Throughout the 20th century, scientists worked on improving agriculture, especially in areas with high populations. Some of the technologies developed included better irrigation systems so farmers could get water to their crops. New machinery was built to handle larger production and to take the burden of agriculture work off of humans. New chemical fertilizers and pesticides were created to increase food production, and new varieties of grains and livestock were developed also for greater production. The Green Revolution has had only limited success. The high costs associated with many of these new technologies have kept the small farmer from taking advantage of them.