Organic fertilizer is slow effect, so it should be applied early, usually should apply it as base fertilizer before sowing or planting, it will better if ferment it before using.The latter topdressing effect is not as obvious as the base fertilizer.

Chemical Fertilizer with quick effect, it should be applied one week in advance as base fertilizer. Topdressing should be applied before the crop critical period or during the absorption peak of nutrition to meet its needs.

Biological fertilizer to play the role of bacteriostasis after the large population of bacteria in the soil , Therefore, it is required to apply early in the precondition for the bacteria has time to Reproductive growth,It can be applied to soil with organic fertilizer, or before engraftment or during engraftment. 
 

Secondly, Notice the application methods

The main role of organic fertilizer is improving soil and providing nutrients, generally used as base fertilizer applied in the soil, so should combined with deep tillage to mix the organic fertilizer with soil evenly, to achieve the purpose of improving the soil.If soil problems is very serious,it can also mix with acid-base multiplication of microbial agents, it will better to improve the soil environment, balance nutrition, increase soil aggregate structure.

In the foundation fertilizer, because the nutrient in organic fertilizer is mainly nitrogen, the nitrogen fertilizer with organic fertilizer can be reduced, you can use 30% for base fertilizer, 70% for topdressing.Phosphate fertilizer and potash fertilizer can be applied as base fertilizer in a lump sum. Phosphate fertilizer is poor in mobility and the effect of later recovery, so phosphate fertilizer should be applied to the soil as base fertilizer.

Topdressing fertilizer is best to use the whole soluble quick-acting fertilizer, such as phosphorus and potassium source library, this fertilizer can be quickly absorbed after the decomposition by vegetables, it has less impact on the soil. Biomass fertilizer due to its small amount can be concentrated in the planting points or with organic fertilizer as base fertilizer. The latter can be topdressing the same kind of biological fertilizer to grow the flora, in order to improve the ability of removing phosphate and potassium solution and disease prevention effect.

Finally, Notice the dosage

Different crops have different stages of growth. The amount of fertilizer required is different.So you should control the fertilizer application amount.You should apply fertilizer according to different need of plant.meanwhile The content of nutrient elements in soil should be considered comprehensively