The largest and perhaps only real threat to sustainable agriculture comes from unchecked population growth and the resulting downstream effects such as changes in the climate , soil erosion , soil salinization , and soil nutrient depletion 持續(xù)農業(yè)所面臨的最嚴重的威脅是無限制的人口增長以及隨之帶來的氣候變化、土壤侵蝕、土壤鹽漬化以及養(yǎng)分耗竭。