Studies On Selection Of Coating Materials And Coating Technique Of Controlled-Release Fertilizers

On base of the cellection of common chemical materials, screened out certain kinds of materials as cohesive agents and used different proscription and manufacturing arts to produce around 200 kinds of coated nitrogen fertilizers. Then, by means of water dissolution, in-door simulating leaching experiments and field trail, the long-lasting releasing coated nitrogen fertilizers were selected. The results were as follows.1. The best cohensive material was WI, which has excellent cohensive properties to form good mambrance to coat the fertilizer. The adaquate concentration of WI was 60% to get best cohensive effect.2. Four kinds of mineral materials-WA,WD,WF and WJ were choosed as better coating materials.3. The coating tachiques and their effects were studied using the cohensive material and coating materials selected . The best produced fertilizer was CRFS06 with the WJ and WA as the cohensive material and coating material respectively.4. In water-disolution experiment, CRFS06 could last for 57 minutes showing a slowly releasing properties. The in-door simulation nitrogen leaching experiment showed a similair trend as the nitrogen absorption of wheat in early growing stages in the field.5. Taking CRF165 as an example, field trial was conducted to study the response of wheat yield to the coated fertilizer. The CRF165 as dressing nitrogen fertilizer for wheat in elongation stage could maintain an adaquate provision of nitrogen for the middle and later growing stages of wheat, so evidently promoted the growth and developments perear and higher grain weight and therefore increased the wheat yield.