【作者】 杨建军；

【导师】 张广军； 李会科；

【作者基本信息】 西北农林科技大学 ， 环境科学， 2004， 硕士

【摘要】 苜蓿是优良豆科多年生草本植物，是目前全球广泛种植的优良牧草。黄土高原是我国苜蓿的传统种植区，也是我国苜蓿种植最集中的地区。随着退耕还林还草工程及农业产业结构调整战略的实施，苜蓿种植面积不断扩大，并已成为黄土高原许多地区农民新的收入增长点。然而苜蓿耗水量大，多年种植会导致深层土壤干燥化，形成生物性土壤下伏干层，从而使土壤水库的调节功能减弱或丧失。苜蓿能否长期发挥经济效益及生态效益引起了广泛关注，如何在生产中减缓或避免土壤下伏干层的形成，已成为该区域苜蓿产业持续发展急需解决的重要问题之一。为此，我们对陕北黄土丘陵沟壑区的苜蓿侧膜种植、播量减半种植、间作种植、及常规种植四种种植模式下苜蓿的经济性状与水分环境关系进行了研究，主要结论如下：四种种植模式下：①苜蓿的株高、分枝数、茎叶比均发生了变化，而且差异显著；②侧膜、减半、间作三种种植模式具有明显的增产效果，侧膜种植增产幅度最大，是对照的1.84倍。③各种植模式的株高、分枝数、茎叶比与产量之间均具有显著的相关关系，其中，株高对产量的作用最大，其它经济性状次之；④各种植模式的4个收获期的产量相对比例基本一致。用求差法分析了各种植模式0～180cm土层土壤水分年变化，均表现为3～5月为缓慢失墒期，6～7月为强烈失墒期，8～10月为增墒期，11月又进入失墒期。各种植模式失墒期谷值与增墒期峰值存在一定差异。用变异系数法分析了各种植模式0～180cm土层水分垂直变化，侧膜种植与间作种植的活跃层较浅，播量减半种植与对照的活跃层较深且不相同。各种植模式0～180cm的贮水量的多少为：侧膜种植>间作种植>播量减半种植>对照,与降水补给量大小顺序相同，侧膜种植的降水补给效果最佳。各种植模式耗水量大小为：间作种植>对照>侧膜种植>播量减半种植；水分利用率的大小顺序为：侧膜种植＞间作种植＞播量减半种植＞对照，各种植模式的降水生产力规律一致。各种植模式降水生产力大小顺序：侧膜种植>间作种植>播量减半种植>对照。侧膜种植最高，对照的最低，更多还原

【Abstract】 Alfalfa is an excellent perennial leguminous grass, which is widely planted in the world. Loess Plateau is not only the traditional district in which alfalfa is planted, but also the intensive district. With the carry out of returning farmland on hill to forest and pasture and strategy adjustment of industry in rural district, Alfalfa became the new increase point of income in many district of Loess Plateau, and the area increased by and by. But the water consumption of alfalfa is very large, if alfalfa was planted perennially, which would lead to the dry layer of deep soil layer, then the function of regulation of soil reserior lost. So whether the alfalfa can better the economic benefit and ecological benefit, and how to slower or avoid the formation of dry layer, has become the emergent demand of development of alfalfa in this district. On the hill-gully region of Loess Plateau, we study the relation between the economic property and water environment under four establishments, which includes the halve sowing establishment, the intercrop establishment, the plastic film mulching establishment and the check establishment.The main results showed:The height, branch number and stem and leave ratio of the four establishments changed. Although there is difference among every establishment, the formation of yield is formed with the same regulation. Based on the yield of the whole year, four establishments has the remarkable increasing effect, and the plastic film mulching establishment has the largest yield, which is 1.84 larger than that of check. Based on the path analysis of the individual plant, there is a very significant linear dependence between the height, branch and stem and leave ratio and yield. There is also a very significant linear dependence between every two of the three treatments. The height affected the yield greatly, but the other three properties have different effect on yield with different order. The soil water is analyzed by margin model, and the seasonal change of soil water is devided into four stage: from March to May, when the soil water-storage lost very slowly; from June to July, when the soil water-storage lost heavily; from August to October, when the soil water-storage increased greatly; in November, the soil water-storage lost very slowly. Based on the analysis of SD and CV, the vertical profile is divided into two parts. The plastic film mulching and intercrop have the same active layer and stable layer, while the halve sowing norm and check have deeper active layer and stable layer.The water-storage capacity of 0-180 cm of the four establishment presents the trend as: the plastic film mulching>the intercrop>the halve sowig norm>the check, and the compensation of rainfall has the same order .The plastic film mulching has the most significant effect. <WP=7>The trend of the water consumption in whole growth stage presents as: the intercrop>the check>the plastic film mulching>the halve sowing norm. The water-use efficiency presents the order as: the plastic film mulching>the intercrop>the halve sowing norm >the check. The precipitation productivity presents the same trend,and the plastic film mulching has the biggest precipitation productivity, while the check has the smallest one. The order of precipitation productivity presents as: the plastic film mulching>the intercrop>the halve sowing norm >the check.更多还原