| For better understanding of the internal mechanism of mulched drip irrigation on water and heat conditions in field and maize yield in black soil region, field experiment were carried out in Heilongjiang Province, China,2014. The experiment was set up two treatments, including mulched drip irrigation, non-mulched drip irrigation. With maize as the test crop, this paper focuses on the characteristics of the changes of micro climate and crop growth in the field. The main conclusions are as follows:(1) The mulched drip irrigation can increase soil temperature in the near ground layer. The higher the soil temperature, the greater the root respiration rate, which is beneficial to improve the growth and photosynthesis of crops. The mulched drip irrigation increased the daily temperature at 5cm,10cm,15cm,20cm,25cm soil depth by 2.88℃-5.33℃,3.04℃-4.81℃,2.19℃-3.74℃,0.02℃-0.52℃, compared with that of the non-mulched treatments.(2) The mulched can increase the reflectivity and decrease the thermal conductivity, then increase air temperature in the near ground layer. At the same time the mulched restrain soil evaporation and prevent soil moisture and atmospheric from exchanging, which lead to reducing the relative humidity of the air. From the point of view of daily data, compared with the non-mulched drip irrigation treatment, the mulched drip irrigation increased air temperature and reduced air humidity at four times at 10 centimeters above the ground,0.40℃,0.23℃,0.33℃,0.46℃ was increased and 1.27%,1.60%,2.35%,1.67% was reduced. The mulched drip irrigation increased air temperature and reduced air humidity at four times at half plant height above the ground,0.20℃, 0.10℃,0.16℃,0.25℃ was increased and 0.46%,0.42%,0.61%,0.82% was reduced.(3) Film mulching had an obvious effect on keeping water and it can restrain the evaporation of soil moisture. Compared with the non-mulched drip irrigation treatment, the mulched drip irrigation reduced soil evaporation volume on ridge (directly below the drip tape) and ridge edge, 46.26% and 49.06% was reduced. The mulched drip irrigation treatment increased the soil moisture content at 0-50 cm soil depth by 46.65% maximum.(4)The mulched drip irrigation treatment has the same influence on the surface layer wind velocity with the mulched drip irrigation treatment which means the speed of the wind increase to the peak first and start to go down. In the same treatment, the wind velocity goes up with the increase of the height. In the same height of different treatment, those under film mulching has a slightly higher wind velosity which is not quite obvious.In the mean time, the correlationship between wind velosity abd temperature reaches a significant lecel.In the mulched drip irrigation treatment,the temperature has a positive corelationship(r=0.795) with the wind velosity when it is 10cm above the ground level.The correlation coefficient reaches r=0.880 when it is 160cm above the ground level.In the unmulched drip irrigation treatment,the temperature has a positive corelationship(r=0.803) with the wind velosity when it is 10cm above the ground level.The correlation coefficient reaches r=0.904 when it is 160cm above the ground level.(5) In terms of crop growth, the growth speed of LAI, plant height, aboveground fresh and dry matter weight for the mulched drip irrigation treatment was greater than those for the non-mulched drip irrigation treatment during the early growing stage. The 100-grain weight of the mulched has increased 0.23g and the yield has increased 314.69kg/hm2. In addition, the mulched drip irrigation treatment increased the nitrogen uptake. The nitrogen content of its corn ear and kernel are 0.60% and 1.19% higher, which increase the content of amino acid, and improve the quality of maize. |
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