Therefore, agriculture provide income earning opportunities for skilled and unskilled labors. On the hand, a large portion of resources such as lands is used in agriculture. Income earned by the trading of agricultural products can be used to invest in other sectors. These characteristics of agriculture can be identified in an underdeveloped economy.  

 However, increase of agricultural output and productivity that is contributed to overall economy can be discussed in several ways. There will be an increase in the demand for agricultural products in line with the economic development. However, failure to supply of food to meet the demand can impact on the growth of economy. Expansion of agricultural exports increases foreign exchange earnings and hence increase foreign reserves at the earlier stage of development. Labor force absorbed to industrial and other sectors of the economy should draw mostly from agricultural sector. Capital required for manufacturing industries is produced from net outcome of agricultural sector. Finally, growth of net cash income of farmers will be an incentive for industrial growth.

 Growth, Economic Development and Sustainable Economic Development

There are two phases that always use in the subject development. One is economic growth. Other is sustainable economic development. Economic growth indicates growth of GDP in a country. Sustainable economic development is defined as the development of economy in a country in line with securing of its environment. Economic development will benefit all the persons equally in the country. 

Some of the Growth theories in brief

Development is not strictly depended on economic situation in a country. In other word, development is not only associated with income and output but changes in institutional, social, administrative structures, common attitudes, customs and beliefs. In early years, scholars’ thinking was to evaluate development process in the world to study why some countries are developed and others are not. As a result of these studies, several development theories have been added to economic literature. These theories are classified as four approaches: the linear stages of growth model, theories and pattern based on the structural change, international dependency and its revolutionary changes, and neoclassical, free market counterrevolution. 

1. The linear-stages theory: - After second world war, some projects such as Marshall Plan which financial and technical supported by US helped to restore and reform their economies. The theory elaborates all industrial countries had been a peasant agricultural economy in earlier days. This means that industrialization is very important factor for growth of an economy.
2. Rostow’s Stages of Growth: - According to this model, countries have to procced several stages or steps to transform from underdevelopment to development. Those steps are traditional society, pre-condition to for take-off into self-sustaining growth, the take-off, drive to maturity, and high consumption period.  
3. The Harrod-Domar Growth Model: - this model says rate of growth of gross national product is determined by national saving ratio and capital-output ratio.
The Lewis Theory of Development: -This explains two sectors of an underdevelopment economy. They are subsistence agricultural sector which has surplus labor. This is an overpopulated sector. Marginal labor productivity of this sector is zero. This that it is possible to withdraw labors without damage to the output. Traditional agricultural sector of a country is belonging to this sector. Next sector of this economy is industrial sector. This modern sector can absorb excess labor of agricultural sector. Speed of expansion of modern sector determined by the rate of industrial investment and capital accumulation. This process leads to economic development.
4. The Neocolonial Dependence Model: -this model interprets that the existence and continuance of underdevelopment is mainly due to historically progression of unequal international capitalist system of rich and poor nations. Cohabitation of rich and poor dominated by unbalance power links with developed countries and less developed countries.

Please refer literature on economic development for more details and other growth theories.

Agricultural contribution to Sri Lankan economy 

 According to Annual Report 2021 published by Central Bank of Sri Lanka, Agricultural activities of Sri Lanka have been increased about 2 per cent in 2021. Coconut, Tea and livestock activities had contributed significantly for the agricultural production during the year 2021. However, Rubber, Rice, vegetable and fruit had shown slowdown during the same year.