Heavy feeders and light feeders and crop rotation
In the vegetable garden, crop rotation plays an important role. Crop rotation means moving vegetables around the garden to maintain soil fertility. By rotating crops from one spot to another each season-or even in the same season, you can preserve and even boost nutrients in the soil. If the same vegetable plants are planted in a bed year after year, the soil may leach out. Thus, it can happen that the plants are more susceptible to pests and diseases (as these are usually specialized for certain plants). In addition, the plants do not get enough nutrients, so that the plants wither and the harvest yields could decrease considerably.
Differing crops use different amounts of soil nutrients and a few crops add nutrients to the soil. According to their nitrogen demand, vegetables are divided into heavy feeders, medium feeders and light feeders. Additionally, some crops are soil builders: soil builders include peas, beans, and cover crops such as clover.
A traditional crop rotation would plant heavy feeders in a dedicated planting bed the first year, followed by medium feeders in the same bed the second year and light feeders in the third year. In the fourth year the soil is allowed to recover and regenerate for a year with green manure and/or soil builders. The green manure plants are not harvested, but cut off and left as mulch or dug into the soil.
It is also important that crops from the same family are not planted in the same spot any more often than every three years. This is the best way to avoid attacks by pests and diseases; specific pests and diseases tend to attack plants from the same family. By rotating plant families, pests are not easily able to find the plants they want to attack.
Vegetables and their nitrogen demand:
|Heavy Feeders||Medium Feeders||Light Feeders||Green Manure|
|Broccoli||Endive||Lamb`s lettuce||Yellow Mustard|
|Potato||Scarlet Runner Bean||Turnip||Phacelia|
|Cabbage||Carrot||Swiss Chard||Red Clover|
|Sweet Corn||Lovage||Garden Radish|
|White Cabbage||Black Salsify|
|Savoy Cabbage||Runner Beans|