不同区域典型土壤紧实胁迫下玉米根-土系统特征差异及调控机理

The program was based on the investigation of soil tillage layer structure in major maize producing areas and the research into subsoiling tillage of plant belt which have been completed four years in succession in Spring Maize Area of Northeast China and Summer Maize Area of Huanghuaihai Plain. The program was aimed at the problem of tillage layer soil bulk density rise resulting from the ascending of plow pan and the problem of tillage layer obstacle seriously affecting maize producing. These problems have appeared in major maize producing areas in recent years. Field investigation in major maize producing areas was combined with root box simulation experiment in greenhouse in the program. Soil samples of different types were selected in typical area of Spring Maize Area of Northeast and Northwest China, Summer Maize Area of Huanghuaihai Plain and Maize Area of South China. Based on the field investigation of soil tillage layer structure and root development, the effect of soil compaction stress and adjusting suitable bulk density was systematically studied on physical properties, nutrient concentration, water content, thermal space efficient, spatial and temporal distribution of root, root physiological function of soil in different types from different areas. The mechanisms of the interaction between root with soil under compaction stress and the relationship between crop growth above aground and yield with soil structure and development was revealed. The effects of soil in different areas on maize rhizosphere, population response mechanism and population regulation method was discussed for the current producing condition with soil obstacle. The program was set up in order to provide quantitative index and target direction of tillage layer optimization for maize of different soil types in different areas. And theory reference can be offered so as to exploit soil producing potential according to local conditions.

针对近年来我国玉米主产区出现犁底层上升导致耕层土壤容重升高，耕层障碍严重影响玉米生长的生产问题，耕作方式与土壤互作效应显著的理论问题，本项目在调查玉米主产区多个试验点土壤结构及连续四年在不同玉米产区进行深松耕作方式研究基础上，结合田间调查与温室根箱模拟实验，选取东北春玉米区、西北春玉米区、黄淮海夏玉米区、南方玉米区代表区域不同类型土壤（黑土、黑垆土、潮土、紫色土），在田间调查耕层结构与根系发育的基础上，系统研究了紧实胁迫与调整适宜容重对不同区域不同类型土壤物理性状、养分、水分、热量空间有效性及根系时空分布的影响，揭示土壤容重胁迫下根-土互作机制及地上部生长发育与土壤结构变化及根系发育的关系，阐述当前土壤障碍生产条件下不同区域土壤玉米根际效应与调控途径，作物高产群体与关键土壤因子的匹配原理与调控机制。以期为玉米耕层优化提供定量化指标，因地制宜挖掘土壤生产潜力提供理论参考。

针对近年来我国玉米主产区出现犁底层上升导致耕层土壤容重升高，耕层障碍严重影响玉米生长的生产问题，耕作方式与土壤互作效应显著的理论问题，本项目在调查玉米主产区多个试验点土壤结构及连续四年在不同玉米产区进行深松耕作方式研究基础上，结合田间调查与温室根箱模拟实验，选取东北春玉米区、黄淮海夏玉米区等玉米主产区代表区域不同类型土壤，田间研究玉米耕层结构与根系发育、空间分布，系统研究了紧实胁迫与调整适宜容重对不同区域不同类型土壤物理性状、土壤养分、水分、热量空间有效性及根系时空分布的影响，分析了不同生态区土壤、根系在不同土壤容重下差异及机理，阐明了紧实胁迫下典型主产区土壤水分、养分、贯穿阻力、热量空间分布及动力学特征以及不同类型土壤与生态区域互作反应。研究表明，贯穿阻力是评价根系穿透性及根-土互作的重要指标，土壤容重胁迫对土壤各土层贯穿阻力影响效应不同，因压实程度及土层深度而不同，0-20cm土层，随着压实紧实程度增加，贯穿阻力升高，尤其是表层0-17cm差异显著。20-40cm 土层，压实土壤贯穿阻力显著高于正常土壤，但压实次数及压实程度影响不大。40cm-70cm深层土壤，差异趋势相反，正常土壤贯穿阻力显著高于压实土壤，容重胁迫对深层土壤的影响会重于表层土壤。长年机械耕作镇压对苗带间与苗带影响差异显著，相较于小型拖拉机，大型拖拉机（CASE210）最大干物质积累日（Tmax）相对延后（3天），快速积累启始（Tstart ）提前（2-3天），结束（Tend）延后（2-10天），并且随压实增加延后增加，最大日积累量降低，重型拖拉机反复压实，改变土壤结构形成逆境。揭示了土壤容重胁迫下根-土互作机制及地上部生长发育与土壤结构变化及根系发育的关系，阐述了当前土壤障碍生产条件下不同区域土壤玉米根际效应与调控途径，作物高产群体与关键土壤因子的匹配原理与调控机制。为玉米耕层优化提供定量化指标，为因地制宜挖掘土壤生产潜力提供理论参考。