Effects of Combined Application of Organic-inorganic Fertilizer on Soil Available Nutrients in Greenhouse Chrysanthemum

A field experiment was conducted to study the effect of the conventional fertilization (CF, 100% chemical fertilizer), the refined organic fertilizer in combining with 20% reduced chemical fertilizer (OF), the bio-organic fertilizer in combining with 20% reduced chemical fertilizer (BIO) and the organic and bio-organic fertilizer combined with 30% reduced chemical fertilizer (COB) on the chrysanthemum yield and soil available nutrients content. The result showed that, compared with CF, the treatments of OF, BIO and COB had the trend of increasing the chrysanthemum yield, significantly improved the soil fertility and regulated the soil pH. CF significantly reduced the soil pH by 0.6, but OF, BIO and COB treatments controlled the pH decrease markedly. Compared with CF, OF, BIO and COB showed no significant effects on soil available-P and available-K content, but significantly increased available-N content by 6.9%, 11.1% and 7.7%, respectively. Compared with CF, OF and COB treatments, BIO significantly increased soil OM content by 3.3%, 5.2% and 3.9%, respectively. The principal component analysis showed that, soil pH and available-N content were the key factors influencing the soil fertility of greenhouse chrysanthemum. 20% chemical fertilizer reduction combined with bio-organic fertilizer is the better practice for improving soil fertility, yield and quality of greenhouse chrysanthemum.