Concepts of Agroecosystems

The agricultural system or agroecosystem is man-engineered ecological system or unit. It

contains both abiotic and biotic components that are interdependent and interacting and through which nutrients are cycled and energy flows. An area with similar types of agro-ecosystem can then be termed an agricultural region. Whittlesay (1936) recognized five criteria to classify agro-ecosystem in a region:

(1) the crop and livestock association;

(2) the methods used to grow the crops and produce the stock;

(3) the intensity of use of labor, capital, and organization, and the resulting output of product;

(4) the disposal of the products for consumption (whether used for subsistence on the farm or sold for cash or other goods); and

(5) the ensemble of structures used to house and facilitate farming operations.

Based on these criteria, in tropical environments it is possible to recognize seven main types of agricultural systems (Grigg 1974, Norman 1979):

1. Shifting cultivation systems

2. Semi-permanent rainfed cultivation systems

3. Permanent rainfed cultivation systems

4. Arable irrigation systems

5. Perennial crop systems

6. Grazing systems

7. Systems with regulated by farming (alternating arable cropping and sown pasture).