不同耕作方式下黑土区农田中小型土壤动物群落特征

[目的]研究中小型土壤动物群落组成、多样性、动态特征及垂直分布情况,反映土壤环境状况,为探索黑土区农田适宜的耕作方式提供参考依据。[方法]采用改良干漏斗(modified tullgren)法分离中小型土壤动物,分析比较了不同耕作方式下中小型土壤动物的群落结构及分布特征。[结果]从研究样地共捕获中小型土壤动物3 749只,隶属47个类群。其中四奥甲螨科(Quadroppiidae)和等节■科(Isotomidae)为试验区的优势类群。3种耕作方式下,0—10 cm土层中小型土壤动物个体数占总个体数的71%,在垂直分布上具有明显的表聚性。深松处理下中小型土壤动物个体数最多(1 671),CK处理下类群数最多(41)。CK处理下中小型土壤动物多样性指数和丰富度指数最高,分别为(2.81)和(3.81);深松处理下中小型土壤动物优势度指数最高(0.15)。不同耕作方式下土壤渗透总量表现为深松CK免耕;土壤含水量和土壤温度表现为深松免耕CK;土壤容重表现为免耕CK深松。中小型土壤动物个体数与土壤容重呈显著正相关(p0.05);中小型土壤动物丰富度指数与土壤有机质呈显著正相关(p0.05);中小型土壤动物均匀度指数与土壤渗透总量呈极显著正相关(p0.01)。[结论]耕作方式对中小型土壤动物的群落结构有明显的影响,深松耕作后显著提高中小型土壤动物个体数,能够有效改善土壤环境,比免耕和传统耕作更有利于中小型土壤动物的生存与繁殖。     

耕作方式对农田土壤水分变化特征及水分利用效率的影响

探讨耕作方式对土壤含水量及水分利用效率的影响,对于高效利用自然降水,提高自然降水利用效率,增加作物产量具有重要的理论与实践意义。因此,采用铝盒称重法测定不同年份、季节、土壤剖面及冻融前后土壤含水量,研究不同耕作方式对土壤含水量及作物水分利用效率的影响。结果表明:在特定时期内土壤含水量随土层深度的增加而减少,特别是土层40cm以下尤为明显,而且随季节呈波动性变化且受降雨影响较大;季节冻融作用明显降低土壤含水量,但深松较其他处理土壤含水量增幅为0.93%~2.23%;土壤贮水量随季节呈先增后降的趋势变化,且生育前期明显高于生育后期;不同耕作方式对田间耗水量和耗水系数无显著影响,但深松耕作显著提高作物水分利用效率,并且水分利用效率与产量的相关性达到极显著水平(r=0.76**)。综合分析认为,保护性耕作结合深松是有效改善耕层结构,增加土壤含水量,提高自然降水利用效率的有效耕作方法。因此,该研究可为东北雨养农业区留茬深松保护性耕作技术的推广提供理论依据。     

不同耕作方式下玉米农田土壤养分及土壤微生物活性变化

通过连续3年的野外调查与室内分析试验,研究了不同耕作方式（翻耕、旋耕、免耕）对玉米农田土壤养分及土壤微生物活性的影响。结果表明,不同耕作方式下土壤pH值略显酸性,土壤容重与土壤总孔隙度变化趋势相反;土壤容重基本表现为:免耕 > 翻耕 > 旋耕;土壤总孔隙度TSP基本表现为:翻耕 > 旋耕 > 免耕,不同耕作方式差异均显著（p<0.05）。不同耕作方式下土壤养分（有机碳、全氮含量）和有效养分（有效磷、铵态氮和硝态氮）均呈现出一致性规律,大致表现为翻耕 > 旋耕 > 免耕,不同耕作方式下土壤全磷含量差异均不显著（p > 0.05）;与免耕相比,土壤微生物量碳和氮、土壤微生物数量（细菌、真菌、放线菌、固氮菌和纤维素菌）均有明显的增加,大致表现为:翻耕 > 旋耕 > 免耕。土壤微生物活度的变化范围为0.38~0.69,依次表现为翻耕 > 旋耕 > 免耕,不同耕作方式下土壤微生物活度差异均显著（p<0.05）。不同耕作方式下土壤微生物量碳周转率高于氮周转率,说明微生物量碳更新比微生物量氮快,其中翻耕处理下土壤微生物量碳和氮更新较旋耕和免耕快。通径分析发现,不同土壤环境因子对土壤微生物活度产生直接和间接负作用,其中有机碳、全氮、硝态氮、铵态氮、细菌数量对土壤微生物活度产生直接效应;土壤微生物量碳、微生物量氮、真菌数量和固氮菌数量对土壤微生物活度产生间接效应。     

海河低平原不同耕作方式下麦田土壤生态环境特征

在片面追求单产导致耕地可持续生产力退化背景下,为探索一种科学合理的土壤耕作模式,优化麦田土壤生态环境,促进耕地生产力可持续提升,于2011-2013年小麦生长季,大田条件下,通过在小麦季设旋耕、深松和深耕3种耕作方式处理,在海河低平原进行了2a研究。在不同土壤耕作方式下,采用环刀法测定麦田土壤容重差异,采用HL20型自动气象数据采集器测定10cm深处土壤温度,采用动态密闭气室法测定土壤呼吸速率,采用TDR法测定土壤含水量,采用平板稀释法测定土壤微生物数量,采用重铬酸钾容量法-磷酸浴法、靛酚比色法、磷酸苯二钠比色法、高锰酸钾滴定法等方法测定土壤酶活性、采用碱解扩散法、碳酸氢钠浸提-钼锑抗比色法、乙酸铵浸提-火焰光度法、重铬酸钾容量法-磷酸浴法等方法测定土壤养分状况,采用重铬酸钾容量法和氯仿熏蒸-K2SO4浸提法分别测定土壤有机碳和微生物量碳含量,成熟时期测定产量、水分利用效率和肥料偏生产力。结果表明:深松处理有利于20-40cm土层土壤容重降低,加深耕层。旋耕处理和深松处理分别有利于表层和深层土壤水分储蓄。深耕处理有利于提高土壤温度,分别比深松处理和旋耕处理提高5.8%和8.8%。深耕处理土壤呼吸作用最高,分别比旋耕处理和深松处理提高8.0%和4.8%。小麦返青至成熟期,深松处理可提高土壤过氧化氢酶和脲酶活性,且深松处理还可提高小麦灌浆后土壤碱性磷酸酶活性;深耕处理和深松处理可分别在灌浆前、后提高表层土壤多酚氧化酶活性。深松处理全生育期碱解氮含量最低;旋耕处理速效磷有"表层聚集"现象;深松处理有利于20cm以下土层速效磷和速效钾积累;深耕处理可提高表层土壤有机质含量,旋耕处理和深松处理分别在返青前、后提高20-40cm土层有机质含量。深松处理有利于真菌和细菌增殖,旋耕则有利于放线菌的增殖。深松处理和旋耕处理分别在不同生育期可提升土壤微生物生物量碳含量。旋耕处理和深松处理分别在小麦返青前和返青后土壤总有机碳含量最高。深松处理可降低麦田耗水量,提高产量、水分利用效率和肥料偏生产力。     

长期施肥与耕作方式对土壤酶活性的影响

通过长期田间试验,研究了白浆土耕种18年后施肥与耕作方式对土壤酶活性的影响。结果表明:无论轮作还是连作施肥,土壤脲酶、蔗糖酶、中性磷酸酶活性均有不同程度提高,施用厩肥尤为明显,OM处理的脲酶活性最大,与CF、CK处理间差异显著,轮作的土壤脲酶活性和中性磷酸酶活性均高于连作;深松处理配施化肥可以提高白浆土的蔗糖酶和脲酶活性,且轮作影响大于连作。     

东北黑土区不同耕作方式土壤养分与酶活性的时空变化

通过田间试验研究了东北黑土区玉米不同耕作方式的土壤养分与酶活性的时空变化规律.结果表明,整个生育期不同处理在各个土层均有较高的碱解氮含量,而在播种前常规耕作高于宽窄行,玉米生长中期则是宽窄行高于常规耕作,收获后各处理含量水平基本一致.有效磷不同处理均表现出养分表聚现象,且宽窄行在各个生育期的不同土层内均高于常规耕作.速效钾含量随着土层的加深降低不十分明显,处理间没有表现出明显的差异,体现了钾素养分移动性大的特点.玉米生长关键期的全量氮、磷、钾变化幅度不大,处理问含量水平一致;有机质含量在2%～3%之间;pH值不同处理均随着土层的加深逐渐升高的趋势,说明不同的耕作措施都有促进土壤表层酸化的现象.不同耕作方式土壤酶活性在整个生育期变化趋势相同,无明显差异.     

不同耕作措施对东北玉米农田土壤物理性质的影响

为了揭示耕作措施对东北玉米田土壤物理性质的影响,本研究进行了连续4年的田间定位试验,探明了深松(ST)、免耕(NT)以及传统耕作(CT)对东北玉米田土壤物理指标(土壤容重、土壤三相比、土壤结构指数以及颗粒组成)的影响。结果表明：与传统耕作相比,深松处理能够显著降低0～20 cm土层的土壤容重(P<0.05),下层土壤(20～40 cm)各处理间差异不显著,其中免耕处理土壤容重最大;同时,深松处理降低了0～40 cm土层的土壤固相比例,显著增加气相比例(P<0.05),而免耕处理增加了下层土壤(20～40 cm)的固相比例,降低了液相比例;深松处理可以显著提高下层土壤的结构指数,平均增加28.3%(P<0.05),另外,深松处理的土壤三相结构距离为15.0,显著低于其他两个处理(18.4和17.7)(P<0.05),使得耕层土壤物理结构更加接近理想状态,免耕与常规耕作处理间的差异不显著;深松可以增加0.002～0.2 mm粒级的比例,0～40 cm土层中土壤颗粒0.002～0.2 mm等级中所占比例大小依次为深松>免耕>传统耕作。种植玉米后,深松耕作措...     

不同施肥与耕作方式下土壤—径流氮磷变化特征

为探讨长期不同施肥与耕作条件下土壤与径流中氮磷化学计量关系变化。在紫色土坡耕地设5个处理：顺坡耕作无施肥(对照,CK)、顺坡耕作+化肥有机肥混施(T1)、顺坡耕作+单施化肥(T2)、顺坡耕作+1.5倍单施化肥增量(T3)和横坡耕作+单施化肥措施(T4),每个处理均设3个重复,分析2008—2017年土壤总氮(TN_S)、总磷(TP_S)含量与化学计量TN_S∶TP_S,以及83场产流事件径流总氮(TN_W)、总磷(TP_W)浓度及化学计量TN_W∶TP_W的变化特征。结果表明：CK处理TN_S、TP_S含量与T1处理差异不显著,但显著低于T2、T3、T4处理,主要是因为化肥施用显著提高土壤氮磷含量。各处理间TN_S∶TP_S无显著差异,其平均值为3.55～4.79,CV值为0.39～0.94,表明施肥对于多年间土壤氮磷比并无显著影响。CK处理的TN<...     

坡耕地不同耕作方式对土壤性状的影响

通过田间实验,在坡耕地采用垄沟种植的耕作方式,设置垄覆膜旋耕(X)、垄覆膜灭茬翻耕(F)、垄覆膜灭茬深松(S)3种处理方式;垄、沟比为60:40.结果显示,不同的耕作方式对土壤产生不同程度的扰动,使土壤耕作层密度总体上存在显著差异,其中0～20 cm及20～40 cm深松耕作方式土壤密度相对较低.其中X处理在一定程度上...     

不同耕作方式对土壤水热变化的影响

为了研究各免耕处理下土壤的水热变化,2005～2008年在黄河流域清水河县对玉米进行了5种不同耕作方式的试验研究。结果表明,土壤含水量、温度在5种不同耕作方式下均达到了显著(p0.05)或极显著(p0.01)差异。①三年间在0～10 cm土层,整个生育期内留高茬覆盖、留低茬覆盖、留高茬、留低茬处理的平均土壤含水量分别较常规耕作增加了29.92%、26.23%、17.30%、13.95%。在0～40 cm土层,留茬覆盖处理能有效地抑制土壤水分蒸发,提高作物的水分利用率。在80～100 cm土层,土壤含水量达到最大值。土壤水分变化主要受季节影响,随秸秆覆盖和降雨量的变化而变化。②土壤温度在5 cm土层变化幅度最大,留茬覆盖能有效地调节土壤温度,使土壤温度日变化平缓,且随土层深度的增加土壤温度的变化幅度减小。③不同耕作方式形成的土壤微环境为玉米的生长发育提供了更好的基础,其中留茬覆盖处理效果最佳,由于水热状况良好,留茬覆盖下作物产量较高。     

Longterm effects of soil compaction and tillage on Collembola and straw decomposition in arable soil

Soil core samples were taken from May 1996 to October 1996 at four week intervals to assess the longterm effects of compaction due to soil tillage on Collembola in arable land. Two different tillage systems were studied: conservation tillage (CS) with rotary harrowing to 120 mm depth and conventional tillage (CT) with a mould board plough to 300 mm depth. Soil compaction was achieved by wheeling with graded loads: 0t, 2 × 2.5t and 6 × 5.0t (wheeling frequency × wheel load) in early spring 1995. Litter decomposition rate was investigated by the minicontainer-method, using two different mesh-sizes: 20 μm (excluding mesofauna) and 500 μ (including mesofauna). The substrate used was winter wheat straw, corresponding to the crop cultivated on the field.We recorded 25 species of Collembola. The abundance of Collembola during the growing season was at a minimum in June in both tillage systems. Thereafter, numbers of individuals increased, probably due to better nutrition. Mesaphorura krausbaueri s.l. was eudominant in CS. In CT Folsomia fimetaria and M. krausbaueri s.l. reached high abundances at the end of August. Harvesting and tilling supported population growth in CS, while numbers in CT decreased. The collembolan species showed different preferences in regard to the tillage system and the grade of compaction. During the first 4 weeks of exposure the decomposition rate of straw was highest. The decomposition rate in the minicontainers with 20 μm mesh-size was higher due to better moisture conditions for the microorganisms. After harvest and tilling the decomposition rate increased, especially in the CS-plots, because of aeration and incorporation of residues. Population fluctuation in the minicontainers was caused by migration of Collembola in response to changing moisture conditions. The main species in the minicontainers were large and mobile. Compared to the surrounding soil, species diversity was reduced.     

转变耕作方式对长期旋免耕农田土壤有机碳库的影响

土壤深松是解决长期旋免耕农田耕层浅薄化、亚表层（>15～30 cm）容重增加等问题的有效方法之一,而将长期旋免耕农田进行深松必然导致农业生态系统中土壤有机碳（soil organic carbon,SOC）及碳固定速率的变化。因此,为对比将长期旋免耕转变为深松前后农田土壤有机碳库变化,该研究利用连续12a 的旋耕和免耕长期定位试验以及在此基础上连续6 a旋耕-深松和免耕-深松定位试验,对比了转变耕作方式对农田土壤0～30 cm有机碳含量、周年累积速率及其固碳量的影响。研究结果表明,经过连续12 a的旋耕和免耕处理（2002－2014）,2014年免耕处理土壤0～30 cm有机碳储量比试验初期（2002年）提高38%,旋耕处理降低了30%,而对照常规处理无显著差异。免耕处理土壤0～30 cm有机碳储量比旋耕处理高约2.6倍（2014年）。长期免耕显著提高了土壤0～30 cm的有机碳含量,2002~2014年其土壤0～30 cm固碳量为16.69 t/hm2,但长期旋耕导致土壤0～30 cm SOC含量显著降低,表现为土壤有机碳的净损耗,年损耗速率为?0.75 t/hm2。而长期旋耕后进行深松（旋耕-深松处理）6年其土壤0～30 cm的有机碳含量较原旋耕处理提高32%～67%,且显著提高了土壤固碳量及周年累积速率;免耕-深松土壤0～30 cm的有机碳周年累积速率较免耕处理下降了42%。长期旋耕造成有机碳水平下降的条件下,将旋耕处理转变为深松处理在短期内更有利于促进土壤有机碳的积累,而将长期免耕处理转变为深松措施,降低了土壤有机碳的累积速率和固碳量。     

Verification of traffic-induced soil compaction after long-term ploughing and 10 years minimum tillage on clay loam soil in South-East Norway

Grain yields are presented from a 10-year field trial with four tillage regimes (annual ploughing, harrowing only, ploughing/harrowing alternate years and minimum tillage) on clay loam. We also present soil physical analyses and use the compaction verification tool (CVT) to assess compaction on plots with annual ploughing and minimum tillage, after using slurry tankers with contrasting wheel loads (4.1 Mg, 6.6 Mg) and wheeling intensities (1×/10×) in the 11th trial year, and yields monitored two years after compaction. Winter wheat yields in the period before compaction were strongly affected by tillage, with annual ploughing giving on average 24% higher yield than direct drilling. Both wheat and oats were far less affected in treatments with harrowing only or ploughing/harrowing alternate years, on average within 6% of annual ploughing. Yields after compaction were affected by both previous tillage and compaction intensity. In the first year, single wheeling after annual ploughing gave 23% yield reduction with 4.1 Mg wheel load and 28% reduction with 6.6 Mg wheel load, whilst multiple wheeling gave 14% reduction at 6.6 Mg wheel load. Yield reductions after minimum tillage ranged from 63% (single wheeling with 4.1 Mg) to 100% (multiple wheeling with 6.6 Mg). Similar trends were found in the second year. The soil physical data indicated that all wheeling led to changes in bulk density, pore sizes and permeability in both topsoil and subsoil on both sampled tillage plots. However, effects in the subsoil were partly masked by the soil's high initial bulk density, partly due to its high clay content. The CVT, which plots air capacity against hydraulic conductivity, suggested some harmful compaction on both plots, with the minimum tillage plot being less affected than the ploughed plot. However, yield results did not support this conclusion, indicating that other factors limited yields on the minimum tilled plot.     

Evaluating the long-term effects of tillage systems on soil structural quality using visual assessment and classical methods

Current agricultural practices and their impacts on the sustainability of crop production can be evaluated by simple and reliable soil structure assessment tools. The study was conducted to determine the effects of long-term (2006–2017) tillage systems on structural quality of a clayey soil using the visual evaluation of soil structure (VESS) and classical field and laboratory measurements. A field experiment with seven tillage systems, representing both traditional and conservation tillage methods, was conducted on a clayey soil in the Cukurova region, Turkey. Soil samples from 0–10, 10–20 and 20–25 cm depths were analysed for mean weight diameter (MWD), porosity and organic carbon. Penetration resistance (PR) was determined in each treatment plot. The VESS scores (<2) of upper 0–5 cm indicated a good structural quality for all tillage systems. The VESS scores were positively related to PR and MWD and negatively to macroporosity (MaP) and total porosity. In reduced and no-till systems, poorer soil structures were observed in subsurface layers where firm platy and angular blocky structures were defined. Mean VESS score (3.29) in 20–25 cm depth where PR was 3.01 MPa under no-till indicated a deterioration of soil structural quality; thus, immediate physical interventions would be needed. Lower VESS scores and PR values under strategic tillage which was created by ploughing half of no-till plots in November 2015 indicated successful correction of compaction caused by long-term no-till. The results suggest that the VESS approach is sensitive and useful in distinguishing compacted layers within the topsoil.     

多年固定道保护性耕作对土壤结构的影响

为了解决拖拉机作业机组作业时造成的土壤普遍压实,在10a连续固定道保护性耕作试验基础上,研究了固定道保护性耕作对土壤容重、孔隙度、紧实度、水分以及冬小麦产量的影响。试验结果表明,对于作物生长带,固定道保护性耕作可以降低0～20cm土层的容重6.8%,提高0～40cm土层土壤总孔隙度4.6%,降低0～30cm土层土壤紧实度31.5%,提高0～1m土层蓄水能力,在固定道占地20%的情况下,仍能提高冬小麦产量10.8%。因此,固定道保护性耕作是减少土壤压实、改善土壤结构、提高小麦产量的有效耕作方式。     

不同耕作措施对土壤水分和青贮夏玉米水分生产率的影响

适宜的耕作与覆盖措施可在不同程度节约农业用水。本文选用了翻耕处理、燃茬免耕处理和覆盖免耕处理为主要耕作措施,开展了为期2a的田间试验,研究不同措施对农田土壤含水量、土面蒸发、夏玉米生长指标、产量和水分生产率的影响。研究结果表明在降雨较少年份(2010年),覆盖免耕处理0～20cm土壤含水量均高于其他2处理,2a试验期间覆盖免耕处理0～120cm土壤贮水量一直高于其他2处理,且其土面蒸发量最小。2a试验期间,覆盖免耕青贮夏玉米产量较翻耕和燃茬免耕分别提高了11%和9%,青贮夏玉米水分生产率分别提高了11.7%和14.8%。覆盖免耕能减少土面蒸发和提高水分生产率,因此建议在北京地区夏玉米种植采用覆盖免耕措施。     

不同耕作方式对水稻产量和土壤肥力的影响

于2005～2006年在双季稻田研究了不同耕作方式对水稻生长、产量和土壤肥力的影响。结果表明:免耕抛秧水稻根干重低于翻耕移栽稻,根系绝大部分分布在表层土壤,根系活力比翻耕处理的高,分蘖时间比翻耕移栽的早而比翻耕抛秧的迟;每公顷有效穗数略低于翻耕抛秧而高于翻耕移栽,结实率高于翻耕处理。随着免耕次数的增加,各处理产量基本持平;免耕1年有利于土壤物理性质的改善,免耕有利于土壤养分在表层土壤富集。     

Changes in soil chemical characteristics with different tillage practices in a semi-arid environment

We examined the effects of various tillage intensities: no-tillage (NT), minimum tillage with chisel plow (MT), conventional tillage with mouldboard plow (CT), and zone-tillage subsoiling with a paraplow (ZT) applied in alternate years in rotation with NT, on the topsoil profile distribution (0–30 cm) of pH, soil organic carbon (SOC), organic N and available nutrients on a semi-arid soil from Central Spain. The equivalent depth approach was used to compare SOC, N and nutrient stocks in the various tillage treatments. Measurements made at the end of 5 years showed that in the 0–30 cm depth, SOC and N had increased under NT and ZT compared with MT and CT. Most dramatic changes occurred within the 0–5 cm depth where plots under NT and ZT had respectively 7.0 Mg ha⁻¹ and 6.2 Mg ha⁻¹ more SOC and 0.5 Mg ha⁻¹ and 0.3 Mg ha⁻¹ more N than under MT or CT. No-tillage and ZT plots, however, exhibited strong vertical gradients of SOC and N with concentrations decreasing from 0–5 to 20–30 cm. In the 0–20 cm layer, higher concentrations of P and K under NT and ZT than under MT or CT were also found. Soil pH under NT and ZT was 0.3 units lower than under MT or CT at a depth of 0–5 cm. This acidifying effect was restricted at the surface layer and in the 20–30 cm interval, pH values under NT and ZT were higher than in MT and CT plots. These results suggest that in the soil studied, ZT in rotation with NT maintain most advantages associated with NT, and present a definite potential for use as a partial-width rotational tillage practice.     

Remediation of subsoil compaction and compaction effects on corn N availability by deep tillage and application of poultry manure in a sandy-textured soil

Subsoil compaction may reduce the availability and uptake of water and plant nutrients thereby lowering crop yields. Among the management options for remediating subsoil compaction are deep tillage and the selection of crop rotations with deep-rooted crops, but little is known of the effects of applications of organic amendments on subsoil compaction. The objectives of this study were to determine the effects of subsoil compaction on corn yield and N availability in a sandy-textured soil and to evaluate the use of deep tillage and surface applications of poultry manure to remediate subsoil compaction. A field experiment planted to corn (Zea mays L.) was conducted from 2000 to 2001 on a Reelfoot fine sandy loam (fine-silty, mixed thermic Aquic Argiudolls) formed in silty alluvium located in southeast Missouri near the Mississippi River. Treatments were arranged in a factorial design with three levels of subsoil compaction and subsoiling and four rates (averaging 0, 6, 11 and 18 Mg ha⁻¹) of poultry manure. Subsoil tillage to a depth of 30 cm had multiple effects, including overcoming a natural or tillage-induced dense layer or pan and increasing volumetric soil water content and crop N uptake, especially in the 2001 cropping year with low early season precipitation. N recovery efficiency (NRE) was significantly higher in the subsoil treatment compared to the highest compaction treatment in 2001. No significant interactions between manure rates and compaction and subsoiling treatments were observed for corn grain and silage yields, N uptake and NRE. Average increases in corn grain yields over all manure rates due to subsoil tillage of compacted soil were 2002 kg ha⁻¹ in 2000 and 3504 kg ha⁻¹ in 2001. Application of poultry manure had a consistent positive effect on increasing grain yields and N uptake in 2000 and 2001 but did not significantly alter measured soil physical properties. The results of this study suggest that deep tillage and applications of organic amendments are management tools that may overcome restrictions in both N and soil water availability due to subsoil compaction in sandy-textured soils.     

机械压实过程中复垦土壤紧实度影响因素的模拟分析

机械碾压造成的土壤压实是土地复垦中面临的主要问题之一,影响土壤压实程度的因素很多,除土壤自身的因素以外,还包括压实机械、压实次数以及土层厚度等。该文基于统计学的理论,采用2×5×4的混合试验设计并建立模拟实验区,使用重锤模拟分析了2种压实机械、不同压实次数(1、3、5、7、9次)和不同土层厚度(0~10cm、10~20cm、20~30cm、30~40 cm)上土壤紧实度的变化情况,并在SPSS中进行变量的方差分析和多重比较,试图找到机械压实过程中影响土壤紧实度的因素及其变化水平。结果表明:增加压实机械的承重轮面积能够有效降低对土壤的压实作用;压实机械、土层厚度和压实次数都是影响土壤紧实度的显著性因素且各因素的贡献率(97%)远高于随机误差;自卸汽车在第5次压实之后就已经使上层土壤紧实度达到最大值,而履带式推土机需要压实7次,土地复垦中应尽量选择履带型机械,碾压次数控制在5~7之内;机械压实的过程中,各土层厚度之间土壤紧实度的大小关系并不是一成不变的,中间层次(10~30 cm)的土壤由于同时受到来自上下2个方向的作用力,紧实度相对较高;不同次数的压实对土壤紧实度的影响深度和程度不同,在一定范围内,随着压实次数的增加,单次压实对土壤紧实度的影响逐渐减小。