The Agriculture sector contributes to the GDP of a country in various ways. Its production stimulates the economy and has backward linkages with other sectors like the petroleum, chemical and machinery industries. Many of these industries depend largely on sales from farmers to make their products. Natural calamities, however, can affect agricultural sector production.
Source: https://www.zupyak.com/p/3355500/t/the-role-of-agriculture-in-developing-indian-economy