EFFECTS OF LONG-TERM BALANCED FERTILIZATION ON MICROBIAL ACTIVITY AND NUTRIENT UPTAKE OF MAIZE IN A FLUVO-AQUIC SOIL
A long-term stationary field experiment on nutrient balance for farming ecosystem in the Fengqiu National Agro-ecological Experiment Station was made use of to investigate effects of balanced or unbalanced, fertilization on micro-bial biomass, enzymatic activities, and soil basal respiration as well as nutrient uptake of maize plants in a fluvo-aquic soil. The experiment was designed to have five treatments: fertilizer NPK, NP, PK, NK, and CK (without fertilization). The root biomass, straw biomass, grain yield, and total uptakes of N, P, K of maize plants were all greatly increased in Treatment NPK, and were also significantly increased in Treatment NP, but were not significantly affected in Treatment PK or NK. In the same treatment, straws and roots were similar in nutrient content, while grains were relatively higher in total N and total P contents, but lower in total K content. Compared to Treatment NPK (balanced fertilization) , the other treatments, lacking one or other nutrient, showed significant decrease in the nutrient in question and/or significant increase in the other nutrients in maize plants, and differed between the treatments in nutrient distribution among roots, straws, and grains. In addition, in all treatments that had P (NPK, NP, PK) , the soils were higher in microbial biomass C, N, P, activities of dehydrogenase, invertase, urease, and alkaline phosphatase, microbial metabolic activity, and basal respiration, but significantly lower in microbial metabolic quotient. However, the P-deficienct fertilization treatment (NK) did not show any significant effects on these soil biological parameters, except for a significant increase in urease activity. The findings demonstrated the role of P, as well as balanced fertilization with N, P, and K in promoting soil microbial growth and metabolic activity, as well as enhancing crop growth and nutrient uptake.
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