Problem: The control of associated biodiversity is one of the great agricultural challenges that farmers face. On monoculture farms, the approach is generally to eradicate associated diversity using a suite of biologically destructive pesticides, mechanized tools and transgenic engineering techniques, then to rotate crops. Although some polyculture farmers use the same techniques, they also employ integrated pest management strategies as well as strategies that are more labor-intensive, but generally less dependent on capital, biotechnology and energy.
What is one of the great agricultural challenges that farmers face?
The answer is the following: The control of associated biodiversity

Problem: Sonam Gyatso, after being granted the grandiose title by Altan Khan, departed for Tibet. Before he left, he sent a letter and gifts to the Ming Chinese official Zhang Juzheng (1525–1582), which arrived on March 12, 1579. Sometime in August or September of that year, Sonam Gyatso's representative stationed with Altan Khan received a return letter and gift from the Wanli Emperor (r. 1572–1620), who also conferred upon Sonam Gyatso a title; this was the first official contact between a Dalai Lama and a government of China. However, Laird states that when Wanli invited him to Beijing, the Dalai Lama declined the offer due to a prior commitment, even though he was only 400 km (250 mi) from Beijing. Laird adds that "the power of the Ming emperor did not reach very far at the time." Although not recorded in any official Chinese records, Sonam Gyatso's biography states that Wanli again conferred titles on Sonam Gyatso in 1588, and invited him to Beijing for a second time, but Sonam Gyatso was unable to visit China as he died the same year in Mongolia working with Altan Khan's son to further the spread of Buddhism.
Who did Sonam Gyatso send gifts to?
The answer is the following: Zhang Juzheng

Problem: After the Civil War, population expansion, railroad construction, and the disappearance of the buffalo herds heightened military tensions on the Great Plains. Several tribes, especially the Sioux and Comanche, fiercely resisted confinement to reservations. The main role of the Army was to keep indigenous peoples on reservations and to end their wars against settlers and each other, William Tecumseh Sherman and Philip Sheridan were in charge. A famous victory for the Plains Nations was the Battle of the Little Big Horn in 1876, when Col. George Armstrong Custer and two hundred plus members of the 7th Cavalry were killed by a force consisting of Native Americans from the Lakota, Northern Cheyenne, and Arapaho nations. The last significant conflict came in 1891.
What two tribes particularly resisted being confined to reservations?
The answer is the following: the Sioux and Comanche

Problem: Many traditional festivals and customs were observed in the old times, which included climbing the City Wall on January 16, bathing in Qing Xi on March 3, hill hiking on September 9 and others (the dates are in Chinese lunar calendar). Almost none of them, however, are still celebrated by modern Nanjingese.
When was the festival of climbing on the city wall celebrated?
The answer is the following:
January 16