Effects Of Organic Mulch On The Soil Of Urban Green Space

In order to study the effect of organic mulch on soil in urban green space, field observation and control experiment were designed in this dissertation. In the field observation, it mulched 3cm, 5cm organic mulch and no cover treatment to study the change of soil moisture, temperature, nutrition, weed control and soil microbes in the depths of 0-10cm, 10-20cm, 20-30cm and 30-40cm in the experimental urban park. Meanwhile, this article designed control experiment in the National Engineering Research Center of Timber Industry, it includes six kinds of mulch (bark, pine needles, leaves, wood chips, garden waste, wood shavings), three mulching thickness (3cm, 6cm, 9cm) , three mulching ways (mulching organic mulch separately, mulching turf separately, mulching organic mulch and turf together) and the control to study the change of soil moisture, temperature, nutrition in the depths of 0-10cm, 10-20cm, 20-30cm and 30-40cm.The result of continual observation from March to December in 2008 shows that : (1)The annual average soil moisture of mulching treatments are higher than control, organic mulch plays an important role on maintaining soil moisture; soil moisture's seasonal variation of all expe??ntal treatments have the same trend, influenced mostly by natural precipitation; mulch's effect to soil moisture is more obvious in depth of 10-20cm; soil moisture is higher separately mulching 3cm pine needles, leaves, wood shavings and garden waste.(2)Soil temperature of mulching treatments are significantly lower in summer and distinctly higher than the control in winter, mulch has effect to decrease soil temperature in hot season and increase soil temperature in cold season; soil temperature's seasonal variation of all experimental treatments have the same trend, soil temperature diurnal-variation(8:00-18:00) scope of mulching treatments are smaller than the control in four seasons; in addition, the peak of soil temperature daily change of mulching treatments is around 16:00, while the valley point is around 8:00.(3)Organic mulch increased soil organic matter content, but has little effect on PH. It increased soil available nitrogen content, this effect is relatively obvious with bark and pine needles treatments in different materials; this influence in different mulching styles: mulching organic mulch separately > mulching turf separately > mulching organic mulch and turf together; mulching 6cm has highest organic matter content in three mulching thickness treatments. The effect of organic mulch to available phosphorus content varies in different treatments: this effect is relatively obvious with pine needles and leaves treatments in different materials; this effect in different mulching thickness: mulching3cm> mulching 6cm > mulching 9cm; this influence in different mulching styles: mulching organic mulch separately > mulching turf separately > mulching organic mulch and turf together. The effect of organic mulch to available kalium content is different between field observation and control experiment results. In the control experiment, the available kalium content of mulching treatments are lower than the control; but in the field observation the content of 5cm mulching treatment is significantly higher than the control; it need further study.(4)The weed coverage and biomass of mulching treatments are significantly lower than the control, and mulching 3cm treatment has minimum weed coverage, mulching 5cm treatment has minimum weed biomass. Organic mulch increased the number of soil bacteria, in particular with 5cm mulching treatment and in 0-10cm soil depth; and it i??ased the number of soil fungi, mulching 5cm thickness treatments has the highest number of fungi in 0-10cm soil depth while mulching 3cm thickness treatments has the highest amount of fungi in10-20cm soil depth; in addition, it increased the number of actinomycetes, the amount of mulching 5cm treatment is significantly higher than the control.In conclusion, pine needles, garden waste, bark played a good role among six organic mulches to maintain soil moisture, improve soil temperature and soil nutrition; while mulching 6cm thickness is best way in three different mulching thickness; in addition, mulching organic mulch separately is the most effective way in different mulching methods.