Surface Straw Research Articles

Evaluating crop nitrogen status in maize leaves: A predictive modelling approach using chlorophyll fluorescence parameters

The consumption of chemical fertilizers has increased eight-fold since the 19th century, outstripping crop yields increases and, emphasizing the need for precise nitrogen (N) assessment in crops to optimize fertilization and mitigate environmental impacts. This study developed a model using chlorophyll fluorescence technology to accurately evaluate the N status in maize leaves while addressing the limitations of current labor-intensive and environmentally sensitive methods. Based on a long-term experiment initiated in 2011, maize hybrid Fumin 985 was sampled in 2021 and 2022 under two crop-straw management strategies (SM: no tillage with surface straw mulch, SP: plough tillage with straw incorporation) and six N application rates. Partial least squares regression (PLSR) models were formulated using chlorophyll fluorescence parameters (ChlF) to assess leaf N content (N leaf). The results indicated that a N application rate of 270 kg ha−1 sufficed to meet crop N requirements. Leaf characteristics such as N leaf, total pigment content (TP), and leaf dry weight (DW leaf) changed significantly with increasing N application rates, influencing rapid chlorophyll fluorescence (OJIP) dynamics. Principal component analysis (PCA) reduced ChlF from 35 to 21, and four models were developed, among which, the model using ChlF and TP was more accurate than the model using DW alone. Key ChlF parameters for PLSR model performance included ABS/RC, φ(Eo), ETo/CSm, and δ(Ro)/(1–δ(Ro)). Although non-destructive N leaf detection using chlorophyll fluorescence technology proved feasible, additional leaf characteristics, such as TP, are necessary to improve model accuracy. Considering local field conditions is essential for the application of this technology at a larger scale. Precise evaluation of N status using chlorophyll fluorescence is beneficial for a more efficient N management and sustainable agriculture.

Appropriateness of introducing earthworms into sustainable agriculture from the perspective of soil carbon emissions

Sustainable agriculture, as an effective method for reducing the risk of soil degradation, is often accompanied by increases in soil fauna populations. However, the effects of soil fauna (such as earthworms) bioturbation on soil carbon (C) emissions remain unclear. We conducted a 31-day incubation experiment to measure the effects of adding straw (1 g) and anecic earthworms on the burrowing characteristics and C emissions using two soils collected from the plow layer and plow pan layers. We also explored the effects of the soil C source (soil organic C (SOC) and exogenous organic matter (OM) inputs) on the soil C emissions induced in the presence of earthworms by meta-analysis. The incubation experiment showed that earthworms increased the loss rate of surface straw (49.4–96.8%; p < 0.05) and the soil C emissions (160.5–455.4%; p < 0.01). Earthworms significantly increased the macroporosity (p < 0.001) and macropore size (p = 0.016), but decreased the macropore number in the plow layer soil. While, only the soil macropore size increased significantly (p = 0.025) under earthworm addition in the plow pan soil. Structural equation models indicated that straw directly influenced the soil macropore size (p = 0.022) and C emissions (p = 0.039) in the plow layer soil, but had no effects on the soil macropore characteristics and C emissions (p > 0.05) in the plow pan soil. Earthworms indirectly affected soil C emissions through effects on the soil macropore size (p < 0.05). Meta-analysis indicated that although earthworms increased C emissions by 51.7% and 25.0% without and with OM inputs (p > 0.224), respectively, the earthworm-induced effects on soil C emissions were not related to OM inputs (p = 0.337). Soil C emissions induced by earthworms decreased as the SOC content increased (from 45.1% to 2.6%), but these effects were not significant at any SOC level (p > 0.154). These findings indicate that the effects of anecic earthworms on soil C emissions can be reflected by the earthworm burrowing characteristics and earthworms increased the soil C emissions in the short term (incubation experiment), but their effects on soil C emissions eventually became non-significant due to reduced anecic-earthworm burrowing activities (most burrows are permanent or semi-permanent) and SOC content increase in the long term (meta-analysis). We therefore recommend that earthworm regulation together with OM inputs could be considered in sustainable agriculture.

Effect of Rotary Speed on Soil and Straw Throwing Process by Stubble-Crushing Blade for Strip Tillage Using DEM-CFD

Strip tillage is a widely used land preparation approach for effective straw management in conservation agriculture. Understanding the dynamic throwing process during the stubble-crushing operation has important implications for seedbed preparation. However, the airflow generated by the high-speed rotation of stubble-crushing blades has yet to be considered. We established a coupled DEM-CFD simulation model and explored the dynamic motion of soil particles varied with their initial depth (at 0, 20, 40, 60, 80 mm depth) and surface straw under different blade rotary speeds (270, 540, 720, and 810 rpm) based on the model. The coupled model simulation results were proved to be well correlated with the field test results by the field high-speed camera test. The simulation results showed that airflow had a significant effect on the longitudinal displacement of straw (p &lt; 0.05). An increase in rotary speed could increase the longitudinal and lateral throwing displacement of soil particles and straw and increase the blade–soil–straw interaction, while there was no directional effect on the vertical motion. The lateral movement of soil particles decreased with increasing soil particle depth. The stubble-crushing operation allowed the exchange of deep and shallow soil layers, as well as the burial of straw. Plain, straight stubble-crushing blades with a rotary speed of 540 rpm were able to form the optimal seeding row with a width of 80.86 mm. The simulation results were useful for assessing the design solutions of high-speed rotational tools and evaluating seedbed preparation practices.

Simulation and Experimental Study of the Tillage Mechanism for the Optimal Design of Wheat Rotary Strip–Tiller Blades

In order to clarify the mechanism of tiller–soil interaction in the process of strip rotary tillage, this paper conducted a simulation and experimental research on four blade configurations composed of three rotary blades (bent C, straight and hoe) at three rotation speeds (280, 380 and 510 rpm). The study found that the soil throwing characteristics of the blades are the key factors affecting the quality of tillage. The increase in the rotation speed not only improved the soil breaking effect, but also enhanced the phenomenon of soil throwing and then led to a reduction in the soil backfill. In the BC configuration (combination of four bent C blades), the bent C blades showed the best soil throwing characteristics and created the best soil fragmentation. However, due to the obvious side throwing of the soil, the backfill effect of soil fragmentation was the worst. The backfill rate was only 8% when the rotation speed was 510 rpm and could not allow reaching the required seed–soil contact during sowing. The hoe blades in the HC configuration (combination of four hoe blades) could collect part of the soil fragments and throw them towards the direction of the machine during the cultivation process, which led to a good soil breaking effect and a low soil side throwing rate. When the rotation speed was 510 rpm, 36% of the soil was backfilled into the seedbed. In the SC configuration (combination of four straight blades), the straight blades could well control the scattering of the side-thrown soil fragments. At a super-high rotation speed (510 rpm), the side throwing rate was only 70%, and the backfill rate was as high as 60%. However, the soil fragments created by the blades were too large (average soil block diameter &gt; 40 mm) and could not form a loose and finely broken seedbed environment. The MC configuration (combination of two straight blades and two hoe blades) benefited from the combination of straight blades and hoe blades, offering outstanding advantages for backfill and soil fragmentation. Therefore, under the condition of a centralized configuration of field surface straw, it is recommended to use the MC configuration of the wheat rotary strip–till planter for cohesive paddy soil.

Design and experiment of a straw clearing mulching no-tillage planter

When soybean is replanted after wheat in parts of China, problems such as a short sowing period, large straw yield and poor mechanization technology emerge; these problems increase the difficulty of sowing subsequent soybeans and negatively affect soybean quality and yield. In addition, the ecological problems associated with straw burning and soil degradation become increasingly severe. Here, a straw clearing mulching no-tillage planter with integrated functions of lateral straw clearing anti-blocking, precision sowing, pesticide spraying, and straw mulching was developed. This planter could perform several functions, including surface straw clearing before sowing, herbicide spraying after sowing, and straw surface uniform mulching. A lateral straw clearing mulching device was designed, and the main parameters and values affecting the working performance of the device were determined. To verify the technical performance and working quality of straw clearing mulching no-tillage sowing, field experiments were conducted, testing the effects of straw clearing mulching no-tillage sowing (SCMNS) and stubble eliminating rotary-tillage sowing (SERS) on the sowing quality, seedling emergence rate, soil hydrothermal characteristics, soybean yield, and comprehensive economic benefits. The qualified indices of seed spacing and sowing depth of SCMNS were 87.2% and 76.5%, respectively, which were significantly higher than those of SERS. SCMNS could enhance the ground temperature, reduce water evaporation, improve water storage, and promote soil moisture conservation. The seedling emergence date of SCMNS was one day earlier than that of SERS. The seedling emergence rate of SCMNS was 89.8%, which was significantly higher than that of SERS. The soybean yields of SCMNS (2809.2 kg·hm−2) and SERS (2207.4 kg·hm−2) significantly differed. SCMNS improved the comprehensive economic benefits by increasing soybean yield and reducing production costs; the net income of 1147.82 €·hm−2 was 50.27% higher than that of SERS.

Sugarcane straw effects on soil compaction susceptibility

Crop residues may buffer part of compressive stress applied over the soil surface. Thus, indiscriminate crop residue removal would magnify soil compaction in highly mechanized cultivation systems, such as sugarcane in Brazil. Nevertheless, the effect of different amounts of sugarcane crop residue (straw) on soil compaction mitigation still needs to be tested. We conducted a laboratory study to quantify the effects of sugarcane straw rates on soil compaction indicators in response to external applied stress. The experiment involved remolded soil cores with four initial bulk densities: 1.25, 1.35, 1.45 and 1.55 Mg m−3, and five amounts of straw were left on soil surface, equivalent to 0, 5, 10, 15 and 20 Mg ha−1. The soil cores were subjected to uniaxial compression test and seven successive vertical static loads (25, 50, 100, 200, 400, 800 and 1600 kPa) were applied over the soil surface using a pneumatic consolidometer. Soil displacement was measured after each applied load. Based on these values, apparent precompression stress (σp), apparent compression index (CI) and final bulk density were calculated as indications of soil deformation. Because, soil inherent properties should not change, we call the changes due to straw layer addition "apparent" in this study. Our results revealed that large amounts (>10 Mg ha−1) of straw increased subtly apparent soil load bearing capacity (i.e., increased up to 15 kPa in apparent σp; 7%). The bulk density change rate (soil deformation) decreased due to presence of straw under low stress (<100 kPa), and increased under high stress (>400 kPa) levels in loose soil. On the other hand, compaction was slightly reduced in compacted soil, with corresponding reduction on apparent CI values. Nevertheless, despite this buffer effect provided straw, we noticed that increases in surface straw amount are likely insufficient to reduce the risk of compaction (little gain in apparent load-bearing capacity), but a reduction of about 5% on the soil deformation (as apparent σp is overcome) could occurs in compacted soils. We advocate that benefits of leaving sugarcane straw covering the soil go beyond the direct “damper” effect, because straw is source of carbon, which is fundamental for enhancing soil structure stability and biological activity, and thus, reducing soil compaction risks or even alleviating soil compaction restrictions to plant growth. Finally, we encourage future studies to test the straw effects under machinery traffic in field conditions, which could involve the additional effect of shear stress over the tyre-straw-soil interface.

The Effects of Earthworms on Fungal Diversity and Community Structure in Farmland Soil With Returned Straw.

BackgroundTo promote the decomposition of returned straw, reduce the incidence of soil-borne diseases caused by returned straw, and accelerate the conversion of straw carbon into soil carbon, we inoculated earthworms into fields with returned straw. The earthworms accelerated straw degradation and promoted carbon conversion. However, the impact of externally inoculated earthworms on the farmland soil ecosystem, especially the structure and the function of its microbial community, remains unclear.MethodsWe analyzed the effects of straw return and earthworms on the diversity of fungal populations and the community structure of dominant fungal taxa in soil by quantifying fungal population size and community composition via PCR amplification of internal transcribed spacer genes and 18S rRNA gene sequencing.ResultsThe results showed that earthworm inoculation significantly accelerated the degradation of rice straw and promoted the conversion of straw carbon to soil carbon. Both fungal abundance and α-diversity (Sobs and Shannon indices) were higher in the plots with surface straw but without earthworms than in those inoculated with earthworms and in the CK. Principal component analysis indicated that straw return increased the diversity and the abundance of the fungal community, whereas earthworms inhibited this expansion of the fungal community caused by straw return. Interestingly, the overall differences in fungal community composition were smallest in plots with straw return, while the dominant fungal community features in plots inoculated with earthworms were closer to those of the CK.ConclusionGenerally, straw return stimulated unclassified_K_fungi, Pseudeurotium, and Fusarium with strong cellulolytic ability. In contrast, the abundances of Stachybotrys, unclassified_c_Sordariomycetes, unclassified_f_Lasiosphaeriaceae, and Schizothecium were higher in the plots inoculated with earthworms and in the CK. Furthermore, evolutionary analysis showed that the evolution of soil fungal communities tended to diverge after straw return, and the evolutionary directions of fungal species in the plots inoculated with earthworms were similar to those in the CK.

Soil-Surface Straw Influences Micrometeorological Conditions Affecting Canola Mortality During Nighttime Frosts

Our objective was to measure alterations in the micrometeorological conditions surrounding canola seedlings during frost periods, and to quantify seedling mortality as a function of straw distribution on the ground surface. The data was acquired from 15 frosts in 2014. We used four treatments, comprising ground surface without straw (SWS), ground surface entirely straw-covered (SEC), sowing line without straw (SLW), and soil with preexisting surface straw (SES), over three experiments. Net radiation (NR), soil heat flux (G), air (Ta), leaf (Lf), rosette (Tr), and surface temperature (Ts), and plant mortality were evaluated. NR was higher in the SEC treatment and lower in the SLW treatment, whereas G was higher on straw-covered ground; Ts and Ta were lower in the SEC than in the other treatments during the most intense frosts. On 06/19, Tr in the SEC and SLW treatments was -0.66 &amp;deg;C and 0.42 &amp;deg;C, respectively; on 08/14, Lf was -3.62 &amp;deg;C and -2.88 &amp;deg;C in the SEC and SLW treatments, respectively. Plant mortality due to the frost on 06/19 was 30% in the SEC treatment, but 0% in the SLW treatment; the frost of 08/14 caused 33.8% mortality in the SEC treatment and 1.25% in the SLW treatment. This therefore showed that removing straw from the sowing line improved the microclimate around the plants, thus reducing canola mortality at the beginning of the growth cycle, which is when frost events most frequently occur.

Effects of surface straw mulching and buried straw layer on soil water content and salinity dynamics in saline soils

Field experiments were conducted to evaluate the effects of wheat straw return methods, which included the use of surface straw mulch and a buried straw layer, on soil water content, electrical conductivity (EC), and sodium adsorption ratio (SAR) of saline sodic soils in an effort to identify useful ways for reducing soil salt accumulation and enhancing soil water content. The results showed that the straw return treatments were effective for inhibiting salt accumulation and soil water loss, resulting in a reduction of EC and SAR but an enhancement of soil water content. After a year-long experiment, compared with the treatment with no straw return, the straw burial and straw mulching treatments decreased the EC by 10.5% and 3.5%, reduced the SAR by 7.4% and 21.5%, and increased the soil water by 0.9% and 4.4%, respectively. Furthermore, the combined application of straw layer burial and surface straw return had a more significant effect than the individual treatments; the positive effect of straw return occurred mainly focused in the topsoil (0–40 cm) and decreased with increasing soil depth. Our results allowed us to conclude that burial of the straw layer was necessary to enhance the effects of surface mulch, and the combination of surface mulch (3.0 t ha−1 of wheat straw) and straw layer burial (6.0 t ha−1 of wheat straw) proved to be a better straw return method than the others.

Glyphosate spraying and earthworm Lumbricus terrestris L. activity: Evaluating short-term impact in a glasshouse experiment simulating cereal post-harvest

A glasshouse experiment was conducted to study if glyphosate spraying has immediate short-term effects on the growth, reproduction and residue incorporation of the earthworm species Lumbricus terrestris L. The experiment simulated post-harvest conditions in no-till cereal cultivation, where L. terrestris often abound, and glyphosate is widely used. Pairs of adult, field-collected L. terrestris (median total mass 11.2 g fresh weight) were kept in fine sand-filled cylinders, with chopped wheat straw on the soil surface as feed. The treatment cylinders were sprayed with glyphosate at normal field application rate [Rodeo® XL 3.0 l ha−1, resulting in 1080 g a.i. ha−1 and “Contact” surfactant (0.5 l ha−1)]; the controls were sprayed with water (N = 12 for both). The treatment and control cylinders were maintained for two months at +15 °C, approximate 60% air humidity and 12h:12h light:dark cycle. All individuals survived the experiment. There was no difference in L. terrestris mass change over the experiment, with an average weight change of +0.96% in glyphosate treatment and −0.93% change in the control (p = 0.66). Glyphosate treatment and control did not differ in cocoon production rate (31 vs 28 cocoons cylinder−1 respectively; p = 0.30). The straw incorporation was slightly but not significantly lower in glyphosate-treated soil (decline in surface straw mass 27.5% vs. 30.5%; p = 0.07). The glyphosate treatment applied represents a commonly used practice in spring cereal cultivation, and it did not affect negatively L. terrestris. The varying study results on the effects of glyphosate on earthworms – and on L. terrestris in particular – may partly arise from notable variation in application rates and the formulation-surfactant combinations used in different experiments which needs to be considered in the ecological risk assessment of glyphosate use.

Effect of Surface Straw Incorporation Rate on Water–Salt Balance and Maize Yield in Soil Subject to Secondary Salinization with Brackish Water Irrigation

Secondary salinization induced by brackish water irrigation has forced agricultural development to increasingly rely on soil management. A two-year field experiment was conducted to explore the effects of different straw incorporation rates (SIRs) within 0 to 20 cm topsoil on the soil water–salt balance, maize yield production, and water use efficiency (WUE) under brackish water irrigation in a naturally non-saline area. Air-dried wheat straw was applied at the rates of 0, 4.5, 9.0, 13.5, and 18.0 t ha−1 (R0–R4) and two salinity levels of irrigation water with the salt content of 1.92 dS m−1 (SL) and 3.20 dS m−1 (SH) were applied for simulating the scenarios of secondary salinization. Results demonstrated that straw incorporation markedly increased the soil water content during two growing seasons, and SIR was directly correlated to the deep percolation, but inversely correlated to the soil water depletion, under both the SL and SH condition. Meanwhile, straw incorporation led to the increase in salt content within the straw incorporation zone, but the total mass of salt deposited in the 0–100 cm soil profile was comparatively reduced as SIR increased due to the increased deep percolation for salt leaching, and such relative alleviation was more pronounced under the SH condition. The significantly increased maize yield and its corresponding WUE were obtained in treatments with high SIR levels. Additionally, an exponential function was used to describe the trend of the yield-increasing rate as SIR increased, and the theoretical maximum of grain and biomass yield calculated from the fitting results were 6483 in 17,282 kg ha−1 under SL, and 5440 and 14,501 kg ha−1 under SH, respectively. Results in this study would be helpful in the adoption of straw incorporation and brackish water irrigation in ways that facilitate soil water availability and reduce the risk of soil salinization.

Soil Management in the Breede River Valley Wine Grape Region, South Africa. 3. Grapevine Performance

Eight cover crop treatments were applied for 12 consecutive years on a medium textured soil in a vineyard near Robertson (33o50'S, 19o54'E). A treatment with full surface straw mulch combined with full surface post-emergence chemical control applied from just before grapevine bud break to harvest (BB) and another with no cover crop combined with BB was also applied. The control consisted of mechanical control in the work row and post-emergence chemical control in the vine row applied from bud break to harvest. In the BB treatments, grapevine shoot growth was significantly higher than in the treatment where a perennial cover crop was established in the work row during both the second (1993/94) and third (1994/95) season after the grapevines were established. The grape yield in all the BB treatments, except the one in which a mixture of Secale cereale L. v. Henog and Vicia faba L. v. Fiord was sown, was significantly higher than that of the control and the treatment in which a perennial cover crop was sown in the work row during the 1995/96 season. During the 2001/02 season, the grape yield of the BB treatment with a full surface straw mulch was significantly higher than that of all the other treatments. The different soil management practices had a significant effect on the N status of the juice, but did not affect wine quality.

Soil Management in the Breede River Valley Wine Grape Region, South Africa. 1. Cover Crop Performance and Weed Control

Eight cover crop treatments were applied for 12 consecutive years on a medium-textured soil in a vineyard near Robertson (33˚50’S, 19˚54’E). A treatment with full surface straw mulch and full surface post-emergence chemical control applied from just before grapevine bud break to harvest (BB), and one with no cover crop combined with BB, were also applied. The control consisted of mechanical control in the work row and post-emergence chemical control in the vine row applied from bud break to harvest. Rotating Triticale v. Usgen 18 (triticale) and Vicia dasycarpa Ten. (vetch) did not improve the dry matter production (DMP) of either species. Average DMP decreased as follows: triticale > Secale cereale L. v. Henog (rye)/Vicia faba L. v. Fiord (faba bean) mixture > triticale/vetch biennial rotation > triticale/vetch annual rotation > vetch. Triticale (BB) resulted in total winter weed suppression from 1995 to 1996 and from 2001 to 2004. Total weed control from bud break to the pea size berry stage of the grapevines was achieved with straw mulch (BB), triticale (BB), rye/faba bean mixture (BB) and triticale/vetch rotated biennially (BB) from 2001 to 2003. For triticale combined with full surface post-emergence chemical control applied from grapevine berry set (AB), and for triticale/vetch rotated annually (BB), this was restricted to 2001 and 2003. From the pea size berry stage to harvest, straw mulch (BB), triticale (BB), vetch (BB), rye/faba bean mixture (BB) and triticale (AB) reduced the weed stand significantly in comparison to the control.

Buttonweed emergence as affected by seed burial depth and straw on the soil surface

Knowledge of the effects of seed burial depth and the presence of straw on the soil surface on weed seedling emergence provides useful information for the development of weed management tactics. Buttonweed (Borreria densiflora DC.) is a troublesome weed that occurs in large infestations in soybean and sugarcane crops from north-central Brazil. This study investigated buttonweed emergence at different seed burial depths and straw amounts present on the soil surface. The experiment was conducted in greenhouse conditions, under a factorial design between four seed burial depths and four amounts of surface straw. Percent seedling emergence and fresh biomass (g) were evaluated at twenty-five days after installation (DAI). Greater buttonweed emergence occurred in seeds that were placed on the soil surface either without surface straw or with up to 1,000 kg ha−1 of straw on the soil surface. With 4,000 kg ha−1 of surface straw, buttonweed emergence was prevented when seeds were placed at a depth of 0.5 cm or deeper in the soil. These data indicated emergence of this weed species was greater at depths near the soil surface and in soils with the least amounts of surface straw. Information generated in this study provides a starting point for the development of knowledge for understanding the biology of buttonweed emergence and its population dynamics. Such information may be directly transmitted to growers and lays the groundwork for an integrated management approach for this weed species.

秸秆隔层对盐碱土水盐运移及食葵光合特性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 秸秆隔层对盐碱土水盐运移及食葵光合特性的影响 DOI: 10.5846/stxb201206150861 作者: 作者单位: 中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,中国农业科学院农业资源与农业区划研究所,石河子大学/新疆兵团绿洲生态农业重点实验室,中国农业科学院农业资源与农业区划研究所,内蒙古河套灌区义长灌域管理局试验站 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31000692);公益性行业(农业)科研专项经费项目(200903001);中央级公益性科研院所基本科研业务费专项资金项目(2012ZL031) Effects of straw interlayer on soil water and salt movement and sunflower photosynthetic characteristics in saline-alkali soils Author: Affiliation: Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Institute of Agricultural Resources and Regional Planning,CAAS,Key Laboratory of Oasis Ecological Agriculture,Xinjiang Production and Construction Corps,Shihezi University,Shihezi Xinjiang,Institute of Agricultural Resources and Regional Planning,CAAS, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:在内蒙古河套灌区通过微区试验,研究了秸秆深埋(S)、上盖秸秆下埋秸秆(简称上秸下秸,S+S)、上盖地膜下埋秸秆(简称上膜下秸,P+S)和地膜覆盖(对照,CK)4种耕作措施对0-40 cm土层水盐运移及食葵光合特性的影响。结果表明:(1)不同措施对土壤水盐调控的效果与作用时期差异较大。P+S在整个生育期内土壤盐分含量和盐溶质浓度较低,控盐效果显著;S+S仅在苗期能保墒控盐,但控盐效果比P+S差,后期出现水减盐增现象,保墒控盐效果也不佳;S在整个生育期内土壤盐分含量和盐溶质浓度最高,控盐效果最差;CK在整个生育期内土壤水分含量变化不大,而盐分含量较高,控盐效果也不明显。(2)不同措施对土壤水盐运移调控程度的差异,导致食葵光合特性也有明显变化。与CK、S、S+S相比,P+S由于其较低的盐溶质浓度环境,明显改善了其光合特性,在苗期、蕾期和花期能提高净光合速率(Pn)和蒸腾速率(Tr),增加气孔导度(Gs),降低胞间CO2浓度(Ci),从而使其作物长势和干物质积累明显高于其它措施。综合试验结果,P+S是内蒙古河套灌区盐碱地改良中优选的控抑盐耕作措施。 Abstract:Insufficient drainage and over irrigation make salinity still a remaining problem in the Hetao Irrigation District of Inner Mongolia. In view of the occurrence characteristics of saline-alkali soils in this area, controlling invalid soil water evaporation and increasing water use efficiency are very important. It has been demonstrated that surface mulching with straw and film and placing a straw interlayer in soil are effective measures for soil salinity control. In this paper, we investigated the influences of integrated application of mulching and straw interlayer on the movement of soil and water and photosynthetic characteristic of sunflower on a typical saline-alkali soil. Micro-plot experiment was established with four treatments: straw interlayer only (S), straw interlayer plus surface straw mulching (S+S), straw interlayer plus surface plastic film mulching (P+S), and surface plastic film mulching (CK). Water and salt contents in the 0-40 cmm soil layer and crop photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) were measured during sunflower growing season. Mulching and straw interlayer significantly modified soil water and salt processes. Compared with the other treatments, the P+S treatment showed lower salt contents and solute concentration in the 0-40 cm soil layer. The S+S treatment increased soil water content and reduced salt content at the seedling stage, but the degree of changes were less than that of the P+S treatment. At later growth stages, the S+S treatment had lower soil water content and higher salt content, suggesting that a straw interlayer plus surface straw mulching was not very effective in soil salinization control. The S treatment had the highest salt content in the whole growing season, an indication that placing a straw interlayer in the soil has limited effect on reducing soil salinity. Although the CK treatment had a higher and table water content in the 0-40 cm soil layer, its salt content remained higher in sunflower growing season. In terms of crop photosynthetic characteristics, compared to the CK, S, and S+S treatments, the P+S treatment significantly increased sunflower Pn, Tr, and Gs, and reduced Ci at seedling stage, bud stage, and flowering stage. In addition, the P+S treatment promoted crop growth, reduced the growth period, and accelerated dry matter accumulation of sunflower plants. We concluded that the P+S treatment was an optimal measure on amelioration of saline-alkali soil in the Hetao Irrigation District. 参考文献 相似文献 引证文献

Evaluation of an online approach for determination of percentage residue cover

An online sensor for measuring residue cover with the help of fast image analysis offers new advantages. A prototype of such a sensor system was tested, though its quality of work under real world conditions can only be specified relative to other methods acting as a reference. Therefore, a combination of different tests was conducted. In field trials with defined surface residue densities (kg ha −1 ) the readings of the camera sensor, a visual standard method (grid) and visual estimations were correlated with each other and with the quantities of surface straw and tillage depth. Correlation coefficients between the methods of 0.7–0.9 were found. The methods were also checked against the results of manually controlled classification of images taken at 70 selected geo-referenced reading points. This yielded the best result for the camera sensor with a correlation coefficient of 0.962. Additionally, in a laboratory test with well-defined artificial cover rates, the characteristic behaviour of image analysis and the grid method was investigated. A slight overrating of the cover by the grid method and a small error caused by the camera lens aberration could be identified. The suitability in principle of online image processing as a new reference method has been demonstrated. However, in the field, the camera sensor provided the greatest reliability, compared to untrained human observers at cover rates below about 50%. At higher residue covers, human perception might have some advantage.

Soybean nodulation and nitrogen fixation in response to soil compaction and surface straw mulching

Soil compaction affects nodulation and nitrogen fixation of soybean ( Glycine max (L.) Merr.). The effects of compaction can be mediated by straw mulch applied at soil surface. To test these hypotheses a field experiment was carried out in 2008 on a Haplic Luvisol (south-eastern Poland). We grew soybean in treatments with different soil compaction levels: non-compacted (NC), moderately compacted (MC) (3 tractor passes) and strongly compacted soil (SC) (5 tractor passes). Each compaction level had treatments without and with surface chopped straw mulch at the rate of 0.5 kg m −2. Nodulation was evaluated by measurements of nodule-size distribution, number, weight, and diameter of nodules and symbiotic nitrogen fixation – by measurement of nitrogenase activity, nitrogen content in leaves, protein content in seeds and seed yield. Soil measurements included bulk density and nitrogen content in the form of N-NO 3 and N-NH 4. In general, nitrogenase activity decreased with increasing soil compaction level. At every compaction level, the nitrogenase activity was higher in the mulched when compared to the unmulched soil. Soil compaction and mulching enhanced the contribution of large nodules, those greater than 0.41 cm and dry weight of individual nodules. Total nodule number and weight decreased in sequence: moderately, strongly and non-compacted soil. Mulch influenced nitrogenase activity and nodulation to a higher extent than compaction. An optimum soybean response in terms of seed and protein yields was observed under mulched MC and the worst – under unmulched SC. Both N content in leaves and nitrate content in soil were lower in mulched than in unmulched soil, irrespective of compaction. Bulk density and N-NO 3 increased with soil compaction level and N-NH 4 remained nearly unchanged. Therefore, our results supported the hypotheses that soil compaction affects nodulation and nitrogen fixation, and that compaction can be mediated by straw mulch. Further studies are needed to assess variability related with different soil and weather conditions.

Mineralização do carbono da palha de aveia e dejetos de suínos aplicados na superfície ou incorporados ao solo

A mineralização do C de dejetos de suínos e de palhas de cereais é um processo ainda relativamente pouco estudado no Brasil. O objetivo deste trabalho foi avaliar a mineralização do C da palha de aveia, dos dejetos líquidos de suínos e da cama sobreposta de suínos, aplicados na superfície ou incorporados em um Argissolo Vermelho distrófico arênico, em condições de laboratório. Utilizou-se o delineamento inteiramente casualizado, com quatro repetições dos seguintes tratamentos: solo; solo + palha incorporada; solo + palha em superfície; solo + cama sobreposta incorporada; solo + cama sobreposta em superfície; solo + dejetos líquidos incorporados; solo + dejetos líquidos em superfície; solo + palha + dejetos líquidos incorporados; e solo + palha + dejetos líquidos em superfície. Durante 80 dias de incubação, a emissão de CO2 foi medida continuamente. Ao final desse período, observou-se que foram mineralizados 59 % do C dos dejetos líquidos e apenas 23 % do C da cama sobreposta. A incorporação dos materiais orgânicos ao solo não resultou em maior mineralização do C, quando comparado à permanência desses na superfície do solo. O N amoniacal, aplicado com os dejetos líquidos de suínos, não aumentou a mineralização do C da palha de aveia.

The effect of wheat straw residue on the emergence and early growth of sugar beet ( Beta vulgaris) and oilseed rape ( Brassica napus)

The management of straw residue can be a concern in non-inversion tillage systems where straw tends to be incorporated at shallow depths or left on the soil surface. This can lead to poor crop establishment because straw residue can impede or hinder crop emergence and growth. Small container-based experiments were undertaken using varying amounts of wheat straw residue either incorporated or placed on the soil surface. The effects on days to seedling emergence, percentage emergence, seedling dry-weight and soil temperature using sugar beet and oilseed rape were investigated because these crops often follow wheat in a cropping sequence. The position of the straw residue was found to be the primary factor in reducing crop emergence and growth. Increasing the amount of straw residue (from 3.3 t ha −1 to 6.7 t ha −1) did not show any consistent trends in reducing crop emergence or growth. However, in some instances, results indicated that an interaction between the position and the amount of straw residue occurred particularly when the straw and seed was placed on the soil surface. Straw placed on the soil surface significantly reduced mean day-time soil temperature by approximately 2.5 °C compared to no residue. When the seed and straw was placed on the soil surface a lack of seed-to-soil contact caused a reduction in emergence by approximately 30% because of the restriction in available moisture that limited the ability for seed imbibition. This trend was reversed when the seed was placed in the soil, but with straw residue still on the soil surface, because the surface straw was likely to reduce moisture evaporation and improved seed-to-soil contact that led to rapid emergence. In general, when straw was mixed in or placed on the soil surface along with the seed, sugar beet and oilseed rape emergence and early growth biomass was significantly restricted by approximately 50% compared to no residue. The consequences of placing seed with or near to straw residue have been shown to cause a restriction in crop establishment. In both oilseed rape and sugar beet, this could lead to a reduction in final crop densities, poor, uneven growth and potentially lower yields that could lower financial margins. Therefore, if farmers are planning to use non-inversion tillage methods for crop establishment, the management and removal of straw residue from near or above the seed is considered important for successful crop establishment.

Mulch decomposition impedes recovery of net carbon sink function in a restored peatland

With the increase in the drainage and extraction of peat for horticultural, agricultural and energy purposes worldwide, there is an increased pressure to restore hydrological conditions essential to the re-establishment of Sphagnum mosses and, therefore, carbon sequestration. Measurements of ecosystem CO2 were conducted at a recently restored vacuum harvested bog in Eastern Québec, Canada. The peatland was restored by blocking the drainage networks to return optimal water table positions for the growth of Sphagnum mosses and the spreading of a dense straw mulch layer to reduce evaporative losses and stabilize the surface for the moss re-growth. However, the return of the moss species is a gradual process and previous studies have suggested that initially the carbon loss from the system actually increase as the mulch decomposes. We examined old and new mulch CO2 production in lab incubations and scaled these results to the ecosystem level in order to determine if mulch decomposition is impeding the net carbon sink function of this peatland. At mean growing season temperatures fresh mulch was observed to release 151.5 μmol CO2 g−1 per day, while older mulch released 145 μmol CO2 g−1 per day. Furthermore, under moist conditions the CO2 release increased for all mulches. However, contrary to most assumptions, Q10 values for all mulches decreased with increasing temperatures and were greater for older mulch than for fresh. Thus, in the short term, the application of a surface straw mulch layer can have significant effects on the carbon balance of a restored peatland. Due to the decomposition of this mulch layer over the first several seasons of restoration, the peatland became a larger source of CO2, despite the increase in production of a re-emerging vegetation layer.