,1, 史东梅,1, 蒋光毅2, 江娜1, 叶青1, 张健乐1Effects of Different Fertilization Methods on Restoration of Eroded and Degraded Cultivated-Layer in Slope Farmland
SONG Ge,1, SHI DongMei,1, JIANG GuangYi2, JIANG Na1, YE Qing1, ZHANG JianLe1通讯作者:
责任编辑: 李云霞
收稿日期:2020-06-26接受日期:2020-10-14网络出版日期:2021-04-16
| 基金资助: |
Received:2020-06-26Accepted:2020-10-14Online:2021-04-16
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宋鸽, 史东梅, 蒋光毅, 江娜, 叶青, 张健乐. 土壤管理措施对坡耕地侵蚀退化耕层的恢复作用[J]. 中国农业科学, 2021, 54(8): 1702-1714 doi:10.3864/j.issn.0578-1752.2021.08.010
SONG Ge, SHI DongMei, JIANG GuangYi, JIANG Na, YE Qing, ZHANG JianLe.
开放科学（资源服务）标识码（OSID）：
0 引言
【研究意义】紫色土是长江上游重要的耕地资源[1,2],成土速度快、土壤矿物质含量高,具有宜水性、宜肥性、宜耕性的特点,但紫色土坡耕地是我国水土流失最为严重的土地类型之一,土层浅薄、结构性差[3],土壤侵蚀强度在5 897 t·km-2·a-1以上[4]。因此,探究不同土壤管理措施对紫色土坡耕地耕层侵蚀的恢复作用,可为地块尺度坡耕地耕层土壤侵蚀恢复及耕层质量提升提供理论支持。【前人研究进展】目前,国内外****针对紫色土坡耕地耕层土壤侵蚀状况及管理措施开展了大量研究。一些研究结果表明,紫色土坡耕地土壤侵蚀强烈,抗蚀性较差,土壤平均侵蚀速率在758—9 854 t·km-2·a-1之间,并且土壤平均侵蚀速率随坡度增加显著增大[2,5];土壤侵蚀对土壤颗粒组成的空间变异性影响显著,坡上部位土壤细颗粒流失严重,在坡下沉积[5];土壤侵蚀强度沿坡面向下逐渐减小,土壤有机质、土壤养分在坡下积聚[5];随雨强增大,坡耕地地表径流量及土壤侵蚀量急剧增加[6]。李富程等[7]的研究表明耕作侵蚀下耕层土壤主要从坡上流失至坡中部位,并在下部堆积,不会导致田间土壤直接流失,水蚀导致坡耕地土壤从坡中流失至坡下,并在泥沙堆积的坡下侵蚀最强,直接造成田间土壤流失。史东梅等[8]的研究表明,与坡上、坡下部位相比,紫色土坡耕地坡中部位砂粒、粉粒、黏粒组成配比适宜,土壤饱和导水率最大,蓄水性能最好。同时,有研究表明在横坡垄作或顺坡垄作基础上进行地膜或秸秆覆盖能够减少土壤侵蚀,并且秸秆覆盖较地膜覆盖效果更好[9];施用生物炭能够提高土壤总孔隙度、毛管孔隙度,增加土壤团聚体含量,提高土壤团聚体稳定性,提升土壤蓄水保水性能[10,11,12,13,14],有利于减少地表径流、土壤侵蚀的发生[15],还能够改良土壤酸度,提高坡耕地土壤养分含量,促进作物生长[16]。【本研究切入点】以往的研究多侧重于坡耕地土壤侵蚀或施加生物炭单一方面的研究,研究土壤管理措施对不同侵蚀程度坡耕地耕层侵蚀的恢复作用对地块尺度坡耕地耕层质量提升具有重要意义。【拟解决的关键问题】本文以3种不同土壤管理措施下5个不同侵蚀程度紫色土坡耕地耕层为研究对象,采用单因素方差分析（One-way ANOVA）检验各指标差异显著性,比较不同管理措施及不同侵蚀程度下的土壤可蚀性,可为紫色土坡耕地耕层质量调控、合理耕层构建、坡耕地持续利用提供参数依据。1 材料与方法
1.1 试验材料及设计
试验地位于重庆市万州区熊家镇（30°55′10″N,108°25′51″E）,属亚热带季风性湿润气候,平均海拔355.5 m,年平均气温17.7 ℃,多年平均降水量1 200 mm且多集中在5—9月,约占全年总降水量70%。试验地土壤类型为紫色沙泥页岩母质发育的紫色土,0—20 cm土层土壤理化性质见表1。Table 1
表1
表1试验前土壤基本理化性质
Table 1
| 土层深度 Soil depth (cm) | 砂粒 Sand (%) | 粉粒 Silt (%) | 黏粒 Clay (%) | 容重 Bulk density (g·cm-3) | 总孔隙度 Total porosity (%) | 毛管孔隙度 Capillary porosity (%) | 土壤抗剪强度 Soil shearing strength (kg·cm-2) |
|---|---|---|---|---|---|---|---|
| 0-10 | 44.00 | 45.33 | 10.67 | 1.33 | 49.56 | 34.01 | 6.32 |
| 10-20 | 42.67 | 45.33 | 12.00 | 1.32 | 48.06 | 33.78 | 7.51 |
新窗口打开|下载CSV
试验始于2018年2月,试验选择地形条件、基础肥力一致的紫色土坡耕地作为试验地,田面坡度均为15°,以侵蚀程度为主处理,管理措施为副处理设置裂区试验。其中设置侵蚀0 cm（S-0）、侵蚀5 cm（S-5）、侵蚀10 cm（S-10）、侵蚀15 cm（S-15）、侵蚀20 cm（S-20）5个侵蚀程度,以S-0为对照;设置不施肥（CK）、施化肥（F）、施生物炭+化肥（BF）3种管理措施。
小区建立时施加生物炭15 t·hm-2,九禾股份有限公司复合肥（N-P2O5-K2O≥45%）277.5 kg·hm-2均匀撒施在土壤表面,经翻耕混入0—10 cm土层,玉米根据当地种植习惯追施尿素（总氮≥46.4%）两次,各处理设3次重复,共45个小区,每个小区面积12 m2（3 m×4 m）。供试玉米品种为农祥11,8月初进行玉米收获。
1.2 土样采集及测定
土壤采样于2018年8月初进行,在铲土侵蚀小区上部、中部、下部按0—10、10—20 cm分层采样,于每层中部用环刀采集土样,用于容重、孔隙度、土壤入渗速率和土壤饱和导水率测定。采集原状土带回实验室自然风干,过筛后用于土壤机械组成测定,3次重复。土壤机械组成采用吸管法测定,土壤抗剪强度采用便携式三头抗剪仪（14.10 Pocket Vane Tester型,荷兰）测定,6次重复。1.3 土壤可蚀性K值
采用Shirazi公式法计算土壤可蚀性K值[17,18],计算公式如下：$K=7.594\left\{ 0.0017+0.0494\exp \left[ -\frac{1}{2}{{\left[ \frac{(Dg+1.675)}{0.6986} \right]}^{2}} \right] \right\}$
Dg=e(0.01Σfiln mi)
R2=0.983
式中,fi为原土壤中第i个粒径级质量分数（%）;mi为第i个粒径级两端数值的算术平均值（mm）;K值为美国制,计算后将K值乘以0.1317,转为国际制单位（t·hm2·h·MJ-1·mm-1·hm-2）。
1.4 数据处理
数据经Excel 2016处理后,采用SPSS 22.0统计软件进行统计分析,采用单因素方差分析（One-way ANOVA）检验土壤各指标的差异显著性。2 结果
2.1 坡耕地耕层土壤物质组成与结构
不同侵蚀程度下坡耕地耕层土壤粒径分布特征差异显著（图1）,随侵蚀程度增大,土壤砂粒含量呈逐渐增大趋势,土壤粉粒、黏粒含量呈逐渐减小趋势。侵蚀程度由S-0增至S-20,土壤砂粒含量由38.1%— 42.4%增加至44.2%—46.4%,增幅随侵蚀程度增加先增大后减小;土壤粉粒含量由46.6%—47.0%减少为44.0%—44.8%,土壤黏粒含量由12.6%— 14.8%减少至9.6%—11.0%,降幅随侵蚀程度增加先增大后减小,这表明随侵蚀程度增大,土壤中细颗粒不断流失,砂粒含量逐渐增大,坡耕地土壤粗骨化现象不断加重。说明坡耕地耕层土壤在人为耕作活动影响下,细颗粒优先迁移,粗颗粒相对集中,耕层土壤质地粗化。0—10 cm土层土壤砂粒含量随侵蚀程度增加,变化幅度均大于10—20 cm土层。同一侵蚀程度下,0—10 cm土层土壤砂粒含量均大于10—20 cm土层,其原因主要是0—10 cm土层土壤耕作后土质较为疏松,存在很多大孔隙,且裸露于地表,土壤中细颗粒更容易受到径流冲刷而流失。图1
新窗口打开|下载原图ZIP|生成PPT图1不同施肥对不同侵蚀程度坡耕地耕层土壤粒径分布特征的影响
不同大写字母表示同一侵蚀程度、同一土层不同管理方式差异显著（P<0.05）;不同小写字母表示同一管理方式、同一土层不同侵蚀程度差异显著（P<0.05）。下同
Fig. 1Effects of different fertilization on soil particle size distribution characteristics of cultivated layer in slope farmland with different erosion degree
Different capital letters indicated that there were significant differences in the same erosion degree and different management measures in the same cultivated-layer (P<0.05). Different lowercase letters indicated that the erosion degree of the same cultivated-layer was significantly different under the same management measures (P<0.05). The same as below
不同土壤管理方式下坡耕地耕层土壤砂粒含量由高到低依次为CK、F、BF,3种管理方式之间土壤砂粒含量变化较为显著。与不施肥的CK相比,F、BF处理对坡耕地耕层土壤砂粒含量的调控作用随侵蚀程度增大先增强后逐渐减弱,F、BF处理下S-10侵蚀程度土壤砂粒含量降幅均最大,分别为4.0%、8.4%。与F处理相比,BF处理下S-0、S-5、S-10侵蚀程度土壤砂粒含量分别下降3.6%、4.0%、4.6%。BF处理对S-0、S-5、S-10侵蚀程度耕层土壤砂粒含量调控作用明显优于F处理,S-15、S-20侵蚀程度下F、BF两种管理措施间并未发生明显变化,但均显著高于CK（P<0.05）。不同土壤管理方式下土壤粉粒、黏粒含量由低到高依次为CK、F、BF,3种管理方式之间土壤黏粒含量变化差异显著（P<0.05）,而土壤粉粒含量仅在S-10侵蚀程度下呈显著差异。与不施肥的CK相比,F、BF处理下S-10侵蚀程度土壤粉粒含量分别增加1.5%、2.9%;F、BF处理下土壤黏粒含量分别增加7.6%— 10.0%、15.2%—22.4%。与F处理相比,BF处理下土壤黏粒含量增加7.0%—11.3%。F、BF处理下S-10侵蚀程度土壤粉粒、黏粒含量与CK相比增幅均最大,土壤粉粒含量分别增加1.5%、2.9%,土壤黏粒含量分别增加10.0%、22.4%。这表明在不同侵蚀程度坡耕地上施加化肥、施加生物炭+化肥均能减少土壤细颗粒流失,减轻土壤粗骨化,且在S-10 侵蚀程度下效果均最好。
不同侵蚀程度下坡耕地耕层土壤容重整体表现为S-0<S-5<S-10<S-15<S-20（图2）,CK处理下S-10、S-15、S-20较S-0、S-5土壤容重显著增大;F、BF处理下,与S-0、S-5、S-10相比,S-15、S-20侵蚀程度下土壤容重变化差异显著（P<0.05）。与S-0相比,S-15、S-20侵蚀程度下土壤容重由1.27—1.40 g·cm-3分别增至1.37—1.48和1.39—1.52 g·cm-3,这表明随侵蚀程度增加,土壤板结现象严重,土壤通气、透水性较差,不利于农作物根系生长。同一侵蚀程度下,10—20 cm土层土壤容重较0—10 cm土层整体呈增大趋势,增加0—2.19%。
图2
新窗口打开|下载原图ZIP|生成PPT图2不同施肥对不同侵蚀程度坡耕地耕层土壤容重的影响
Fig. 2Effects of different fertilization on soil bulk density of cultivated layer in slope farmland with different erosion degree
不同管理措施下坡耕地耕层土壤容重变化差异显著,其中BF处理下土壤容重显著小于CK、F处理（P<0.05）,而F处理下较CK下降趋势不明显。BF处理下S-0、S-5、S-10、S-15、S-20各侵蚀程度土壤容重分别为1.27、1.29、1.32、1.37和1.39 g·cm-3,与CK相比,各侵蚀程度土壤容重分别减小9.5%、9.0%、8.5%、7.0%、8.1%,这说明施加生物炭+化肥能够显著降低土壤容重,效果优于单施化肥,可能是由于生物炭的多孔性以及较低的堆积密度降低了土壤容重[19]。BF处理下随侵蚀程度的增加改良效果呈下降趋势,各侵蚀程度10—20 cm土层土壤容重改良效果均优于0—10 cm土层。
土壤孔隙度是表征土壤疏松程度及水分容量大小的重要指标,由图3、4可知,不同侵蚀程度下坡耕地耕层土壤总孔隙度、毛管孔隙度变化规律相同,由大到小依次为S-0、S-5、S-10、S-15、S-20,且变化差异显著（P<0.05）。这表明随侵蚀程度增加土壤孔隙度不断减小,土壤通气、透水性能逐渐减弱。随侵蚀程度增加,S-5、S-10、S-15、S-20侵蚀程度下土壤总孔隙度下降幅度分别为1.7%—3.1%、3.6%—6.1%、2.6%—6.5%、2.5%—3.0%;CK处理S-10侵蚀程度下土壤总孔隙度下降幅度最大;F、BF处理S-15侵蚀程度下土壤总孔隙度降幅最大,较S-10相比降幅分别为4.9%、6.5%。随侵蚀程度增加,土壤毛管孔隙度下降幅度先增大后减小,CK、F处理S-10侵蚀程度下土壤毛管孔隙度下降幅度最大,BF处理S-15侵蚀程度下土壤毛管孔隙度下降幅度最大,较S-10下降4.1%。同一侵蚀程度,0—10、10—20 cm土层土壤总孔隙度、毛管孔隙度未发生明显变化,其主要原因是耕作层（0—20 cm）土壤经常受到人为扰动,土质均较为疏松。
图3
新窗口打开|下载原图ZIP|生成PPT图3不同施肥对不同侵蚀程度坡耕地耕层土壤总孔隙度的影响
Fig. 3Effect of different fertilization on soil total porosity of cultivated layer in slope farmland with different erosion degree
图4
新窗口打开|下载原图ZIP|生成PPT图4不同施肥对不同侵蚀程度坡耕地耕层土壤毛管孔隙度的影响
Fig. 4Effects of different fertilization on soil capillary porosity of cultivated layer in slope farmland with different erosion degree
由图3、4可知,不同土壤管理措施下0—10、10—20 cm土层土壤总孔隙度、毛管孔隙度均表现为CK<F<BF（P<0.05）。BF处理下各侵蚀程度土壤总孔隙度分别较F处理增加2.0%、2.8%、3.6%、1.9%、1.6%,土壤毛管孔隙度分别较F处理增加4.5%、4.6%、4.8%、3.5%、3.4%。BF处理S-0侵蚀程度0—10 cm土层土壤总孔隙度、毛管孔隙度均最大,分别为50.9%、37.7%;CK处理下10—20 cm土层土壤总孔隙度最小,为41.1%,0—10 cm土层土壤毛管孔隙度最小,为31.8%。F、BF处理对坡耕地耕层土壤总孔隙度、毛管孔隙度的改良效果随侵蚀程度的增加先增强后逐渐减弱,两种管理措施对S-10侵蚀程度土壤总孔隙度、毛管孔隙度改良效果均最好;F、BF处理下S-10侵蚀程度土壤总孔隙度分别较CK增加4.5%、8.2%。这表明施加生物炭+化肥能够显著增加耕作层土壤孔隙,有效改善土壤结构,提高土壤通气、透水性能,这与生物炭疏松多孔、密度小、含有丰富的有机大分子密切相关[20]。
随侵蚀程度增加,耕层土壤抗剪强度整体呈先增大后减小的趋势（图5）,不同管理措施下S-10侵蚀程度土壤抗剪强度均增加至最大值,在8.71—9.56 kg·cm-2之间,随着侵蚀程度进一步增加,S-20侵蚀程度下土壤抗剪强度达最小值,在8.60—9.45 kg·cm-2之间,其原因可能是随着侵蚀程度的增加,耕作层（0—20 cm）抗剪切破坏能力较弱的疏松土壤在径流冲刷作用下大量流失,土壤板结现象逐渐加重,土壤抗剪能力呈增大趋势,而随着侵蚀程度的进一步加剧,土壤细颗粒大量流失,土壤粗骨化现象严重,因此土壤抗剪切破坏能力呈下降趋势。0—10 cm土层各侵蚀程度土壤抗剪强度在8.65—10.07 kg·cm-2之间,10—20 cm土层土壤抗剪强度较0—10 cm土层下降0.3%—1.7%,这可能是由于0—10 cm土层土壤受人为扰动后降雨引起土壤板结所致。
图5
新窗口打开|下载原图ZIP|生成PPT图5不同施肥对不同侵蚀程度坡耕地耕层土壤抗剪强度的影响
Fig. 5Effects of different fertilization on soil shear strength of cultivated layer in slope farmland with different erosion degree
不同管理措施下坡耕地耕层土壤抗剪强度存在较大差异,由小到大依次为CK、F、BF,在BF处理S-0侵蚀程度下土壤抗剪强度较F处理未发生明显变化,但F、BF处理较CK处理土壤抗剪强度显著增强（P<0.05）;S-5、S-10、S-15、S-20侵蚀程度下CK、F、BF处理间土壤抗剪强度变化差异显著（P<0.05）。F、BF处理对土壤抗剪强度的改良效果呈先增强后逐渐减弱的趋势。S-10侵蚀程度下,F、BF处理0—10 cm土层土壤抗剪强度较CK处理增幅最大,分别为7.9%、12.2%。
2.2 坡耕地耕层土壤渗透性能
坡耕地耕层土壤渗透性能直接影响耕层地表径流形成、土壤抗旱性能及生产性能[8]。不同侵蚀程度下坡耕地耕层土壤渗透性能存在较大差异（图6—8）。土壤初始入渗率、稳定入渗率、平均入渗率由大到小依次为S-0、S-5、S-10、S-15、S-20,差异显著（P<0.05）。S-0侵蚀程度下土壤初始入渗率在12.29—17.19 mm·min-1之间,与S-0相比,S-20侵蚀程度下土壤初始入渗率下降78.1%—88.5%。S-20侵蚀程度下土壤初始入渗率降幅最大,S-10侵蚀程度次之,S-20较S-15下降43.1%—46.9%,S-10较S-5下降30.6%—38.2%。土壤稳定入渗率下降幅度随侵蚀程度增加先增大后减小,CK处理下S-10侵蚀程度的降幅最大,与S-5相比下降40.8%,F、BF处理下S-15侵蚀程度的降幅最大,与S-10相比分别下降42.5%、46.5%;土壤平均入渗率随侵蚀程度的变化规律与土壤稳定入渗率一致,S-0侵蚀程度下土壤平均入渗率在2.50—6.92 mm·min-1之间,S-20较S-0下降76.6%—84.0%,这表明随着侵蚀程度的增加,土壤渗透性能逐渐减弱,更容易产生地表径流,导致耕层土壤流失。同一侵蚀程度下,随土层深度增加坡耕地耕层土壤初始入渗率、稳定入渗率、平均入渗率均逐渐下降,0—10 cm土层土壤初始入渗率、稳定入渗率、平均入渗率分别为3.41—21.57、0.48—4.99、0.62—6.92 mm·min-1,与0—10 cm土层相比,10—20 cm土层土壤初始入渗率、稳定入渗率、平均入渗率分别下降22.8%—65.2%、0.9%—12.7%、0.8%—29.2%。图6
新窗口打开|下载原图ZIP|生成PPT图6不同施肥对不同侵蚀程度坡耕地耕层土壤初始入渗率的影响
Fig. 6Effects of different fertilization on soil initial infiltration rate of cultivated layer in slope farmland with different erosion degree
图7
新窗口打开|下载原图ZIP|生成PPT图7不同施肥对不同侵蚀程度坡耕地耕层土壤稳定入渗率的影响
Fig. 7Effects of different fertilization on soil stable infiltration rate of cultivated layer in slope farmland with different erosion degree
图8
新窗口打开|下载原图ZIP|生成PPT图8不同施肥对不同侵蚀程度坡耕地耕层土壤平均入渗率的影响
Fig. 8Effect of different fertilization on soil average infiltration rate of cultivated layer in slope farmland with different erosion degree
不同土壤管理方式下坡耕地耕层土壤初始入渗率、稳定入渗率、平均入渗率存在较大差异,BF处理土壤初始入渗率、稳定入渗率、平均入渗率均最大,F处理次之,CK处理最小,差异显著（P<0.05）。CK、F、BF处理土壤初始入渗率分别为2.30—12.29、2.49—13.51、2.80—17.19 mm·min-1。F处理对S-10侵蚀程度土壤初始入渗率调控作用最明显,与CK相比增加26.4%;BF处理对S-5、S-10侵蚀程度土壤初始入渗率调控效果均较为明显,分别较CK增加49.9%、51.9%。F、BF处理对S-10侵蚀程度土壤稳定入渗率、平均入渗率调控效果较好,F、BF处理下土壤稳定入渗率分别较CK增加70.7%、178.4%,土壤平均入渗率分别较CK增加79.4%、146.0%。施用生物炭+化肥对耕层土壤渗透性能的调控效果较好,这是由于施用生物炭后耕层土壤容重显著降低、孔隙度明显增大,土壤通气、透水性能得到改善,从而提高了耕层土壤的渗透性能。
不同侵蚀程度下坡耕地耕层土壤饱和导水率由大到小依次为S-0、S-5、S-10、S-15、S-20（P<0.05）（图9）。随侵蚀程度增加,土壤饱和导水率下降幅度先增大后减小,侵蚀程度增至S-15、S-20时土壤饱和导水率急剧下降,CK、F、BF处理下S-15侵蚀程度降幅均达最大值,与S-10相比分别下降44.5%、52.6%、59.6%;与S-0相比,S-20侵蚀程度下土壤饱和导水率下降79.7%—85.8%。这表明随侵蚀程度增加,土壤通透性能减弱,不利于拦蓄降雨,从而加速坡耕地土壤侵蚀。随土层深度增加土壤饱和导水率显著降低,0—10 cm土层土壤饱和导水率在0.47—3.15 mm·min-1之间,约为10—20 cm土层的1.05—1.63倍,这主要是因为10—20 cm土层土壤较紧实,土壤孔隙少,不利于土壤水分下渗。
图9
新窗口打开|下载原图ZIP|生成PPT图9不同施肥对不同侵蚀程度坡耕地耕层土壤饱和导水率的影响
Fig. 9Effects of different fertilization on soil saturated hydraulic conductivity of cultivated layer in slope farmland with different erosion degree
不同管理措施下坡耕地耕层土壤饱和导水率存在较大差异（图9）,S-0、S-5、S-10侵蚀程度下3种管理方式土壤饱和导水率差异显著,CK（0.38—2.11 mm·min-1）<F（0.43—2.48 mm·min-1）<BF（0.49—2.90 mm·min-1）（P<0.05）,说明F、BF处理对S-0、S-5、S-10侵蚀程度坡耕地耕层土壤饱和导水率调控作用均较为明显,且BF处理优于F处理。F、BF处理对S-10侵蚀程度土壤饱和导水率调控作用均最明显,与CK相比分别增加39.0%、90.2%。F、BF处理对10—20 cm土层土壤饱和导水率的调控作用较0—10 cm土层更为明显。
2.3 不同管理措施对坡耕地耕层土壤侵蚀恢复作用
土壤可蚀性是指土壤对侵蚀的敏感程度[21,22],是土壤对侵蚀营力分离和搬运作用的敏感性指标,也是评价坡耕地耕层土壤质量的重要指标。由表2可知,不同侵蚀程度下,坡耕地耕层土壤可蚀性K值存在显著差异,整体表现为S-0>S-5>S-10>S-15>S-20（P<0.05）,S-0土壤可蚀性K值在0.04832—0.04839 t·hm2·h·MJ-1·mm-1·hm-2之间,与S-0相比,S-20侵蚀程度下土壤可蚀性K值下降0.1960%—0.2192%,这表明随侵蚀程度增加,土壤可蚀性K值不断减小,这主要是因为土壤侵蚀导致土壤细颗粒大量流失,土壤粗骨化严重,能够被径流冲刷的细颗粒逐渐减少,因此土壤可蚀性降低。CK、F处理下均表现为S-10侵蚀程度土壤可蚀性K值降幅最大,与S-5相比,分别下降0.0685%、0.0582%,BF处理下S-15侵蚀程度降幅最大,较S-10下降0.0812%。0—10 cm土层土壤可蚀性K值在0.04822—0.04836 t·hm2·h·MJ-1·mm-1·hm-2之间,与0—10 cm土层相比,10—20 cm土层土壤可蚀性K值增加0.0359%—0.0557%,其原因主要是随着土层深度增加,土壤黏粒含量逐渐增加,而细颗粒易受径流冲刷不断流失,导致土壤可蚀性增大。Table 2
表2
表2不同土壤管理措施及侵蚀程度下坡耕地耕层土壤可蚀性K值变化特征
Table 2
| 管理措施 Management measure | 土层深度 Soil depth (cm) | 侵蚀程度 Erosion degree | ||||
|---|---|---|---|---|---|---|
| S-0 | S-5 | S-10 | S-15 | S-20 | ||
| CK | 0-10 | 0.04832Ca | 0.04829Bb | 0.04826Cc | 0.04824Cd | 0.04822Ce |
| 10-20 | 0.04834Ca | 0.04832Cb | 0.04828Cc | 0.04826Cd | 0.04824Ce | |
| F | 0-10 | 0.04834Ba | 0.04832Ab | 0.04829Bc | 0.04827Bd | 0.04825Be |
| 10-20 | 0.04836Ba | 0.04834Bb | 0.04832Bc | 0.04829Bd | 0.04826Be | |
| BF | 0-10 | 0.04836Aa | 0.04835Ab | 0.04833Ac | 0.04829Ad | 0.04827Ae |
| 10-20 | 0.04839Aa | 0.04837Aa | 0.04835Ab | 0.04831Ac | 0.04829Ad | |
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不同管理措施下,土壤可蚀性K值差异显著（P<0.05）,BF处理下土壤可蚀性K值最大,F处理次之,CK最小。这表明施加生物炭+化肥后,土壤可蚀性增强,这可能是由于施加化肥、生物炭+化肥后土壤容重下降,土壤板结问题得到改善,且土壤黏粒含量增加,土壤可蚀性增大。与CK相比,F、BF处理下土壤可蚀性K值增加幅度随侵蚀程度增加先增大后减小,S-10侵蚀程度下两种措施较CK增加幅度最大,分别增加0.0684%、0.0720%。CK处理下S-20侵蚀程度0—10 cm土层土壤可蚀性K值最小,为0.04822 t·hm2·h·MJ-1·mm-1·hm-2。F、BF两种管理措施对0—10 cm土层土壤可蚀性K值的改良效果优于10—20 cm土层。
由表3可知,3种管理措施下土壤可蚀性K值与各土壤属性指标相关程度具有较好的一致性。CK、F、BF处理下土壤可蚀性K值均与土壤砂粒含量、土壤容重呈极显著负相关关系（P<0.01）,与土壤粉粒含量、黏粒含量、土壤总孔隙度、毛管孔隙度、土壤初始入渗率、稳定入渗率、平均入渗率、饱和导水率呈极显著正相关关系（P<0.01）。
Table 3
表3
表3土壤属性指标与土壤可蚀性K值相关系数
Table 3
| 管理措施 Management measure | 砂粒 Sand | 粉粒 Silt | 黏粒 Clay | 容重 Bulk density | 总孔隙度 Total porosity | 毛管孔隙度 Capillary porosity | 土壤抗剪强度 Soil shearing strength | 初始入渗率 Initial infiltration rate | 稳定入渗率 Infiltration capacity | 平均入渗率 Average infiltration rate | 饱和导水率 Hydraulic conductivity |
|---|---|---|---|---|---|---|---|---|---|---|---|
| CK | -0.997** | 0.996** | 0.998** | -0.982** | 0.992** | 0.996** | 0.363 | 0.995** | 0.988** | 0.990** | 0.993** |
| F | -0.992** | 0.991** | 0.992** | -0.965** | 0.992** | 0.988** | 0.569 | 0.981** | 0.977** | 0.980** | 0.976** |
| BF | -0.996** | 0.997** | 0.996** | -0.996** | 0.993** | 0.994** | 0.534 | 0.984** | 0.973** | 0.980** | 0.983** |
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3 讨论
3.1 坡耕地土壤侵蚀性K值的影响因素分析
紫色土坡耕地耕层浅薄、水稳性差、抗侵蚀能力弱,侵蚀模数高达3 464—9 452 t·km-2·a-1[23,24],耕层土壤侵蚀现象严重。土壤可蚀性是指土壤受雨滴击溅、径流冲刷以及壤中流等作用而被分散和搬运的难易程度[21-22,25],是表征土壤侵蚀敏感程度的重要指标[24,25],是土壤质地、渗透性能、团聚体稳定性等土壤属性以及降雨、地形、土壤管理措施共同作用的结果,人为不合理使用进一步加剧了坡耕地土壤侵蚀,增强了土壤可蚀性。相关研究表明,随开垦年限增加、坡度增大[26],土壤可蚀性均逐渐增强[27];布设埂坎、水平沟的坡耕地上地块土壤可蚀性K值高于下地块,而无措施坡耕地与之相反;在地块尺度中,中下坡位土壤可蚀性K值相对较高[24];添加1%含量的生物炭能够显著降低土壤可蚀性,但施加7%含量生物炭土壤可蚀性K值显著增大。朱冰冰等[27]的研究表明土壤可蚀性K值与土壤有机碳含量、水稳性团聚体含量及团聚度关系最为密切,土壤有机质含量、水稳性团聚体含量越高、团聚度越大土壤抗侵蚀性能越好,本研究在后续试验中将增加有机质、团聚体与土壤可蚀性相关关系研究。徐文秀等[24]的研究表明土壤可蚀性K值与土壤黏粒含量、粉粒含量呈正相关,与土壤砂粒含量呈极显著负相关（P<0.01）,与本研究结果基本一致,本研究表明,土壤可蚀性K值与土壤砂粒含量、土壤容重呈极显著负相关关系（P<0.01）,与土壤粉粒含量、黏粒含量、土壤总孔隙度、毛管孔隙度、土壤初始入渗率、稳定入渗率、平均入渗率、饱和导水率呈极显著正相关关系（P<0.01）,这主要是由于土壤越疏松,土壤孔隙越大,耕层土壤越容易在径流冲刷作用下大量流失,加剧耕层浅薄化。不同侵蚀程度紫色土坡耕地耕层土壤可蚀性K值在0.04822—0.04839之间,随侵蚀程度增加,土壤细颗粒大量流失,粗骨化严重,能够被径流冲刷的细颗粒逐渐减少,土壤可蚀性降低,说明坡耕地耕层土壤侵蚀进行到一定程度后土壤可蚀性呈下降趋势,这与邓良基等[26]的研究一致。3.2 土壤管理措施对耕层土壤抗侵蚀性能的影响
生物炭是多孔的轻质物质[28,29],对土壤结构、理化性质的影响主要体现在降低土壤容重、增加土壤孔隙度、改善土壤渗透性能及土壤团聚体等方面,进而提高土壤的抗侵蚀性能[29,30]。施加生物炭+化肥处理下耕作层（0—20 cm）土壤容重较对照组显著下降,降低6.7%—9.0%,但较单施化肥处理相比改良效果不显著,施加生物炭+化肥较单施化肥显著提高了耕作层（0—20 cm）土壤总孔隙度、毛管孔隙度,分别增加3.3%—8.2%、5.1%—8.4%。OGUNTUNDE等[28]研究认为,施加生物炭后土壤容重下降9%,土壤孔隙度增加10.7%;刘祥宏[31]通过人工模拟降雨试验对不同生物炭施用量下的耕作层（0—10、10—20 cm）土壤属性差异进行分析,结果显示施加生物炭能够降低土壤容重、提高土壤团聚体稳定性,延迟产流时间,并且对质地较差、肥力较低的土壤改良效果较好;HSEU等[32]的研究结果表明施加稻壳生物炭后土壤容重下降12%—25%,土壤有效含水量增加18%—89%,土壤流失量显著降低35%—90%;JIEN等[33]的研究表明施加生物炭后土壤饱和导水率较未施加生物炭增加1.8倍,土壤容重下降21.4%,土壤流失量下降64%,与本研究具有较好的一致性。施加生物炭+化肥处理下土壤可蚀性K值显著增大,较对照组、单施化肥处理分别增加0.0956%— 0.1404%、0.0431%—0.0720%,这可能是由于施加生物炭后土壤细颗粒流失量下降,土壤容重、孔隙度得到改善,耕作层土壤通气透水性增强,导致坡耕地土壤可蚀性增大。研究表明,生物炭自身的易蚀性在一定程度上会限制生物炭对土壤抗侵蚀性能的改良效果[29];施加生物炭可以延迟土壤产流时间,但作用效果微弱;相同土壤容重条件下的风干土,施加生物炭并不能够降低其地表径流[31]。本研究表明,施加生物炭+化肥较单施化肥在提高紫色土坡耕地耕层土壤耕性方面效果更为显著,施加生物炭+化肥能够明显调控耕层土壤耕性,这主要是由于生物炭能够显著增加耕层土壤孔隙,降低土壤容重,有利于形成上松下紧的耕层构型。随侵蚀程度增大,施加生物炭+化肥对耕层土壤的改良效果先增强后减弱,对S-10侵蚀程度下各土层土壤属性指标的改良效果最好,对侵蚀程度较高的耕层土壤作用效果不显著。因此需要进行长期试验,进一步分析使用生物炭对不同侵蚀程度土壤的改良效果。
4 结论
4.1 随侵蚀程度增大,紫色土坡耕地耕层土壤砂粒含量显著增加,黏粒含量显著下降,土壤容重显著增大,耕层土壤粗骨化、板结现象严重,土壤渗透性能逐渐减弱,容易产生地表径流导致耕层土壤流失,加速坡耕地土壤侵蚀,不利于农作物根系生长。4.2 单施化肥、施生物炭+化肥两种管理措施对耕层土壤属性改良效果随侵蚀程度的增大先增强后减弱,对S-10侵蚀程度下各指标调控效果均最为显著。施加生物炭+化肥处理对紫色土坡耕地耕层土壤属性改良效果优于单施化肥。
4.3 紫色土坡耕地土壤可蚀性K值在0.04822— 0.04839 t·hm2·h·MJ-1·mm-1·hm-2之间,随侵蚀程度增加土壤可蚀性逐渐减小。单施化肥、施用生物炭+化肥处理对S-10侵蚀程度的土壤可蚀性调控效果均最好,分别较CK增加0.0648%、0.1404%。
综上所述,施生物炭+化肥处理能够显著改善坡耕地耕层土壤结构及渗透性能,减轻坡耕地土壤粗骨化,有利于坡耕地可持续利用。
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Soil aggregate is an key soil fertility identification index which determines the quality and erosion resistance of soils. Soil organic carbon content somehow influences soil stability and soil water-stable aggregate forms. It is a critical driving factor of soil fertility and soil cushioning property. Farming measures also influence changes in soil organic carbon pool and different farming measures have different effects on soil physical and chemical property. To find proper tillage measures on slope croplands in purple soils, the effects of across- and along-slope ploughs on soil aggregate stability in purple soils were studied. Through plot runoff experiments, the characteristics of water-stable aggregates and organic carbon contents in top soils (0~20 cm) were studied. On the slope-land of South China, peasants preferred doing along-slope plough than across-slope plough because ease of along-slope plough. However, rill erosion easily occurred in along-slope plough conditions, especially in big rainfall events. This worsened the degree of soil erosion in the region. On the other hand, research on soil nutrient loss in across-slope plough conditions has sown that due to high risks and inputs, across-slope plough farming was unacceptable to most peasants. Studies have shown that soil aggregate organic carbon content accounts for 90% of surface soil nutrients and agricultural production activities occurred mostly in surface soils. This research studied the effects of across- and along-slope ploughs on water-stable aggregates and organic carbon in surface purple soils. The study offered some theoretical bases for effective utilization of soil management measures in slope-land conditions. Results showed that compared with along-slope plough, across-slope plough increased aggregate water stability index by 38.99%. Aggregate dispersion index in along-slope plough was 1.64 times that in across-slope plough. This suggested that erosion resistance in across-slope plough was stronger than in along-slope plough conditions. Compared with along-slope plough, the average content of >0.25 mm water-stable aggregate in across-slope plough increased by 3.62%. Meanwhile, the average contents of water stable aggregate in >5 mm, 5~3 mm and 3~2 mm sizes in across-slope plough were higher than in along-slope plough. This suggested that across-slope plough significantly improved the >2 mm water-stable aggregate content. Percent destruction of soil aggregates in across-slope plough decreased by 3.05%, compared with along-slope plough. Also mean weight diameter (MWD) in across-slope plough was 1.39 times that in along-slope plough conditions. Organic carbon contents in 0.5~2 mm aggregates of the two tillage types were the highest. Under the two tillage measures, percent organic carbon contents in >0.25 mm aggregates decreased with decreasing diameter, reaching the lowest value in 0.5~0.25 mm aggregates. There was no significant difference between the two tillage measures in organic carbon contents in 2~1 mm aggregates, but significant differences existed in the other sizes aggregates. Across-slope plough significantly improved water-stable aggregate contents. It also had a better effect on soil retention capacity of organic carbon and better improved soil structure.
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Soil aggregate is an key soil fertility identification index which determines the quality and erosion resistance of soils. Soil organic carbon content somehow influences soil stability and soil water-stable aggregate forms. It is a critical driving factor of soil fertility and soil cushioning property. Farming measures also influence changes in soil organic carbon pool and different farming measures have different effects on soil physical and chemical property. To find proper tillage measures on slope croplands in purple soils, the effects of across- and along-slope ploughs on soil aggregate stability in purple soils were studied. Through plot runoff experiments, the characteristics of water-stable aggregates and organic carbon contents in top soils (0~20 cm) were studied. On the slope-land of South China, peasants preferred doing along-slope plough than across-slope plough because ease of along-slope plough. However, rill erosion easily occurred in along-slope plough conditions, especially in big rainfall events. This worsened the degree of soil erosion in the region. On the other hand, research on soil nutrient loss in across-slope plough conditions has sown that due to high risks and inputs, across-slope plough farming was unacceptable to most peasants. Studies have shown that soil aggregate organic carbon content accounts for 90% of surface soil nutrients and agricultural production activities occurred mostly in surface soils. This research studied the effects of across- and along-slope ploughs on water-stable aggregates and organic carbon in surface purple soils. The study offered some theoretical bases for effective utilization of soil management measures in slope-land conditions. Results showed that compared with along-slope plough, across-slope plough increased aggregate water stability index by 38.99%. Aggregate dispersion index in along-slope plough was 1.64 times that in across-slope plough. This suggested that erosion resistance in across-slope plough was stronger than in along-slope plough conditions. Compared with along-slope plough, the average content of >0.25 mm water-stable aggregate in across-slope plough increased by 3.62%. Meanwhile, the average contents of water stable aggregate in >5 mm, 5~3 mm and 3~2 mm sizes in across-slope plough were higher than in along-slope plough. This suggested that across-slope plough significantly improved the >2 mm water-stable aggregate content. Percent destruction of soil aggregates in across-slope plough decreased by 3.05%, compared with along-slope plough. Also mean weight diameter (MWD) in across-slope plough was 1.39 times that in along-slope plough conditions. Organic carbon contents in 0.5~2 mm aggregates of the two tillage types were the highest. Under the two tillage measures, percent organic carbon contents in >0.25 mm aggregates decreased with decreasing diameter, reaching the lowest value in 0.5~0.25 mm aggregates. There was no significant difference between the two tillage measures in organic carbon contents in 2~1 mm aggregates, but significant differences existed in the other sizes aggregates. Across-slope plough significantly improved water-stable aggregate contents. It also had a better effect on soil retention capacity of organic carbon and better improved soil structure.
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土壤侵蚀是导致坡耕地耕层土壤质量退化和土壤生产力不稳定的关键因素。该文以紫色丘陵区坡耕地为例，对坡耕地不同地力等级耕层土壤质量、渗透性能及耕层类型进行聚类分析，讨论了土壤侵蚀对坡耕地耕层厚度影响及合理耕层土体构型。结果表明：（1）紫色土坡耕地耕层土壤质量具有中等程度变异性，有效土层厚度（15～80 cm）和耕层厚度（15～25 cm）变异系数分别为12.18%和37.26%，土壤有效磷变异系数可达94.51%，说明土壤物理指标变异性小于化学指标变化；三级以下地力耕层构型为近似全虚或全实剖面结构，五等地力坡耕地产量下降50%左右。（2）紫色土坡耕地不同坡位、不同垂直深度的耕层土壤物理性质、持水性能及耕作性能差异显著（P<0.05），土壤容重为上坡>下坡>中坡， 土壤抗剪强度为上坡>中坡>下坡，土壤稳定入渗为下坡>中坡>上坡，土壤贯入阻力表现为中坡>上坡>下坡；除土壤入渗外，土壤容重、抗剪强度、贯入阻力均表现为底土层>心土层>耕层；坡耕地0～40 cm 土层中蓄存降水可被农作物利用70%左右。（3）中度侵蚀程度坡耕地，年均耕层厚度薄化值为1.04～3.04 mm，坡耕地合理耕层建立可选择有效土层厚度、耕层厚度、土壤容重、土壤抗剪强度、土壤有机质、土壤渗透性为坡耕地合理耕层评价最小数据集，耕层构型总体保持上虚下实型、耕层厚度20～25 cm、有效土层厚度50～60 cm。（4）紫色土坡耕地可分为四种耕层类型，其障碍耕层主要表现为有效土层厚度限制型（第II类）、耕层厚度限制型（第III类）和土壤养分限制型（第IV类），分别占耕层总量30%、10%、3%；紫色土坡耕地合理耕层建立应重点关注有效土层厚度和耕层厚度调控。研究结果可为客观认识土壤侵蚀与紫色土坡耕地耕层退化关系、合理耕层构建提供理论依据和技术参数支持。
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土壤侵蚀是导致坡耕地耕层土壤质量退化和土壤生产力不稳定的关键因素。该文以紫色丘陵区坡耕地为例，对坡耕地不同地力等级耕层土壤质量、渗透性能及耕层类型进行聚类分析，讨论了土壤侵蚀对坡耕地耕层厚度影响及合理耕层土体构型。结果表明：（1）紫色土坡耕地耕层土壤质量具有中等程度变异性，有效土层厚度（15～80 cm）和耕层厚度（15～25 cm）变异系数分别为12.18%和37.26%，土壤有效磷变异系数可达94.51%，说明土壤物理指标变异性小于化学指标变化；三级以下地力耕层构型为近似全虚或全实剖面结构，五等地力坡耕地产量下降50%左右。（2）紫色土坡耕地不同坡位、不同垂直深度的耕层土壤物理性质、持水性能及耕作性能差异显著（P<0.05），土壤容重为上坡>下坡>中坡， 土壤抗剪强度为上坡>中坡>下坡，土壤稳定入渗为下坡>中坡>上坡，土壤贯入阻力表现为中坡>上坡>下坡；除土壤入渗外，土壤容重、抗剪强度、贯入阻力均表现为底土层>心土层>耕层；坡耕地0～40 cm 土层中蓄存降水可被农作物利用70%左右。（3）中度侵蚀程度坡耕地，年均耕层厚度薄化值为1.04～3.04 mm，坡耕地合理耕层建立可选择有效土层厚度、耕层厚度、土壤容重、土壤抗剪强度、土壤有机质、土壤渗透性为坡耕地合理耕层评价最小数据集，耕层构型总体保持上虚下实型、耕层厚度20～25 cm、有效土层厚度50～60 cm。（4）紫色土坡耕地可分为四种耕层类型，其障碍耕层主要表现为有效土层厚度限制型（第II类）、耕层厚度限制型（第III类）和土壤养分限制型（第IV类），分别占耕层总量30%、10%、3%；紫色土坡耕地合理耕层建立应重点关注有效土层厚度和耕层厚度调控。研究结果可为客观认识土壤侵蚀与紫色土坡耕地耕层退化关系、合理耕层构建提供理论依据和技术参数支持。
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采用随机区组试验，研究了四川紫色丘陵区坡耕地不同耕作和覆盖方式对玉米生育期中水土及养分流失的影响。结果表明：秸秆覆盖对减少水土流失和增加玉米产量的效果均优于地膜覆盖。秸秆覆盖能显著减少地表径流(73.9%-86.2%), 但增加了壤中流(15.4%-156.4%);使径流总量降低32.5%-66.6%，并极显著降低土壤侵蚀总量达96.4%-98.1%。地膜覆盖虽能在一定程度上减少壤中流和径流总深，但差异未达到显著水平。土壤N平均损失量达37.4 kg/hm2，其中70.1%经由壤中流流失。秸秆覆盖虽然增加了一定的壤中流N损失，但能减少N流失总量达12.8%-65.1%。土壤P素损失量相对较小，仅为9.32 kg/hm2，并主要随侵蚀泥沙迁移，占流失总量的92.1%。土壤K损失量达183.3 kg/hm2，其流失载体也主要是侵蚀泥沙，占96.5%。因此，两种覆盖方式均能显著控制土壤P和K的损失。无论是秸秆还是地膜覆盖，与顺坡垄作相比，横坡垄作均能减少地表径流、地下径流、土壤侵蚀量及氮、磷、钾素总流失量，同时还能提高玉米产量。从简便、增产和防治面源污染的角度考虑，紫色土区坡耕地最适宜的种植方式为平作+秸秆覆盖。
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采用随机区组试验，研究了四川紫色丘陵区坡耕地不同耕作和覆盖方式对玉米生育期中水土及养分流失的影响。结果表明：秸秆覆盖对减少水土流失和增加玉米产量的效果均优于地膜覆盖。秸秆覆盖能显著减少地表径流(73.9%-86.2%), 但增加了壤中流(15.4%-156.4%);使径流总量降低32.5%-66.6%，并极显著降低土壤侵蚀总量达96.4%-98.1%。地膜覆盖虽能在一定程度上减少壤中流和径流总深，但差异未达到显著水平。土壤N平均损失量达37.4 kg/hm2，其中70.1%经由壤中流流失。秸秆覆盖虽然增加了一定的壤中流N损失，但能减少N流失总量达12.8%-65.1%。土壤P素损失量相对较小，仅为9.32 kg/hm2，并主要随侵蚀泥沙迁移，占流失总量的92.1%。土壤K损失量达183.3 kg/hm2，其流失载体也主要是侵蚀泥沙，占96.5%。因此，两种覆盖方式均能显著控制土壤P和K的损失。无论是秸秆还是地膜覆盖，与顺坡垄作相比，横坡垄作均能减少地表径流、地下径流、土壤侵蚀量及氮、磷、钾素总流失量，同时还能提高玉米产量。从简便、增产和防治面源污染的角度考虑，紫色土区坡耕地最适宜的种植方式为平作+秸秆覆盖。
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DOI:10.1016/j.agee.2014.01.007URL [本文引用: 1]
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该研究通过野外坡耕地小区施用1%秸秆生物炭1年后的对比试验，揭示生物炭对川中丘陵区紫色土耕作层土壤水力学参数、大孔隙度及其对饱和导水率的贡献率所产生的影响。试验设对照区与施用生物炭区2个处理，各处理有3个平行小区，耕作层土壤分为表层和亚表层（2～7和>7～12 cm）。比较2个处理小区试验结果，可以发现：1）施用生物炭导致植物难以利用的土壤滞留水和易流失的结构性孔隙水的含量（θstr）下降，而基质性孔隙中植物有效水含量显著提高（P<0.05），由（0.058?0.003）cm3/cm3增加至（0.085?0.002）cm3/cm3；2）表层和亚表层土壤中对产流起主要贡献的半径>125 μm的总有效孔隙度分别平均增加54%和8%，其中孔径>500 μm的孔隙增加最为明显，高达110%和355%；3）表层和亚表层土壤的饱和导水率分别平均增加45%和35%。研究证明，施用生物炭，一方面，能增加土壤有效水的持水量，有利于植物抗旱；另一方面，提高土壤导水率，有利于水分入渗，从而减少地表径流及土壤侵蚀的发生。
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该研究通过野外坡耕地小区施用1%秸秆生物炭1年后的对比试验，揭示生物炭对川中丘陵区紫色土耕作层土壤水力学参数、大孔隙度及其对饱和导水率的贡献率所产生的影响。试验设对照区与施用生物炭区2个处理，各处理有3个平行小区，耕作层土壤分为表层和亚表层（2～7和>7～12 cm）。比较2个处理小区试验结果，可以发现：1）施用生物炭导致植物难以利用的土壤滞留水和易流失的结构性孔隙水的含量（θstr）下降，而基质性孔隙中植物有效水含量显著提高（P<0.05），由（0.058?0.003）cm3/cm3增加至（0.085?0.002）cm3/cm3；2）表层和亚表层土壤中对产流起主要贡献的半径>125 μm的总有效孔隙度分别平均增加54%和8%，其中孔径>500 μm的孔隙增加最为明显，高达110%和355%；3）表层和亚表层土壤的饱和导水率分别平均增加45%和35%。研究证明，施用生物炭，一方面，能增加土壤有效水的持水量，有利于植物抗旱；另一方面，提高土壤导水率，有利于水分入渗，从而减少地表径流及土壤侵蚀的发生。
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DOI:10.2136/sssaj1988.03615995005200010032xURL [本文引用: 1]
DOI:10.3864/j.issn.0578-1752.2020.09.012URL [本文引用: 1]
【Objective】Purple soil slope farmland is an important cultivated land resource for agricultural production in southern hilly area. In order to study the effects of soil erosion on the physical properties and mechanical properties degradation of purple soil slope arable land, based on the classification of soil degradation, the change characteristics of physical and mechanical properties and soil degradation index under different erosion degrees were quantitatively analyzed. 【Method】With non-eroded plots as control group, the soil permeability, soil mechanical properties and soil degradation index of cultivated-layer were compared and analyzed under 5 cm (S-5), 10 cm (S-10), 15 cm (S-15) and 20 cm (S-20) erosion conditions by shovel soil erosion simulation test method, and the degradation degree of physical and mechanical properties of sloping farmland was quantitatively analyzed. 【Result】Soil permeability of cultivated-layer under different erosion degrees was CK>S-5>S-10>S-15>S-20. The initial infiltration rate, stable infiltration rate, average infiltration rate and saturated water conductivity of soil decreased with the increase of erosion degree. Soil permeability index of each layer under different erosion degrees was 0-20 cm soil layer>20-40 cm soil layer. Soil mechanical properties of different erosion degrees were CK<S-5<S-10<S-15<S-20. Soil shear strength and soil compacted degree increased with erosion degree. Soil mechanical indexes of all layers under different erosion degrees were 0-20 cm soil layer<20-40 cm soil layer. The contribution rate of soil shear strength to the first axis was the largest, and soil shear strength was the main factor affecting the change of soil physical properties and mechanical properties under different erosion degrees. Soil physical properties and mechanical properties were ranked as stable infiltration rate>soil compaction>saturated water conductivity>average infiltration rate>initial infiltration rate>shear strength. Soil degradation index of under different erosion degrees was S-5 (-8.71%)>S-10 (-10.95%)>S-20 (-12.17%)>S-15 (-15.37%). S-15 had the greatest influence on the topsoil physical properties, and the S-15 soil degradation index was the smallest, with the degree of soil degradation being severe. 【Conclusion】Soil compaction was serious in slope farmland of purple soil. According to soil infiltration and mechanical properties, the soil degradation grade with different erosion degree could be classified into four grades: undegraded, mild degradation, moderate degradation and severe degradation. The results could provide the technical parameters for the identification and restoration control of the quality degradation process of sloping farmland.
DOI:10.3864/j.issn.0578-1752.2020.09.012URL [本文引用: 1]
【Objective】Purple soil slope farmland is an important cultivated land resource for agricultural production in southern hilly area. In order to study the effects of soil erosion on the physical properties and mechanical properties degradation of purple soil slope arable land, based on the classification of soil degradation, the change characteristics of physical and mechanical properties and soil degradation index under different erosion degrees were quantitatively analyzed. 【Method】With non-eroded plots as control group, the soil permeability, soil mechanical properties and soil degradation index of cultivated-layer were compared and analyzed under 5 cm (S-5), 10 cm (S-10), 15 cm (S-15) and 20 cm (S-20) erosion conditions by shovel soil erosion simulation test method, and the degradation degree of physical and mechanical properties of sloping farmland was quantitatively analyzed. 【Result】Soil permeability of cultivated-layer under different erosion degrees was CK>S-5>S-10>S-15>S-20. The initial infiltration rate, stable infiltration rate, average infiltration rate and saturated water conductivity of soil decreased with the increase of erosion degree. Soil permeability index of each layer under different erosion degrees was 0-20 cm soil layer>20-40 cm soil layer. Soil mechanical properties of different erosion degrees were CK<S-5<S-10<S-15<S-20. Soil shear strength and soil compacted degree increased with erosion degree. Soil mechanical indexes of all layers under different erosion degrees were 0-20 cm soil layer<20-40 cm soil layer. The contribution rate of soil shear strength to the first axis was the largest, and soil shear strength was the main factor affecting the change of soil physical properties and mechanical properties under different erosion degrees. Soil physical properties and mechanical properties were ranked as stable infiltration rate>soil compaction>saturated water conductivity>average infiltration rate>initial infiltration rate>shear strength. Soil degradation index of under different erosion degrees was S-5 (-8.71%)>S-10 (-10.95%)>S-20 (-12.17%)>S-15 (-15.37%). S-15 had the greatest influence on the topsoil physical properties, and the S-15 soil degradation index was the smallest, with the degree of soil degradation being severe. 【Conclusion】Soil compaction was serious in slope farmland of purple soil. According to soil infiltration and mechanical properties, the soil degradation grade with different erosion degree could be classified into four grades: undegraded, mild degradation, moderate degradation and severe degradation. The results could provide the technical parameters for the identification and restoration control of the quality degradation process of sloping farmland.
URL [本文引用: 1]
研究生物炭施用方式及用量对土壤水分入渗、蒸发特性的影响，可为旱区农业与生态建设中应用生物炭改良土壤水文特性提供科学依据与技术支持。该文采用室内土柱模拟方法，研究了3种生物炭施用方式A（施在表层0~10 cm）、B（施在下层>10～20 cm）和C（施在耕层0～20 cm）和4种质量添加比例（0、1%、2%和4%）对土壤水分湿润峰、累积入渗量及蒸发的影响。结果表明：生物炭对土壤水分入渗、蒸发的影响受施用方式和用量的共同制约。与对照（不施生物炭）相比，A与C施用方式在1%和2%用量均可以减缓湿润峰运移速度，而较高用量（4%）可以促进湿润峰运移；B施用方式2%用量明显促进湿润峰运移，1%与4%用量无明显影响；以入渗时间50 min为例，A4%能显著增加累积入渗量，增量达对照的10.63%（P<0.05），而B1%、A1%、C2%、C1%、C4%可显著降低累积入渗量（P<0.05），减少量分别达对照的13.90%、12.46%、8.49%、5.32%、4.66%，其余处理与对照相比差异不显著。在同一施用方式下，除C2%和C1%外，各处理累积入渗量均随生物质炭用量增加而呈上升趋势。各处理土壤湿润峰运移距离与时间之间呈幂函数关系，且累积入渗量与时间关系可用Kostiakov入渗经验公式描述，Philip入渗模型可用于描述耕层（0～20 cm）混合生物炭土壤累积入渗量变化过程。各处理35d累积蒸发量与对照相比差异不显著。A4%可显著增加耕层土壤入渗能力，在改良质地较黏土壤入渗性能时，在土壤表层添加较高用量（4%）生物炭效果较好。
URL [本文引用: 1]
研究生物炭施用方式及用量对土壤水分入渗、蒸发特性的影响，可为旱区农业与生态建设中应用生物炭改良土壤水文特性提供科学依据与技术支持。该文采用室内土柱模拟方法，研究了3种生物炭施用方式A（施在表层0~10 cm）、B（施在下层>10～20 cm）和C（施在耕层0～20 cm）和4种质量添加比例（0、1%、2%和4%）对土壤水分湿润峰、累积入渗量及蒸发的影响。结果表明：生物炭对土壤水分入渗、蒸发的影响受施用方式和用量的共同制约。与对照（不施生物炭）相比，A与C施用方式在1%和2%用量均可以减缓湿润峰运移速度，而较高用量（4%）可以促进湿润峰运移；B施用方式2%用量明显促进湿润峰运移，1%与4%用量无明显影响；以入渗时间50 min为例，A4%能显著增加累积入渗量，增量达对照的10.63%（P<0.05），而B1%、A1%、C2%、C1%、C4%可显著降低累积入渗量（P<0.05），减少量分别达对照的13.90%、12.46%、8.49%、5.32%、4.66%，其余处理与对照相比差异不显著。在同一施用方式下，除C2%和C1%外，各处理累积入渗量均随生物质炭用量增加而呈上升趋势。各处理土壤湿润峰运移距离与时间之间呈幂函数关系，且累积入渗量与时间关系可用Kostiakov入渗经验公式描述，Philip入渗模型可用于描述耕层（0～20 cm）混合生物炭土壤累积入渗量变化过程。各处理35d累积蒸发量与对照相比差异不显著。A4%可显著增加耕层土壤入渗能力，在改良质地较黏土壤入渗性能时，在土壤表层添加较高用量（4%）生物炭效果较好。
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DOI:10.1016/j.catena.2012.05.012URL [本文引用: 2]
The analysis of global soil erodibility data by Salvador Sanchis et al. (2008) showed that there is a significant climate effect on soil erodibility which allows for a split of the data into two subsets, one for prevailing cool conditions and another for prevailing warm conditions (defined using the Kappen climate classification). Despite the recognition of this new dichotomous variable, prediction of soil erodibility values remained very poor. This paper presents a new technique for dealing with such a variability by calculating probability density functions of soil erodibility K values when the user knows a set of textural parameters and the climatic classification of the site. Finally the user has the possibility to decide, on the basis of local knowledge, which K value to use. The procedure has been implemented in a freeware software named KUERY available for the scientific community. Finally, as an illustration, the methodology is applied to a catchment in south Italy. Crown Copyright (c) 2012 Published by Elsevier B.V.
DOI:10.1071/SR16332URLPMID:33584863 [本文引用: 2]
Food security entails having sufficient, safe, and nutritious food to meet dietary needs. The need to optimise nitrogen (N) use for nutrition security while minimising environmental risks in sub-Saharan Africa (SSA) is overdue. Challenges related to managing N use in SSA can be associated with both insufficient use and excessive loss, and thus the continent must address the 'too little' and 'too much' paradox. Too little N is used in food production (80% of countries have N deficiencies), which has led to chronic food insecurity and malnutrition. Conversely, too much N load in water bodies due mainly to soil erosion, leaching, limited N recovery from wastewater, and atmospheric deposition contributes to eutrophication (152 Gg N year-1 in Lake Victoria, East Africa). Limited research has been conducted to improve N use for food production and adoption remains low, mainly because farming is generally practiced by resource-poor smallholder farmers. In addition, little has been done to effectively address the 'too much' issues, as a consequence of limited research capacity. This research gap must be addressed, and supportive policies operationalised, to maximise N benefits, while also minimising pollution. Innovation platforms involving key stakeholders are required to address N use efficiency along the food supply chain in SSA, as well as other world regions with similar challenges.
URL [本文引用: 1]
198 9年以来三峡地区开展的侵蚀泥沙13 7Cs示踪的初步研究表明:三峡地区紫色土陡坡耕地侵蚀强烈,坡度>2 5°的坡耕地,侵蚀速率高达712 6 94 5 2t/(km2 ·a) ;黄壤质地粘重,抗蚀性好,坡度2 9°的陡坡耕地的侵蚀速率仅2 5 0 9t/(km2 ·a)。林草地侵蚀轻微,坡度2 5°林草地的侵蚀速率为30 6 6 88t/(km2 ·a) ,较坡耕地大致低一个数量级。上世纪6 0年代以来,开县小江河床上涨强烈,两岸滩地也有淤积发生,淤积厚度10 70cm不等,低滩地泥沙淤积厚度大于高滩地。开县春秋水库小流域输沙模数为15 6 0t/(km2 ·a) ,由于谷地泥沙淤积极为有限,此值基本可代表该流域的侵蚀模数。全国土壤侵蚀遥感普查公布的川东平行岭谷区侵蚀模数为30 0 0 5 0 0 0t/(km2 ·a)。
URL [本文引用: 1]
198 9年以来三峡地区开展的侵蚀泥沙13 7Cs示踪的初步研究表明:三峡地区紫色土陡坡耕地侵蚀强烈,坡度>2 5°的坡耕地,侵蚀速率高达712 6 94 5 2t/(km2 ·a) ;黄壤质地粘重,抗蚀性好,坡度2 9°的陡坡耕地的侵蚀速率仅2 5 0 9t/(km2 ·a)。林草地侵蚀轻微,坡度2 5°林草地的侵蚀速率为30 6 6 88t/(km2 ·a) ,较坡耕地大致低一个数量级。上世纪6 0年代以来,开县小江河床上涨强烈,两岸滩地也有淤积发生,淤积厚度10 70cm不等,低滩地泥沙淤积厚度大于高滩地。开县春秋水库小流域输沙模数为15 6 0t/(km2 ·a) ,由于谷地泥沙淤积极为有限,此值基本可代表该流域的侵蚀模数。全国土壤侵蚀遥感普查公布的川东平行岭谷区侵蚀模数为30 0 0 5 0 0 0t/(km2 ·a)。
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URL [本文引用: 2]
应用美国通用土壤流失方程(USLE)和土壤侵蚀预报模型(WEPP)中的土壤可蚀性K值,对四川各类自然土壤和旱耕地土壤可蚀性特征进行了研究.结果表明:土壤可蚀性K值与土壤理化性质直接相关,自然土壤和旱耕地土壤可蚀性K值在0.268～0.344之间,紫色土的分布面积和K值较大,是易遭受侵蚀的土壤.应采取增施有机肥、实行坡改梯等措施,加强对耕地、高可蚀性土壤侵蚀的综合防治.
URL [本文引用: 2]
应用美国通用土壤流失方程(USLE)和土壤侵蚀预报模型(WEPP)中的土壤可蚀性K值,对四川各类自然土壤和旱耕地土壤可蚀性特征进行了研究.结果表明:土壤可蚀性K值与土壤理化性质直接相关,自然土壤和旱耕地土壤可蚀性K值在0.268～0.344之间,紫色土的分布面积和K值较大,是易遭受侵蚀的土壤.应采取增施有机肥、实行坡改梯等措施,加强对耕地、高可蚀性土壤侵蚀的综合防治.
URL [本文引用: 2]
The values of soil erodibility K under different degradation and restoration periods were calculated by the EPIC model and the dynamic changes of soil erodibility during the process of land degradation and restoration were systematically studied. The results showed that after cultivated, soil particles developed towards coarseness and organic matter contents was decreased, while during the periods of restoration, soil erodibility was decreased with the increasing of SOM gradually. K values were closely correlated with soil phy-chemical properties, among which the organic matter content determined its erodibility fundamentally. Thus vegetation recovery and rehabilitation to improve the organic matter and promote formation of aggregates and their stability are principal countermeasures to reduce soil erodibility for the Loess Plateau.
URL [本文引用: 2]
The values of soil erodibility K under different degradation and restoration periods were calculated by the EPIC model and the dynamic changes of soil erodibility during the process of land degradation and restoration were systematically studied. The results showed that after cultivated, soil particles developed towards coarseness and organic matter contents was decreased, while during the periods of restoration, soil erodibility was decreased with the increasing of SOM gradually. K values were closely correlated with soil phy-chemical properties, among which the organic matter content determined its erodibility fundamentally. Thus vegetation recovery and rehabilitation to improve the organic matter and promote formation of aggregates and their stability are principal countermeasures to reduce soil erodibility for the Loess Plateau.
DOI:10.1002/(ISSN)1522-2624URL [本文引用: 2]
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This paper investigated and analyzed the effects of biochar on maize plant growth, yield and soil properties in field experiment, with the biochar addition at the rates of 0, 20 t/hm2 and 40 t/hm2. The results showed that, compared with the control (no biochar used), biochar amendment with 20 t/hm2 and 40 t/hm2 biochar inhibited the maize growth at the beginning growth, showed in lower plant height, less biomass and leaf chlorophyll content. With biochar addition at the rates of 20 t/hm2, the maize plant maintained higher biomass, leaf area index and chlorophyll content in the late growth stage, but no significantly difference with 40 t/hm2. With the biochar addition at the rates of 20 and 40 t/hm2, soil organic carbon were increased by 34.79% and 44.93%, soil total nitrogen increased by 4.88% and 12.20%, respectively. Biochar amendments significantly increased soil pH and soil volumetric water content, but decreased soil bulk density. Compared with conventional treatment, the maize yield were increased by 4.80% and 2.20%, with the biochar addition at the rates of 20 t/hm2 and 40 t/hm2, but no significantly difference with control. The results above provided a theoretical basis for biochar on improving soil fertility and enriching the efficiency of crop production in the Huang-huai-hai Plain.
URL [本文引用: 1]
This paper investigated and analyzed the effects of biochar on maize plant growth, yield and soil properties in field experiment, with the biochar addition at the rates of 0, 20 t/hm2 and 40 t/hm2. The results showed that, compared with the control (no biochar used), biochar amendment with 20 t/hm2 and 40 t/hm2 biochar inhibited the maize growth at the beginning growth, showed in lower plant height, less biomass and leaf chlorophyll content. With biochar addition at the rates of 20 t/hm2, the maize plant maintained higher biomass, leaf area index and chlorophyll content in the late growth stage, but no significantly difference with 40 t/hm2. With the biochar addition at the rates of 20 and 40 t/hm2, soil organic carbon were increased by 34.79% and 44.93%, soil total nitrogen increased by 4.88% and 12.20%, respectively. Biochar amendments significantly increased soil pH and soil volumetric water content, but decreased soil bulk density. Compared with conventional treatment, the maize yield were increased by 4.80% and 2.20%, with the biochar addition at the rates of 20 t/hm2 and 40 t/hm2, but no significantly difference with control. The results above provided a theoretical basis for biochar on improving soil fertility and enriching the efficiency of crop production in the Huang-huai-hai Plain.
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DOI:10.1016/j.catena.2013.06.021URL [本文引用: 1]
Highly weathered soils in humid Asia are characterized by low soil fertility and high soil erosion potential. This study evaluates the influences of biochar made from the waste wood of white lead trees (Leucaena leucocephala (Lam.) de Wit) on the physicochemical and biological properties of long-term cultivated, acidic Ultisol. This study used three application rates (0%, 2.5%, and 5% (wt/wt)) of the biochar with an incubation time of 105 d for all cases. Soils were collected at 21 d, 42 d, 63 d, 84 d and 105 d during the incubation period to evaluate changes in soil properties over time. A simulated rainfall event (80 mm h(-1)) was performed to estimate soil loss for all treatments at the end of the incubation time. Experimental results indicate that applying biochar improved the physicochemical and biological properties of the highly weathered soils, including significant increases in soil pH from 3.9 to 5.1, cation exchange capacity from 7.41 to 10.8 cmol (+) kg(-1), base cation percentage from 6.40 to 26.0%, and microbial biomass carbon (MBC) from 835 to 1262 mg kg(-1). Compared with the control (i.e., no biochar), biochar application decreased bulk density from 1.4 to 1.1 Mg m(-3), increased K-sat by 1.8 times and increased the mean weight diameter (MWD) of soil aggregates from 2.6 cm to 4.0 cm. Incorporating biochar into the soil significantly reduced soil loss by 50% and 64% at 2.5% and 5% application rates, respectively, compared with the control. The formation of macroaggregates in the biochar-amended soils is the critical factor to improve soil erosion potential. Based on these results, a 5% application rate of biochar is considered as suitable for highly weathered soil because this application rate efficiently improves soil physiochemical properties and reduces soil loss. (C) 2013 The Authors. Published by Elsevier B.V.
