一、根据蔬菜对养分需求的原则安排茬口。把需氮肥较多的叶菜类、需磷肥较多茄果类和需钾肥较多的根茎类蔬菜相互轮作倒茬;把深根性的豆类、瓜类、茄果类,同浅根性的白菜、甘蓝、黄瓜、葱蒜类蔬菜进行轮换倒茬。这样可使土壤不同层次中的养分得到充分利用。一般需肥较多的叶菜类,后茬最好安排需磷肥较多的茄果类。吸肥快的黄瓜、芹菜、菠菜等,下茬最好安排对有机肥第二反应较好的西红柿、茄子、辣椒等。 二、以有利于减轻病虫害为原则安排好茬口。如黄瓜霜霉病、枯萎病、白粉病或蚜虫等,对瓜类蔬菜有感染传毒能力,连作黄瓜更为不利,如改种其他类蔬菜,就能收到减轻或消灭病虫害的效果。如葱蒜采收后种大白菜,可使软腐病明显减轻。粮菜轮作、水旱轮作,对土壤传染性病害的控制更为有效。 三、以缓解土壤酸碱度,平衡土壤肥力为原则安排好茬口。如种植马铃薯、甘蓝等会增加土壤酸度, First, according to the principle of vegetable nutrient requirements arranged stubble. Need more nitrogen fertilizer leafy vegetables, need more phosphate fertilizer and soya-toed potatoes and more need to rotate each other rotation of potatoes; the deep-rooted beans, melons, solanaceae, with shallow root cabbage, Cabbage, cucumber, onion and garlic rotation of the stubble. This allows nutrients in different levels of the soil to be fully utilized. Generally need to fertilizer more leafy vegetables, after the best arrangements for more phosphate fertilizer solanaceous. Fast fat absorption of cucumber, celery, spinach, etc., the best arrangements for the second best organic fertilizer on the second tomato, eggplant, peppers and so on. Second, in order to help alleviate pests and diseases as the principle of arranging a good stubble. Such as cucumber downy mildew, blight, powdery mildew or aphids, etc., on the infection of melons and vegetables poisoning, even more cucumber is adverse, such as re-planting of other types of vegetables, you can receive to reduce or eliminate pests and diseases. Such as onion and cabbage after harvest, can significantly reduce the soft rot. Crop rotation, drought and rotations, the control of soil-borne diseases more effective. Third, in order to ease the soil pH, balance the principle of soil fertility arrangements stubble. Such as planting potatoes, cabbage and other will increase soil acidity,