本文關(guān)鍵詞： 平篩 旋篩 土壤可蝕性 土壤干團聚體指標(biāo) 土壤風(fēng)蝕度　出處：《河北師范大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：土壤風(fēng)蝕是風(fēng)對地表土壤的侵蝕、搬運、堆積的過程。土壤風(fēng)蝕破壞地表,造成土壤營養(yǎng)物質(zhì)損失,導(dǎo)致土地荒漠化。土壤可蝕性是土壤風(fēng)蝕研究的重要方面,土壤干團聚體是影響土壤可蝕性的重要參數(shù),其組成結(jié)構(gòu)和基本特性是決定土壤侵蝕、壓實、板結(jié)等物理過程與作用的關(guān)鍵指標(biāo)之一,同時也是土壤肥力的基礎(chǔ)和評價土壤質(zhì)量的重要指標(biāo)。通過對土壤風(fēng)蝕度(EF)、平均幾何直徑(GMD)、平均質(zhì)量直徑(MWD)、分形維數(shù)D的分析,可以進一步闡明干團聚體特征間接量化土壤可蝕性,而根據(jù)平篩和旋篩兩種篩分方式對干團聚體指標(biāo)影響的研究并不多見。因此,本文選取河北壩上康保縣境內(nèi)四種地類(草地、林地、留茬地、翻耕地)74個土壤樣品,對土壤樣品進行平篩、旋篩篩分和土壤理化性質(zhì)處理,比較土壤干團聚體粒徑分布,從而探究平篩和旋篩對于土壤干團聚體指標(biāo)以及土壤機械組成的影響,不同土地利用方式間的干團聚體指標(biāo)差異,進而評價本區(qū)域內(nèi)土壤可蝕性現(xiàn)狀等,研究結(jié)果表明:(1)通過對平篩、旋篩所得出的土壤粒度組成進行Mann-Whitney U檢驗的差異性分析發(fā)現(xiàn),平篩和旋篩以0.84mm粒級為分異界限,小粒級(0.84-0.5mm、0.5mm)處差異性不顯著,在大粒級(20mm、20-5mm、5-2mm、2-0.84mm)差異性顯著,呈現(xiàn)出大粒級的土壤顆粒差異性顯著,而小粒級不顯著的現(xiàn)象。由于該地區(qū)礫石含量較高和平篩的震蕩作用中礫石打散較大團聚體,一定程度上影響土壤機械組成,粒徑較大的土壤顆粒被破碎后造成可蝕性顆粒有所增多,呈現(xiàn)出隨EF值降低差異增大的趨勢,使平篩的EF值高于旋篩。同時0.84mm(0.84-0.5mm、0.5mm)粒級差異性不顯著也是平篩與旋篩EF差異性不顯著的原因。(2)通過對GMD、WMD、D干團聚體指標(biāo)進行二元相關(guān)性分析和Mann-Whitney U檢驗差異性分析,在平篩、旋篩團聚體指標(biāo)二元相關(guān)性分析中,GMD、WMD、D、EF都呈現(xiàn)極顯著正相關(guān);D、EF指標(biāo)差異性不顯著,EF(0.84mm)差異性不顯著符合粒度組成分析中的結(jié)論,而差異性分析中GMD、WMD指標(biāo)差異性顯著,同時在相關(guān)性分析的1:1線圖中呈現(xiàn)出平篩GMD、WMD的值普遍高于旋篩,平篩和旋篩的GMD、WMD指標(biāo)同大粒級(20mm、20-5mm、5-2mm)土壤粒度組成均為極顯著正相關(guān),同小粒級(0.5mm)均為極顯著負相關(guān),由于礫石可能打散大粒級的土壤顆粒,增加了2-0.84mm粒級不可蝕土壤顆粒,土壤抗蝕性增強,從而使得平篩GMD、WMD指標(biāo)的值高于旋篩。(3)平篩和旋篩的分形維數(shù)D與小粒級(0.5mm)均為極顯著正相關(guān),同大粒級(20mm、20-5mm、5-2mm、2-0.84mm)均為極顯著負相關(guān),并且平篩和旋篩的D顯著正相關(guān)但差異性不顯著。平篩和旋篩的GMD、WMD之間差異性顯著,并呈現(xiàn)平篩大于旋篩的情況;D在不同地類均與礫石含量呈現(xiàn)顯著負相關(guān),而GMD與WMD指標(biāo)只在林地地類中與礫石含量存在顯著相關(guān)性,D與不同粒級的相關(guān)性分析中同樣優(yōu)于GMD、WMD,因此,D在表征不同地類土壤的粒度組成的能力強于GMD、WMD指標(biāo),分形維數(shù)D對于表征土壤可蝕性和土壤風(fēng)蝕狀況相較于GMD、WMD更為穩(wěn)定,另外,發(fā)現(xiàn)分形維數(shù)D對于小粒級描述更為敏感,而GMD、WMD指標(biāo)對于土壤的大粒級更為敏感。(4)在不同地類的土壤團聚體指標(biāo)均值分析中,林地在平篩和旋篩均為抗蝕性最強的地類,其GMD、WMD均值最高,D、EF均值最低。留茬地抗蝕性優(yōu)于翻耕地,留茬地EF低于翻耕地,且GMD、WMD高于翻耕地,D小于留茬地。農(nóng)田防護林和耕地留茬作為壩上地區(qū)的主要防風(fēng)蝕手段具有明顯抗蝕效果,生態(tài)效益明顯。(5)平篩、旋篩作為篩分土壤粒度組成的先行步驟對于土壤風(fēng)蝕研究產(chǎn)生基礎(chǔ)性影響,其對于土壤粒度組成的影響將會進一步影響土壤干團聚體指標(biāo),本文對于平篩的GMD、WMD值高于旋篩,在土壤機械組成的大粒級(20mm、20-5mm、5-2mm、2-0.84mm)差異性顯著的情況進行了分析,對于礫石含量較高的風(fēng)蝕區(qū)的土壤使用平篩篩分有可能產(chǎn)生誤差;GMD、WMD、D、EF之間的相關(guān)性分析中,平篩和旋篩保持了各指標(biāo)間相關(guān)性分析的一致性,但旋篩的相關(guān)性系數(shù)均高于平篩,旋篩的相關(guān)性均優(yōu)于平篩。因此,旋篩相較于平篩對于土壤篩分和土壤粒度還原具有一定的優(yōu)越性。(6)通過EF、GMD、WMD、D與土壤理化性質(zhì)、土壤機械組成的相關(guān)性分析中發(fā)現(xiàn),研究區(qū)EF、D與礫石含量在各地類均為顯著相關(guān),土壤抗蝕性指標(biāo)更多的受到礫石含量較高的影響。有機質(zhì)、碳酸鈣與EF、GMD、WMD干團聚體指標(biāo)在林地、留茬地、翻耕地中的相關(guān)性較差。草地地類中各團聚體指標(biāo)與有機質(zhì)相關(guān)性較好,有機質(zhì)與粘粒有利于草地中土壤團聚體形成。翻耕地和留茬地由于受到耕作制度、農(nóng)田分散管理的影響、林地由于受到防護力種植株距、走向、樹齡、樹種等影響,以及長期的風(fēng)蝕導(dǎo)致有機質(zhì)含量較低,使土壤GMD、WMD、D、EF與有機質(zhì)、碳酸鈣、粘粒、砂粒指標(biāo)在林地、留茬地、翻耕地中無相關(guān)性。因此,較高的礫石含量會對不同篩分方式的土壤機械組成造成影響,而風(fēng)蝕區(qū)由于長期遭受風(fēng)蝕,礫石含量普遍較一般土壤高,同時土壤有機質(zhì)含量較低,會導(dǎo)致土壤干團聚體指標(biāo)的差異,對表征土壤可蝕性造成影響。
[Abstract]:Soil erosion is the wind erosion on the surface of the soil, handling, stacking process. Soil erosion destroy the surface, resulting in soil nutrient loss, resulting in land desertification. Soil erodibility is an important aspect of soil erosion, soil dry aggregate is the influence of soil erodibility of the important parameters, the structure and basic characteristics is to determine the soil erosion, compaction, compaction index is one of the key physical processes and function, but also the basis of soil fertility and soil quality assessment is an important indicator. The soil erosion degree (EF), geometric mean diameter (GMD), mean weight diameter (MWD), analysis of the fractal dimension D, can further clarify dry aggregate characteristics of indirect quantification of soil erodibility, and based on the flat screen and rotating screen two screening methods on dry aggregate index is rare. Therefore, this paper selects the Hebei dam in Kangbao County land four Class (grassland, woodland, stubble, farmland) of 74 soil samples, soil samples on the flat screen, rotary screen and soil physicochemical properties, soil dry aggregates, so as to probe into the flat screen and rotating screen effects on soil dry aggregate index and soil mechanical composition, aggregate index the difference between the stem of different land use patterns, and to evaluate the regional soil erosion status, the results of the study show that: (1) based on the flat screen, rotary screen the soil particle size composition of Mann-Whitney U test analysis on the difference of the flat screen and rotating screen with 0.84mm size difference line of small size (0.84-0.5mm, 0.5mm). The difference is not significant, in large size (20mm, 20-5mm, 5-2mm, 2-0.84mm) showed significant difference, the difference of soil particle size was large, and the small size is not significant. The phenomenon of gravel content and higher in the area The shock effect of flat screen in scattered gravel aggregates, have a certain effect on the soil mechanical composition, particle size of larger particles were broken by soil erodibility particles increased, decreased with increasing the difference of the EF value, the EF value is higher than the flat screen, rotary screen. At the same time 0.84mm (0.84-0.5mm, 0.5mm) no significant differences in size is also flat screen and rotating screen EF had not significant difference. (2) based on GMD, WMD, D index analysis of dry aggregates two yuan Mann-Whitney correlation analysis and U test the difference, in flat screen, aggregate index of two yuan in correlation analysis, rotating screen GMD, WMD. D, EF showed a highly significant positive correlation; D, EF index had not significant difference, EF (0.84mm) had not significant difference with grain size analysis of the conclusion, and the difference of GMD in WMD, there were significant differences in 1:1 at the same time, correlation analysis of the line graph showing a flat screen GMD. W MD鐨勫，

本文編號：1446899