Feeding Plants to Feed the World A sequence of activities to teach the nutrient story to middle and high school students By Kent Lewarne “ E
NGLAND AND ALL civilized nations stand in deadly peril... As mouths multiple, food sources dwindle.”1These words by Sir William Crookes in
1898 in his inaugural speech as the president of the Brit- ish Academy of Sciences, underscored his prediction that by the 1930s, humans would begin dying of hunger in large numbers. The audience sat silently, straining to hear his every word. Crookes spoke of many of the same issues we face today such as finite supplies of arable land, loss of soil fertility, limited “natural fertilizers” such as manure and bird droppings, and crop rotation. He argued that the best farming practises at the time would not be enough to stymie world hunger. For Crookes, the answer was in making what he called “chemical manure”, the discovery of which was the greatest challenge of their time. Today modern agriculture faces similar challenges. How
are we going to feed an estimated world population of 9 bil- lion people by the year 2050? As the world population con- tinues to increase, it is worth noting the available arable land (land capable of being ploughed and used to grow crops) and land in permanent crops is increasing slightly in developing countries but decreasing in developed countries. As a result, we must grow more food on less land. With fewer students involved directly with agriculture,
there is a disconnect in which fewer young people know where their food comes from today. To address this disconnect, the following two activities provide a way to introduce students to the concept that producing enough food to feed an ever grow-
ing population will require higher and higher crop yields. The activities were developed to help teachers better connect stu- dents to the issues of feeding the world in the 21st century. In Canada almost 89 million acres2 are considered to be
farmland. In the USA this number is a staggering 915 mil- lion acres.3 But for many students, the question remains, “What is an acre?” Activity 1 – What is an Acre? answers that question for them. Once the students are familiar with the concept of the acre, its on to Activity 2 – The Bushel Bas- ket. This activity allows students to visualize what a bushel actually is and as a bonus teachable moment, will allow a discussion of the history of our weights and measurements and how they have evolved over time. Many students will have seen a basket similar in size to the bushel basket but now they will know its history.
Assessing Prior Knowledge To get started, ask your students, “What do humans need to
live?” Their answers will likely include, “air, water and food.” If you probe a bit deeper and ask, “Why do we need air, water and food?” they will eventually understand what each of these is used for in the human body, and ultimately that the energy derived from the chemical reactions in the human body drives all human activities. Now expand the discussion to include plants. “What do plants need to live?” Almost in unison the class will indicate, “water, soil and sunlight!” It is rare, but possible, that anyone answers food (or nutrients). If you probe, many will respond that plants make their own food (a fact drilled into their head from studies of photosynthesis in ear- lier grades). Here is your opportunity to go a little deeper. Ask your class, “What are the five basic needs of plants?”
GREEN TEACHER 113 Page 39
Photographs: Kent Lewarne
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