Which process limits long-term maize yields in ancient, terraced Andean agricultural systems?

💡 Explanation

When maize is cultivated repeatedly, nitrogen depletion occurs because of its high nitrogen demand and removal from the soil during harvest, leading to declining yields over extended periods if nutrient replenishment methods are absent. Therefore, nitrogen limits long-term yields, rather than potassium fixation, phosphorus runoff, or calcium buildup each of which require different mechanisms and environmental factors.

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