Final answer:
Britain's introduction of cotton cultivation during the off-season for food crops allowed Egyptian farmland to be used more efficiently, leading to the doubling of effective acreage. This, combined with modern irrigation systems and the introduction of large-scale farming technologies during the Industrial Revolution, revolutionized agriculture in Egypt.
Step-by-step explanation:
The agricultural change introduced by Britain in Egypt that doubled the effective acreage and allowed farmers to grow two to three crops a year was the introduction of cotton cultivation during the winter months when food crops were not being grown. This change was part of a broader modernization effort led by Muhammad Ali, the ruler of Egypt in the early 19th century. He encouraged the growth of cotton as a cash crop in the winter, built irrigation systems to increase agricultural productivity, and sold the cotton to Britain. The profits were then used to modernize various sectors in Egypt including the military and education systems. This transformation in Egyptian agriculture meant that land could be far more efficiently utilized throughout the year, which significantly increased the potential output and profitability of farming in the region.
Alongside the cultivation of cotton, the impact of agricultural productivity was further enhanced by other historical technological innovations such as the development of the three-field rotation system, metal plows, and irrigation systems. The British also introduced new farming technologies during the Industrial Revolution, which included gasoline-powered tools like tractors and combine harvesters, further revolutionizing agriculture by making it more efficient and profitable.