| China is a big country in agriculture and the shortage of water resources is the major bottleneck restricting in agricultural development,especially in the arid and semi-arid regions of north China.At the same time,China is also a big straw country,the effective use of straw has an important role in protecting the environment and increasing the income of farmers.In this study,two types of covering methods(ridge and furrow covered with straw,Ridge covered with film and furrow covered with straw)and four types of coverage(2500,5000,7500 and 10000 kg/hm~2)were combined.The effects of different treatments on soil temperature,moisture,nitrate nitrogen,growth and yield of summer maize were investigated by comparing flat and non-coverage.The specific findings were as follows:(1)The study on soil temperature during summer maize growth period found that the“low temperature effect”of straw mulching was stronger in the early stage of summer maize than in the middle and late stage.Overall,the regulation of soil temperature increased with the increase of the amount of straw,with the depth of soil layer.The effect of soil temperature at 0 cm at the early growth stage was the greatest,and it was the greatest at 5 cm in the middle and later stages.The treatment of 2500 kg/hm~2 on temperature was not significantly different from that of the CK,and the difference between 5000 and 10000 kg/hm~2 was significant.During the whole growth period,the coverage of the four species decreased by 0.55°C,1.85°C,2.72°C and 3.12°C on average compared with CK.(2)The study on soil moisture during summer maize growth period found that the average water consumption in the whole growth period was 0.56 mm,7.47 mm,8.87 mm and12.65 mm more than that of the CK.The role of straw-covered steam reduction was mainly in the vegetative growth stage and each straw were 4.19 mm,7.44 mm,16.41 mm,and 17.73mm less than the CK.The transpiration promotion effect was mainly manifested in the reproductive growth stage and were 5.37 mm,17.89 mm,26.43 mm and 31.52 mm more than that of the CK.Coverage has a greater impact on soil moisture at 0~50 cm,and the greater depth,the smaller impact.(3)The study on nitrate nitrogen during summer maize growth period found that the nitrate nitrogen of 0~80 cm covered by the treatment decreased by 5.09%~17.91%on average,the proportion of 80~160 cm increased gradually with the increase of the coverage,with an average of 3.67%~20.25%.The percentage of nitrate nitrogen in the 160~200 cm soil layer was the smallest,ranging from 12.22%to 12.64%.The coverage of this layer was significantly different from that of the CK(P<0.05).The soil nitrate content showed a“>”change overall with the depth of soil layer.The change of 0~40 cm in each treatment was relatively flat(12.62 to 17.56 mg/kg).The content of nitrate nitrogen in the treatment were slightly lower than that of the CK.The change of 40~140 cm was larger(13.21~28.24mg/kg),and when the coverage was greater than 7500 kg/hm~2,the difference was significant(P<0.05).The change of 140~200 cm was smaller(9.82~16.38 mg/kg).As the result of leaching,the peak nitrate content in the covering conditions was reduced by 10 to 50 cm compared to the CK.The more coverage,the lower peak position.(4)The study on growth of summer maize during its growing period found that the covering treatment can significantly affect the plant height,leaf area and dry matter quality of the maize during the growth period.Compared with the CK,the seedling stage was reduced.The plant height at the filling stage reached the maximum in the covering treatment,which was 7.5%~14.3%higher than that of the CK.The leaf area index peaked at the tasselling stage,which was 5.6%~30.0%higher than the CK.The dry matter quality had the largest difference at the filling stage,with an average increase of 15.4%~49.6%compared with the CK,and when the amount was greater than 7500 kg/hm2,the effect of the coverage on the accumulation of dry matter was no longer obvious.In mature period,the total root length increased by 38.99%~152.63%compared with the CK,the root surface area increased by33.52%~100.70%.the root system showed a shallow distribution,in 0~100 cm soil layer,the proportion of the root length decreased with the depth of soil increased.The percentage of root length in the 0~20 cm soil layer was 41.98%~47.99%,and the root length of the coverage soil was significantly different from the CK(P<0.05).When the soil depth was greater than 40 cm,the proportion of root length gradually decreases with increasing coverage.(5)The study on the yield and components of the summer maize growth period found that the ear length increased by 1.98%~17.01%,the ear coarseness increased by 3.05%~11.87%,the ear number increased by 6.75%~26.06%,and the grain weight increased by3.78%~21.27%,the yield under coverage increased by 5.49%~27.17%than the CK,except for LG1,the other treatments had significant differences compared with the control(P<0.05).The water use efficiency increased by 5.61%~21.23%than the CK,and there was a significant difference between the treatments and CK(P<0.05).For comprehensive comparison,it was recommended that straw mulching technology should be applied in the semi-arid areas of Guanzhong,and coverage of 7500 kg/hm~2(MG3)was appropriate,which means water saving,production and straw utilization efficiency increasing. |
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