| In the northwest Loess Plateau semi-arid rain-fed conditions. This paper studied the effects of four different mulching modes: 6750 kg/hm2(T1), 9000 kg/hm2(T2), 11250 kg/hm2(T3), 13500 kg/hm2(T4), with the main comparison of regular no coverage planting(CK) and the auxiliary comparison of whole film casing Dibble Seeding(T5). The effects on soil moisture, soil temperature, yield and water use efficiency in different whole straw mulching amounts are studied. The main achieved results are as follows:(1)Different whole straw mulching amounts has a significant effect on both winter wheat yield and WUE. In the four mulching modes, the winter wheat yield was increased by 12.1%-23.3% with CK, The cause of the production is that the mulching whole maize straw can significantly improve the number of spike, and the production and number of spike was significantly positive correlation(r=0.815*), compared with CK, when compared with T5 decreased by 6.2%. In the four mulching modes, WUE is increased by 13.4%-26.8%with CK; but there was no significant difference compared with T5. T2 has the most significant improvement of production and WUE among the four modes, which indicates that the most suitable amount of whole straw mulching is 9000 kg/hm2.(2)Mulching amounts has a significant effect on soil moisture. The average soil water storage amount in 0-200 cm layer in the whole stages of mulching modes are significantly higher than that in CK and T5, with an increase of 0.7%-1.0% when compared with CK(T1 is the highest followed by T2) and 0.6% when compared with T5. The average soil water storage amount in 0-200 cm layer in the whole stages of T2 has an increase of 1.0% and 0.7% when compared with CK and T5 respectively.Soil moisture of 0-200 cm are significantly different amomg different growth period in addition to the maturity stage. The biggest difference is in the turning green stage,with a range of 1.7%. The smallest difference is in the heading stage. Specifically, the effect of improving moisture differs in every stage. Each mulching amount can significantly improve soil moisture in 0-200 cm before filling stage. Jointing stage has the biggest difference when compared with CK among all growth stages, with a significant increase of 1.3%; after flowering, the moisture improving effect of whole maize straw mulching starts to be weakened. Compared with T5, soil moisture of four mulching modes is better than T5, which is significantly higher than T5 with an average increase of 1.3% in the in the seedling stage, and an average increase of 0.2%-0.6% in other stages.In whole growth period, the average soil moisture differs in different layers. Differences is greater 90cm-below soil layer than 90cm- above soli layer, and the largest differnce appears in 120-150 cm soil layer, with a range of 2.9%(T1&CK). Among the four mulching amounts, the biggest difference appears in 120-150 cm soil layer, with a range of 2.1%(T1&T3). In the view of soil moisture temporal dynamics differnce, the biggest differnce appears in 90-120 cm soil layer in the flower stage, with a range of 4.2%(T4&T5).(3)Different whole straw mulching amounts has a significant effect on lowering the temperature when compared with CK&T5. Straw mulching can lower so the 0-25 cm soil temperature in the whole growth stage.In the four mulching modes, T1 & T2 has no significant difference with CK, but T3&T4 is lower than CK with 1.28℃&1.34℃. The four mulching modes are significantly lower than T5 with 1.55-2.25℃, among which T4 is the most significcant. Differnces are not obvious among the the four mulching modes.Average temperature of 0-25 cm soil layer in different stages has divergence. Winter stage has the max divergence, and the range is 1.3℃(T1&T5).Compared with CK, the effect of increasing temperature is showed before winter stage(seeding stage-winter stage), and T2 has the most significant effect in seeding stage with a temperature difference of 1.1℃(T2&CK). After turning green stage, effect of lowering temperature is showed, and jointing stage has the significant effect with a temperature difference of 3.5℃(T4&T5). In the view of soil temperature temporal dynamics differnce, the biggest differnce appear in 5cm soli of flower stage, with a range of 5.9℃(T4&T5).In the whole growth stage, the soil layer is deeper, the average soil temperature is lower. It is 5cm soil layer that has the most obvious effect of lowering the temperature when comparing the four mulching modes with CK & T5, with the max range of 1.31℃ & 3.39℃.In straw mulching modes, the change differnce of soil temperature is evening > noon > morning when compared in a day. Compared with CK, the effect of increasing temperature is in 5cm & 10 cm in the morning in T2, with the temperature difference of 1.29℃& 1.32℃ respectively; the most significant effect of declining soil temperature is generally in the noon and in the evening, with a range of 3.32℃(T3 & CK) appearing in 5cm layer in the noon. Compared with T5, each soil layer of whole maize straw mulching is showing the effect of decling temperature in whole day, and the most obvious decling effect is in 5cm layer in noon, with the temperature differnce of 4.76℃(T3&T5).(4)Straw mulching has a significant effect on delaying growth period, with a max delay of 9d & 11 d when compared with CK&T5. The larger the amount of mulching, the more delayed day of growth. The effect appears after turning green satge, since too much mulching leads to a too low temperature in turning greeen stage, which delays the normal growth and development of winter wheat.(5)Whole maize straw mulching can improve single stem substance accumulation and the main growth period plant height of winter wheat, in addtion, can also improve individual plants and its constituent organs moisture of winter wheat significantly in the main growth stage. |
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