不同植被间土壤水分与养分竞争研究

发布时间：2018-05-26 03:40

本文选题：土壤水分 + 土壤养分　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：为了研究不同植被间土壤水分、养分竞争关系以及防护林带对农田土壤水分养分的影响,分别以黄土高原水蚀风蚀交错区神木县六道沟流域及黑河中游张掖绿洲为试验区,对黄土高原水蚀风蚀交错区4种相邻植被间(撂荒地、柠条地、苜蓿地和农地)的水分竞争关系进行研究,主要测定了不同植被间、不同距离内土壤水分含量;以及对张掖绿洲农田土壤水分、养分、农作物产量的空间分布进行研究,主要测定距离林带2 m(D2)、14 m(D14)、29 m(D29)和42 m(D42)处土壤水分含量、土壤硝态氮含量及作物产量。研究结果表明:(1)绿洲农田防护林带对其西侧邻近农田土壤水分含量与农作物产量影响显著,越靠近林带农田土壤水分含量与农作物产量越低,从距离林带2m范围内的农作物产量到距离林带10 m范围内农作物产量增加了51%,相比之下,从距离林带14 m农作物产量到距离林带42 m产量增加了17%,故防护林带对农作物产量的影响主要集中于距离林带10 m范围内。(2)农田土壤剖面硝态氮含量随着与林带距离的减小而增大,随着土层深度的增加而增大。不同时期距离林带2 m、14 m处深层(200 cm-300 cm)农田土壤硝态氮含量迅速增大;相比之下距离林带29 m、42 m处深层(200 cm-300 cm)土壤硝态氮含量略微增大或者保持不变。靠近林带的D2、D14有超过70%的土壤硝态氮积累到2m以下土层,而远离林带的D29,D42深层土壤硝态氮积累量仅占总积累量40%;不同时期上层(0-200 cm)土壤硝态氮积累量无明显差异,且上层土壤硝态氮积累量仅占总积累量的18%。绿洲防护林的存在可能导致靠近林带农田土壤硝态氮在深层(2 m以下)大量积累,有可能对地下水造成污染。(3)陕北水蚀风蚀交错区4种植被类型中农地0-400 cm土层土壤总储水量最高,苜蓿地土壤总储水量最低,柠条地略高于苜蓿地,深根性植物柠条和苜蓿相邻处测点的土壤含水量在所有测点中最低。故深根性植物柠条和苜蓿耗水量大,耗水深度超过4 m。撂荒地和农地土壤含水量随着靠近柠条地和苜蓿地呈下降趋势,随着与柠条地距离的逐渐减小,撂荒地土壤含水量逐渐减小,呈梯度变化趋势,且柠条大量利用深层土壤水分,同时对邻近撂荒地影响深度至少有3 m,在水平方向上对撂荒地土壤水分的影响距离至少有6 m。(4)临近农地的苜蓿和临近撂荒地的柠条有较高的生物量指标,证明这两种深根系植物吸收利用了相邻地块的土壤水分。因此,柠条和苜蓿对土壤水分竞争激烈,不宜搭配种植,而深根浅根植物搭配扩大了深根系植物根系吸水空间,有利于其生长,可构建复合植被。
[Abstract]:In order to study the relationship between soil moisture and nutrient competition among different vegetation and the effect of shelterbelt on soil moisture and nutrients in farmland, the Ludaogou Valley of Shenmu County and Zhangye Oasis in the middle reaches of Heihe River were used as experimental areas, respectively, in the water erosion ecotone of the Loess Plateau. The water competition between four adjacent vegetation (abandoned land, Caragana korshinskii, alfalfa land and farmland) in the water erosion ecotone of the Loess Plateau was studied. The spatial distribution of soil moisture, nutrient and crop yield in Zhangye oasis was studied. The soil moisture content, nitrate nitrogen content and crop yield were determined at the distance of 2 m ~ 2 ~ 2 ~ 2 ~ (14) m D ~ (14) C ~ (14) D ~ (29) ~ (29) and 42 m ~ (2) ~ (2) ~ (2) ~ (2) ~ (2) ~ (2). The results showed that the oasis farmland shelterbelt had a significant effect on the soil moisture content and crop yield in the west of the oasis, and the closer the forest belt, the lower the soil moisture content and crop yield. The crop yield increased by 51% from 2 m from the forest belt to 10 m from the forest belt. From 14 m distant forest belt to 42 m distance forest belt yield increased by 17%, so the effect of shelterbelt on crop yield was mainly concentrated in 10 m distance forest belt. The distance decreases and increases, It increases with the depth of soil. The nitrate nitrogen content of farmland soil increased rapidly at 2 ~ 14 m from forest belt in different periods, while it increased slightly or remained unchanged at a depth of 200 cm-300 路cm from 29 m ~ 42 m from forest belt. More than 70% of the soil nitrate nitrogen accumulated to the soil layer below 2m in the area near the forest belt, while the accumulation amount of nitrate nitrogen in the deep soil of D29 ~ (2 +) D _ (42) far from the forest belt accounted for only 40% of the total accumulation amount, but there was no significant difference in the nitrate nitrogen accumulation in the upper layer (0-200 cm) in different periods. The accumulation of nitrate nitrogen in the upper soil only accounted for 18% of the total accumulation. The existence of oasis shelterbelt may lead to the accumulation of nitrate nitrogen in the farmland near the forest belt below 2 m deep layer. It is possible to pollute groundwater. (3) the total water storage of farmland in 0-400 cm soil layer is the highest, and that of alfalfa land is the lowest, and Caragana korshinskii is a little higher than that of alfalfa land. The soil moisture content was the lowest at the adjacent sites of Caragana korshinskii and alfalfa. Therefore, the water consumption of Caragana korshinskii and alfalfa is large, and the water consumption depth is more than 4 m. The soil moisture content of abandoned land and farmland decreased with the close to Caragana and alfalfa land, and gradually decreased with the distance from Caragana land. The soil moisture content of abandoned land decreased gradually, and Caragana korshinskii made a large use of deep soil moisture. At the same time, the influence depth of adjacent abandoned land was at least 3 m, and the influence distance of horizontal direction on soil moisture in abandoned land was at least 6 m 路m ~ (4) alfalfa close to farmland and Caragana korshinskii close to abandoned land had higher biomass index. It is proved that these two deep root plants absorb and utilize soil moisture from adjacent plots. Therefore, the competition between Caragana and alfalfa for soil moisture is fierce, so it is not suitable to plant with collocation, while the collocation of deep root and shallow root plants expands the water absorption space of deep root plants, which is beneficial to their growth and can be used to construct compound vegetation.
【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】：2015
【分类号】：S152.7;S158

【相似文献】