In order to study the effects of biochar application on the soil physicochemical properties

enzyme activities and cucumber yield

and find a scientific basis for the popularization and application of biochar in agriculture

field experiments were conducted in greenhouse demonstration area

Rugao Institute of Agricultural Sciences

Jiangsu province. Biochar was incorporated into the soil at the rates of 0

5

10

20

30 and 40 t/hm2

respectively. The results showed that biochar application had significant effects on soil physicochemical properties and enzyme activities. The optimal rates of biochar application were 40 t/hm2 and 30 t/hm2 for improving the soil physicochemical properties and soil nutrient content

respectively. Biochar application reduced the soil bulk density by 0.88% to 10.52%

while increased the soil porosity

saturated water content

field water capacity

saturated hydraulic conductivity

organic matter

total nitrogen

the nitrate nitrogen content

ammonia nitrogen content

and available phosphorus by 3.68% to 7.53%

27.96% to 119.25%

30.73% to 55.05%

1.89% to 224.61%

10.39% to 54.56%

6.06% to 22.58%

2.33% to 45.63%

235.71% to 414.29% and 19.37% to 77.76%

respectively

compared with the control treatment. The activities of soil urease and catalase and the cucumber yield increased at first and then decreased with the biochar application increasing. The activities of soil urease and catalase were the highest when the biochar application amount were 30 t/hm2 and 20 t/hm2

respectively

and they were increased by 104.57% and 15.38% compared with the control

respectively. The cucumber yield increased dramatically by 21.80% compared with the control treatment when the application rate of biochar was 30 t/hm2. The principal component analysis showed that the soil quality with different biochar application rates decreased in the order of C4＞C5＞C3＞C2＞C1＞CK. The applying biochar in soil could not only increase cucumber yield

and improve the physical and chemical properties of soil and the soil nutrient content

but also improve the biological properties (such as: soil enzyme activities).