|Better Farming Series 20 - Upland Rice (FAO - INADES, 1977, 30 p.)|
31. Fertilizers are different.
- according to the crop rotation:
Plants do not all take the same quantity of each mineral salt out of the soil. Before sowing rice, you must therefore give back to the soil the mineral salts taken out by the preceding crop.
These mineral salts are contained in chemical fertilizers.
- according to regions:
The soils of different regions are often different; they do not contain the same quantity of each mineral salt.
For example, a soil very poor in nitrogen must be given a lot of nitrogen.
You can see that a soil is poor in nitrogen if the young leaves turn yellow.