is poison to both man and animal. The bitter kind contains more of the poison, but both kinds have it.
In the sweet kind, the poison is concentrated on the bark or skin of the crop, not so much on the flesh or meat. In the bitter kind, the poison is spread out on whole crop.
Weather and environment also have something to do with the cassava’s poison content. When there is much nitrogen in the soil, there is more poison in the cassava where potassium in the soil is high, the poison in the cassava is low.
A long dry season increases the cassava’s poison content: wet soil as during the rainy season lowers its poison content. Because of this, it is said that cassava contains poison in Summer.
According to scientists, cassava’s poison contains more or less 30-150 mg of hydrocyanic acid (a milligram is one part of a thousand grams). If the hydrocyanic acid content is less than 50 mg it will not be harmful to eat. If it will exceed 100 mg. the poison content could be dangerous.
In the ordinary way of cooking, the poison disappears in the sweet kind but in the bitter kind, about 20 mg per kilo remains in the fresh peeled cassava.
According to experts, the amount of hydrocyanic acid in cassava is poisonous from one-half mg (.5 mg) up to 3.5 mg per kilo of the person eating the cassava. Thus, a person who weighs 50 kilos will be poisoned if he consumes one and one-fourth (1 1/4) kilo of bitter cassava. When his stomach begins to ache and he starts vomiting, or his mind
becomes confused after eating cassava, then he has been poisoned.
The poison in cassava disappears during cooking, so, cooking cassava as suman is a safe way of eating cassava. Besides, suman preparation entails removal of bark, grating, extracting the juice, before cooking. Grating and extracting the juice already removes the poison, and it is further evaporated during cooking.
Other ways of removing the poison in cassava are: chopping, soaking in water, heating up to 57°C, and exposing in the sun. It is best not just to steam it but to cook it well. Even the bitter kind loses its poison when cooked well.
But it is always better to buy the sweet kind. This is known if, upon removal of the bark, the flesh is sweet. The meat of the sweet cassava tastes sweet!
Sources: Greenfields November 1982; Greenfields December 1980; PRIS Extension Bulletin, Dept. of Agriculture No. 1 English 1986