夏玉米宽窄行集雨覆盖种植土壤水分运移及其模拟研究

发布时间：2018-08-17 10:27

【摘要】：黄土高原南部地区属于暖温带季风气候,该地夏玉米各生育期降雨分布不均,作物供需不协调,严重地影响着作物的生长和产量的形成。农田地膜覆盖可以调节土壤水分的供需关系,改善作物生长状态,对作物增产稳产具有重要的意义。本试验设置露地平作种植(CK)、(60:60)等距垄沟处理(RE)、(80:40)宽窄行垄沟处理(RW),使用TRIME-TDR及EM50对农田土壤水分进行动态监测,并通过HYDRUS-2D模型对夏玉米土壤水分进行了模拟,最后,利用模型深入研究土壤水分的运移状态,揭示覆膜保水效应的规律。通过研究关中旱作区地膜覆盖栽培方式,对深入地了解农田土壤土壤水分变化,提高夏玉米产量有着积极的作用,为完善覆膜集雨种植技术提供必需的理论依据。通过试验研究,得到的结论如下:(1)在夏玉米收获后,覆盖处理可以显著地提高浅层土壤水分含量,0-40 cm土壤水分含量变化最剧烈。在轮作系统中,覆膜栽培下的冬小麦消耗了土壤深层水分,但在玉米整个生育期之后,土壤深层水分得到了补给,这有利于轮作农田生态的可持续性。在作物的耗水量方面,覆盖改变了作物耗水的时空分布,覆盖条件下夏玉米前期耗水量减少,中期耗水量增加,后期耗水量减少。三年平均水分利用效率RW和RE较CK增幅为36.73%和33.44%,宽垄集雨效果优于等行距起垄覆膜效果优于对照处理。覆膜有效地提高了降雨的利用效率,优化了降雨的生产潜力。三年平均降雨利用效率RW和RE较CK增幅为23.91%和29.06%。(2)采用2014年田间实测水分含水量数据对HYDRUS-2D模型进行标定,使用2015年的数据进行验证,模型可较好地反映土壤水分运动过程。从RMSE、MAE、MRE三种评价指标来看,评价指标变化范围分别为0.011-0.030 cm3.cm-3,0.0001-0.027cm3.cm-3和3.62-10.49%。该模型适用于黄土高原半湿润区覆膜情景,可以弥补大田试验费时的不足,为黄土高原地区适宜的农田种植方式提供理论和数据支持。土壤表层含水量的实测值与模拟值差异较大,主要是由于耕作改变了土壤的性质。反演的土壤参数和实测值有差异,其中,实测的残余含水量高于反演值,实测的饱和含水量低于反演值。土壤表层(0-20cm)饱和导水率与实测值相差较大,这主要是由于耕作改变了土壤的物理性质,使得大田的模拟数据和室内的测试数据相差较大。(3)探究沟垄内部的水量变化和通量变化可以发现,在时空分布不均的夏玉米生长季,垄作为独立单元,在降雨时,垄子区域作为“库”进行蓄水;当产生季节性干旱时,垄内的水分将补给到沟内以供土壤蒸发和根系吸收。设置沟垄比(沟:垄)为20:40、25:35、30:30、35:25四个梯度时,可以发现,不同沟垄比主要差异表现在土壤蒸发和土壤贮水量,这说明覆膜减少蒸发是保水、提高贮水量的主要原因。
[Abstract]:The southern part of the Loess Plateau belongs to the warm temperate monsoon climate. The rainfall distribution of summer maize in each growing period is uneven and the crop supply and demand are not coordinated which seriously affects the growth of crops and the formation of yield. Film mulching in farmland can regulate the supply and demand of soil water, improve the growth state of crops, and play an important role in increasing and stabilizing the yield of crops. In this experiment, (CK), (60:60 was planted in open field) (RE), (80:40 was treated with equal-distance ridge and furrow) the dynamic monitoring of farmland soil moisture was carried out by TRIME-TDR and EM50 using TRIME-TDR and EM50, and the soil moisture of summer maize was simulated by HYDRUS-2D model. Finally, the soil moisture of summer maize was simulated. The model was used to study the migration state of soil water and to reveal the rule of water retention effect of film mulching. By studying the cultivation methods of plastic film mulching in Guanzhong dryland area, it has a positive effect on understanding the change of soil moisture in farmland and improving the yield of summer maize, which provides the necessary theoretical basis for perfecting the technique of mulching and rainwater harvesting. The results are as follows: (1) after summer maize harvest, mulching treatment can significantly increase the soil moisture content in shallow layer from 0 to 40 cm. In the rotation system, winter wheat under film mulching consumes deep soil moisture, but after the whole growth period of maize, the deep soil moisture is replenished, which is beneficial to the sustainability of cropland ecology. In the aspect of crop water consumption, mulching changed the temporal and spatial distribution of crop water consumption. Under the condition of mulching, the water consumption of summer maize decreased in the early stage, increased in the middle period, and decreased in the later period. Compared with CK, the average water use efficiency (RW) and RE increased by 36.73% and 33.444.The effect of wide ridge rainwater collection was better than that of equal row spacing, and the effect of film mulching was better than that of CK. Film mulching can effectively improve rainfall utilization efficiency and optimize rainfall production potential. Compared with CK, the average rainfall utilization efficiency (RW) and RE increased by 23.91% and 29.06% respectively. (2) the HYDRUS-2D model was calibrated with the field water moisture data of 2014, and the data of 2015 was used to verify the model. The model could reflect the process of soil moisture movement. According to the three evaluation indexes, the range of evaluation indexes is 0.011-0.030 cm ~ (-3) ~ 0.0001-0.027 cm ~ (-3) and 3.62-10.49 respectively. The model is suitable for mulching film in semi-humid region of Loess Plateau, which can make up for the shortage of time-consuming field test and provide theoretical and data support for the suitable planting mode of farmland in Loess Plateau. The difference between the measured and simulated values of soil surface water content is mainly due to the change of soil properties by tillage. There are differences between the soil parameters and the measured values. The measured residual water content is higher than the inversion value, and the measured saturated water content is lower than the inversion value. The difference between the saturated water conductivity of soil surface (0-20cm) and the measured values is mainly due to the change of the physical properties of the soil by tillage. As a result, there is a big difference between the field simulation data and the indoor test data. (3) it can be found that in the growing season of summer maize with uneven spatial and temporal distribution, the ridge, as an independent unit, can be found as an independent unit when rainfall occurs in the furrow and ridge. The ridge area serves as a "reservoir" for water storage; when seasonal drought occurs, the water in the ridge is supplied to the ditch for soil evaporation and root absorption. When the furrow / ridge ratio (furrow: ridge) is 20: 40, 25: 35: 30: 30: 35: 25, it can be found that the main differences of furrow / ridge ratio are soil evaporation and soil water storage, which shows that the main reason for water retention and water storage is to reduce evaporation by mulching film.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S513;S152.7

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