Cuba's agriculture after the 1959 revolution had been based on large-scale, capital intensive monoculture, which made Cuba heavily dependent on the socialist bloc for subsidized agrichemical inputs and for set prices of agricultural exports. However, with the collapse of the Soviet Union and its Eastern European allies in 1989–90, Cuba's inputs of fertilizer, pesticides, and petroleum dropped by more than half Cuba responded with a dramatic shift in its agricultural development model that featured appropriate technology, alternative organization of labor, alternative planning, and environmental preservation. Cuban pest control efforts now focus on biological control and on enhanced monitoring and diagnostic techniques. Soil management emphasizes biofertilizers and vermiculture. Minimum tillage and crop rotation are frequent practices among Cuba's independent farmers, agricultural cooperatives, and state farms. The transition to low-input agriculture has decreased the exodus of people from rural areas to cities, and has lead to establishment of lab or camps with volunteer labor and long-term programs for rebuilding rural communities. To address the loss of important food imports while ensuring environmental conservation, agricultural planning now gives priority to crop rotations, city gardens, and introduction of food crops in sugar cane areas.