was key to the increased food production. Students may not realize the amount of nutrients (nitrogen, phosphorus, and potassium or NPK) needed to produce the huge yields required to feed an ever-increasing population. The Bushel Basket activity below will help students to explore the nutri- ent requirements of some common crops. The story of nutrients is complex. Today, many of our
Although this may seem like the same question, it will elicit slightly different responses. Most will again give you the standard answers of sunlight, water and soil. By ask- ing “What is in the soil that plants need?”, you will eventu- ally get to food or nutrients. But the food that plants need is not in the same as we require. Plants need food like nitro- gen, phosphorus and potassium. These are the big three of plant macronutrients (a substance required in relatively high amounts by living organisms), and are the three basic needs of plants after light (sunlight) and water. Soil itself is actu- ally not one of the basic needs, but rather does do a good job of providing these macronutrients in natural systems. There are many other media that could act as a bedding material for plants, soil just does a good job of serving up macronutrients. Besides the big three, there are many essential elements that plants need (14 depending on what source you use), but for our purposes we will focus on the big three: nitrogen, phos- phorus and potassium or NPK in the following activities.
Activation Across North America, most of us are fortunate to know
that we will have food to eat each day. But as the world pop- ulation increases towards an estimated nine-billion people by the year 2050, will this still be the case? In 1950, 790 mil- lion hectares of farmland were used to produce 628 million tonnes of grain.4 By 1992, essentially the same amount of land, produced 1.7 billion tonnes of grain.5 The world popu- lation doubled to around 3 billion around 1960. The increase in food demand was met by the expansion of agriculture and by increased mechanization. The second doubling of world population, from three to six billion people occurred by the year 2000. The food required to feed this increase in popu- lation was generated on virtually the same amount of land. The increase in yield to feed the second doubling was due primarily to the use of commercial fertilizers and improved crop varieties, the so-called Green Revolution. The use of high yield varieties, along with the use of commercial fertil- izers, irrigation and pesticides replaced traditional farming practices in many areas of the world. The What is an Acre? activity below will help students to understand the amount of land we need for food production. During the Green Revolution, crop yields increased
enough to keep pace with the demand for food production. The use of fertilizer to replenish soil nutrient deficiencies
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ecosystems are no longer the ecosystems found in textbooks – grassland, deciduous forest and aquatic ecosystems but are ecosystems working in conjunction with agriculture or agro- ecosystems. The impact of nutrients on these ecosystems is a source of intense research and great concern. Nitrogen and phosphorus loading in aquatic ecosystems is well docu- mented. There is no doubt that agriculture is playing a role in the changes happening in the nutrients cycles of these ecosystems. Today, for example, it is estimated that about half of the nitrogen in each and every one of us was origi- nally “fixed” not by bacteria but by the industrial-production of nitrogen.6 Without this process we would not be able to avoid the famines that were predicted. But the use of nutrients to increase yields has some issues
as well. Some of the nutrients used are ending up in places other than our food. Portions of them are finding their way into our water and air. This creates environmental issues such as eutrophication of our waters and climate change. Today, more than ever, producers and the entire agriculture industry are well aware of the economic and environmental concerns associated with the use of nutrients in food produc- tion. The agriculture community is making large strides to address all three pillars of sustainability (economy, environ- ment and society) by implementing best management strat- egies to reduce the use and impact of nutrients. One such strategy is 4R Nutrient Stewardship: producers are using the right source of nutrient, at the right time, in the right place and at the right rate. These practises help to ensure that agri- culture is doing its part to continue to grow the food for an ever-increasing population but in a way, that is both environ- mentally sustainable and economically viable.
Kent Lewarne is a high school science teacher in Prairie Spirit School Division in south central Manitoba, with 30 years experience. He is the Program Coordinator for the Riverwatch program across southern Manitoba, and for the past six years, het has worked as an Educational Coordina- tor for Nutrients for Life Canada (NFL).
Notes
1. Hager, T. (2008). The alchemy of air: a Jewish genius, a doomed tycoon, and the scientific discovery that fed the world but fueled the rise of Hitler. New York: Broadway Books.
2. Nourishing the Planet in the 21st Century. (2008). Retrieved May 06, 2017, from
https://www.nutrientsforlife.ca/learning-materials/
3. Hager, T. (2008). The alchemy of air: a Jewish genius, a doomed tycoon, and the scientific discovery that fed the world but fueled the rise of Hitler. New York: Broadway Books.
4. John Heard, Manitoba Agriculture, Personal Communication, 07-May-2017
5. Mitchell Timmerman, Manitoba Agriculture, Personal Communication, 05-May-2017 6.
www.statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/agrc25a-eng.htm
7.
https://www.agcensus.usda.gov/Publications/2012/Online_Resources/High- lights/Farms_and_Farmland/Highlights_Farms_and_Farmland.pdf
8. Nourishing the Planet in the 21st Century. (2008). Retrieved May 06, 2017, from
https://www.nutrientsforlife.ca/learning-materials/
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