Residue management induced changes in soil organic carbon and total nitrogen under different tillage practices in the North China Plain

Crop residue retention has been considered a practicable strategy to improve soil organic carbon(SOC) and total nitrogen(TN), but the effectiveness of residue retention might be different under varied tillage practices. To evaluate the effects of residue management on the distribution and stocks of SOC and TN under different tillage practices, a bifactorial experiment with three levels for tillage practices(no-tillage, rotary tillage, and conventional tillage) and two levels for residue managements(residue retention and residue removal) was conducted in the North China Plain(NCP). Results showed that after a short experimental duration(3–4 years), concentrations of SOC and TN in the 0–10 cm layer were higher under no-tillage than under conventional tillage, no matter whether crop residues were retained or not. Residue retention increased SOC and TN concentrations in the upper layers of soil to some degree for all tillage practices, as compared with residue removal, with the greatest increment of SOC concentration occurred in the 0–10 cm layer under rotary tillage, but in the 10–30 cm layer under conventional tillage. The stocks of SOC in the 0–50 cm depth increased from 49.89 Mg ha–1 with residue removal to 53.03 Mg ha–1 with residue retention. However, no-tillage did not increase SOC stock to a depth of 50 cm relative to conventional tillage, and increased only by 5.35% as compared with rotary tillage. Thus, residue retention may contribute more towards SOC sequestration than no-tillage. Furthermore, the combination between residue retention and no-tillage has the greatest advantage in enhancing SOC and TN in the NCP region.     

秸秆还田深度对春玉米农田土壤有机碳、氮含量和土壤酶活性的影响

为研究秸秆还田旋耕深度对土壤理化性质和酶活性的影响,明确不同秸秆还田深度条件下土壤理化性质与酶活性的关系,在3年（2016—2018年）田间微区定位试验条件下,研究秸秆旋耕还田10 cm（S₁D₁）、20 cm（S₁D₂）、30 cm（S₁D₃）和秸秆移除旋耕10 cm（S₂D₁）、20 cm（S₂D₂）、30 cm（S₂D₃） 6个处理对东北春玉米农田土壤理化性质和酶活性的影响。结果表明：旋耕深度（D）及其与秸秆处理（S）交互作用（S×D）显著影响土壤有机碳（SOC）含量,0~20 cm土层S₁D₁、S₁D₂处理SOC含量较S₁D₃处理高1.2%~16.0%,而20~40 cm土层S₂D₃处理SOC含量最高。旋耕深度、秸秆处理及两者交互作用对土壤硝态氮（NO₃^--N）和铵态氮（NH₄⁺-N）含量、蔗糖酶和过氧化氢酶活性影响显著。在0~40 cm土层,D₁、D₂旋耕深度下秸秆还田处理NO₃^--N含量比秸秆移除处理平均提高46.9%和34.9%,NH₄⁺-N含量平均降低31.6%和4.4%。在各旋耕深度下,S₁处理0~20 cm土层蔗糖酶和脲酶活性高于S₂处理,20~30 cm土层过氧化氢酶活性低于S₂处理。相关性分析表明,SOC、土壤全氮（TN）与NO₃^--N、NH₄⁺-N含量和蔗糖酶活性呈显著正相关,与pH、土壤含水量（SWC）呈显著负相关。主成分分析表明,与S₁D₁相比,S₁D₂对0~20土层蔗糖酶、脲酶、过氧化氢酶活性和0~40 cm土层SOC、TN含量影响更明显。综上所述,秸秆旋耕还田20 cm可改善0~40 cm土层养分水平,提高土壤酶活性,推荐为东北春玉米产区农田土壤培肥的合理秸秆还田方式。     

Effects of subsoiling depth,period interval and combined tillage practice on soil properties and yield in the Huang-Huai-Hai Plain,China

Compaction layers are widely distributed in the Huang-Huai-Hai Plain, China, which restrict root growth and reduce yields. The adoption of subsoiling has been recommended to disrupt compacted soil layers and create a reasonable soil structure for crop development. In this paper, the effects of subsoiling depth(30, 35 and 40 cm), period interval(2 or 3 years) and combined pre-sowing tillage practice(rotary cultivation or ploughing) on soil condition improvement was studied on a tidal soil in the Huang-Huai-Hai Plain. Seven tillage patterns were designed by combining different subsoiling depths, period intervals and pre-sowing. The evaluation indicators for soil condition improvement were as follows: thickness of the plough layer and hard pan, soil bulk density, cone index, soil three-phase R values, alkali nitrogen content, crop yield, and economic benefits. The results showed that subsoiling can significantly improve the soil structure and physical properties. In all subsoiling treatments, the depth of 35 or 40 cm at a 2-year interval was the most significant. The thickness of the plough layer increased from 13.67 cm before the test to 21.54–23.45 cm in 2018. The thickness of the hard pan decreased from 17.68 cm before the test to 12.09–12.76 cm in 2018, a decrease of about 40.07%. However, the subsoiling combined presowing tillage practice, that is, rotary cultivation or ploughing, was not significant for soil structure and physical properties. For all subsoiling treatments, the soil bulk density, cone index and soil three-phase R values of the 15–25 cm soil layer were significantly lower compared to single rotary cultivation. Subsoiling was observed to increase the soil alkaline nitrogen and water contents. The tillage patterns that had subsoiling at the depth of 35–40 cm at a 2-year interval combined with rotary cultivation had the highest alkali nitrogen and water contents, which increased by 31.08–34.23% compared with that of the single rotary cultivation. Subsoiling can significantly increase the yield both of wheat and corn, as well as the economic benefits. The treatment of subsoiling at the depth of 35 cm at an interval of 2 years combined with rotary cultivation had the highest annual yield and economic benefits. For this treatment, the annual yield and economic benefits increased by 14.55 and 62.87% in 2018, respectively. In conclusion, the tillage patterns that involved subsoiling at a depth of 35 cm at a 2-year interval along with rotary cultivation are suitable for the Huang-Huai-Hai Plain.     

深旋松耕作法对华北缺水区壤质黏潮土物理性状及作物生长的影响

【目的】针对华北高产农区连年旋耕导致耕层变浅、犁底层变厚变硬、耕层生产能力下降的问题,探讨深旋松耕作法在华北地区作物生产上的可行性。【方法】在河北吴桥地区设置了4种耕作处理,即传统旋耕15 cm、间隔深松耕30 cm、深旋松耕30 cm、深旋松耕50 cm,研究大田条件下不同耕作方法对土壤性质与作物产量的影响。【结果】（1）不同耕作处理对土壤蓄水量的影响较大,深旋松耕处理表现出利于降水入渗、储蓄更多水分的优势,并且越是干旱的时段,表现越突出。在冬小麦返青期深旋松耕处理土壤蓄水量均极显著高于旋耕处理和间隔深松处理,其中深旋松耕50 cm处理的0—50 cm土层土壤蓄水量分别比旋耕处理和间隔深松处理增加11.69 mm和10.56 mm,提高12.21%和10.90%。（2）不同耕作方法对土壤容重影响很大,耕作一年半之后,深旋松耕两个处理在0—30 cm土层容重显著低于深松和旋耕两个处理,其中深旋松耕30 cm在20—30 cm土层容重分别比深松和旋耕低了13.67%和13.99%,深旋松耕50 cm在20—30 cm土层分别比深松和旋耕低了14.20%和14.51%,30—50 cm土层深旋松耕50 cm土层依然显著低于其他处理,其中,40—50 cm土层分别比深松和旋耕低了22.66%和22.80%,深松处理在冬小麦播前略低于旋耕处理,之后的时期则与旋耕处理间几乎没有差异。（3）耕作方式的不同对土壤性质有影响,并进而影响作物群体LAI、干物质积累和灌浆速率以及产量的形成,对冬小麦季影响最为显著,其中冬小麦花期深旋松耕50 cm处理的群体LAI分别比旋耕处理和间隔深松处理提高51.98%和39.22%,干物质积累量分别比旋耕和间隔深松处理提高26.78%和16.92%,冬小麦灌浆30 d时深旋松耕50 cm分别比深松和旋耕的籽粒干重提高10.37%和11.40%。（4）所有耕作处理中,深旋松耕土壤耕作处理的作物产量显著高于深松耕作和旋耕耕作,其中耕作一年半后夏玉米季深旋松耕50 cm处理产量达到了13 822.68 kg•hm-2,深旋松耕30 cm处理产量也达到了13 127.87 kg•hm-2,均显著高于旋耕处理,对比旋耕处理分别增产38.19%、31.24%。【结论】考虑生态经济等因素的综合考虑,深旋松耕30 cm处理为最适合华北缺水区的耕作方法。     

耕作和秸秆还田方式对东北春玉米吐丝期根系特征及产量的影响

【目的】针对东北春玉米主产区秸秆处理的突出矛盾,优化秸秆还田方式对促进该区农业绿色可持续发展意义深远。本文研究了耕作和秸秆还田方式对春玉米根系形态及分布特征、干物积累和产量的影响,旨在为该区域耕作措施调整、实现秸秆还田维持耕地农业生产提供理论依据。【方法】2017—2018年在辽宁沈阳进行田间试验,采用二因素随机区组设计,分别设置秸秆全层翻耕还田(PTS)、秸秆条带翻耕还田(PSS)、秸秆全层旋耕还田(RTS)和秸秆条带旋耕还田(RSS)4个处理。分析不同耕作和秸秆还田方式下春玉米根长、根干重及其空间分布、植株地上部干物质积累动态和产量性状的差异。【结果】耕作和秸秆还田方式对吐丝期春玉米根长及其分布、根干重和比根长影响显著。在0—30 cm垂直土层,PTS处理根长2017年和2018年分别高出其他处理7.9%—43.2%和17.3%—41.5%;在30—60 cm垂直土层,秸秆条带还田(PSS和RSS处理)根长较秸秆全层还田(PTS和RTS处理)平均高出20.1%和20.3%;以植株为中心,PTS处理距植株0—10 cm的根长分布最高,RTS处理最低。根干重在0—10 cm土层表现为R...     

Maize straw application as an interlayer improves organic carbon and total nitrogen concentrations in the soil profile: A four-year experiment in a saline soil

Soil salinization is a critical environmental issue restricting agricultural production. Deep return of straw to the soil as an interlayer (at 40 cm depth) has been a popular practice to alleviate salt stress. However, the legacy effects of straw added as an interlayer at different rates on soil organic carbon (SOC) and total nitrogen (TN) in saline soils still remain inconclusive. Therefore, a four-year (2015–2018) field experiment was conducted with four levels (i.e., 0, 6, 12 and 18 Mg ha^–1) of straw returned as an interlayer. Compared with no straw interlayer (CK), straw addition increased SOC concentration by 14–32 and 11–57% in the 20–40 and 40–60 cm soil layers, respectively. The increases in soil TN concentration (8–22 and 6–34% in the 20–40 and 40–60 cm soil layers, respectively) were lower than that for SOC concentration, which led to increased soil C:N ratio in the 20–60 cm soil depth. Increases in SOC and TN concentrations in the 20–60 cm soil layer with straw addition led to a decrease in stratification ratios (0–20 cm:20–60 cm), which promoted uniform distributions of SOC and TN in the soil profile. Increases in SOC and TN concentrations were associated with soil salinity and moisture regulation and improved sunflower yield. Generally, compared with other treatments, the application of 12 Mg ha^–1 straw had higher SOC, TN and C:N ratio, and lower soil stratification ratio in the 2015–2017 period. The results highlighted that legacy effects of straw application as an interlayer were maintained for at least four years, and demonstrated that deep soil straw application had a great potential for improving subsoil fertility in salt-affected soils.     

耕作方式与秸秆还田对麦田土壤有机碳积累的影响

通过大田定位试验,研究了稻麦两熟制下耕作方式与秸秆还田对麦田土壤总有机碳积累的影响。结果表明:秸秆还田可以显著提高土壤总有机碳和土壤微生物生物量碳的含量,其中旋耕+连续3季稻麦秸秆还田处理使土壤总有机碳含量提高了37.19%,翻耕+连续3季稻麦秸秆还田处理使土壤微生物生物量碳含量提高了62.88%;翻耕处理的15～25 cm土层土壤总有机碳和微生物生物量碳含量显著高于旋耕处理;在相同秸秆还田方式下,旋耕处理的0～7 cm和7～15 cm土层的微生物熵显著大于翻耕处理,而15～25 cm土层的则相反。     

秸秆还田模式对土壤有机碳及腐植酸含量的影响

通过9年水稻-小麦轮作田间定位试验,探讨南方稻麦两熟制农田秸秆还田模式对土壤有机碳(SOC)和腐植酸(HE)的影响。试验设置仅麦秆稻季还田(W)、仅稻秆麦季还田(R)、秸秆稻麦季均还田(RW)和秸秆均不还田(CK)共4个处理。结果表明,秸秆还田显著(P0.05)提高了0~10 cm土层SOC,对土壤总氮(TN)无明显影响;不同秸秆还田模式处理下,0~10 cm土层SOC及TN大小为WRWRCK;10~20 cm SOC及TN大小均为WCKRWR,但各处理之间的差异均不显著。秸秆还田处理中,0~10 cm土层土壤HE、富里酸(FA)和胡敏酸(HA)均低于CK,而在10~20 cm土层则高于CK。不同秸秆还田方式间,0~10 cm土层的HE、FA和HA以W处理为最高,其土壤腐殖化程度最大;而10~20 cm土层则以RW处理为最高,W处理的土壤腐殖化程度最小。相比其他秸秆还田模式,麦秸稻季还田能更好地提高土壤表层有机碳含量和腐殖质品质。     

玉米秸秆还田模式对土壤肥力和玉米产量的影响

为探讨西辽河平原灌区玉米秸秆还田适宜模式,于2016年在连作玉米田设深翻秸秆还田(DR)、旋耕秸秆还田(RR)、深翻秸秆还田施用腐熟剂(DR+D)和旋耕秸秆还田施用腐熟剂(RR+D)4个处理,以旋耕不还田(CK)为对照,研究不同还田模式对土壤速效养分、土壤酶活性和玉米产量的影响。结果表明:RR+D和RR分别较CK增产24.56%和28.00%,DR和DR+D产量与CK无显著差异。RR+D处理显著(P<0.05)提高了表层(0~10 cm)土壤碱解氮含量(增幅94.56%),其他处理表层土壤速效养分含量与CK无显著差异。各秸秆还田处理可不同程度提高不同土层土壤酶的活性。综合来看,该地区以旋耕秸秆还田施用腐熟剂模式的效果较好。     

深翻、有机无机肥配施对稻田水分渗漏和氮素淋溶的影响

【目的】针对我国长江中下游地区稻麦轮作区常年浅耕与不合理施肥导致的土壤犁底层增厚与土壤板结的问题,研究深耕(打破部分犁底层)与施肥方式对稻田土壤容重、土壤紧实度、土壤水分渗漏量、氮素淋溶量及氮素形态的影响,阐明稻田氮素淋溶量与耕作、施肥方式的响应机制,为稻田合理耕层构建提供理论依据。【方法】(1)基于2015年安徽省舒城县设置两种耕作方式(旋耕12 cm、深翻20 cm)、3种等氮量施肥方式(仅施化肥处理T1、秸秆还田配施化肥处理T2、有机与无机肥配施处理T3)的田间定位试验,2019—2020年监测土壤容重与紧实度以及稻季水分渗漏与氮素淋溶量。(2)通过原状土柱模拟试验,研究深翻30 cm(打破犁底层)对稻田水分渗漏量的影响。【结果】(1)田间试验结果表明,深翻20 cm较旋耕12 cm降低了耕层土壤容重与紧实度,但没有显著增加水稻生育期的水分渗漏量,仅在分蘖期增加7.4%,孕穗期之后无显著影响。(2)土柱试验结果显示,深翻30 cm(打破犁底层)水分渗漏量较旋耕12 cm和深翻20 cm显著增加,淹水时分别增加19.0%与11.0%,非淹水时分别增加23.0%与21.5%。(3)田...     

土壤耕作方式及秸秆还田对土壤性质和烤烟性状的影响

为研究土壤耕作方式及秸秆还田对土壤性质和烤烟性状的影响,设置2种耕作深度（常规旋耕15 cm、机械深耕30 cm）与添加秸秆的交互试验。结果表明：深耕能提高土壤容重和孔隙度,降低0～20 cm土层全氮、有效磷、速效钾和碱解氮含量,提高20～40 cm土层养分的含量;秸秆还田可以显著降低土壤容重,提高土壤孔隙度,显著提高0～20 cm土层的全氮、速效钾和碱解氮含量;土壤微生物变化不明显,可能与耕作年限较短有关。     

土壤耕作技术对小麦出苗质量、根系功能及粒重的影响

【目的】 针对黄淮平原农作区一年两熟条件下玉米秸秆还田严重影响麦苗质量的突出问题,探索适宜的土壤耕作技术以提高小麦幼苗质量,最终提高产量。【方法】 2016—2018年连续2年,在河南省新郑市辛店镇黄岗村开展田间试验。采用随机区组设计,将翻耕、耙、镇压3个因素组合配套实施8个处理,分别为深翻耕+旋耕（DT+RT;DT：30 cm,RT：15 cm）、深翻耕+耙（DT+H）、深翻耕+旋耕+镇压（DT+RT+C）、深翻耕+耙+镇压（DT+H+C）、旋耕（RT）、旋耕+耙（RT+H）、旋耕+镇压（RT+C）、旋耕+耙+镇压（RT+H+C）。对小麦出苗率及幼苗质量进行调查,并在越冬期、返青期、拔节期、抽穗期、灌浆期、蜡熟期对根系进行调查分析,分别在灌浆期对小麦籽粒性状、收获后对小麦产量及其构成因素进行调查分析。【结果】 小麦播种后20 d,不同土壤耕作处理间幼苗质量差异显著。旋耕后出苗整齐度高于深翻耕,而深翻耕后出苗率、基本苗数和株高高于旋耕。相同耕、镇压因素处理下,耙后出苗率增幅为1.0%—5.7%,相同耕、耙因素处理下,镇压后出苗率增幅为0.06%—8.3%;同时深翻耕后,极少出现缺苗、断垄,RT处理缺苗、断垄的累计长度最高,两年平均为55 cm。从越冬期到蜡熟期,不同土壤耕作处理的根系活力均呈现“高-低-高-低”的变化趋势,DT+H+C处理最高;在越冬期和拔节期,镇压和耙处理后,与无镇压、耙处理相比,根系活力均提高。单株次生根数目在抽穗期达到最大,DT+H+C处理最高,两年最高值分别为45.2条与40.2条;与无耙处理相比,耙处理后,单株次生根数目最高增加14.8%,与无镇压处理相比,镇压处理后,单株次生根数目最高增加12.2%。花后5—10 d,DT+H+C和RT+H+C处理的籽粒灌浆速率增长幅度显著高于其他处理,开花后20 d达到峰值,其中DT+H+C处理籽粒灌浆速率比其他处理高1.0%—19.4%,达显著水平。灌浆期籽粒千粒重,在花后0—15 d,DT+H+C处理增长最快,DT+RT处理增长最慢,花后25—30 d,DT+H+C处理千粒重最高,较RT处理提高20.8%。从不同土壤耕作技术对籽粒产量及其构成因素的影响来看,DT+H+C处理的籽粒产量最高;耙和镇压处理的单位面积穗数、穗粒数和千粒重的变化并不规律,籽粒产量均有明显提升,幅度为1.4%—12.2%。经济效益方面,与当地以往耕作方式RT相比,RT+H、RT+H+C、RT+C、DT+H+C、DT+H处理所得效益均高于RT处理,其中DT+H+C处理产生经济效益最高,两年平均比RT处理高12.3%。【结论】 黄淮平原农作区当前一年两熟制条件下,不同土壤耕作技术影响幼苗质量,旋耕有利于出苗的整齐度提高,而深翻耕则有利于出苗率及幼苗均匀度提高,株高增高,为冬前形成壮苗奠定基础;深翻耕将耕层加深,利于根系下扎,促进次生根数目的增加以及耕层根系活力的提高,间接影响籽粒产量。综合考虑植株根系生长发育、生育后期籽粒灌浆速率、粒重形成和产量表现等,研究认为黄淮农作区DT+H+C处理土壤耕作技术是当前的最佳选择。     

Strip deep rotary tillage combined with controlled-release urea improves the grain yield and nitrogen use efficiency of maize in the North China Plain

Inappropriate tillage practices and nitrogen(N) management have become seriously limitations for maize(Zea mays L.) yield and N use efficiency(NUE) in the North China Plain(NCP). In the current study, we examined the effects of strip deep rotary tillage(ST) combined with controlled-release(CR) urea on maize yield and NUE, and determined the physiological factors involved in yield formation and N accumulation during a 2-year field experiment. Compared with conventional rotary tillage(RT) and no-t...     

Effects of Tillage Practices on Water Consumption,Water Use Efficiency and Grain Yield in Wheat Field

Water shortage is a serious issue threatening the sustainable development of agriculture in the North China Plain, with the winter wheat (Triticum aestivum L.) as its largest water-consuming crop. The effects of tillage practices on the water consumption and water use efficiency (WUE) of wheat under high-yield conditions using supplemental irrigation based on testing soil moisture dynamic change were examined in this study. This experiment was conducted from 2007 to 2010, with five tillage practice treatments, namely, strip rotary tillage (SR), strip rotary tillage after subsoiling (SRS), rotary tillage (R), rotary tillage after subsoiling (RS), and plowing tillage (P). The results showed that in the SRS and RS treatments the total water and soil water consumptions were 11.81, 25.18% and 12.16, 14.75% higher than those in SR and R treatments, respectively. The lowest ratio of irrigation consumption to total water consumption in the SRS treatment was 18.53 and 21.88% for the 2008–2009 and 2009–2010 growing seasons, respectively. However, the highest percentage of water consumption was found in the SRS treatment from anthesis to maturity. No significant difference was found between the WUE of the flag leaf at the later filling stage in the SRS and RS treatments, but the flag leaf WUE at these stages were higher than those of other treatments. The SRS and RS treatments exhibited the highest grain yield (9573.76 and 9507.49 kg ha⁻¹ for 3-yr average) with no significant difference between the two treatments, followed by P, R and SR treatments. But the SRS treatment had the highest WUE. Thus, the 1-yr subsoiling tillage, plus 2 yr of strip rotary planting operation may be an efficient measure to increase wheat yield and WUE.     

Fractionation of soil organic carbon in a calcareous soil after long-term tillage and straw residue management

No-tillage (NT) and straw return (S) collectively affect soil organic carbon (SOC). However, changes in the organic carbon pool have been under-investigated. Here, we assessed the quantity and quality of SOC after 11 years of tillage and straw return on the North China Plain. Concentrations of SOC and its labile fractions (particulate organic carbon (POC), potassium permanganate-oxidizable organic carbon (POXC), microbial biomass carbon (MBC), and dissolved organic carbon (DOC)), components of DOC by fluorescence spectroscopy combined with parallel factor analysis (PARAFAC), and the chemical composition of SOC by ¹³C NMR (nuclear magnetic resonance) spectroscopy were explored. Treatments comprised conventional tillage (CT) and NT under straw removal (S0), return of wheat straw only (S1), or return of both wheat straw and maize residue (S2). Straw return significantly increased the concentrations and stocks of SOC at 0–20 cm depth, but NT stratified them with enrichment at 0–10 cm and a decrease at 10–20 cm compared to CT, especially under S2. Labile C fractions showed similar patterns of variation to that of SOC, with POC and POXC more sensitive to straw return and the former more sensitive to tillage. Six fluorescence components of DOC were identified, mainly comprising humic-like substances with smaller amounts of fulvic acid-like substances and tryptophan. Straw return significantly decreased the fluorescence index (FI) and autochthonous index (BIX) and increased the humification index (HIX). No-tillage generally increased HIX in topsoil but decreased it and increased the FI and BIX below the topsoil. Relative abudance order of the chemical composition of SOC was: O-alkyl C>alkyl-C>aromatic-C>carbonyl-C. Overall, NT under S2 effectively increased SOC and its labile C forms and DOC humification in topsoil and microbially-derived DOC below the topsoil. Return of both wheat and maize straw was a decisive factor in promoting SOC in the plow layer. The stratification of SOC under NT may confer a long-term influence on carbon sequestration.     

滨海地区不同耕作方式对土壤水分及夏玉米生长发育的影响

针对河北省滨海地区夏玉米地土壤耕层变浅、病虫草害严重的问题,以当地习惯的耕作方式免耕为对照,设置深翻30cm后旋耕(T1)、深松40 cm后旋耕(T2)、旋耕(T3)3种耕作方式,分析各处理对土壤水分及夏玉米生长发育的影响。研究结果表明,T1或T2处理均提高了土壤耕层含水量,其中以深松40 cm后旋耕保墒效果最佳;T1或T2处理均增大了玉米叶面积指数、穗长、穗粒数、千粒质量和产量,降低了空秆率,其中以播前深松40 cm后旋耕效果最佳。本研究选用的3种耕作措施中,播前先深松40cm再翻耕的耕作方式最适宜该地区。     

滨海地区不同耕作方式对土壤水分及夏玉米生长发育的影响

针对河北省滨海地区夏玉米地土壤耕层变浅、病虫草害严重的问题,以当地习惯的耕作方式免耕作对照,设置深翻30 cm后旋耕(T1)、深松40 cm后旋耕(T2)、旋耕(T3)3种耕作方式,分析各处理对土壤水分及夏玉米生长发育的影响。结果表明,T1或T2处理均提高了土壤耕层含水量,其中以深松40 cm后旋耕保墒效果最佳;T1或T2处理均增大了玉米叶面积指数、穗长、穗粒数、千粒质量和产量,降低了空秆率,其中以播前深松40 cm后旋耕效果最佳。选用的3种耕作措施中,播前先深松40 cm再翻耕的耕作方式最适宜该地区。     

潮土区小麦、玉米残体对土壤有机碳的贡献——基于改进的RothC模型

【目的】为进一步了解秸秆还田对土壤有机碳(SOC)的提升效果,探究作物残体(根系与秸秆)对潮土区SOC的贡献,为华北冬小麦-夏玉米区SOC提升提供理论依据。【方法】基于腐解试验的有机物料碳残留率数据,获得4种有机物料在RothC-26.3模型最优时对应的DPM/RPM参数值(易分解植物残体和难分解植物残体的比值)。利用修订的DPM/RPM参数,获得了改进的RothC-26.3模型,并用郑州潮土区短期腐解试验(2012年11月至2013年11月)和长期定位试验数据(1990—2008年)进行验证,模拟出郑州潮土区冬小麦-夏玉米轮作系统中小麦、玉米残体在3种不同施肥处理下(不施肥CK,平衡施肥NPK和秸秆还田NPKS)对新形成SOC的贡献。【结果】在模型达到最优时,小麦根系(wheat root,WR)、小麦秸秆(wheat straw,WS)、玉米根系(corn root,CR)和玉米秸秆(corn straw,CS)的DPM/RPM值分别为0.89、3.04、4.35和3.25。模型结果显示,CK处理小麦根系、玉米根系的碳投入占碳投入的比例均为50%,而来源于小麦根系、玉米根系的SOC(0—20 cm)占新形成的SOC比例分别为60%、40%;小麦根和玉米根固碳效率分别为15.5%、10.8%;NPK处理小麦根系、玉米根系的碳投入占碳投入的比例分别为60%、40%,而来源于小麦根系、玉米根系的SOC(0—20 cm)占新形成SOC的比例分别为71%、29%;小麦根和玉米根固碳效率分别为17.5%、11.4%;NPKS处理小麦根系、玉米根系、玉米秸秆的碳投入的比例分别为47%、21%、32%,而小麦根系、玉米根系、玉米秸秆对新形成的SOC(0—20 cm)贡献分别为50%、22%、28%;小麦根系、玉米根系、玉米秸秆的固碳效率分别为16.9%、11.2%、11.4%。总之,冬小麦-夏玉米轮作系统中无论是不施肥、平衡施肥还是秸秆还田处理,小麦根系对新形成SOC的贡献率(50%—71%)大于玉米根系和玉米秸秆对新形成SOC贡献率(22%—40%)。源自小麦的SOC占新形成SOC的比例均分别大于源自小麦的碳投入占总碳投入的比例,而源自玉米的投入及其对新形成SOC的贡献则反之。小麦根系的固碳效率(15.5%—17.5%)大于玉米根系和玉米秸秆的固碳效率(10.8%—11.4%)。【结论】改进后的RothC模型可用来探究潮土区冬小麦-夏玉米轮作系统中小麦、玉米残体对新形成SOC的贡献。郑州潮土区冬小麦-夏玉米轮作系统中小麦根系对新形成SOC的贡献率均大于玉米根系和玉米秸秆的贡献率。根茬还田(尤其是小麦根茬还田)更有利于提升土壤有机碳含量。     

粉垄耕作对黄淮海北部春玉米籽粒灌浆及产量的影响

【目的】在黄淮海北部引入一种称作“粉垄”的新型深土耕作措施,旨在解决由于连年旋耕所致的犁底层上移、耕层变浅,限制作物产量提高的现实问题。【方法】以旋耕和深松为对照,设置粉垄30 cm、粉垄50 cm、粉垄30 cm+地膜、粉垄50 cm+地膜等处理,探究其对春玉米灌浆和产量的影响。【结果】与旋耕和深松相比,粉垄利于水分入渗,增加了土壤贮水,改善了土壤水分供给,提高了春玉米的穗粒数和籽粒含水率;尽管灌浆渐增期不具有优势,且耕作深度越深,起始生长势和平均灌浆速率越低,但灌浆快增期和缓增期平均灌浆速率随耕作深度增加的优势突出;最终粉垄的百粒重和产量显著高于两对照。粉垄加盖地膜保存了更多水分,显著提高了穗粒数,灌浆渐增期灌浆速率便优势明显,且耕作深度越深,优势越明显,加之灌浆期延长,百粒重和产量显著高于未覆膜两处理。【结论】粉垄覆膜的新型耕作措施为打破犁底层、解决耕层变浅、促进作物增产提供了一种新的可行方法。     

玉米秸秆不同还田方式对黑钙土物理性质和产量的影响

为提高东北玉米集约化生产区秸秆资源利用和培肥土壤,采用大区对比试验,设置常规栽培(对照)、秸秆覆盖还田、秸秆粉碎旋耕还田和秸秆翻埋还田,采用常规方法探索半干旱地区玉米秸秆对土壤物理性质及产量的影响。结果表明:常规栽培方式(对照)土壤容重最大,为1.38g·cm~(-3),其次为覆盖还田、翻埋还田和旋耕还田,与对照相比分别降低了3.00%、8.06%和7.46%。0~20cm土层,吐丝期翻埋还田处理土壤含水量分别比常规栽培、覆盖还田、旋耕还田高12.20%、7.35%和16.30%;成熟期翻埋还田土壤含水量分别比常规栽培、覆盖还田和旋耕还田高18.52%、17.64%和22.63%。20~40cm土层,吐丝期翻埋还田土壤含水量分别比常规栽培、覆盖还田和旋耕还田高14.90%、13.73%和15.82%;成熟期翻埋还田土壤含水量分别比常规栽培、覆盖还田和旋耕还田高14.98%、14.66%和17.82%。覆盖还田处理的行粒数最大,其它还田方式略低。不同方式秸秆还田各处理间玉米产量存在一定差异,其年平均产量最高为秸秆翻埋还田,较对照提高9.6%。