黄土高原地区种植豆科绿肥协调土壤水分和氮素供应的效应及机理

发布时间：2018-03-18 09:20

  本文选题：豆科绿肥　切入点：冬小麦　出处：《西北农林科技大学》2016年博士论文　论文类型：学位论文

【摘要】：作为一个典型的雨养农业地区,我国黄土高原地区农业生产的可持续发展不断面临着水分亏缺和土壤贫瘠所带来的挑战。夏闲期种植并翻压绿肥作物不仅可以有效培肥地力、促进后茬作物生长和产量形成,同时能在时间和空间层面上提高养分、水分、光热等自然资源的利用率,因此,本研究通过在渭北旱塬地区开展长期的田间定位试验(2008年~至今),深入研究黄土高原地区种植不同豆科绿肥(长武怀豆、大豆和绿豆,夏季裸地休闲为对照)以及冬小麦生长季不同施氮水平(0,108,135,162 kg N/ha)对土壤水分和氮素供应的影响,初步探究豆科绿肥协调土壤水分和氮素供应的效应及机理,旨在为恢复并发展我国绿肥产业体系提供科学的理论依据和技术支撑。取得的主要结果如下:(1)通过4年的田间定位试验数据,研究发现旱地连续多年种植并翻压豆科绿肥较传统的裸地夏休闲能够有效促进后茬冬小麦苗期的生长(冬季单株分蘖数和春季总茎数)、后期的产量形成(产量、生物量和公顷穗数)和养分吸收状况。然而,由于需要额外的劳动成本和田间管理投入,豆科绿肥体系较高的生产成本严重影响该体系的经济效益。此外,施用氮肥较不施氮显著提高旱地冬小麦生长状况、产量形成、养分吸收和经济效益,然而三种氮肥施用量间无显著差异;(2)通过6年的田间定位试验结果并结合当地57年的降雨气象资料,详细分析我国渭北旱源冬小麦种植区降雨时空分布特征,初步研究黄土高原地区不同降雨年型条件下应用豆科绿肥对后茬冬小麦产量和水分利用效率的影响,同时探究豆科绿肥协调旱地土壤水分平衡的内在机理。发现连续多年夏闲期种植豆科绿肥的确会消耗土壤水分,同时该措施会因降雨年型的不同而对后茬冬小麦产量带来不同程度的影响。当年降雨量较为丰沛时,种植豆科绿肥所引起的夏闲期土壤水分亏缺能够得到及时补充,豆科绿肥可增加旱地冬小麦生产量;反之,干旱年份则该措施将带来严重的减产效果。整体来看,试验期间种植并翻压豆科绿肥较夏休闲显著提高冬小麦产量和水分利用率,平均提高幅度分别为13%和27%。同时,豆科绿肥对促进旱地土壤水分平衡也发挥着重要的作用;(3)结合长达374天的豆科绿肥的腐解试验,进一步探究了豆科绿肥生育期所累积的氮素在旱地传统的冬小麦种植体系中吸收、转化和利用的内在机制。研究发现,试验期间平均每年豆科绿肥在其盛花期通过其地上部和根系生物量积累共计53~76 kg N/ha氮素,通过一年的翻压还田,至少有32 kg N/ha绿肥氮素经过土壤微生物的分解矿化作用释放到周围环境中;其中,约有7~27 kg N/ha最终被后茬的冬小麦吸收利用。整体来看,豆科绿肥体系平均每年氮素总投入量为164 kg N·ha-1·yr-1,氮素携出量平均为114 kg N·ha-1·yr-1,最终导致该体系每年约有50 kg N·ha-1·yr-1的氮素盈余在土壤中。旱地夏闲期应用豆科绿肥能够有效替代13~48%(平均为31%)的冬小麦生长季无机氮肥用量。此外,连续4年种植豆科绿肥可降低夏闲期间土壤硝态氮向深层(100~200 cm)淋溶的风险,平均降低硝态氮淋溶19.6 kg N/ha;(4)通过5年的田间试验结果,探究我国黄土高原地区应用豆科绿肥对旱地麦田土壤碳库和氮库库容的影响;同时采用One-compartment模型,对土壤有机碳库周转的动态机制进行了拟合。发现在黄土高原地区的夏闲期种植短期的豆科绿肥,其生物量及碳、氮养分累积与生长周期呈极显著的幂函数关系。经过一年的腐解矿化,旱地麦田土壤中豆科绿肥地上部和根系的平均碳素残留率分别为26%和33%;而相应的平均氮素残留率分别为31%和52%。与基础土样相比,夏闲期连续多年种植并翻压豆科绿肥显著提高旱地麦田表层土壤有机碳、活性有机碳和全氮含量以及相应的库容储量。此外,试验第5年表层土壤有机碳库储量与平均每年作物碳还田量间呈现显著的正相关关系,并且每年至少需要0.68 Mg C·ha-1·yr-1的作物碳还田量才能够基本维持基础土壤的有机碳库储量(19.04 Mg C/ha)。通过One-compartment模型,本研究计算出我国黄土高原地区旱地土壤有机质的矿化速率(1%)和腐殖化系数(23%)。此外,我们预测需要近22年的时间该类型土壤的有机碳库容才能达到周转平衡状态,说明目前土壤有机碳库尚未达到饱和状态,还有继续固持碳素的潜力和空间。整体来看,在黄土高原地区传统的冬小麦-夏休闲体系中长期引入绿肥作物能够有效促进冬小麦生长和养分吸收、提高冬小麦生产力水平和水分利用效率,并能够替代部分冬小麦生长季的无机氮肥施用量;同时,种植豆科绿肥能够有效降低土壤矿质氮向深层淋溶的风险,并显著提高旱地表层土壤肥力水平。因此,在黄土高原地区发展绿肥产业体系具有一定的可行性,同时将对我国发展稳产高效、环境友好型的现代化农业带来深远的影响。
[Abstract]:As a typical rainfed agriculture area, sustainable development of agriculture in the Loess Plateau of China are facing water shortage and poor soil brought challenges. During the summer fallow period and planting green manure crops can not only effectively improve soil fertility and crop growth and yield formation to promote, and can improve the nutrient in time and space aspects of water, utilization of natural resources such as heat rate, therefore, this study was carried out through the long-term test in Weibei dryland (2008 - present), different planting green manure legume research area of the Loess Plateau (Huai bean, soybean and mung bean, summer fallow and winter wheat as control) the growing season of different nitrogen levels (0108135162 kg N/ha) effects on soil water and nitrogen supply, preliminary study on effect and mechanism of coordination of leguminous green manure soil moisture and nitrogen supply, to The recovery and development of China's green industry system to provide theoretical basis and technical support of science. The main results are as follows: (1) through the field test data of 4 years, the study found that in successive years and planting leguminous green manure than the traditional bare summer leisure can effectively promote the following winter wheat seedling growth (winter the number of tillers per plant and total stem number), spring late yield (yield, biomass and spike number) and nutrient uptake. However, due to the need for additional labor cost and field management system, serious leguminous green manure higher production costs affect the system economic benefits. In addition, less nitrogen fertilizer nitrogen fertilization significantly improve dryland winter wheat growth status, yield, nutrient absorption and economic benefits, however, there was no significant difference between the three kinds of nitrogen fertilizer; (2) through 6 years of field test results when combined with Rainfall meteorological data of 57 years, a detailed analysis of the Weibei Dry land winter wheat planting characteristics of temporal and spatial distribution of rainfall area, the yield and water use efficiency of winter wheat using leguminous green manure in different rainfall years preliminary study on the condition of loess plateau area, and explore the internal mechanism of leguminous green manure in upland soil water balance and coordination for many consecutive years. Found in summer fallow period of leguminous green manure will deplete the soil moisture at the same time, the measures for different rainfall types and the yield of winter wheat stubble bring about different effects. When the rainfall is abundant, planting leguminous green manure in summer fallow period caused by soil water deficit can be added in a timely manner, Leguminosae green manure can increase the yield of Winter Wheat in dryland; on the contrary, the drought measures will bring serious production effects. Overall, during the test of planting and turning over green fertilizer than legume The summer fallow significantly increased winter wheat yield and water utilization rate, the average increase rate was 13% and 27%. respectively. At the same time, green manure on soil water balance in Dryland promotion also plays an important role; (3) with 374 days of leguminous green manure decomposition test, nitrogen and further explore the growth period of leguminous green manure accumulated in planting system of Winter Wheat in Dryland in the traditional absorption mechanism of transformation and utilization. The study found that the average annual leguminous green manure during the test in its flowering through the shoot and root biomass accumulation of total nitrogen by 53~76 kg N/ha, returning pressure over a year, at least 32 kg N/ha nitrogen mineralization after decomposition of green manure the soil microorganisms released to the surrounding environment; among them, there are about 7~27 kg N/ha was eventually after the winter wheat crop absorption and utilization. Overall, the average annual total investment of legume nitrogen 1 system 64 kg N - HA-1 - yr-1, nitrogen uptake averaged 114 kg N - HA-1 - yr-1, eventually lead to nitrogen surplus of approximately 50 kg of N - HA-1 - yr-1 system of the year in the soil. In summer fallow period application of leguminous green manure can effectively replace 13~48% (average 31%) season of inorganic nitrogen fertilizer the growth of winter wheat. In addition, 4 consecutive years of leguminous green manure in summer fallow period can reduce soil nitrate nitrogen to the deep layer (100~200 cm) leaching risk, reduce the average nitrate leaching to 19.6 kg N/ha; (4) through the field test results of 5 years, to explore the application of leguminous green manure on the Loess Plateau in China effect of dry soil carbon and nitrogen storage capacity; at the same time using the One-compartment model, the dynamic mechanism of soil organic carbon turnover fitting. Found in the Loess Plateau during summer fallow planting short bean green manure, biomass and carbon, nitrogen accumulation and growth cycle A very significant power function relationship. After a year of decomposition of carbon mineralization, average shoot and root soil in dryland wheat, the residual rate of legumes were 26% and 33%; and the average nitrogen corresponding residual rate was 31% compared with 52%. and foundation soil samples in summer fallow period and planting pressure over consecutive years leguminous green manure significantly improve dryland wheat, soil organic carbon, labile organic carbon and total nitrogen content and storage reserves accordingly. In addition, there is a significant positive correlation between the test surface fifth years reserves of soil organic carbon pool and the average annual crop carbon residue amount, organic carbon storage and annual crop carbon returning amount of at least 0.68 Mg C HA-1 yr-1 can maintain the basic foundation soil (19.04 Mg C/ha). Through the One-compartment model, this study calculates the mineralization rate in China Loess Plateau Dryland Soil organic matter (1%) and rot Colonization factor (23%). In addition, we predict the need for nearly 22 years the soil organic carbon storage in order to achieve turnover equilibrium, the soil organic carbon library has not yet reached saturation, and continue holding carbon potential and space. Overall, the introduction of long-term green manure crops can effectively promote the growth and nutrition of winter absorption of wheat in the Winter Wheat Yellow Soil Plateau traditional summer fallow system, improve Winter Wheat Productivity and water use efficiency, and can replace part of winter wheat growing season of inorganic nitrogen; at the same time, the risk of leguminous green manure can effectively reduce soil mineral nitrogen to deep leaching, and significantly improve the fertility level of the surface Dryland Soil in the Loess Plateau region. Therefore, the development of green industry system has certain feasibility, while the stable development of our country's modern efficient, environment friendly Agriculture has a far-reaching impact.

【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S55;S512.11
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本文编号：1628977