Relations between organic substrate formula and yield and quality of ginger

The effects of different organic substrate formulas on growth of ginger were studied with the design of the double saturated D-optimal regression. A mathematical model was developed, in which the content of corn straw and available NPK in substrate were independent variables, and ginger yield and quality were dependent variables, respectively. The results show that the effects of corn straw on ginger yield and quality are greater than those of the available NPK. Under the low level conditions, ginger yield and quality increase with the contents of corn straw and available NPK in organic substrate. When the content of available NPK is 2588 and 1468 mg/kg, the yield and quality of ginger reach the highest 75.98 t/ha and 88.17, respectively; and when the content of corn straw is 41.5%, ginger yield reaches a record high 82.50 t/ha, then ginger yield gradually reduces with the increase of corn straw and available NPK content; however, the optimum ginger quality is 98.02 with 50.0% corn straw content. The optimum organic substrate formulas calculated by computer are 35.6%–46.0% corn straw content and 2238–3180 mg/kg available NPK content.