CROPPING SYSTEMS
This unit treats the distribution of crops in time, i.e. whether shifting cultivation, continuous cropping, monoculture, or crop rotation and the distribution of the crops in space on the field, (i.e. whether intercropping or sole cropping) as well as the level of management and resources utilized to produce the crop, (i.e. whether production is intensive or extensive) and the type of crops grown, (i.e. whether orchard, arable cropping, pasturing, or forestry). The advantages and disadvantages of each cropping systems and the principles of the rotations were also discussed.
CROPPING SYSTEMS
Cropping system is not only interested in the types of crops grown, but also on how those crops are distributed on the field at any given time and how this distribution changes over time. In addition, the level of management and amount of resource inputs are integral aspects of a cropping system.
This unit would explain to you the various cropping systems and the conditions that give rise to such cropping systems. The advantages and disadvantages of each cropping system are also treated.
The term cropping system is used to describe the pattern in which crops are grown in a given area over a period of time and includes the technical and managerial resources that are utilized. In short, when we talk about the cropping system of a given area, we are not only interested in how those crops are distributed on the field at any given time but also how this distribution changes over time. In addition, the level of management and amount of resource inputs are integral aspects of a cropping system.
Cropping systems are classified based on the following criteria
A VIDEO ABOUT CROPPING SYSTEM
In this system, the farm is not at a permanent location. Instead, a piece of land is cleared, farmed for a few years and then abandoned in preference for a new site. While the new site is being farmed, natural vegetation is allowed to grow on the old site. Eventually, after several years of bush fallows, the farmer returns to the original location. The practice of moving the home along with the farm is discontinued and in its place the practice of making home stationary is common in tropical Africa.
Common features of shifting cultivation
Factors necessitating shifting cultivation
Disadvantages of shifting cultivation
In contrast to shifting cultivation, continuous cropping implies the cultivation of the same piece of land year after year. Fallowing may occur, but it never occurs more than a season or two. The absence of a protracted fallow periods means that other soil management practices must be employed in order to maintain high soil fertility.
Agricultural practices for maintaining soil fertility under continuous cropping
Advantages of Continuous Cropping
The practice of growing different kinds of crops, one at a time, in a definite sequence on the same piece of land is referred to as crop rotation. In designing a good crop rotation, the farmer must decide what crops to have in the rotation, in what sequence the crops should occur, and for how many years or season each cycle of the rotation must run.
A good rotation that provides for maintenance or improvement of soil productivity usually includes a legume crop to promote fixation of nitrogen, a grass or legume sod crop for maintenance of humus, a cultivated or inter tilled crop for weed control and fertilizers. Perennial legumes and grasses may leave 2 to 3 tons of dry weight per acre of roots residues in the soil when plowed down.
Factors that affect crop rotation
The choice of a rotation for a particular farm depends upon the following:
Factors to consider in deciding the sequence of crops (principles of crop rotation)
Types of Crop Rotation
In planning crop rotation, the farmer may decide to consider his entire field as one plot. He then rotates the crops in sequence on the field. At any given time, there is only a crop on the field, and that crop would not return again until the next cycle some years later.
Example of a 3-year crop rotation as practiced in Savanna zone of Africa
This system, however, has certain disadvantages:
Most farmers who practice crop rotation find it more convenient to divide their field into as many plots as there are years in the rotation. The farmer then starts with a different crop on each plot and progress through the rotation. In this scheme, all the crops are present on the farm at any given time. Example of such type of rotation is given below.
Example of a 3-year crop rotation found in guinea savanna region of West Africa
Advantages of Crop Rotation
A VIDEO ABOUT CROP ROTATION
This is the practice of incessantly cultivating the same type of crop on the same piece of land year after year. For example sugar cane farming in Bachita, Nigeria
Disadvantages of monoculture
Advantages of monoculture
The main advantage of monoculture is that it permits maximum concentration of production effort on a single target crop.
The practice of growing one crop variety in pure stands on a field is referred to as sole cropping. In this practice, only one crop variety occupies the land at any one time. The alternative practice of growing two or more crops simultaneously on the same field is called inter-cropping.
The various crops in the inter-crop do not necessarily have to be sown or harvested at the same time, the main requirement is that they are on the field at the same time for a significant part of their growing periods.
Types of inter-cropping
Factors that determine the crops combination and spatial arrangement
Evaluating yield from inter-cropping
The relative yield of each component crop in an inter-cropping situation is the yield of that component in the inter-cropping situation divided by what that crop would have yielded as a sole crop, covering the same area as the inter-crop and managed at the same level. Suppose, for example, that a field with a crop combination of maize and cow-peas yields 1.5 tonnes/hectare of maize and 0.25 tonnes/ha. of cowpeas.
If the expected sole crop yield of maize is 2.0 t/ha and that of cow-peas is 0.5 t/ha. Then the relative yield of maize is 1.5/2.0 = 0.75 and the relative yield of cow-peas is 0.25/0.50 = 0.50.
The sum of the relative yields of the various component crops in the inter-crop is sometimes called the relative yield total. A little reflection of how many times the land area used for inter-crop would be required to produced the same yields of the component crops when they are grown as sole crops. The relative yield total is therefore more conventionally referred to as land equivalent ratio (LER).
Mathematically:
LER = relative yield of crop A and relative yield of crop B + relative yield of crop In the maize/ cow-peas combination considered above the LER = 0.75 + 0.25 = 1.25. An LER greater than 1.0 implies that for that particular crop combination, inter-cropping yielded more than growing the same number of stands of each crop as sole crops. An LER of less than 1.0 implies that the inter-cropping was less beneficial than sole cropping.
LER can also be calculated based on the monetary value of the yield obtained from the various inter-crop and sole crop situation and make comparisons on this basis.
Calculating LER by comparing the total energy value of the yield in kilo calories in various situations and compared the values to determine which arrangement was most beneficial.
Advantages of inter-cropping
Disadvantages of inter-cropping
Shifting cultivation and inter-cropping are the predominant practice among the peasant farmers of Tropical Africa while the large scale farmers of East and Southern Africa as well as irrigated agriculture of the Nile valley in Egypt practice sole cropping with crop rotation. In each of these cases continuous cropping is the rule rather than shifting cultivation.
Plantation agriculture mainly practice sole cropping such as oil palm, cocoa, rubber, coffee and tea. In some instance, they may be inter-cropped with food crops when the plantation is still young. For arable cash crop such as tobacco and groundnuts, sole cropping is the rule but the sole crop may be subjected to shifting cultivation, or to continuous cropping with rotation.
Cropping systems is basically concerned with the distribution of crops in time and space as well the resources expended in the production of crop and the types of crops that are grown. Cropping system of a given area is influenced by climatic conditions, resources available and level of management skills of the farmer. The principles of crop rotation, advantages and disadvantages of various cropping systems were highlighted in this unit.