Alfred N. Pearson received his professional education at the Royal School of Mines, London, where he was awarded a royal exhibition in 1874. In 1877 he went to the state of Kutch (or Cutch), India, where he was involved in the development of mineral resources. That same year he was appointed acting professor of biology at Elphinstone College, Bombay (now Mumbai) and acting curator of the Victoria and Albert Museum in that city. In 1880 he became resident engineer at the Wynaard Gold Mining Company and in 1882 acting meteorological reporter for western India. The next year he published The development of the mineral resources of India (1883), a booklet containing four lectures that he had delivered in Bombay. He was elected a Fellow of the University of Bombay in 1884.
Towards the end of 1884 Pearson moved to Australia, where in 1885 he was an examiner in natural science subjects at the University of Melbourne. The next year he was appointed government agricultural chemist in the civil service of Victoria, with headquarters in Melbourne. In 1887 he served on the Royal Commission investigating the control of rabbits in Australia. His post was changed to that of chemist for lands, agriculture and water supply in 1889 and that same year he published A search for knowledge and other papers (Melbourne, 1889, 145p). During the next twelve years he published at least two pamphlets, one on Manures and manuring... (1895), the other on The beet sugar industry in Victoria (1901), and delivered two papers before the Australian Association for the Advancement of Science on the relation between the chemical analysis of a soil and its productiveness (1898) and on "The scientific directing of a country's agriculture" (1900). He participated in the intercolonial conference of inquiry into rust in wheat, and in 1900 was chairman of the board to inquire into the butter industry.
In January 1902 Pearson was appointed director of agriculture for the Colony of Natal, stationed in Pietermaritzburg. In July that year he and the surveyor-general of the colony reported on the agricultural prospects of the territory. Their report was well received, but Pearson's interest in agricultural research rather than in farming for profit led to differences with government officials and led to his appointment in January 1904 (with reduced salary) as director of agricultural experiments and chemistry. His headquarters were at Cedara, north-west of Pietermaritzburg, where an agricultural experiments station was established in 1902. There he planted over 1000 varieties of field crops and more than 200 types of grasses. Two orchards were planted and a dairy section established with various breeds of foreign cattle to improve local stock. His wide agricultural knowledge and the results of his many experiments on the use of manures and fertilisers, planting times, varieties of plants, and agricultural machinery, were written up for publication in the Natal Agricultural Journal and Mining Record, for example, "The chemist in the sugar mill", and "Cotton" (1904); "Chicory", "Experiment farms in Natal", "Forage crops", "Manures", "Onion growing", "Tobacco curing", and "Winter grasses" (1905). In 1905, with the agricultural chemist Alexander Pardy* as co-author, he wrote a review article on the history and current position of "The sugar industry of Natal" for the volume Science in South Africa (pp. 423-438), published in preparation for the joint meeting of the British and South African Associations for the Advancement of Science in South Africa later that year. An agricultural school was started at Cedara in 1906, offering a two-year diploma course. Pearson also started agricultural experiment stations at Winklespruit on the South Coast (for experiments with sugar cane, cotton, and other semi-tropical plants), at the Weenen irrigation settlement (to study irrigation problems), and at Stanger.
Though his work was promising, it was not recognised by the Natal government, perhaps because of his differences with them. Early in 1906 the government instructed him to reduce expenditure on the experimental farms and as a result he resigned his post in March that year. In 1907 he returned to Victoria, Australia, to set up a model farm, but the enterprise failed. He remained in Australia for the rest of his life.