Changes in total, mineralizable and light fraction soil organic matter with cropping and tillage intensities in semiarid southern Alberta, Canada

There has been a trend toward increased cropping intensity and decreased tillage intensity in the semiarid region of the Canadian prairies. The impact of these changes on sequestration of atmospheric CO₂ in soil organic carbon (C) is uncertain. Our objective was to quantify the changes in total, mineralizable and light fraction organic C and nitrogen (N) due to the adoption of continuous cropping and conservation tillage practices. We sampled three individual long-term experiments at Lethbridge, Alberta, in September 1992: a spring wheat (Triticum aestivum L.)-fallow tillage study, a continuous spring wheat tillage study and a winter wheat rotation-tillage study. Treatments had been in place for 3–16 years. In the spring wheat-fallow study, different intensities (one-way disc > heavy-duty cultivator > blade cultivator) of conventional tillage (CT) were compared with minimum tillage (MT) and zero tillage (ZT). After 16 years, total organic C was 2.2 Mg ha⁻¹ lower in more intensively worked CT treatments (one-way disc, heavy-duty cultivator) than in the least-intensive CT treatment (blade cultivator). The CT with the blade cultivator and ZT treatments had similar levels of organic C. The CT treatments with the one-way disc and heavy-duty cultivator had light fraction C and N and mineralizable N amounts that were about 13–18% lower than the CT with the blade cultivator, MT or ZT treatments. In the continuous spring wheat study, 8 years of ZT increased total organic C by 2 Mg ha⁻¹, and increased mineralizable and light fraction C and N by 15–27%, compared with CT with a heavy-duty cultivator prior to planting. In the winter wheat rotation-tillage study, total organic C was 2 Mg ha⁻¹ higher in a continuous winter wheat (WW) rotation compared with that in a winter wheat-fallow rotation. The lack of an organic C response to ZT on the WW rotation may have been due to moldboard plowing of the ZT treatment in 1989 (6 years after establishment and 3 years before soil sampling), in an effort to control a severe infestation of downy brome (Bromus tectorum L.). Our results suggest that although relative increases in soil organic matter were small, increases due to adoption of ZT were greater and occurred much faster in continuously cropped than in fallow-based rotations. Hence intensification of cropping practices, by elimination of fallow and moving toward continuous cropping, is the first step toward increased C sequestration. Reducing tillage intensity, by the adoption of ZT, enhances the cropping intensity effect.     

Tillage and mulch effects on soil physical environment, root growth, nutrient uptake and yield of maize and wheat on an Alfisol in north-west India

Field experiments were conducted for 6 years on a silty clay loam to study the effect of soil management on soil physical properties, root growth, nutrient uptake and yield of rainfed maize (Zea mays L.) and wheat (Triticum aestivum L.) grown in a sequence. Treatments were: no-tillage (NT), NT+pine needle mulch at a rate of 10 t ha⁻¹ (NT+M), conventional tillage (CT), CT+pine needle mulch at a rate of 10 t ha⁻¹ (CT+M) and deep tillage (DT). The soil is classified as a Typic Hapludalf and has compact sub-surface layers. The NT treatment increased the bulk density of the surface layer but this problem was not observed in the no-tilled treatment having mulch at the surface (NT+M). The CT+M and NT+M treatments favourably moderated the hydro-theregime resulting in greater root growth, nutrient uptake and grain yields of maize and wheat. The DT treatment, imposed only once, at the beginning of the study, also enhanced root growth and grain yields. The yields were similar to the mulched treatments for maize and somewhat less than the mulched treatments for wheat. Mulched treatments generally showed significantly greater total uptake of N, P and K than corresponding unmulched ones. Since NT+M was comparable to CT for maize and superior for wheat, the latter is preferable since it does not require ellaborate tillage.     

The impact of tillage and residual nitrogen on wheat

Wheat (Triticum aestivum L.) yield and quality is influenced by management of the previous crop but is highly dependent on current year management. The objective of this study was to evaluate the response of winter wheat seeded in two tillage systems [conventional tillage (CT) and no-till (NT)] to four N rates applied to a previous cotton (Gossypium hirsutum L.) crop (0, 67, 134, and 202 kg ha⁻¹). The experiment with wheat was conducted on a Dothan sandy loam (fine, loamy siliceous, thermic Plinthic Kandiudults) at the University of Florida North Florida Research and Education Center near Quincy, FL from 1995 to 1997. For most plant characteristics, there was a tillage x N x year interaction. Greater plant emergence (79.4 vs. 65.3%) and grain N (23.5 vs. 21.5 g kg⁻¹), and lower grain moisture (139 vs. 142 g kg⁻¹) were obtained under NT than CT, respectively, in one out of two years. Nitrogen applied to a previous cotton crop increased wheat grain yields, plant height and seed number under NT in 1995–1996 and CT in 1996–1997, head density under NT in both years, harvest index under CT in 1996–1997, and grain N concentration in 1995–1996 and 1996–1997 due to residual plant and soil N. With every 1 kg N applied to a previous cotton crop, wheat grain yields increased by 5.38 kg ha⁻¹ under NT, whereas grain yield under CT was not influenced by N application to cotton in 1995–1996. In 1996–1997, grain yields increased by 4.96 and 4.23 kg ha⁻¹ for wheat grown in NT and CT, respectively. Generally, wheat seeded in NT following cotton did not decrease stand or yields compared to CT and wheat grain yields and grain N content increased with N fertilization of the previous crop. However, we would have to apply about 134 kg N ha⁻¹ to a previous cotton crop to maximize wheat production under NT and CT.     

玉米免耕留膜可减少后茬轮作春小麦水氮用量

【目的】河西绿洲灌区玉米普遍采用地膜覆盖措施,其收获后地膜的完整率仍高达70%。研究后茬小麦继续利用该地膜条件下相适应的水氮耦合管理,以期最大化发挥农资的效益,提高小麦产量和氮肥利用率。【方法】2016—2017年度,在甘肃河西绿洲灌区玉米–小麦轮作田进行三因素裂区田间试验。选择头茬玉米进行免耕 (NT) 和传统耕作 (CT) 的田块,在后茬小麦播种时,保留免耕玉米的覆盖地膜,免耕进行小麦播种,而在传统耕作玉米地块,清理残膜,粉碎后翻入土壤中。在两种耕作处理方式下,设传统灌水减量20% (1920 m3/hm2,I1) 和传统灌水量2400 m3/hm2 (I2) 两个灌溉处理,传统施氮减量40% (135 kg/hm2,N1)、传统施氮减量20% (180 kg/hm2,N2) 与传统施氮225 kg/hm2 (N3) 三个施氮水平,组成12个处理。从春小麦出苗20 d后,每15 d采集植株样,测定各器官含氮量,计算营养器官的氮素转运量、转运率、营养器官氮素转运对籽粒贡献率及氮素收获指数。【结果】与传统耕作相比,免耕留膜各处理显著提高了春小麦地上部氮素累积量,两年提高10.9%～14.2%。灌水减量20%+施氮减量20%处理提高了春小麦地上部氮素累积量,较传统耕作、灌水与施氮处理提高4.3%～6.1%。免耕较传统耕作提高了春小麦叶、茎营养器官氮素向穗部的转运量、转运率及对籽粒的贡献率,以免耕同步集成减量20%灌水+减量20%施氮 (NTI1N2) 处理提高幅度较大,较灌水减量20%+施氮减量40% (CTI1N3) 处理叶、茎氮素向穗部的转运量分别提高31.9%～45.7%与54.5%～61.5%,转运率分别提高15.5%～16.3%与20.8%～23.1%,对籽粒的贡献率分别提高13.3%～29.0%与26.4%～36.7%。NTI1N2处理可获得较高籽粒产量与氮素收获指数,较CTI2N3处理分别提高15.2%～22.0%与7.6%～10.0%。【结论】在玉米–小麦轮作体系下,前茬免耕玉米覆盖的地膜对后茬小麦生长依然有显著效果。而且,此时减少20%的常规灌水量和常规施氮量,可以获得更高的产量和氮肥利用率。因此,在河西绿洲灌区小麦–玉米轮作体系中,应推广玉米收获后采用免耕,并在后茬小麦继续使用覆盖的地膜,同时减少20%的灌水量和氮肥施用量。     

Tillage effects on soil aggregation,organic carbon fractions and grain yield in Eum‐Orthic Anthrosol of a winter wheat–maize double‐cropping system,Northwest China

Conservation tillage has been applied in vast semi‐arid regions of the Guanzhong Plain, Northwest China. The tillage effects on soil aggregation, organic carbon (OC) stabilization and grain yield on this plain have not been fully elucidated. A 9‐year field experiment was established from 2002 on a silty clay loam soil (Eum‐Orthic Anthrosol) growing winter wheat–maize in a double‐cropping system. Six conservation tillage treatments were applied by different combinations of rotary tillage (RT), subsoiling (SS) and no‐till (NT), with or without finely chopped straw retention. Conventional tillage (CT) acted as the control. Results showed that in the surface (0–10 cm) soil, the proportion of water‐stable aggregates (WSA) <0.05 mm was 18% less while that for WSA >2 mm was 98% more under NT treatments compared with CT. Additionally, the oxidizable OC content in WSA 0.25–2 mm was 27% greater under NT treatments compared with CT. The OC stocks increased under SS by 17%, RT by 16% and NT by 15% relative to CT. Grain yield (wheat + maize) showed similar increasing trends in all the tillage treatments compared with CT. Both OC stocks and grain yield were larger in treatments with than without straw retentions. These results indicate that NT is beneficial for OC accumulation in WSA but is limited in its ability to improve soil structure in this region. SS plus straw retention (fine‐chopped or as a mulch) is an effective practice to improve soil structural stability, OC accumulation and soil productivity of Eum‐Orthic Anthrosols in Northwest China.     

Converting from no-tillage to pre-seeding tillage: Influence on weeds, spring wheat grain yields and N, and soil quality

On the Canadian prairies there has been a steady increase in no-till seeding coupled with more frequent cropping, facilitated by the greater use of snow management to increase stored soil water. Although no-till seeding can gradually improve soil conservation and soil quality, it may also increase the incidence of grassy weed infestations and thus cause more frequent use of costly herbicides, such as glyphosate. Our objective was to determine if no-till producers experiencing grassy weed problems could introduce pre-seeding tillage for a few years to more economically control perennial weeds, without adversely affecting grain yield and quality, and soil quality. An experiment in which spring wheat (Triticum aestivum L.) was grown for 9 years with no-tillage management on an Orthic Brown Chernozem (Typic Haplobroll) with treatments involving snow management and N rate, placement and timing, was converted to a study of pre-seeding shallow (5–7.5 cm) tillage with a cultivator, versus no-tillage, by replacing the N timing treatment in the tenth year. The experiment was then continued for three more years, during which we assessed the effect of tillage on weed populations, grain yield and N content, and on soil quality. Soil quality was also assessed following one more year during which the entire study site was summerfallowed and subjected to four tillage operations. Weed populations generally were not affected by tillage or snow management treatments, but differed among N rate and placement treatments, though not in a way that could be easily interpreted. Tillage had no effect on yield or grain N content. It increased the erodible fraction of soil (dry sieving), but did not affect wet aggregate stability. Neither microbial biomass C, nor C and N mineralization were affected by the change in tillage method. We conclude that the judicious use of shallow pre-seeding tillage in an otherwise no-till cropping system can be tolerated to manage persistent grassy weed problems without deleteriously influencing soil quality, grain yield or protein.     

增温对保护性耕作下冬小麦籽粒蛋白质含量的影响

冬小麦是世界主要粮食作物之一，气候变暖可能显著影响冬小麦籽粒蛋白质含量，但其影响机制还不明确。针对该问题，该研究在中国冬小麦主产区华北平原开展连续3 a（2017-2019）免耕（No Tillage，NT）和常规耕作（Conventional Tillage，CT）下的田间增温试验。结果表明，增温提前了冬小麦返青期，延长了冬小麦营养生长阶段时长，提高了冬小麦叶面积指数和群体净光合速率。2019年增温处理下冬小麦开花期茎叶氮素积累量提升了20.17%（CT）、99.21%（NT），花后茎叶氮素转移量提升了24.62%（CT）、134.21%（NT），茎叶氮素对籽粒的贡献率提升了2.43%（CT）、46.10%（NT）。增温影响了冬小麦产量构成，增温下冬小麦有效小穗数略减，部分年限千粒质量略增。NT处理增温增产，CT处理增温增产不明显，总的趋势为NT处理连续3 a平均产量低于CT处理。增温还显著提升了冬小麦籽粒蛋白质含量（P<0.05），连续3 a平均籽粒蛋白质含量提升了14.28%（CT）、17.39%（NT）。综上，研究表明增温会通过改变冬小麦生理特征显著促进氮素向籽粒转化，并且增温下冬小麦有效小穗数减少使得原本将进入更多籽粒中去的氮素都进入到最终有效籽粒中去，进而显著增加籽粒蛋白质含量。研究结果可为气候变化对冬小麦籽粒蛋白质含量的影响提供科学依据。     

渭北旱塬玉米田保护性轮耕土壤固碳效果与增产增收效应

针对渭北旱塬降水少、季节性差异大及长期采用单一土壤耕作制度等制约作物增产增收的因素,该研究探索有利于提高旱作农田土壤质量及作物生产能力的轮耕模式。2007-2012年在陕西合阳实施了渭北旱塬春玉米连作田6种不同轮耕模式的长期定位试验,设置以免耕(NT,no-tillage)、深松(ST,sub-soiling)和翻耕(CT,continuous tillage)3种耕作处理组合集成的6种轮耕模式(NT?ST、ST?CT、CT?NT、NT?NT、ST?ST和CT?CT),测定各轮耕模式下春玉米田土壤容重和有机碳储量,分析各轮耕模式下春玉米籽粒产量、水分利用效率和经济效益的变化规律。结果表明:1)在疏松土壤、减少耕作机械碾压次数,改善土壤结构和降低容重等方面,6种轮耕模式以NT?ST表现最佳,ST?ST次之,差异显著(P0.05)。2)6种轮耕模式在0~60 cm土层土壤有机碳平均储量较试验前均增加幅度6.6%~17.4%。NT?NT轮耕模式对增加表层土壤有机碳储量具有优势,且与各处理间差异显著(P0.05)。NT?ST轮耕模式可改变耕层土壤有机碳储量分布特征,进而使土壤营养均匀分布。3)6种轮耕模式5年春玉米籽粒产量、水分利用效率和经济效益综合评价分析,NT?ST轮耕模式最高,分别为9 338.8 kg/hm2、22.6 kg/(hm2·mm)和7 600.5元/hm2;其次是ST?CT,其中NT?ST轮耕模式下春玉米籽粒产量、水分利用效率和经济效益较其他处理增加幅度分别为3.7%~15.7%、17.6%~45.8%和10.1%~40.4%,差异显著(P0.05);且5种轮耕模式下作物籽粒产量、水分利用利用效率和经济效益均高于传统CT?CT模式。综上所述,在6种轮耕模式下,以NT?ST(免耕与深松逐年轮换)轮耕模式下土壤容重和有机碳储量最佳,生产能力最强,水分利用率最高,是渭北旱塬地区春玉米连作田最佳适宜轮耕模式,其次是ST?CT(深松与翻耕逐年轮换)轮耕模式。     

轮耕对土壤物理性状和冬小麦产量的影响

针对华北地区土壤连续单一耕作存在的主要问题,进行了土壤轮耕效应的研究。试验选择冬小麦夏玉米玉两熟区连续5 a免耕田,设置免耕、翻耕和旋耕3种轮耕处理（即免耕一免耕,免耕一翻耕和免耕一旋耕）,冬小麦播种前进行耕作处理。研究结果表明：多年免耕后进行土壤耕作（翻耕、旋耕）可以显著降低土壤体积质量;旋耕显著降低0～10 cm土壤体积质量,翻耕则降低0～20 cm体积质量;随时间变化各处理土壤体积质量差异逐渐降低。翻耕、旋耕均显著增加了0～10 cm土壤总孔隙,同时翻耕显著增加了10～20 cm土壤总孔隙;翻耕、旋耕显著提高了5～10 cm毛管孔隙。0～10 cm土壤饱和导水率表现为旋耕＞翻耕＞免耕,翻耕、旋耕在5%水平上显著高于免耕;10～20、20～30 cm土层均表现为翻耕＞旋耕＞免耕,且10～20 cm翻耕5%水平上显著高于免耕;饱和导水率与体积质量呈显著线性负相关。翻耕、旋耕有效穗数与免耕相比分别提高了24.1%、22.3%;冬小麦的实际产量表现为：旋耕＞翻耕＞免耕,翻耕、旋耕分别比免耕增产11.8%、16.9%。总之,长期免耕后进行土壤耕作有利于改善土壤物理性状,提高作物产量。     

轮耕对渭北旱塬春玉米田土壤理化性状和产量的影响

为了揭示不同轮耕处理对渭北旱塬春玉米田土壤理化性状及春玉米产量的影响,于2008—2010年在陕西合阳设置了免耕深松免耕(NT/ST/NT)、深松翻耕深松(ST/CT/ST)、翻耕免耕翻耕(CT/NT/CT)、免耕免耕免耕(NT/NT/NT)、深松深松深松(ST/ST/ST)和翻耕翻耕翻耕(CT/CT/CT)6种轮耕模式,测定和分析了各轮耕处理下土壤容重、土壤养分与玉米产量差异。结果表明:(1)各轮耕处理降低了土壤容重,提高了土壤孔隙度,增加了田间持水量,且以NT/ST/NT处理效果最佳;与对照CT/CT/CT相比,NT/ST/NT处理0～20cm和20～40 cm土层土壤容重分别降低11.43%和9.79%,土壤孔隙度分别增加11.05%和9.87%。(2)NT/ST/NT处理对耕层0～20 cm土层土壤有机质和全氮含量影响显著(P<0.05),0～60 cm土层土壤有机质平均含量最高(10.36 g.kg 1),土壤全氮含量平均值比试验开始前和对照CT/CT/CT分别提高10.65%和4.31%;各耕作处理对0～20 cm土层土壤全氮和碱解氮含量影响较大,而对20～40 cm土层土壤有效磷和速效钾含量影响较大,保护性轮耕处理对土壤培肥效应显著(P<0.05)高于传统翻耕处理。(3)NT/ST/NT、ST/CT/ST、CT/NT/CT、NT/NT/NT和ST/ST/ST处理产量比对照CT/CT/CT处理分别增产22.42%、16.33%、3.77%、9.91%和14.18%(P<0.05),以NT/ST/NT处理春玉米增产率最高。     

Total, particulate organic matter and structural stability of a Calcixeroll soil under different wheat rotations and tillage systems in a semiarid area of Morocco

Wheat production in Morocco is constrained by both scarce climate and degraded soil quality. There is an urgent need to revert production decline while restoring country’s soils. Among conservation tillage systems known for their improvement in yield, no-till technology was found to influence soil quality as well. Soil quality indices are also affected by wheat rotations at medium and long-terms. This paper discusses changes in selected properties of a Calcixeroll soil, including total and particulate soil organic matter (SOM), pH, total N and aggregation, subjected, for 11 consecutive years, to various conservation and conventional agricultural systems. Tillage systems included no-tillage (NT) and conventional tillage (CT). Crop rotations were continuous wheat, fallow–wheat, fallow–wheat–corn, fallow–wheat–forage and fallow–wheat–lentils. Higher aggregation, carbon sequestration, pH decline and particulate organic matter (POM) buildup are major changes associated with shift from conventional- to NT system. Better stability of aggregates was demonstrated by a significantly greater mean weight diameter under NT (3.8 mm) than CT system (3.2 mm) at the soil surface. There was 13.6% SOC increase in (0–200 mm) over the 11-year period under NT, while CT did not affect much this soil quality indicator. Another valuable funding is the stratification of SOC and total nitrogen in NT surface horizon (0–25 mm) without their depletion at deeper horizon compared to tillage treatments. Fallow–wheat system resulted in reduction of SOC compared to WW, but 3-year wheat rotation tended to improve overall soil quality. Benefits from crop rotation in terms of organic carbon varied between 2.6 and 11.7%, with fallow–wheat–forage exhibiting the maximum. Combined use of NT and 3-year fallow rotation helped to improve soil quality in this experiment.     

Morphology and distribution of wheat and maize roots as affected by tillage systems and soil physical parameters in temperate climates: an overview

Congregated information on maize and wheat root morphology and their distribution as influenced by tillage and soil physical conditions is meager. Root growth under no-tillage (NT) or conventional tillage (CT) is variable: Under NT, higher bulk density slows root elongation and provides shorter roots but simulate root branching; results may be opposite depending on soil texture. Under CT, soil compaction may have negative effects on root growth, with roots exhibiting plasticity. In humid climates, low soil temperatures can reduce root length density (RLD) and increase the diameter of spring cereals under NT. Tillage intensity induces a different distribution of nutrients, a trend which increases with time resulting in higher RLD in the topmost layer of NT. Compared to maize it is difficult to present an overview of the effect on tillage on the RLD of wheat due to inconclusive results. Adequate placements of banded starter fertilizer will effectively build up an early root system of maize, especially at suboptimal growth temperatures. Many studies reported a higher or similar grain yield of maize or wheat under NT compared to CT in temperate climates. However, the limited information or the conflicting results will promote the topic for inclusion in future breeding programs.     

Residue,tillage and N-fertilizer rate affected yield and N efficiency in irrigated spring wheat

Yield and nitrogen (N)-content in wheat was studied under applied treatments of crop residues (legume vs. cereal), tillage depths (deep vs. shallow) and N-fertilizer rates (0, 40, 80, 120 and 160 kg ha^?1) at wheat-maize cropping systems. Experiments were conducted at Agronomy Research farm, the University of Agriculture, Peshawar Pakistan, during winter season 2009–2010 and 2010–2011 crop growth seasons. Well-chopped crop residues (5 t ha^?1) on dry matter basis of legume (Vigna unguicuata) and cereal (Zea mays) were applied to soil and subsequently plowed with mold-board plow as deep tillage (DT) and cultivator as shallow tillage (ST) treatment (main plot treatments). A month after residue and tillage application, seedbed was prepared and wheat was planted with drill in rows 25 cm apart in middle of November each year. Phosphorus and potassium were applied uniformly 80 and 40 kg ha^?1, respectively during seedbed preparation. N-fertilizer rates were applied in two splits: half 15 days after sowing (DAS) and other half 45 DAS (sub-plot treatment). Uniform cultural practices were applied during crop growth and development. Legumes residues amendments showed better responses than cereal but lower than no-residue treatment for N-content in leaf blade before anthesis (LBA), after anthesis (LAA), straw N-content (SNC), grain N-content (GNC), grain N-uptake (GNU), crop N-removal (CNR), recovery efficiency of added nitrogen (REAN), N-use efficiency (NUE), grain N-uptake (GNU) and grain yield. Likewise, shallow tillage proved better than deep tillage system for LBA, LAA, SNC, GNC, GNU, CNR, REAN, NUE, GNU and grain yield. Increased N-fertilizer from control onwards showed significant (p > 0.05) increments in LBA, LAA, SNC, GNC, GNU, CNR, N-uptake and grain yield. Treatments interaction was also found significant (p > 0.05). Study suggested, regardless of the given treatments, GNU and grain yield were in strong positive linear relationship. Legume residue incorporated shallow out yielded GNU and NUE of spring wheat in wheat-maize cropping system. It is concluded that LR and ST with 120 kg N ha^?1 ensures production of good wheat quantity and quality.     

河西灌区不同耕作与秸秆还田方式对春小麦出苗及产量的影响

出苗率及出苗整齐度在很大程度上决定了作物生长状况和产量丰欠,针对不同耕作措施结合秸秆还田对绿洲灌区小麦出苗及群体动态影响研究薄弱问题,研究不同秸秆还田与耕作方式对小麦出苗与产量的影响,以及二者的相关关系,对于优化耕作措施具有重要指导意义。2014—2015年,在甘肃河西绿洲灌区,通过田间定位试验,研究了不同秸秆还田和耕作措施[少耕25~30 cm高茬收割秸秆立茬还田(NTSS)、少耕25~30 cm高茬收割秸秆覆盖还田(NTS)、翻耕25~30 cm高茬收割秸秆还田(TS)和不留茬翻耕(CT)]对小麦出苗状况及产量、产量构成因素的影响,以期为优化试区小麦栽培技术提供依据。结果显示,与CT相比,NTSS、NTS降低了小麦出苗率以及出苗整齐度,TS则提高了小麦出苗率以及出苗整齐度。NTSS、NTS较CT的分蘖数分别高7.4%~10.5%、14.6%~19.1%,分蘖成穗率分别高13.5%~20.1%、33.0%~34.7%,有效穗数分别高7.5%~9.3%、10.3%~11.2%,穗粒数分别高15.7%~16.1%、18.5%~22.6%,千粒重分别高7.2%~8.9%、13.9%~14.2%,但TS与CT在以上指标间没有显著差异。NTSS、NTS与CT相比较,分别增产16.6%~17.4%、18.6%~21.4%,以NTS增产幅度较大,比TS高10.3%~11.0%。穗数和穗粒数的增加是少耕秸秆还田获得高产的主要原因,出苗率及整齐度对产量影响不显著。同时NTSS和NTS均获得较高的收获指数,提高比例分别为9.4%~10.7%与10.5%~11.1%,说明少耕秸秆还田提高籽粒产量的另一原因是提高了光合产物向籽粒中的转化。本研究表明,少耕秸秆还田是适用于试区小麦高产的理想耕作措施。     

Abundance and depth stratification of soil arthropods as influenced by tillage regimes in a sandy loam soil

Different tillage regimes can change soil micro‐environmental characteristics, which may influence the distribution and abundance of soil arthropods. In this study, soil arthropods and soil properties under a winter wheat–summer maize cropping system were investigated in different tillage regimes over four seasons at two depths. The tillage treatments included conventional tillage (CT ), tillage once a year (T1), tillage every two years (T2) and no‐tillage (NT ). The results showed that the primary taxa of soil arthropod were Acarina (65.8%), Collembola (28.5%), Diplura (1.4%) and Coleoptera (1%) over the whole sampling period. The total arthropod density was influenced by tillage treatments and season of sampling. Values for CT plots were significantly greater than those for the NT plots in autumn and spring. In contrast, the Shannon–Wiener diversity index (H’) and the evenness index (J) were relatively higher in CT treatment. The Acarina/Collembola (A/C) ratio was significantly smaller in NT treatment for some sampling seasons as mites were more sensitive to tillage practices. The QBS ‐ar index did not show a clear pattern among treatments in this study. Soil arthropods notably showed seasonal variation in depth stratification. Relative to CT , the total soil arthropods in the NT plots tended to concentrate in the upper layer due to soil compaction in the lower layer. The climate conditions and soil physical properties were the main factors affecting the soil arthropod distribution and composition, as the soil chemical and microbial properties did not differ significantly among all tillage treatments.     

No-tillage and conventional tillage effects on durum wheat yield, grain quality and soil moisture content in southern Italy

No-tillage (NT) is becoming increasingly attractive to farmers because it clearly reduces production costs relative to conventional tillage (CT). However, many producers in southern Italy are reluctant to adopt this practice because NT can have contrasting consequences on grain yield depending on weather conditions. The effect of NT and CT on continuous durum wheat (Triticum durum Desf.) under rainfed Mediterranean conditions was studied, over a 3-year period (2000–2002) at two locations (Foggia and Vasto) in southern Italy. Yield, grain quality [thousand kernel weight (TKW), test weight (TW) and protein content (PC)] and soil water content were assessed.Higher yield was obtained with NT than CT in the first 2 years at Foggia. In contrast, mean yield and quality parameters at Vasto were similar for the two treatments, except in the third year in which CT produced more than NT (4.6 Mg ha⁻¹ versus 2.9 Mg ha⁻¹). At Foggia, TW and TKW were higher in NT than CT in all years. Highest PC was obtained under CT (19.6% and 15.5% for CT versus 14.7% and 11.4% for NT, respectively, in the growing season 2000–2001 and 2001–2002) indicating that grain was shriveled with low starch accumulation.At Foggia, where this study was part of a long-term experiment started in 1995, a strong correlation was observed between yield and rainfall during the wheat growing season. The coefficient of determination (R²) values for CT and NT were 0.69^* and 0.31 ns, respectively, and the regression straight line crossed around 300 mm of rainfall. These results indicate that NT was superior below this rainfall value, whereas more rainfall enhanced yield in CT. We conclude that NT performed better at Foggia with limited rainfall during the durum wheat growing season. The superior effect of NT in comparison to CT, was due to lower water evaporation from soil combined with enhanced soil water availability.     

长期免耕覆盖对旱地冬小麦旗叶光合特性及干物质积累与转运的影响

【目的】小麦开花后光合特性对干物质积累和转运具有重要作用,而土壤水分是影响作物光合作用最重要的环境因子。研究长期定位试验条件下免耕覆盖的蓄水保墒作用和小麦冠层光合有效辐射传输特征,及其对小麦光合特性和干物质转运规律的影响,以期为旱区作物生产及农田高效用水提供理论依据。【方法】本文以山西临汾20年免耕覆盖和常规耕作两种耕作方式的长期定位试验为平台,于2013年休闲期和小麦生育期对土壤水分,小麦生育后期光合有效辐射、旗叶光合参数、干物质积累和产量构成因素进行了测定。【结果】在休闲期和小麦生育期,与常规耕作方式相比,免耕覆盖耕作0—160 cm土层土壤储水量显著增加,平均提高了12%,其中在土壤水分含量的最低时期(灌浆前期)比常规耕作提高21%(P0.01)。在抽穗和灌浆前期免耕覆盖处理的小麦截获的光合有效辐射比常规耕作高163μmol/(m2·s),其中在灌浆前期二者差异最大,达19.3%(P0.05),并且免耕覆盖下小麦中上层和中下层都有充分利用光能的机会。在灌浆前期免耕覆盖比常规耕作处理的小麦旗叶气孔导度平均增加39%,二氧化碳利用能力平均增加11%,瞬时水分利用效率提高了22%;小麦抽穗后到成熟期免耕覆盖处理的小麦旗叶净光合速率平均比常规耕作高39%,收获期籽粒重和植株总重分别比常规耕作高57%和46%(P0.01),并且开花后干物质积累量对籽粒的贡献率达到了64%。从产量构成因素来看,免耕覆盖的小麦穗数和千粒重分别比常规耕作高31%和10%,实收产量比常规耕作高41%(P0.01)。免耕覆盖耕作方式下的土壤蓄水保墒能力缓解了因水分胁迫作用而出现的光合午休现象,保证了小麦光合速率处于较高水平;同时免耕覆盖增强了小麦开花后干物质的积累能力,并且籽粒干物质的主要来源是开花后干物质的积累,而常规耕作则是以开花前贮藏的同化物量为主要来源。【结论】在晋南旱区,采用长期免耕覆盖的耕作方式可提高土壤水分的保蓄能力和光能截获能力,增强冬小麦的净光合效率、瞬时水分利用效率及干物质积累与转运,协调产量构成因素之间的关系,提高小麦产量。     

适宜耕作模式提高黄淮海平原冬小麦产量并改善土壤水肥状况

为了探索黄淮海小麦生产适宜的耕作模式,该研究设计长期定位试验（2017年—2022年）对比了简化耕作模式深耕（deep tillage, DT）、轮耕（rotational tillage, RT）和免耕（no-tillage, NT）对冬小麦产量和土壤水肥状况的影响。结果表明：RT处理显著提高了冬小麦苗期0～20 cm土层土壤水分吸收利用情况,冬小麦孕穗期、灌浆期RT处理0～20、>20~40 cm土层土壤含水量显著高于DT、NT处理。RT处理0～20、>20～40 cm土壤全氮、有机质含量和碳氮比含量较DT、NT处理显著提高, 2021—2022年0～20 cm土壤全氮、有机质含量、碳氮比RT处理较DT和NT处理分别显著提高40.45%和31.58%、56.66%和45.34%、11.62%和9.91%。2020—2021年和2021—2022年RT处理冬小麦产量较DT、NT处理分别显著提高20.20%、13.39%和20.35%、18.74%。RT处理显著增加了冬小麦千粒质量,其产量变异系数最低,产量可持续指数最高,说明RT处理有助于增加冬小麦生产力稳定性和可持续性,可以实现黄淮海冬小麦高产稳产。研究可为黄淮海平原冬小麦生产应用一年深耕、两年免耕的轮耕耕作模式提供理论指导与技术支撑。     

耕作方式对农田土壤理化性质、微生物学特性及小麦营养品质的影响

  【目的】  耕作措施对土壤健康和作物营养品质提升具有关键作用,明确不同耕作方式对土壤理化性质、微生物学特性及小麦营养品质的影响,为集约化农田可持续管理提供理论依据。  【方法】  田间试验自2012年起在山东德州进行,供试土壤为潮土,种植制度为小麦–玉米轮作。设置4种耕作模式处理:传统耕作、旋耕、休耕和免耕。2020年,采集0—20 cm土层土样分析土壤物理、化学性质和细菌群落结构,采集小麦籽粒样品分析其营养品质。  【结果】  与传统耕作相比,免耕、休耕和旋耕处理显著提高了土壤含水量、铵态氮、硝态氮、有机质、全氮及有效磷含量,休耕还显著提高了土壤容重,降低了土壤孔隙度。免耕、休耕和旋耕处理显著提高土壤微生物量碳、氮含量以及土壤细菌群落多样性指数,休耕及免耕处理提高土壤厚壁菌门(Firmicutes)、疣微菌门(Verrucomicrobia)的相对丰度,降低放线菌门(Actinobacteria)的相对丰度。从营养品质变化来看,休耕显著提高小麦籽粒蛋白质、淀粉、微量元素的含量,旋耕和免耕显著增加小麦籽粒蛋白质含量,除天冬氨酸外,其他16种氨基酸组分变化趋势与氨基酸总量变化基本一致。Pearson相关性分析及冗余分析(RDA)结果表明,小麦籽粒淀粉、铁、锌、硒含量与土壤含水量、铵态氮、硝态氮、有效磷、微生物量碳、微生物量氮均呈显著正相关关系,其中铵态氮(F=25.7,P=0.002)、微生物量碳(F=4.9,P=0.008)、全氮(F=3.3,P=0.028)、土壤pH (F=3.1,P=0.036)是影响小麦营养品质的主要环境因子。  【结论】  减少对土壤扰动的耕作方式可不同程度地改变土壤环境因子及细菌群落结构,与旋耕、免耕相比,休耕更有利于小麦籽粒蛋白质、淀粉、微量元素、氨基酸组分含量的积累,是改善土壤健康状况和提升小麦营养品质的有效耕作措施。     

春小麦秸秆还田对后茬玉米干物质积累及产量形成的调控效应

干物质是作物光合作用产物的最高形式,其积累动态特性与籽粒产量有密切关系,研究前茬作物不同秸秆还田方式对后茬地膜覆盖作物地上干物质积累特性与产量形成的影响,对优化作物高产高效栽培理论和技术具有重要意义。本研究通过田间试验,在干旱内陆灌区研究了前茬春小麦不同秸秆还田方式(免耕秸秆覆盖还田,NTM;免耕秸秆立茬还田,NTS;传统翻耕秸秆还田,CTS;传统翻耕无秸秆还田,CT,对照)对后茬玉米地上干物质积累规律及产量形成的调控效应。结果表明:前茬春小麦免耕秸秆还田(NTM,NTS)提高了后茬玉米地上干物质最大增长速率和干物质平均增长速率,延迟了干物质最大增长速率出现的时间,以NTM处理作用效果最明显,较CT玉米地上干物质最大增长速率和干物质平均增长速率分别提高5.7%、11.2%,玉米地上干物质最大增长速率出现时间延迟3.4d,差异达显著水平(P0.05)。NTM、NTS处理可长时间保持后茬玉米相对较高的地上干物质积累速率,有效延缓吐丝至灌浆期后茬玉米地上干物质积累速率的降低,维持较长的地上干物质积累期,提高完熟期地上干物质积累量,NTM和NTS较CT处理玉米收获期地上干物质积累量分别提高11.3%和9.9%(P0.05)。NTM、NTS和CTS比CT处理分别增产15.6%、13.0%和7.8%,以NTM处理增产幅度较大,较CTS增产7.3%(P0.05),增产的主要原因为穗数、穗粒数及粒重的协同提高。通过关联矩阵分析表明,通过优化前茬春小麦秸秆还田方式影响后茬玉米穗数来调控群体大小,进而协调穗粒数与粒重,通过三者相互协调发展可实现增产。因此,前茬春小麦免耕25～30cm覆盖秸秆还田(NTM)是典型干旱内陆灌区优化后茬玉米干物质积累特性及获得高产的理想耕作措施。