| A field experiment was set up with different amount of straw mulch and the cover ways in the dry agricultural land of Weibei dry plateau from 2007 to 2009.The study analysed on spatial distribution dynamic of soil moisture, soil physical and chemical properties, growth and development index with winter wheat.The main conclusion showed that:1. The two-year located experiment showed that soil water content and amount which covered by the different amount of coverage in the same mulching mode was positively correlated.Compared with the no-tillage,while the straw mulching quantity was 9 000, 6 000 and 3 000 kg/hm~2 during the entire period, soil moisture content of full coverage from 0 to 200 cm layer, increased by 18.4%,12.7% and 8.2% respectively. In the growth covering stage, soil moisture content which covered with 9 000, 6 000 and 3 000 kg/hm~2 of 0～200 cm layer, increased respectively by 8.5%,3.6% and 1.8%. The soil moisture content of full period which covered the different ways in the same amount of coverage of coverage was superior to growth stages and control. While the straw mulching quantity was 9 000, 6 000 and 3 000 kg/hm~2, in the 0～200 cm layer, soil moisture content of full coverage increased by 11.5%,10.0% and 8.0% respectively compared with the growth stages coverage, increased by 19.2%,12.9% and 8.8%。2.Compared with the no-tillage, the mulch treatment soil temperature changing performance is: 0～10 cm>10～15 cm>15～25 cm after sowing stage from 8:00 am to 18:00 pm.Increase of straw covering quantity results in that of soil temperature decreasing.Compared with the control, the entire period cover way with the straw cover quantity of 9 000, 6 000 and 3 000 kg/hm~2, soil temperature reduction scope respectively is 0～4.5, 0.5～3.5 and 0.3～3.0℃from 0 to 10 cm layer. The period of duration cover way with the straw cover quantity of 9 000, 6 000 and 3 000 kg/hm~2, soil temperature reduction scope respectively is 0～2.5, 0～2.5 and 0～1.5℃.The same amount of coverage in different ways to cover the whole range of coverage than the growth temperature is more obvious way of covering. 3. The straw mulching can increase the soil respiration, reduce the soil bulk density, increase the great particle size aggregates and reduce the small particle size aggreagtes. Compared with the control, the soil bulk density decreased varying from 0.9% to 6.5%, the entire period cover way with the straw cover quantity of 9 000, 6 000 and 3 000 kg/hm~2.In the growth stage with the straw cover quantity of 9 000, 6 000 and 3 000 kg/hm~2, the soil bulk density reduction ranged from 1.2% to 6.1%.The amplitude of the soil bulk density reduction in the growth stage as the straw quantity increasd is greater than the growth and fallow stage. After two-year straw localization processing, 0～40 cm soil mechanical stability of the aggregates increased with soil depth, in which >5 mm aggregates increased, 5～2 mm aggregate change is not obvious,<2 mm mechanical stability aggregate reduced, particularly 0.5～0.25 mm is the most significant.>0.25 mm mechanical stability of the aggregate sum showed that in full coverage mode, performance for the 9 000 kg/hm~2>6 000 kg /hm~2>3 000 kg /hm~2>CK, the growth mode of covering the performance of the 9 000 kg /hm~2>6 000 kg/hm~2>3 000 kg/hm~2>CK.>0.25 mm water stable aggregate sum showed that covering the whole manner of different mulch, 0～20 cm soil layer signed 3 000 kg/hm~2>CK>9 000 kg/hm~2>6 000 kg/hm~2, in the growth mode of covering different covers show to 9 000 kg/hm~2>3 000 kg/hm~2>6 000 kg/hm~2>CK.4. After continuously two year localization cover experiment processing harvest,0～40 cm soil layer of different mulch the organic matter, the total phosphorus,the available phosphorus and the total potassium were different than the degree of increase, compare with CK.Compared with CK,in the low quantity of coverage (such as 6 000 and 3 000 kg/hm~2), the entire nitrogen, the available nitrogen and the available potassium increased, the high mulch treatment (9 000 kg/hm~2) decreased. The phosphatase, the urease and the sucrase's tendency of two years is basicly consist: along with soil layer depth's increase, the enzyme activity reduces, but the identical level different cover quantity processing the urease, the phosphatase, the sucrase enzyme activity was higher than CK.5. Straw mulch can delay the growth period.Covering at the first year that could retard 14 d, the mulch treatment effect was obviously.Covering at the second year entire journey mulch treatment to excel in the period of duration mulch treatment, the bigger the cover quantity, the more the period of duration delay time.6. Filling stage is the key to the formation of wheat grain weight.In this period,it has a direct impact on photosynthetic capacity of wheat grain dry matter accumulation.In the slightly increasing stage, the grain filling rate of four treatment decreased gradually in the following order:CK,3000,6000,9000 kg/hm~2.However,In the fast and the slowly increasing stage,the grain filling rate of control was different with the slightly increasing stage.The grain filling rate can be arranged in the following order as 3 000 kg/hm~2>6 000 kg/hm~2>CK>9 000 kg/hm~2.The grain filling duration of 9 000 kg/hm~2 was longer than contrast's 6 d, 6 000 and 3 000 kg/hm~2's grain filling duration were almost the same as control's. During the fast and the slowly increasing stage,the contribution rate of 9 000, 6000and 3000 kg/hm~2 were all larger than control's,while in contrary for the slightly increasing stage.7. With the straw mulching amount of 9 000, 6 000 and 3 000 kg/hm~2, the winter wheat yield of the full stage coverage in differenr mulching mode were remarkably increased by 41.1%～65.7% (P<0.05) than contrast, the growth stages were also increased with 27.1%～30.2% (P<0.05). As far as mulching manner is concered,the difference of water use efficiency between the whole growth period of coverage and growth stage is relatively small. Whether the full coverage or growth stage coverage, the water use efficiency (WUE) was always largest in the amount of 3 000 kg/hm~2. Compared with the contrast,the WUE of full coverage was remarkably increased by 31.5% (P<0.05), the growth stage was significantly enhanced by 12.8% (P<0.05) in average of two years.
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