Date Received: 27-08-2021 / Date Accepted: 21-01-2022
The study aimed to indentify the proper substitution ratio of chemical fertilizers with microbial organic fertilizer pellets obtained from composted chicken manure for improving fruit yield and fruit quality of 5-6 years - Suu pomelo in Doan Hung, Phu Tho province. The treatments consisted of the following: control treatment (the chemical fertilizer dose conventionally used by farmers’) (1.5kg NPK (5:10:3) + 1.75kg NPK(12:5:7) + 0.5kg K2SO4/plant/year) and the substitution of 25%, 50%,70% and 100% chemical fertilizer with microbial organic fertilizer pellets in such a way to ensure equal N supply in each treatment. The results showed that the substitutions of 25% and 50% chemical fertilizers with microbial organic fertilizer pellets stabilized soil pH, increased the contents of soil nitrogen, phosphorus and potassium and significantly increased fruit yield as compared to chemical fertilizer application. Substitution with 50% microbial organic fertilizer pellets gave the highest fruit yield with 25.61 tons/ha and economic profit with VND568.95 milion per ha, increased by 148.49 million VND/ha compared to the control. Application of microbial organic fertilizer pellets along with chemical fertilizer led to the increase of fruit quality. The substitution of chemical fertilizer with 50% and 100% microbial organic fertilizer pellets statistically increased total sugar, vitamin C and dry matter in fruits as compared to application of chemical fertilizer.
