【作者】 陈兵；

【导师】 李军；

【作者基本信息】 西北农林科技大学 ， 作物栽培学与耕作学， 2006， 硕士

【摘要】 在黄土高原植被建设与土壤水分循环研究中发现,人工植被土壤干化在日益严峻地威胁着黄土高原人工林草正常生长,土壤干层的形成已经成为植被重建的严重隐患。定量研究黄土高原人工草地水分生产力和土壤水分利用特征,摸清不同类型人工牧草地的生产力变化和草地下土壤干燥化规律,评价不同类型人工牧草地水分生产力的稳定性,为制订黄土高原植被建设规划与种植人工牧草技术方案提供科学决策依据,具有重大的理论意义与生产应用价值。本研究主要采用黄土高原典型气候区大面积的野外人工草地生产力和土壤水分的实地调查和计算机系统动力学模型数值模拟研究相结合的方法。对黄土高原人工草地生产力调查结果表明,黄土高原半湿润、半干旱、半干旱偏旱区的人工草地水分生产力水平与当地土壤水分环境和牧草生长年限密切相关。人工草地普遍存在着土壤干燥层,干燥化程度表现为干旱偏旱区>半干旱区>半湿润区。组建了黄土高原长武、镇原、固原、安塞、海原、榆林等地逐日气象要素序列、典型土壤剖面理化性状、作物生长参数、田间耕作措施、肥料特性参数和种植制度等数据库。在模型参数修订的基础上,依据实际观测结果验证了EPIC模型对黄土高原地区紫花苜蓿和沙打旺水分生产力和土壤有效水变化的模拟精度。应用EPIC模型模拟了半湿润区、半干旱区、半干旱偏旱区、北部风沙区沙打旺和紫花苜蓿草地10～30年的水分生产力和根层的土壤水分的变化。经过分析得出以下结论:(1)紫花苜蓿的风干草产量和根层有效水含量的模拟值与实测值的相关系数分别为0.8957和0.9884,沙打旺的风干草产量和根层有效水的模拟值与实测值的相关系数分别为0.714和0.9962,表明EPIC能够应用在黄土高原地区人工草地的模拟研究中。(2)半湿润区紫花苜蓿30年的水分生产潜力模拟值为4.262～13.456t/hm~2,根层有效水含量在第8年达到极低值,受土壤水分降低的影响,苜蓿的水分生产力水平开始降低,干旱胁迫日数开始加重,且分别与当年和前一年的降雨量成正相关和负相关变化。草地下土壤干层出现在2～10m深度,不随降水的补给作用而减缓。(3)半干旱区紫花苜蓿20年的水分生产潜力模拟值为1.695～5.735t/hm~2,根层有效水含量在第7年达到低值域水平,并在2～10m出现干燥层,且不受降雨的补给作用。受根层土壤水分递减的影响,固原紫花苜蓿前7年生产力水平较高,后期的水分生产力较低,干旱胁迫程度加重,生产力和干旱胁迫日数的年际变化受当年和上年降雨量影响,分别呈正、负相关性。(4)半干旱偏旱区紫花苜蓿20年的水分生产潜力模拟值为0.509～5.79t/hm~2,根更多还原

【Abstract】 It was found that soil desiccation is restricting artificial vegetation plantation day by day, and has became a serious hidden trouble of vegetations restoration during the study of vegetation restoration and soil water circulation. It is important for theory significance and production application to study water potential productivity and soil water using characteristic on the artificial pastures quantificationally, to explore the grass productivity change and the law of soil desicctation on artificial pasture, and to evaluate the stability of water productivity on different type artificial pasture on loess plateau.In this study, the method of actuarial investigation of forage productivity and soil moisture on artificial pasture combined with numerical simulation value by dynamic crop model were used. The investigated results of grass productivity and soil moisture on artificial pastures show that, the level of forage productivity on artificial pastures in semi-humid area, semiarid area, and semiarid prone drought area is compact with soil water and grass growth age. Soil desiccation has been occurring on all kind of pastures, and the degree of desiccation presents that it is worst in semiarid prone drought area, and worse in semiarid area, bad in semi-humid area. The daily weather, soil profile characteristic, crop growth parameter, tillage operations, fertilizer characteristic and cropping system databases of EPIC model on loess plateau were constructed. Based on EPIC model parameter modification, simulated effect validation on forage productivity and soil water amount of alfalfa and A. adsurgen pasture with actuarial measure values, the EPIC model were used to simulate forage productivity and root zone soil water change of alfalfa and A. adsurgen pasture at semi-humid area, semiarid area, semiarid prone drought area and north windy sandy area on loess plateau region for 10～30 year growth period, the water potential productivity and soil water change on artificial pasture were analyzed systematically. The conclusion show as followings:Based on parameter recension of EPIC model, the correlation coefficient between simulated alfalfa forage yield and root zone soil water with observed value were 0.8957 and 0.9884, the correlation coefficient between simulated A. adsurgen forage yield and root zone soil water with observed value were 0.714 and 0.9962, indicated that EPIC model could be applied to simulation study of artificial pasture on Loess plateau.更多还原