Identification of Crops According to Life Cycle and Nature


Identification of Crops  According to Life Cycle and Nature

Government agencies and agricultural managers require information on the spatial distribution and area of cultivated crops for planning purposes. Agencies can more adequately plan the import and export of food products based on such information.

Although some ministries of agriculture and food security annually commission their staff to map different crop types, these ground surveys are expensive and yet cover only a sample of farms. Remote sensing data, together with ancillary information, enable the determination of the spatial distribution of crops at varying spatial scales with relatively little financial resources. This can, however, be achieved with various degrees of uncertainty, as some crops are spectrally similar and pixel sizes sometimes bias the estimation of crop acreages.

You will remember that we dealt with the various types of soil in the last article.  We want to identify various plants so as to make a link between these plants and the suitable soil which will facilitate their growth, under suitable climatic conditions. The article will, definitely, lead us to the various types of soil that accommodates plants.

Read On: Types of Soil: Characteristics and Importance

Classification According to Life Cycle

Life cycle is the period from germination to harvesting. On this basis, crops are subdivided into four groups.

1. Annual crops: These are crops that complete their life cycle once in a year or a growing season- during which the vegetative and reproductive stages are completed, e.g. maize, rice, cowpea, millet, vegetables, cotton, groundnut, etc.

2. Biennial crops: These are crops that complete their life cycle in two years or two growing seasons. In the first year, a plant undergoes the vegetative stages, where leaves and roots are produced in abundance, the plant also elongates; but during the second year, plants undergo reproductive stages where flowers, fruits and seeds are produced, e.g. carrot, lettuce, cabbage, ginger, etc.

3. Perennial crops: These are crops that complete their life cycle once in three years. In the first two cycles (once in three years) they undergo the vegetative stages, while in the last year, the reproductive stages will be completed, e.g. rhizome, sugar cane, banana. A perennial plant that can survive for thirty years and above is called permanent crop- e.g. cocoa, kola nut, mango, oil palm, rubber, and coconut, etc.

4. Ephemerals: They are crops that complete their life cycle once in three or four months and can undergo two or three life cycles in a year, e.g. tomato.


Classification According to Nature

Here, let us take a look at the following.

1. Vegetables: Vegetable crops are grown, principally, for their leafy nature; they are consumed, raw or cooked. They are good sources of vitamins. They are tropical crops that perform well at high temperature and high humidity. They can be grown all the year round, provided that there is sufficient water supply. They require well-drained soil that is rich in humus. Vegetable crops include tomatoes, pepper, lettuce, cabbage, cucumber, carrots.

2. Cereal crops: Cereal crops or grain crops are those which are cultivated for their seeds. They constitute a bulk of the world's food supply; cereals crops are more compact and can be stored for a much longer period than root crops, mainly due to their low moisture content. They also have the advantage of a high yield relative to the seed planted; cereals crops are regionalized. Oats are the dominant cereals of the colder regions of the world. Wheat and barley are the most important cereals of warm temperature zones; while in the tropical regions of the world, rice, maize, guinea com and the millet form the bulk of the diet of large sections of communities. The cereals/grains have high starch content and also contain varying amount of protein, the embryo contains oil and vitamins occur in the outer tissue of the seeds.

Read On: What are Agricultural Systems in Nigeria?

Soil Requirements for Cereals

Cereals are regionalized, and because of this reason soil requirement varies with the type of region. For example, consider the following.

a. Rice (Oryza sativa): Rice requires rich loam to clayey soil retentive of water and rich in humus; however, rice can be grown practically on all types of soilprovided there is adequate supply of moisture. However, too light or porous and heavy soils are not recommended. Rice can stand a pH level of 4.5 to 8.7, but it does best at pH 5 to 6.5. Swamp rice prefers flooded conditions, but it is, however, not aquatic and so it needs aeration; while upland rice prefers well-drained soil, under humid conditions.

b. Maize (Zea mays): This requires a wide range of well-drained soil; precisely, it requires from sandy-loam to clayey-loam which are rich in humus, and plant nutrients. The soil should be alkaline or almost neutral. Maize does poorly on heavy or sandy soil. The good performance of maize does not depend so much on the amount of rainfall, but on distribution.

c. Guinea corn (Sorghum spp.): Dawa Guinea corn grows well in most soil, but does poorly on sand and clay. It thrives best on loamy soil. It can stand salty soil due to its ability to tolerate alkaline conditions. It is a short-day plant and is typically suited for the tropics having high temperature.

d. Millet (Pennisetum spp.): Gero Millet requires less moisture to germinate compared to any other crop. The crop performs best in rich, well-drained soil, but it will do well in loamy soil, sandy-loams and in soil lacking humus.

e. Wheat (Triticum monococcum): Wheat performs best in soil with medium to heavy texture such as silt and clay-loam; the soil must be well-drained and very fertile. The soil should be, particularly, rich in nitrogen, which is necessary for the production of highly proteinous grains such as wheat.

3. Root and Stem: Root and stem crops constitute the main sources of starch to the greater part of tropical population. These crops are not all that important in the world market, but they are of immense help locally. They are less susceptible to attack from pests, and are of very high yield. Among the most important of these root and stem crops are cassava and yam, respectively. 

Others include coco-yam, potatoes, etc. They can grow in almost all types of soil but perform best on well drained, sandy loam or light alluvial soil rich in nutrients. Too dry soil can cause poor tuber development and too wet soil tends to make tuber putrid.

4. Legumes: Legumes constitute an important part of the diet of most of tropical communities. They are important not only in their food value to human beings but also in the fact that they supply the pertinacious fodder for tropical livestock. Legumes also replenish soil nitrogen due to the presence of nodules on their roots. Their ability to replenish soil nitrogen gives them a key position in crop rotation.

Read On: Definition and Importance of Agricultural Extension

Soil requirements for legumes

Note that because of the differences in the amount of rainfall the soil requirements for legumes differ.

i. Groundnut (Arachis hypogea): This grows on almost any type of soil, except heavy clay- low in organic matter. However, groundnut prefers light sandy soil for good seed formation. The soil should also be rich in phosphate and sulphur. It requires plenty of sunshine and, relatively high temperature, particularly at maturity, harvesting and storage.

ii. Cowpea (Vigina unguiculata): Cowpea is a very hard crop, adapted to a wide range of soil. It does best on well-drained sandy loam soil but can do well on sandy or clay soil. However, very fertile soil induces excessive vegetative growth and poor pod formation. The appropriate nitrogen-fixing bacteria must also be present.

iii. Soya bean (Clycine max.): This crop requires a fairly flat to moderately slopping, well-drained loamy soil; gravel and heavy textured soil should be avoided. There must be sufficient moisture for the crop to germinate. Its moisture requirements before germination are greater than that of maize. Yield is very badly affected if draught occurs during pod filling stage.

5. Oil crops: These are crops that provide vegetable oil for domestic and industrial use- e.g. sun-flower, soya-bean, oil palm, groundnut, melon, coconut and cotton.

i. Oil palm (Elaeis Guineensis): Oil palm thrives well in closed-loam of alluvia friable types; and the optimum pH is 5.5-6.5. Average daily sunshine should be up to 6 hours per day.

ii. Cotton (Gossypium spp.): This requires well-drained, rich loamy soil and not very high organic matter- to check excessive vegetative growth which reduces formation.

6. Tree/cash crops: Tree crops are plants which can stay on the same piece of land for many years. They are at times, also called cash crops. Transplanting to the permanent site follows if the crop goes through the nursery e.g. cocoa or oil palm. Routine cultural practices like weeding or slashing, roughing, spraying, etc., will be recurrent activities to eliminate pests that compete for light, water and nutrients. Most of the plants in this category can stay for 3 -50 years, yielding every year; because of their long stay on the permanent farm site, they require:

a. Cocoa (Theobroma cacao): Cocoa requires soil that is well aerated and retains moisture during the dry season. The soil should be easy to penetrate but need not, necessarily, be very deep; but it must be enough to allow root penetration. It should be rich in nutrients and have good structure and texture. The best soils are clay and loam; this is because they retain more moisture during the dry season. Shallow soils with impervious layers are not good for planting cocoa, because the impervious layer does not allow for root penetration which may be up to a depth of about 7m.

b. Rubber (Hevea brazillensis): The rubber plant is a member of the family Moraceae. It is classified as Ficus elastic. An attractive tree, a member of the mulberry family, grown as a houseplant in its juvenile state; it thrives well around the tropics, growing-perhaps, to a height of 30 m (100 ft). Its thick, deeply veined leaves are a glossy, dark green and can grow to be 38 cm (15 in) long. It flourishes under adverse conditions.

Conclusion on 
Identification of Crops According to Life Cycle and Nature

We have given; classification of plants according to the nature of produce has given a clear distribution of these crops- in terms of the different soil requirements necessary for growth and development. We also exposed you to how to identify various types of plants based on soil requirements. These requirements not only enhance good growth, but they also give the farmer better deal for his efforts.

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