Maize Doctor

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The Maize Doctor is a classification document developed by scientists at the International Plant Nutrition Institute (IPNI)¹ to establish a set of standard simple identification markers for the health of maize crops by examining the leaves. A healthy plant - able to extract sufficient nutrition and water from the ground - will have shiny leaves with a rich, dark green color (1). The other marker numbers - 2 through 8 - classify the causes for an unhealthy plant: (7) and (8) respectively show the effect of disease infection and chemical damage, (2) through (6) identify any deficiencies of the top soil. A phosphorus deficiency (2) causes reddish-purple marks, a potassium deficiency (3) causes drying of firing at the tips and edges of the lower plant leaves, a nitrogen deficiency (4) causes a yellow line that moves along the middle of the leaf, a magnesium deficiency (5) causes whitish stripes along the veins and a purplish color on the underside of the leaves, and a lack of water (6) causes the leaves to roll up and become grayish.
        Typically - as explained by Dale and Carter - the ground is organically enriched by the decay of animals and plants which eventually creates a fertile layer of topsoil.² Any disruption to this process, principally from human activity - hunting animals, thereby eliminating organic enrichment sources, and felling trees, which stem erosion - diminishes soil’s capacity. They argue that - with few exceptions - man was never able to sustain civilization for more than 30 to 70 generations because of this reason. Because of the invention of fertilizers, however, contemporary civilizations have made it possible to artificially enrich the soil and sustain civilization beyond the 70 generation time frame.
        Maize is one of the most grown crops in South Africa. In order to combat pressures on food stocks from growing populations, increased agricultural intensity has more frequently caused the depletion of the ground. As Montgomery describes in Dirt – The Erosion of Civilizations, ‘we have transformed our fertile soil into sterile dirt.’³ In agriculture, as with mining, something is removed from the ground; harvesting crops is an extractive practice whose increasingly harmful consequences are evidenced through leaf discoloration.

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