The world history of grain production is almost as long as the history of humans. There is evidence that wheat was cultivated in China before 3000 BC and that wheat was the chief crop in ancient Egypt and Palestine. Barley was first planted in southwestern Asia. Rapeseed was one of the first crops grown by humans. Canola (shown left), a type of rapeseed, has only recently been grown in Canada. Corn is the only major crop originating in North America. It was grown by the Indian peoples here, as described in the records of Christopher Columbus. Today, Saskatchewan is the leading producer of grain crops in Canada. Saskatchewan is referred to as "The Wheat Province" because it produces more than 60% of Canada's total wheat production. Saskatchewan also produces crops such as barley (shown left), oats, flaxseed and canola. Crop choice depends largely on type of soil, length of the growing season and available soil moisture. More than fifteen kinds of grain and oilseeds crops are grown in the province. Each type of grain and oilseed crop has many varieties. There are more than sixteen different varieties of wheat grown in the province, and more than a thousand varieties of wheat grown world­wide. The cropland of Saskatchewan is divided into four areas based roughly on climate, vegetation and soil type. Yields of crop varieties may vary from area to area. In order to decide which crop to seed, producers must consider both the yields in the area and the special characteristics of the crop variety such as the number of growing days needed for the plant to reach maturity, resistance to plant diseases and susceptibility to pests. For example, each crop variety requires a certain number of days to mature. The farmer must be aware of the number of "frost­free days" in the area and select a crop that will mature in this time period. The performance of any variety will vary from year to year and place to place depending on the insects, weather conditions, disease occurrence and management practices. Modern grain production consists of a series of large­scale and mechanized processes. Each process requires specialized pieces of equipment. Tillage is similar to the process of hoeing a garden. It aerates the soil, rids the soil of weeds, buries plant matter that eventually rots and replenishes lost soil nutrients and prepares a seed bed for seeding. Modern equipment allows for tillage and seeding at the same time. New tillage techniques and implements are constantly being designed and used by farmers. Conservation tillage techniques such as zero tillage are necessary in much of Saskatchewan because the prairie soil is dry and easily eroded by wind and water. Seed must be obtained from seed growers or grain that was harvested in the previous year. It must be cleaned prior to seeding. There are many different types of seeding equipment. Basically, they all open a furrow in the soil, drop the seed in at an even depth, cover the seed and pack the soil. Fertilizer may be placed with the seed or spread prior to or after seeding. Spraying chemicals is the most common method of crop protection against damage from weeds, insects, fungi and diseases. Nowadays, several other alternatives are being used by innovative farmers to minimise environmental damage. Improper use of crop protection chemicals can have devastating longterm effects on the environment. More research is being done into less hazardous biological control products and practices such as Integrated Pest Management. Harvest begins when the crop is sufficiently mature for its intended use. Silage crops are harvested when they are still green. Grain crops, oilseeds and alternative crops are harvested when they are ripe.