The main economic products of Malawi are tobacco, tea, cotton, groundnuts, sugar and coffee. These have been among the main cash crops for the last century, but tobacco has become increasingly predominant in the last quarter-century, with a production in 2011 of 175,000 tonnes. Over the last century, tea and groundnuts have increased in relative importance while cotton has decreased. The main food crops are maize, cassava, sweet potatoes, sorghum, bananas, rice, and Irish potatoes and cattle, sheep and goats are raised. The main industries deal with agricultural processing of tobacco, tea and sugar and timber products. The industrial production growth rate is estimated at 10% (2009). History of agriculture in Malawi Colonial period Although Nyasaland, as the country was known before 1964, had some mineral resources, particularly coal, these were exploited in colonial times. Without economic mineral resources, the protectorate's economy had to be based on agriculture, but in 1907 most of its people were subsistence farmers. In the mid-to-late 19th century, manioc, rice, beans and millet were grown in the Shire Valley, maize, cassava, sweet potatoes and sorghum in the Shire Highlands, and cassava, millet and groundnuts along the shores of Lake Nyasa (now Lake Malawi). These crops continued to be staple foods throughout the colonial period, although with less millet and more maize. Tobacco and a local variety of cotton were grown widely. Europeans wrongly criticised the practice of shifting cultivation in which trees on the land to be cultivated were cut down and burnt and their ashes dug into the soil to fertilize it. The land was used for a few years after another section of land was cleared. Compared to European, North American and Asian soils many sub-Saharan African soils are low in natural fertility, being poor in nutrients, low in organic matter and liable to erosion. The best cultivation technique for such soils involves 10 to 15 years of fallow between 2 or 3 years of cultivation, the system of shifting cultivation and fallowing that was common in Nyasaland as long as there was sufficient land to practice it. Throughout the protectorate, the colonial Department of Agriculture held negative attitudes towards African agriculture, which it failed to promote and favoured European planter interests. Although in the early years of the 20th century, European estates produced the bulk of exportable cash crops directly, by the 1940s, a large proportion of many of these crops (particularly