| Southwest of songnen plain in heilongjiang province, fertile soil, mild climate, mainly produced crops of corn, soybeans, wheat, flax, is an important commodity grain production base. Because the region is located in mid-latitudes, temperate continental monsoon climate, the cultivation of the region mainly depends on rain. In recent years, due to the increasing deterioration of the ecological environment, the underground water level drops, uneven distribution of rainfall of the year, in the region in the spring sowing time easy to appear the phenomenon of spring drought. Straw mulching cover technology as a kind of more efficient cultivation mode of farmland, since it has water keep moisture, improve soil environment and soil physical and chemical properties of water heating, in the agricultural production at home and abroad to get a number of exploration and verification. For straw mulching planting patterns in our country also has carried on the related research, most of the test is in northwest arid region, solves the problems of regional agricultural water and soil resources utilization efficiency, however, these studies is limited to the difference of crop varieties and plant growing region climate differences, the same coverage measures have different effects, therefore, to seek for the north black soil region of songnen plains cover cultivation mode, the reasonable use of black soil resources, improve the utilization efficiency of soil moisture, increase food production is urgently needed to solve problems.Based on the songnen plains hinterland of Harbin xiangfang farm for test location, choose suitable for northern area growth "farmers 254" as a test of corn varieties, respectively, set up the control group, stubble stubble, strip naked, broken rod cover and the whole rod covers five different cover processing pattern, discusses the differences in different way and straw mulching quantity for the region’s corn soil hydrothermal condition and the influence of the corn plant production. By analyzing the differences of farmland ecological environment index, the similarities and differences between plant growth and soil water use efficiency, and the farmland SPAC transmission model of soil moisture of different coverage under the condition of soil moisture migration condition is simulated, the results of the analysis for the improvement of the songnen plain black soil area of soil and water resources utilization and development of efficient cultivation model provides practical guiding significance. The main results were as follows:(1) In five different processing conditions, the soil temperature integral will happen as the lifting of environmental temperature and different amplitude fluctuations. Due to the control group with no straw mulching, so the processing under the condition of soil temperature range is larger, the change of soil temperature range of 13.9-13.9 ℃, with the increment of straw mulching and bare soil stubble processing area of the soil temperature changes in the range of 15.2-15.2 ℃, and the covering area of soil temperature range is 15.6-25.3 ℃, embodied in soil temperature as the amplitude decreased with the increase of the cover, at the same time, the straw covering the area of the soil temperature in every birth of plant growth during the period of soil temperature at a relatively high level. For the soil moisture content, the degree of change between 0 to 30 cm soil layer is most obvious, in the process of corn plant growth, soil moisture content will embody the whole first decreases after increasing trend, as a result of the existence of straw inhibited the invalid evaporation of water, therefore, in different period, straw mulching under the condition of soil moisture content is higher than the control group. In mid-july, corn in the most vigorous growth period, the bare earth stubble treatment under the condition of soil moisture content is 24.3%, with stubble treatment under the condition of soil moisture content is 23.1%, broken rod cover and the whole rod cover processing under the condition of moisture content of 25.7% and 25.9%, respectively, were compared with the control group increased by 1.6%,1.6%,3.0% and 3.2%, with the increase of amount of straw mulching, for soil moisture conservation effect is more superior.(2) From the perspective of the growth process of crops, first of all, the straw cover affected crop seedling germination, because of the influence of the comprehensive effect of moisture and heat, in five different cover processing conditions, with stubble and whole pole covered under the condition of two kinds of processing state of emergence to weaker than other three kinds of treatment. For individual growth of plant growth, leaf area index, stem diameter and root density and other plant traits measurement shows that the control of the plant plant height is 261.2 cm, bare soil stubble stubble, strip, broken rod cover and the whole rod processing plant under the condition of high 267.3 cm,259.4 cm,267.7 cm and 258.7 cm, which covers the condition of broken rod cover and bare soil stubble processing conditions of maize plant height advantage is more obvious. For stem diameter, leaf area of plants showed the same change rule. Analysis of plant root density and the distribution of the root system, the roots of the plant are mainly distributed in soil between 10-20 cm, horizontal range of 12.5-25 cm, the area of root system distribution law of more than 90%, at the same time, along with the growth period, plant roots down continuously, along with the increase of the amount of straw mulching in different soil layer, the roots of the plant density had a certain degree of increase, shows that coverage of plant underground and aboveground part reflects the strong growth advantage.(3) In the maize seed sowing before and after the autumn harvest, nutrients in the soil will appear different degree of change, among them, the soil bulk density in the plant at the end of its fertility is lower than before planting situation, the reason was that the plant growth process consumes a lot of organic and inorganic substances in the soil. And under the condition of different coverage, soil bulk density differences also exist certain differences, in 4 cover processing conditions, broken rod stubble coverage and bare soil, under the condition of two kinds of different dry density of soil change, to illustrate the two kinds of soil environment more suitable for plant growth and development, for soil nutrient transport ability is stronger. In addition, the total nitrogen, available phosphorus and available potassium absorption process, with the increase of amount of straw mulching, the consumption of elements increases gradually, the plants to absorb elements ability is stronger.(4) Collect different test block of corn, fruit ear character statistics the corn spike length, spike in the coarse, bald length, grain number and grain number and hundred grain weight and other characteristic parameters, and then calculate the maize yield per hectare area, in which economic output in the control group was 9131.3 kg·hm2, stubble stubble, strip and bare soil, broken rod cover and the whole rod cover treatment under the condition of economic crop yields were 10126.52 kg·hm2,10010.94 kg·hm2,10416.28 kg· hm2 and 9383.34 kg·hm2, respectively, compared with the control group increased by 10.89%,9.62%,14.07% and 2.76%. In the study of the important factors that affect yield in maize panicle traits, grain Numbers per line is most closely associated with the production relations, the correlation coefficient is 0.8845. In addition, according to the different plant dry matter accumulation of calculated coverage of disposal of corn plant under the condition of the ground and underground part of the relative growth rate and net assimilation rate, by contrast, in each plant reproductive period, plant relative growth rate is higher than that of underground part above ground relative growth rate, at the same time, the coverage of plants growth condition is better than the control group. In the perspective of economic benefit analysis of different cover the difference effect of processing conditions, so the grain in the land of net income is 9396.83 yuan, stubble stubble, strip bare soil, broken rod cover and the whole rod cover processing conditions of net benefits were 10811.93 yuan,11217.05 yuan and 9532.34 yuan,10615 yuan, among them, the bare earth covered stubble and broken rod processing conditions of relatively high ratio of economic benefit is remarkable. Analysis from the perspective of water-saving efficiency, under the condition of straw mulching treatment in 4, as the increase of moisture content were 1312.0 kg,1209.2 kg, 1720.3 kg and 852.57 kg, water-saving efficiency were 138.24 yuan and 127.26 yuan,172.56 yuan and 127.26 yuan, from the point of view of economic benefit, broken rod cover processing conditions for the most suitable for the region to promote the cultivation mode of production.(5) By SPAC water migration transmission model, using the MATLAB language to run the model solving, cover with three different conditions for different boundary conditions, simulation under the condition of rain cover, under the condition of soil moisture migration process and the simulation results with the actual measured value has carried on the contrast analysis, under the condition of different mulching treatment, the error of the measured values between the simulated values are controlled within 10%, the simulation precision of the results conform to the provisions of the permissible error range. Result shows that the model is applicable to the black soil region of songnen plains soil moisture migration process simulation, and can be further prediction of soil moisture.The results of different cover cropping patterns in the songnen plain in heilongjiang province to provide theoretical basis for practical application. Combination with different coverage two-dimensional soil water movement model is established, and used to simulate after rain, soil moisture dynamic change trend field. Analysis in combination with the data measured in field trials, for agricultural water and soil resources in the region to provide theoretical support, high efficiency, energy saving and sustainable development to seek appropriate northern drought region’s agricultural production mode to lay a solid foundation. |
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