In order to study the effects of combination of super absorbent polymer and microbial fertilizer on soil microbial biomass carbon

nitrogen and enzymes activities

four treatments

including no application of super absorbent polymer and microbial fertilizer (CK)

combination of super absorbent polymer and microbial fertilizer (A)

single application of microbial fertilizer (B) and single application of super absorbent polymer (C) were set up in the dryland area of the Loess Plateau. The spatial and temporal dynamics of soil microbial biomass carbon

nitrogen and enzymes activities of 0-10

10-20

20-40 cm soil layers during oat growth was analysed. The results showed that: (1) During the whole growth period

soil microbial biomass carbon showed a double-peak curve

the peaks appeared at the booting and filling stages. The soil microbial biomass nitrogen showed the trend of first decreasing

next increasing and then decreasing

with the highest content at the seeding stage. All the soil catalase

invertase and urease activities showed a single-peak curve

with the peak activities of soil catalase and invertase at the booting stage

and the peak of soil urease at heading stage. (2) Except CK

all the soil microbial biomass carbon

nitrogen

soil catalase

invertase and urease activities showed 0-20 cm > 0-10 cm > 20-40 cm. The combination treatment (A) had significant effects on 0-10

10-20 cm soil layer (p<0.05)

the single treatments (B

C) had significant effects only on 10-20 cm soil layers (p<0.05). (3) In 10-20 cm soil layer

compared with other three treatments

the combination treatment (A) all had the significant effects (p<0.05). Soil microbial biomass carbon was improved by 4.82%~40.28%

soil microbial biomass nitrogen improved by 8.44%~68.66%

soil catalase activity improved by 13.32%~60.16%

invertase activity improved by 10.45%~39.14% and urease activity improved by 12.40%~55.62%. (4) Combination treatment (A) had significant effects both on grain and biological yield (p<0.05)

the increasing range was 8.40%~20.12% and 10.80%~25.09%. So the combination of super absorbent polymer and microbial fertilizer had best effects on improving soil microbial activity and oat yield in the dry farmland of Inner Mongolia Loess Plateau.