Deep Tillage,Soil Moisture Regime,and Optimizing N Nutrition for Sustaining Soil Health and Sugarcane Yield in Subtropical India

A field experiment was conducted at ICAR-Indian Institute of Sugarcane Research, Lucknow, with three tillage practices (T₁: Control- two times ploughing with harrow and cultivator, each followed by planking before sugarcane planting; T₂: Deep tillage with disc plough (depth 25–30 cm) before planting followed by harrowing, cultivator, and planking; and T₃: Subsoiling at 45–50 cm and deep tillage with disc plough/moldboard plough (depth 25–30 cm) followed by harrowing, cultivator, and planking before planting, two soil moisture regimes (M₁: 0.5 irrigation water (IW)/cumulative pan evaporation (?CPE) ratio and M₂: 0.75 IW/CPE ratio) at 7.5 cm depth of IW, and four N levels (N₁- 0, N₂- 75, N₃- 150, and N₄-225 kg N ha^?1) in sugarcane plant crop. Deep tillage and subsoiling increased porosity and reduced bulk density in surface/subsurface soil. Further, these physical changes also improved soil biological and chemical properties responsible for higher crop growth and yield. Deep tillage and subsoiling reduced the compaction by 6.12% in 0–15 cm depth in sugarcane plant crop at maximum tillering stage. The highest N uptake (158.5 kg ha^?1) was analyzed with deep tillage and subsoiling compared to all other tillage practices. Maintaining suboptimal moisture regime with deep tillage and subsoiling showed the highest IW use efficiency (157.16 kg cane kg^?1 N applied). Mean soil microbial biomass carbon (SMBC) in ratoon crop was higher compared to plant crop. During initial tillering stage, ratoon crop showed higher SMBC with application of deep tillage and subsoiling (1209 mg CO₂-C g^?1 soil day^?1) at 0–15 cm depth and 1082.9 mg CO₂-C g^?1 soil day^?1 at 15–30 cm depth. Thus, it could be concluded that besides improving sugarcane yield, soil health could be sustained by adopting subsoiling (45–50 cm depth) and deep tillage (20–25 cm depth), with soil moisture regime of 0.75 IW/CPE and application of 150 kg N ha^?1 in sugarcane (plant crop).     

深松35 cm可改善潮棕壤理化性质并提高小麦和玉米产量

【目的】我国传统耕作深度一般为20 cm,长期不变的翻耕深度降低耕层厚度,增加了犁底层厚度,影响作物的生长。研究小麦—玉米一年两季的种植模式下深松耕作的效果,为大田耕作管理提供技术支持。【方法】田间试验在山东烟台潮棕壤上进行。设计4个耕作处理,分别为常规翻耕20 cm (CK)、深松30 cm、深松35 cm、深松40 cm。小麦播种前进行耕作处理,所有处理均结合耕作一次性基施腐殖酸复合肥 (N–P₂O₅–K₂O=18–10–12) 1125 kg/hm2。玉米免耕,在拔节期追施一次化肥。于小麦、玉米收获期取0—10 cm、10—20 cm、20—30 cm及30—40 cm土层土壤样品,测定土壤速效养分含量与土壤容重,计算三相比,并调查小麦、玉米产量。【结果】与CK相比,深松30 cm、35 cm、40 cm小麦季分别增产10.9%、15.3%和15.5%,玉米季分别增产12.0%、14.9%和9.4%(P < 0.05);10—40 cm土层土壤容重降低了0.03～0.18 g/cm3。其中,小麦季0—10 cm土层中CK处理土壤容重显著低于各深松处理,深松35 cm处理0—10 cm与10—20 cm土层土壤容重显著高于其他各处理;玉米季0—10 cm与10—20 cm土层土壤容重最低的处理为深松35 cm,且显著低于其他处理。小麦季深松30 cm处理各土层土壤三相比 (R值) 在13.2～15.9之间,总体最小,玉米季则以深松40 cm三相比值总体最小,在6.03～8.81之间。深松处理增加了20—40 cm土层有效养分含量,其中深松35 cm处理的20—40 cm土层有效磷和速效氮含量增加最为明显,分别为0.56～37.4 mg/kg与31.9～77.8 mg/kg;速效钾各土层的增加则以深松30 cm最为显著,为24.3～100 mg/kg;有机质含量以深松40 cm增加量最大,为0.95～0.69 g/kg。【结论】深松耕作可显著降低当季土壤容重,增加当季与下一季作物产量,提高土壤耕层以下20—40 cm土层的养分有效性,综合各机械能耗与耕作效果,以深松35 cm最佳。     

深松深度对砂姜黑土耕层特性、作物产量和水分利用效率的影响

研究深松深度对砂姜黑土耕层特性、作物产量和水分利用效率的影响,可为构建砂姜黑土合理耕层的耕作深度指标提供依据。本研究基于多年定位大田试验,采用大区对比设计,设置4个深松深度(30 cm、40 cm、50 cm、60 cm)处理,以旋耕(RT,平均耕作深度为15 cm)作为对照,研究不同深松深度对土壤紧实度、土壤三相比(R)值、作物根系形态、作物产量和水分利用效率的影响。研究结果表明,深松深度增加能显著降低土壤紧实度,使土壤的三相比(R)更加合理,进而促进作物根系生长。不同深松深度中,深松60 cm处理的土壤紧实度和三相比(R)值与对照相比降幅最大,深松40 cm处理的冬小麦根系生物量最大,深松50 cm处理的夏玉米根系生物量最大。深松不仅增加作物产量,还提高作物水分利用效率。深松30 cm处理的周年作物产量最高,比对照增产12.2%,但与深松40 cm处理差异不显著。深松50 cm处理的周年水分利用效率最高,但与深松30 cm和深松40 cm处理差异不显著。深松30 cm、40 cm和50 cm的周年水分利用效率比对照分别增加9.1%、8.8%和12.7%。因此,砂姜黑土适宜的深松深度为30~40 cm。     

耕作方式对冀西北栗钙土土壤物理性状及莜麦生长的影响

为了探索不同耕作方式对冀西北栗钙土农田土壤物理性状及莜麦生长的影响,以河北省张北县10 a栗钙土长期定位试验莜麦田为研究对象,研究了免耕、松耕和翻耕对莜麦田土壤容重、土壤含水率、土壤硬度及莜麦生长的影响。结果表明:松耕和翻耕可以显著降低莜麦播种期到拔节期土壤容重,播种期免耕土壤容重1.49 g/cm3,松耕和翻耕分别为1.31和1.30g/cm3;不同耕作方式对土壤含水率影响不大;免耕显著提高土壤硬度,拔节期免耕土壤硬度58.51kg/cm2,为松耕1.74倍(P0.05),为翻耕2.53倍(P0.01);栗钙土土壤硬度与土壤容重、土壤含水率关系模型表明高土壤容重条件下土壤硬度对土壤含水率更敏感,低土壤含水率条件下土壤硬度对土壤容重更敏感;免耕莜麦株高和叶面积生长受到抑制,穗数和穗粒数显著降低,经济产量413.79 kg/hm2,分别为松耕和翻耕的62.27%和51.64%。栗钙土莜麦田免耕与松耕、翻耕相比土壤容重大,土壤硬度高,莜麦产量显著降低;3种耕作方式中,松耕是兼顾生态与经济效益的耕作措施。     

不同秋耕措施对黄土高原春玉米田土壤物理质量的影响

合理耕作是改善土壤物理质量及构建合理耕层的重要措施之一,对黄土高原农田改良具有重要意义。本研究采用旋耕、深翻和深松3种秋耕措施,探究了不同秋耕措施对黄土高原春玉米田0～30 cm土壤物理质量的影响。结果表明:深翻5～30 cm各层次土壤容重较旋耕显著降低了10.1%～14.58%,土壤总孔隙度和土壤充气孔隙度则分别显著增加了11.59%～22.37%和26.52%～75.2%。深翻10～30 cm各层次土壤容重较深松显著降低了6.56%～13.48%,土壤总孔隙度则显著增加了9.3%～17.1%。深翻0～10cm各层次土壤毛管孔隙度较深松显著增加了7.41%～11.75%,10～30 cm各层次土壤质量含水量显著增加了5.46%～16.57%。此外,5～10 cm土壤固、液、气三相比偏离以旋耕最佳,10～30 cm各层次则以深翻为最佳。综合来看,旋耕改善了5～10 cm土壤物理质量,深翻改善了10～30 cm土壤物理质量,采用旋耕+深翻轮耕模式可能是该研究区构建春玉米田合理耕层的潜在措施之一。     

提升雨养夏玉米—冬小麦两熟体系生产力和土壤硝态氮累积的最优耕作模式

【目的】研究耕作模式对旱地雨养夏玉米–冬小麦(以下简称玉–麦)两熟体系生产力的影响,并对深松、翻耕在轮耕模式中的作用进行评价。【方法】定位试验于2015—2021年在中国农业科学院洛阳旱农试验基地进行。设置夏免耕秋免耕(SNAN)、夏深松秋免耕(SSAN)、夏免耕秋3年免耕1年翻耕(SNA3N1P)、夏深松秋3年免耕1年翻耕(SSA3N1P)和传统夏秋季均翻耕(CT) 5种耕作模式,调查了玉米、小麦的产量和水分利用效率,2020年测定了玉米收获期0—40 cm土层土壤容重、养分含量和酶活性,以及2019—2020年度小麦收获期0—380 cm土层的硝态氮累积量。【结果】1)与CT处理相比,SNAN、SSAN、SNA3N1P和SSA3N1P处理的玉米、小麦和周年产量分别显著提高了28.4%～33.5%、23.7%～25.0%和27.1%～30.3%,水分利用效率分别显著提高了19.6%～39.2%、20.2%～29.3%和29.5%～34.5%,0—5 cm和20—40 cm土层土壤容重显著降低,0—5 cm土层的有机质含量以及0—40 cm多数土层的全氮、有效磷、速效钾含量和脲酶、蔗糖...     

Preliminary observations on effects of tillage systems on soil physical properties, cotton root growth and yield in Gezira Scheme, Sudan

The decline in cotton yields in the Gezira Scheme, Sudan, has been partially attributed to deterioration in soil physical properties and the formation of a plough pan 20 cm deep as a result of the repeated use of the disc plough for land preparation. This field study was conducted during the 1990/91 season at the Gezira Research Station Farm to evaluate the effect of tillage on some soil physical properties of Vertisols, root growth and yield of cotton (Gossypium barbadense L.). Three tillage systems were used: disc harrowing (DH), three bottom disc plough (DP) and subsoiling (SS). Infiltration rates, bulk densities, soil penetration resistance, moisture depletion and root and shoot growth were measured. The results indicated that infiltration rate was not increased significantly by SS. Plant height and shoot dry matter were significantly higher with SS at later growth stages. Bulk density of the plough pan at 135 days after sowing accounted for 90% of the observed variation in subsoil root dry weight while soil penetration resistance accounted for 59% of the variation. Subsoiling increased water use efficiency 25 and 13% over DH and DP respectively. Subsoiling increased cotton yields over DH but the increase over DP was not significant.     

微孔深松耕降低土壤紧实度提高棉花产量与种籽品质

长期传统耕作导致土壤紧实形成犁底层是影响农田土壤质量和作物生长的关键障碍因子之一。为解决这一问题,于2013年4月至2014年5月在山西运城南花农场开展为期1 a的大田试验,对比研究微孔深松耕技术和旋耕机旋耕15~20 cm的传统耕作方法对土壤紧实度以及棉籽品质性状和生长发育的影响。结果表明:微孔深松耕技术较传统耕作方式,棉花苗期犁底层40 cm处土壤紧实度由9 069.70降低到558.80 k Pa,吐絮期犁底层40 cm处的土壤紧实度由8 089.70降低到1 174.20 k Pa,吐絮期0~40 cm土层中微孔深松耕土壤容重最大为1.05 g/cm3,传统耕作最大为1.56 g/cm3;在30 cm土层中,微孔深松耕的总根量比传统耕作方式多187.03%;微孔深松耕处理棉株棉铃的5室铃率较传统耕作增加15.00%,每个棉瓤的种子数平均增加1~2粒;棉籽的籽指、密度、绒长均明显增加,脂肪含量显著降低(P0.05),蛋白质含量显著增加(P0.05),单株铃数比传统耕作增加6.34%,铃质量增加5.75%,皮棉产量增加10.12%。效益分析表明,采用微孔穴深松耕作种植棉花,每公顷净收益增加3 338.00元。该研究揭示了微孔深松耕作可有效打破犁底层,具有疏松土壤紧实度,并提高棉籽品质增加棉花产量,为该项技术应用于生产提供试验依据。     

Effects of rotational tillage practices on soil structure,organic carbon concentration and crop yields in semi‐arid areas of northwest China

Continuous conventional tillage can cause serious soil degradation in rain‐fed agriculture, which reduces crop productivity. Adopting suitable tillage practices is very important for improving the soil and increasing crop productivity. Between 2007 and 2010, a 3‐year field study was conducted in semi‐arid areas of southern Ningxia, China, to determine the effects of rotational tillage practices on bulk density, soil aggregate, organic carbon concentration and crop yields. Three tillage treatments were tested: no‐tillage the first and third year and subsoiling the second year (NT/ST/NT); subsoiling the first and third year and no‐tillage the second year (ST/NT/ST); and conventional tillage each year (CT). A conventional tillage treatment was used as the control. Under the rotational tillage treatments, the mean soil bulk density at a depth of 0–60 cm was significantly (P < 0.05) decreased by 4.9% compared with CT, and with the best effect under ST/NT/ST. The soil organic carbon (SOC) concentration and aggregate size fractions and stability at 0–40 cm depth were significantly (P < 0.05) increased in rotational tillage treatments when compared with the conventional tillage, and the ST/NT/ST treatment produced the highest increases. Significant differences were detected in the SOC concentration in 2 to 0.25–mm size fractions at 0–30 cm depth between rotational tillage treatments and conventional tillage. Biomass and grain yield with the rotational tillage practices were significantly positively influenced over 3 years, and ST/NT/ST produced the highest average crop yields among the three treatments. Therefore, it was concluded that the application of rotational tillage with subsoiling every 2 years and no‐tillage every other year (ST/NT/ST) should be of benefit in promoting the development of dryland farming in semi‐arid areas of northwest China.     

气压深松土壤孔隙度测试与分析

为了明晰气压深松土壤孔隙度的变化规律及其效果,利用温纳电阻率法测试气压深松前、后的土壤孔隙度,并以孔隙度增加率为指标进行分析,结果表明:深松气压和水平距离对孔隙度增加率有极显著影响(P0.01),而犁底层容重没有显著影响;水平距离0.7 m内的土壤孔隙度增大,犁底层孔隙度增加率随水平距离增加呈现先缓慢变化在0.4 m处出现峰值后,急速减小的变化趋势,水平距离0.1~0.4 m的孔隙度增加率均值显著大于0.5~0.6 m的孔隙度增加率均值(P0.05);深松气压2.2和1.8 MPa作用下的犁底层孔隙度增加率差异不显著,但均显著大于1.4 MPa作用下的犁底层孔隙度增加率(P0.05),1.8 MPa为最佳深松气压。结论可为气压深松技术及其设备的研发提供依据。     

海南热区香蕉地预破土凿式深松机设计与试验

针对海南热带农业区香蕉地现有深松机具匮乏、松土质量差等问题，该研究研制了一款预破土凿式深松机，首先确定整机深松方式，并采用三维建模方法建立深松机整体模型；进一步确定了深松机的整体结构与工作原理，并设计阐述了深松机的关键结构参数。基于田间试验，对深松作业后的土壤坚实度及土壤容重进行测定，确定了前进速度、深松深度、破土刃入土深度为对土壤坚实度及土壤容重有显著影响效果的因素。进一步以土壤坚实度及土壤容重为响应值，基于Box-Behnken设计试验得到响应值与显著性参数的二阶回归模型，并针对显著性参数进行寻优，得到最佳组合：前进速度为1.15 m/s、深松深度为350 mm、破土刃入土深度为250 mm。在标定的最优参数下进行的田间验证试验结果表明，土壤坚实度为752 Pa，土壤容重为1.48 g/cm3，与预测值（734 Pa，1.42 g/cm3）之间的误差分别为2.4%、4.2%，验证了分析的可信性。最后通过与现有传统深松机具开展的对比试验得出：相较于传统深松机具，预破土凿式深松机作业后，土壤坚实度下降6.39%，土壤容重下降9.76%，进一步证明本次试验研制样机适用于海南热区香蕉地深松作业，该机器的设计可为海南热带地区香蕉地深松技术的推广与应用提供参考。     

不同培肥措施对土壤物理性状及无机氮的影响

通过田间动态监测,在东北中部黑土区比较了不同培肥措施下0~60 cm土壤三相比、容重、含水量及无机氮的变化。结果表明,黑土的土壤容重在深松后随着玉米生育进程逐渐向初始状态(1.36~1.54 g cm-3)恢复;与常规栽培(T1)相比,深松+深追肥(T3)和深松+深追肥+增施有机肥(T4)可有效降低玉米成熟期时的土壤容重,改善土壤结构,使20~40 cm层次的土壤三相比接近理想值,T4处理下在成熟期(R6)20~30 cm和30~40 cm土层土壤三相比分别为53.4∶25.2∶21.4和50.9∶25.1∶24.0;此外,T4处理下20~40 cm土壤容重至成熟期时仍保持在1.16~1.29 g cm-3。深松促进了硝态氮的下移,优化了土壤中氮的分配;在开花后,T4处理下20~40 cm土层中硝态氮含量占总含量的31.1%~37.5%,有效的满足了生育后期根系对养分的需求;T4处理下20~50 cm土壤含水量显著提高,较T1处理下平均提高18.0%。研究表明,深松+深追肥+增施有机肥可以改善土壤物理环境,尤其是在20~40 cm,并能显著提升土壤水养库容能力,从而促进养分吸收,提高玉米产量。     

深松对春玉米根系形态特征和生理特性的影响

为研究深松对春玉米根系形态特征和生理特性的影响。以郑单958和先玉335为供试品种,设旋耕(R)、深松加旋耕(S+R)2个处理,于2012和2013年进行田间试验。结果表明,深松可以显著提高2个品种春玉米实测产量(P0.05)、春玉米乳熟期和完熟期根干质量(P0.05)且40 cm以下土层尤为明显。2个品种春玉米30 cm土层处的株、行间根幅均表现为S+R小于R处理,其中行间根幅的差异达到了显著水平(P0.05),单株根条数和比根长均表现为S+R显著高于R处理(P0.05)。乳熟期60 cm以下土层根系活力S+R高于R处理且随着土层的加深差异逐渐增大,超氧化物歧化酶和过氧物酶活性在吐丝期和乳熟期各土层S+R均高于R处理,而丙二醛含量低于旋耕处理。深松促进根系特别是下层根系干质量的增加,增加根系纵深分布,春玉米根系重心下移,并保持较高的生理活性,是其能够增产的重要原因。该文可为春玉米高产栽培提供依据。     

内蒙古河套平原灌区玉米适宜耕作方式研究

【目的】浅旋耕是内蒙古河套灌区常用的耕作方式,长期采用浅旋耕导致耕层变浅、犁底层变硬、土壤保水保肥能力下降。本文探索了翻耕和深松对内蒙古河套平原灌区不同产量水平下玉米农田土壤肥力的作用,以明确适宜本地区长期可持续的耕作技术。【方法】本研究在巴彦淖尔市黄河沿岸进行。选择了长期引黄灌溉,且分别采用浅旋耕 (10—15 cm)、传统翻耕 (20—30 cm) 和深松 (30—35 cm) 3种耕作措施及低、中、高3个产量水平地块。在玉米收获后,采集0—20、20—35和35—50 cm土层样品,测定土壤容重、土壤固液气三相比、土壤水分含量和养分含量,调查玉米产量,分析传统翻耕和深松对不同产量水平地块土壤质量及玉米产量的作用效果,以及不同产量水平地块采用深松和传统翻耕的增产潜力。【结果】3个产量水平土壤上,深松和翻耕较浅旋耕处理的土壤含水量分别提高7.25%～32.11%、5.36%～21.91%,土壤容重降低5.23%～8.61%、0.69%～4.91%,土壤固液气三相比R值降低12.24%～89.97%、7.30%～57.74%,土壤全氮含量提高了17.88%～55.60%、9.81%～22.25%,土壤速效磷含量提高21.23%～41.26%、10.84%～22.04%,土壤速效钾含量提高36.85%～71.99%、6.01%～50.99%,土壤有机质含量提高28.85%～54.14%、14.63%～36.38%;深松的效果显著好于传统翻耕。低、中、高产量水平地块采用深松,玉米的增产潜力分别为29.56%、25.37%、16.13%,采用传统翻耕分别为22.75%、16.96%、16.55%,采用深松的增产潜力大于采用翻耕。【结论】内蒙古河套平原耕作措施由浅旋耕改为深松与传统翻耕,能显著改善低、中、高产肥力地块土壤的理化特性,并提高玉米产量,其中深松效果均好于传统翻耕。低肥力与中肥力水平下采取深松耕作效果最佳,高肥力水平下深松与传统翻耕均可。     

不同耕作模式对小麦—玉米轮作下潮土养分和作物产量的影响

通过分析裂区设计下的6个处理,即小麦季深耕和旋耕2个主处理×玉米季免耕播种、行间深松和行内深松3个副处理:(1)旋耕+免耕播种(RT—NT);(2)旋耕+行间深松(RT—SBR);(3)旋耕+行内深松(RT—SIR);(4)深耕+免耕播种(DT—NT);(5)深耕+行间深松(DT—SBR);(6)深耕+行内深松(DT—SIR),对土壤养分含量和作物产量影响,筛选适宜于小麦—玉米轮作体系的耕作模式。结果表明,各处理土壤养分含量在小麦、玉米两季中均随土层深度增加而降低。小麦季,旋耕处理0—10cm土层土壤全氮、碱解氮、有效磷含量、硝态氮含量显著高于深耕处理;但深耕增加当季30—40cm土层土壤有机质、全氮、碱解氮、有效磷、硝态氮、铵态氮含量。玉米季,DT—NT处理0—30cm土层有机质含量较RT—NT处理增加40.1%～64.3%。RT—SBR、RT—SIR处理显著提升土壤0—30cm全氮含量,其中RT—SBR处理0—10cm土层全氮含量最高,为1.4g/kg。RT—SIR处理显著增加0—20cm土壤碱解氮含量,较RT—NT显著增加15.0%～25.3%。在0—40cm土层,DT—SBR处理的有效磷含量最高,而RT—SBR处理的速效钾含量最高。DT—SIR处理显著提升20—50cm土层硝态氮和铵态氮含量,其中硝态氮含量为8.5～30.4mg/kg,铵态氮含量为2.6～8.9mg/kg。与小麦季相比,玉米季提升10—20cm土层有机质含量、0—50cm土层的碱解氮、有效磷、速效钾含量以及40—50cm土层的硝态氮、铵态氮含量。DT—SBR和DT—SIR处理穗长、百粒重、收获指数和产量显著高于其他处理,且二者产量较RT—NT处理显著增加6.4%～10.8%。玉米季DT—SIR处理的肥料偏利用率和经济效益最高。综上所述,深耕+行内深松处理有利于增加土壤养分含量,且增产效果较好,在本研究中最优。     

Water transmission characteristics of a Vertisol and water use efficiency of rainfed soybean (Glycine max (L.) Merr.) under subsoiling and manuring

In Vertisols of central India erratic rainfall and prevalence of drought during crop growth, low infiltration rates and the consequent ponding of water at the surface during the critical growth stages are suggested as possible reasons responsible for poor yields (<1 t ha⁻¹) of soybean (Glycine max (L.) Merr.). Ameliorative tillage practices particularly deep tillage (subsoiling with chisel plough) can improve the water storage of soil by facilitating infiltration, which may help in minimizing water stress in this type of soil. In a 3-year field experiment (2000–2002) carried out in a Vertisol during wet seasons at Bhopal, Madhya Pradesh, India, we determined infiltration rate, root length and mass densities, water use efficiency and productivity of rainfed soybean under three tillage treatments consisting of conventional tillage (two tillage by sweep cultivator for topsoil tillage) (S₁), conventional tillage + subsoiling in alternate years using chisel plough (S₂), and conventional tillage + subsoiling in every year (S₃) as main plot. The subplot consisted of three nutrient treatments, viz., 0% NPK (N₀), 100% NPK (N₁) and 100% NPK + farmyard manure (FYM) at 4 t ha⁻¹ (N₂). S₃ registered a significantly lower soil penetration resistance by 22%, 28% and 20%, respectively, at the 17.5, 24.5 and 31.5 cm depths over S₁ and the corresponding decrease over S₂ were 17%, 19% and 13%, respectively. Bulk density after 15 days of tillage operation was significantly low in subsurface (15–30 cm depth) in S₃ (1.39 mg m⁻³) followed by S₂ (1.41 mg m⁻³) and S₁ (1.58 mg m⁻³). Root length density (RLD) and root mass density (RMD) of soybean at 0–15 cm soil depth were greater following subsoiling in every year. S₃ recorded significantly greater RLD (1.04 cm cm⁻³) over S₂ (0.92 cm cm⁻³) and S₁ (0.65 cm cm⁻³) at 15–30 cm depth under this study. The basic infiltration rate was greater after subsoiling in every year (5.65 cm h⁻¹) in relation to conventional tillage (1.84 cm h⁻¹). Similar trend was also observed in water storage characteristics (0–90 cm depth) of the soil profile. The faster infiltration rate and water storage of the profile facilitated higher grain yield and enhanced water use efficiency for soybean under subsoiling than conventional tillage. S₃ registered significantly higher water use efficiency (17 kg ha⁻¹ cm⁻¹) over S₂ (16 kg ha⁻¹ cm⁻¹) and S₁ (14 kg ha⁻¹ cm⁻¹). On an average subsoiling recorded 20% higher grain yield of soybean over conventional tillage but the yield did not vary significantly due to S₃ and S₂. Combined application of 100% NPK and 4 t farmyard manure (FYM) ha⁻¹ in N₂ resulted in a larger RLD, RMD, grain yield and water use efficiency than N₁ or the control (N₀). N₂ registered significantly higher yield of soybean (1517 kg ha⁻¹) over purely inorganic (N₁) (1392 kg ha⁻¹) and control (N₀) (898 kg ha⁻¹). The study indicated that in Vertisols, enhanced productivity of soybean can be achieved by subsoiling in alternate years and integrated with the use of 100% NPK (30 kg N, 26 kg P and 25 kg K) and 4 t FYM ha⁻¹.     

玉米秸秆全量深翻还田对高产田土壤结构的影响

为达到玉米生产耕层最适深度(22 cm)和耕层最适土壤容重(1.1~1.3 g×cm~(-3)),解决内蒙古平原灌区耕层浅、犁底层坚硬且厚的农田土壤结构问题,分别选用连续1、2、3、4年秸秆深翻还田定位试验地,秋收后玉米秸秆全量粉碎深翻还田,秸秆年均还田量为20 034.97 kg×hm-2,形成秸秆深翻还田1~4年的4个试验处理(SF1-SF4),以不深翻秸秆还田的处理为对照(CK),研究土壤容重、土壤坚实度、土壤团聚体及其稳定性、土壤肥力及p H随不同年限秸秆深翻还田的变化规律。结果表明:1)SF1-SF4处理0~40 cm土层,土壤容重和土壤坚实度比CK显著减小。2)0~20 cm土层,SF4处理0.25 mm团聚体比例(R0.25)、几何平均直径(GWD)和平均重量直径(MWD)均比CK显著减小;SF1处理土壤团聚体破坏率(PAD)比CK显著降低9.56%,不稳定指数(SWA)随深翻年限增加而显著降低;团聚体分形维数SF4比CK显著增大7.30%。3)20~40 cm土层,SF1和SF2处理R0.25比CK分别显著增加13.69%和17.83%;SF2处理的MWD和GWD分别比CK显著增加23.92%和53.38%;SF1-SF4处理的PAD比CK显著降低,且SF2显著高于SF1和SF3;而SF1-SF4的SWA比CK显著增加,且随秸秆深翻年限的增加呈逐渐升高趋势;团聚体分形维数SF2比CK显著降低7.39%。4)土壤有机质含量SF1-SF4比CK显著增加,且SF2-SF4处理显著大于SF1;速效氮、速效磷和速效钾SF1-SF4比CK显著增加,土壤p H SF3、SF4比CK显著降低。总之,深翻秸秆还田1~4年对0~40 cm土层土壤影响显著;深翻秸秆还田2年适合土壤犁底层结构的改良,深翻秸秆还田3年和4年适合土壤耕层结构的改良。玉米秸秆全量深翻还田既能达到耕作土壤的目的,同时也增加了土壤有机质,降低土壤团聚体破坏率和土壤水稳性团聚体的不稳定系数,利于培肥耕层土壤。     

不同机械深耕的改土及促进作物生长和增产效果

长期不合理耕作导致土壤结构性能恶化、土壤耕性变差,限制作物根系下扎、影响土壤生产潜力发挥。为了改善土壤耕层构造,该试验采用自主研发的改土机械ES-210型深松犁和前置式心土(亚表层)耕作犁进行深耕,以灭茬旋耕(常规耕作)为对照,进行大区耕作对比试验。结果表明:1)深松、亚表层耕作处理与对照相比,耕层土壤固相率分别降低1.6%~3.3%、2.8%~4.5%,液相、汽相相对增加,三相比更趋于合理化;打破犁底层,降低耕层土壤硬度,其中20~35 cm土层效果更为明显;耕层土壤有效水含量上升1.1%~1.2%、0.9%,束缚水(无效水)含量下降0.4%~1.1%、0.5%~0.9%。2)深松、亚表层耕作处理比对照根长增长,其中甜菜增长5.1%、2.9%,大豆增长11.5%、13.2%;干物质积累量增加,其中甜菜增加2.3%~4.1%、3.1%~4.8%,大豆增加7.8%~10.0%、10.4%~13.6%;3)深松、亚表层耕作处理与对照相比,其中甜菜增产8.5%、12.6%;大豆增产5.0%、6.1%;深松及亚表层耕作改土处理分别比对照增收1003.3、1454.4元/hm2,其中收益大小为亚表层耕作处理深松处理对照。可见,采用ES-210深松犁及心土耕作犁深耕改土,改变了土壤耕层构造,起到扩库增容的效果;改善了作物根系生长环境,提高了作物产量,为今后农业耕作机械的发展提供了技术支撑。     

旋耕转深松和秸秆还田增加农田土壤团聚体碳库

土壤耕作和秸秆还田能够显著影响土壤结构和养分周转,也是土壤团聚体分布及更新周转的主要驱动因素。该研究基于连续9 a的旋耕-深松定位试验,对比了长期旋耕农田转变为深松以及秸秆还田对农田土壤0~50 cm土壤团聚体分布、稳定性及团聚体碳含量的影响,分析了团聚体碳对土壤有机碳的贡献率及相互关系。研究结果表明,将长期旋耕农田转变为旋耕-深松农田显著影响了0~50 cm土层的团聚体分布及其碳含量。旋耕-深松配合秸秆还田(RTS-STS)模式能够显著提高表层土壤较大粒级团聚体的比例,且显著提高了土壤团聚体稳定性,分别比旋耕-深松无秸秆还田(RTA-STA)、旋耕秸秆还田(RTS)和旋耕无秸秆还田(RTA)处理高6.1%、65.4%和87.8%;同时,RTS-STS处理显著提高了0~20 cm土层团聚体碳含量和对有机碳的贡献率,虽然在20~30和30~50 cm土层之间,2个处理的团聚体碳含量差异并不明显,但RTS-STS处理的团聚体碳含量对有机碳的贡献率较0~20 cm土层和RTS处理显著降低。通过耕作方式转变、秸秆还田和两者的交互作用对土壤团聚体分布及其碳含量影响的作用力分析可看出,耕作、秸秆及其交互作用是影响不同土层中各处理在不同粒级团聚体分布比例及碳含量差异的主要因素。通过相关分析表明,土壤有机碳含量与团聚体稳定性及其自身碳含量之间存在显著或极显著的正相关关系。旋耕-深松配合秸秆还田(RTS-STS)模式促进了0~20 cm土壤团聚体的形成和稳定,提高了土壤团聚体碳库和对有机碳的贡献,对提升土壤有机碳水平具有积极意义。     

Effects of compaction on soil hydraulic properties,penetration resistance and water flow patterns at the soil profile scale

The aim of this study was to quantify the effects of compaction on water flow patterns at the soil profile scale. Control and trafficked plots were established in field trials at two sites. The trafficked treatment was created by four passes track‐by‐track with a three‐axle dumper with a maximum wheel load of 5.8 Mg. One year later, dye‐tracing experiments were performed and several soil mechanical, physical and hydraulic properties were measured to help explain the dye patterns. Penetration resistance was measured to 50 cm depth, with saturated hydraulic conductivity (K_s), bulk density, and macroporosity and mesoporosity being measured on undisturbed soil cores sampled from three depths (10, 30 and 50 cm). Significant effects of the traffic treatment on the structural pore space were found at 30 cm depth for large mesopores (0.3–0.06 mm diameter), but not small mesopores (0.06–0.03 mm) or macroporosity (pores > 0.3 mm). At one of the sites, ponding was observed during the dye‐tracing experiments, especially in the trafficked plots, because of the presence of a compacted layer at plough depth characterized by a larger bulk density and smaller structural porosity and K_s values. Ponding did not induce any preferential transport of the dye solution into the subsoil at this site. In contrast, despite the presence of a compacted layer at 25–30 cm depth, a better developed structural porosity in the subsoil was noted at the other site which allowed preferential flow to reach to at least 1 m depth in both treatments.