In developed countries , amount of food produced being increased is a positive effect of agricultural changes in the past century.
Agricultural changes in developed countries were set up such as application of fertilizers etc so as to achieve a maximum yield as the increasing population all over the world means increase in food production to cater for individuals and to prevent starvation and death.
Agricultural changes were also done to ensure goods produced have a very high quality.
The remaining options such as Desertification, Clearing of rainforests and contamination can be referred to as part of the negative effect of agricultural changes in the past century.
