Evaluation of soil extractants for silicon availability for sugarcane

Adequate evaluation and interpretation of silicon (Si) phytoavailability in soil is a key to fertilizer recommendation. This study was conducted to determine the effect of soil texture on the choice of Si extractant, and provide baseline data on the relationship between extractable Si and sugarcane Si accumulation. The effects of soil texture and extractant solutions of Si were investigated on soil of nine areas of sugarcane cultivation. Si contents in clayey soils were higher than in sandy soils only in the extraction with standard calcium chloride, acetic acid, potassium chloride (KCl), and sodium acetate buffer. Other extractants failed to reveal differences in the Si availability among the three soil textures. The choice of the extractant should consider soil texture for the determination of adequate Si contents in soils planted with sugarcane, and the extractants that proved to be more efficient in the three soil textures was acetic acid and KCl.     

土壤调理剂对日光温室土壤理化性质和蔬菜产量、品质的影响

试验研究了土壤调理剂对日光温室土壤理化性质和蔬菜产量、品质的影响。结果表明,施用土壤调理剂能够明显改善土壤结构,增强土壤保水能力,与对照相比,施用2次调理剂后土壤容重降低6.36%,土壤总孔隙度增加4.97%,田间持水量增加6.75%,渗透系数提高46.28%;调理剂还能增加土壤养分含量,提高土壤保肥能力;调理剂能够提高蔬菜的产量和品质,对番茄品质的改善效果尤为明显;调理剂与秸秆配合施用效果更佳。     

Changes in soil physical properties of four different fields during and after upland reclamation that involved grading

Abstract

A number of clusters of resting spores of an endophyte were found to have colonized the nodal root axes and first order lateral roots of sorghum at the heading stage. The clusters with a diameter ranging 15 to 20 μm consisted of a number of spores with a diameter in the range of 2 to 5 μm. Based on the morphological characteristics, the endophyte was tentatively assigned to Polymyxa sp. The clusters were distributed in the epidermis and the hypodermis, but mostly in the latter. The clusters were absent in the tissues internal to the hypodermis. The number of cells colonized by the clusters in the hypodermis, the hypodermal cell lignification identified by the phloroglucinol-HCl test, and the cortical sclerenchyma development were examined acropetally in three nodal roots which emerged from the third node. The colonized cells accounted for less than about 10% of the total number of the hypodermal cells in the first 8 cm portion, but beyond this part, their number increased and they accounted for 10 to 35%. Hypodermal cell lignification and cortical sclerenchyma development were clearly recognized approximately in the first 9 and 6 cm portion, respectively, but they were not observed beyond this part. Even in this portion, however, no endophyte colonization was observed in any tissues internal to the hypodermis. These findings suggest that in sorghum the hypodermis itself, regardless of cell lignification, may function as a barrier to protect the inner tissues from further colonization by the spore clusters of Polymyxa sp.     

Interrelation between soil physical properties and Enchytraeidae abundances following a single soil compaction in arable land

In spring 1995 a silty clay soil was compacted dynamically by wheeling with graded wheel loads up to 6 times. The reaction towards wheeling was recorded immediately. In the following 3 years some soil physical parameters as well as the Enchytraeidae abundances were recorded regularly. To the first wheeling, the soil reacted plastically in vertical direction. The reaction became elastically after the 4th wheeling. After the 6th passage with a 5‒tonnes wheel load soil structure collapsed totally, which can be concluded from the stress ratios. After the wheeling event, abundances of Enchytraeidae decreased obviously compared to uncompacted plots. The increase in air permeability, air capacity, and the decrease of soil bulk density depend on primary tillage events. The recovery of Enchytraeidae abundances developed in parallel. Abundances seem to be regenerated in the 3rd year after the wheeling event. Primary tillage can help to induce biological and macroscopic structural regeneration of the top soil after a compaction event.     

Temporal changes of soil physical and hydraulic properties in strawberry fields

Even over short time intervals, soil properties are subject to variation, especially in managed soils. The objective of this study was to assess the temporal changes of soil physical and hydraulic properties in strawberry fields cultivated under surface drip fertigation in Turuçu, Brazil. Intact core samples were collected from the near surface soil layer of seedbeds to determine the total porosity (TP), macroporosity (MA), matrix porosity, bulk density (BD), available water capacity (AWC), field capacity, wilting point and Dexter’s S index. Aggregate samples were collected from the arable layer to determine the aggregate size distribution and aggregate mean weight diameter. All samples were collected from 15 strawberry fields and at four different times during the 2007–2008 strawberry growing cycle. Although soil pore‐solid relations are expected to adjust soon after seedbed construction, their variation was only evident after >13 weeks. Even though values of TP and MA decreased with time, and those of BD increased near the end of the growing cycle, all the soils maintained their capacity to support root activity as indicated by critical values of Dexter’s index (S > 0.03). The amount of relatively large aggregates (9.51–2.00 mm) and AWC increased towards the end of the strawberry cultivation cycle. With changes in soil structure improving soil physical quality, strawberry development benefitted. We showed that if farmers gradually increase the amount of water through fertigation to a maximum value occurring at the end of crop cycle instead of applying water at a constant rate, water and energy use efficiency in agriculture would improve.     

多年固定道保护性耕作对土壤结构的影响

为了解决拖拉机作业机组作业时造成的土壤普遍压实,在10a连续固定道保护性耕作试验基础上,研究了固定道保护性耕作对土壤容重、孔隙度、紧实度、水分以及冬小麦产量的影响。试验结果表明,对于作物生长带,固定道保护性耕作可以降低0～20cm土层的容重6.8%,提高0～40cm土层土壤总孔隙度4.6%,降低0～30cm土层土壤紧实度31.5%,提高0～1m土层蓄水能力,在固定道占地20%的情况下,仍能提高冬小麦产量10.8%。因此,固定道保护性耕作是减少土壤压实、改善土壤结构、提高小麦产量的有效耕作方式。     

Using soil organic matter fractions as indicators of soil physical quality

The objective of this study was to evaluate the use of chemical and physical fractions of soil organic matter (SOM ), rather than SOM per se , as indicators of soil physical quality (SPQ ) based on their effect on aggregate stability (AS ). Chemically extracted humic and fulvic acids (HA and FA ) were used as chemical fractions, and heavy and light fractions (HF and LF ) obtained by density separation as physical fractions. The analyses were conducted on medium‐textured soils from tropical and temperate regions under cropland and pasture. Results show that soil organic carbon (SOC ), SOM fractions and AS appear to be affected by land use regardless of the origin of the soils. A general separation of structurally stable and unstable soils between samples of large and small SOC content, respectively, was observed. SOM fractions did not show a better relationship with AS than SOC per se . In both geographical regions, soils under cropland showed the smallest content of SOC , HA and carbon concentration in LF and HF , and the largest HF /LF ratio (proportion of the HF and LF in percent by mass of bulk soil). With significant associations between AS and SOC content (0.79**), FA /SOC (r  = −0.83*^*), HA /FA (r  = 0.58*^*), carbon concentration of LF (r  = 0.69*^*) and HF (r  = 0.70*^*) and HF /LF ratio (r  = 0.80*^*), cropland showed lowest AS . These associations indicate that SOM fractions provide information about differences in SOM quality in relation to AS and SPQ of soils from tropical and temperate regions under cropland and pasture.     

Soil bulk density corrections for providing a better relationship with root growth in gravelly soil

Abstract

Bulk density of a Tifton (Plinthitic Paleudult; fine loamy, siliceous, thermic) soil containing 5.8 to 11.0% of the sample weight as pebbles was 0.06–0.12 g/cc lower when corrections were made for presence of pebbles or concretions. A method for determining the bulk density of the soil matrix between pebbles or concretions is outlined. After adjustment, the bulk density at which root penetration was inhibited in this soil closely approximated that for soils which do not contain concretions. The proposed procedure reflects more nearly how bulk density changes where plant roots are growing than previously published procedures do.     

5种土壤调理剂对大蒜田土壤理化性质和大蒜产量的影响

试验研究了两个不同用量的5种土壤调理剂(麦饭石、牡蛎壳、蒙脱石、硅钙矿和有机肥)对土壤理化性质和大蒜产量的影响。结果表明,5种调理剂均能降低土壤容重,提高土壤孔隙度:施用前期麦饭石处理的土壤容重显著降低,后期则蒙脱石处理土壤容重降低明显。在大蒜生长前期,施用高量牡蛎壳、蒙脱石和有机肥均显著提高了土壤碱解氮含量;蒙脱石显著降低了土壤速效磷含量,高量有机肥则明显增加了土壤速效磷含量;麦饭石、蒙脱石、硅钙矿和有机肥均能显著提高土壤速效钾含量,牡蛎壳对土壤速效钾含量影响不大。蒙脱石、硅钙矿和有机肥在大蒜生长前期均显著提高了土壤有机质含量,后期则只有高量有机肥比对照有显著增加。麦饭石、蒙脱石和有机肥3种土壤调理剂对土壤pH值有降低作用,而牡蛎壳和硅钙矿两种土壤调理剂对土壤pH值有增加作用。土壤调理剂对大蒜叶枯病有一定减轻作用。5种调理剂与对照相比均有一定增产功效,但只有蒙脱石和高量有机肥增产效果显著。     

Applications of S‐theory in the study of soil physical degradation and its consequences

The S‐theory for soil physical quality is introduced. It is shown how values of S can be determined from the water retention characteristic curve. It is also explained how, when experimental data are not available, pedotransfer functions can be used to obtain estimates of S. Although S was first introduced as an index of soil physical quality, it is being increasingly found that it is a useful numerical quantity that can be used in equations for prediction of a range of soil physical properties. Its use is illustrated with examples for hydraulic conductivity, friability, tillage, compaction, penetrometer resistance, plant‐available water, root growth and readily dispersible clay. The main merit of S derives from the fact that given values of S have the same meaning and consequences in different soils. It is described how S can be used to identify areas of land where physical degradation or amelioration are taking place, and to evaluate management practices that will give sustainable land use. Copyright © 2007 John Wiley & Sons, Ltd.     

碱化盐土掺砂对土壤理化性状和玉米产量影响的研究

为解决内蒙古河套平原黏性碱化盐土土壤黏重,作物难以正常生长、产量低下等问题,对河套平原黏性碱化盐土进行了土壤耕层(0~20 cm)掺砂的土壤改良试验,研究掺砂对土壤理化性状和玉米产量的影响。结果表明:试验区土壤掺砂可以降低土壤容重,改变土壤机械组成和土壤质地,提高了黏性碱化盐土的通气孔隙度,改善土壤的通气透水性,降低土壤全盐量和碱化度,有效改善玉米生长环境,提高了玉米的产量。掺砂20%处理的土壤容重从1.64 g/cm3(CK)降低到1.49 g/cm3,土壤通气孔隙度从8.57%提高到18.17%,达到正常范围,使土壤砂粒、粉粒、粘粒含量比例趋向适中,土壤质地由壤质黏土转变为黏壤土,土壤全盐量下降了13%,碱化度降低了21%,玉米产量提高了301%。综合分析,掺砂20%处理对当地碱化盐土改良效果较为适宜。     

The effects of dairy cow weight on selected soil physical properties indicative of compaction

The effect of treading by dairy cows of three different weights on soil physical properties was investigated under different soil moisture deficit (SMD) treatments in the south of Ireland. SMD was used as a readily predicable surrogate for volumetric water content. Animal treading in grassland ecosystems is known to affect soil and vegetation properties, which can influence agricultural system productivity. Treading action can result in reduced soil water infiltration and increased runoff. In Ireland short winter housing and early spring turnout are key elements of low cost grass based production. However, there is potential for soil damage as a consequence of animal treading during early spring and late autumn. This study shows that SMD is the main factor affecting changes in bulk density (BD), soil shear strength, penetration resistance (PR) and total porosity. At high SMD (dry), soil was less sensitive to trampling damage than at low SMD (wet). At SMD 0 mm, BD increased by 6.1% post trampling, whereas it only increased by 3.1, 4.0 and 0.5% at SMD 11, 14, and 29 mm, respectively. Average soil BD was 2.3% greater immediately post trampling, and 4.6% greater in the hoof marks. PR was significantly greater following trampling by the heavy weight cow compared with the light or medium weight cow. There was no significant effect of cow weight on soil water content or soil BD. The results indicate that forecasted SMD can be used as a management input for rotational grazing systems to protect soil quality.     

一膜两年覆盖条件下耕作方法对旱作玉米产量及土壤物理性状的影响

为了优化全膜双垄沟播玉米土壤耕作技术,实现土壤质量保育和增产增效,布设田间定位试验,比较研究了一膜两年全膜双垄覆盖条件下,少免耕对玉米产量、水分利用效率(WUE)、经济效益及土壤物理性状的影响。结果表明:一膜两年用条件下,深松耕—免耕较对照能显著提高玉米的籽粒产量、水分利用效率、收获指数、总产值及产投比,其籽粒产量、水分利用效率、收获指数、总产值及产投比分别较对照提高22.8%,22.0%,15.0%,17.4%,17.4%;深松耕—免耕具有降低表层土壤容重、紧实度,增加土壤总孔度、大团聚体含量及饱和导水率的作用,全膜双垄沟播玉米采用深松耕—免耕具有明显的稳增产增效及土壤结构改善的作用,建议在全膜双垄沟播玉米种植体系中推广应用。     

水旱轮作制下连续秸秆覆盖对土壤理化性质和作物产量的影响

采用田间定位试验研究方法,于2008～2010连续3年研究了水旱轮作制下连续秸秆覆盖对土壤理化性质和作物产量的影响。结果表明,连续秸秆覆盖显著降低了土壤表层（05cm）容重,提高了05cm和515cm土层土壤含水量。同时连续秸秆覆盖还田还可以显著提高025cm土层土壤有机质、碱解氮、速效磷和速效钾含量。秸秆覆盖对表层（05cm）土壤养分状况的效应更明显。秸秆连续覆盖5季后,05cm土层土壤速效钾含量的增幅（7.64%～15.33%）速效磷（7.52%～10.03%）碱解氮（7.30%～8.74%）有机质（6.08%～7.53%）。秸秆覆盖还田后,可以提高作物产量。其中旱季作物（小麦、油菜）的增产效应要高于水季作物（水稻）,并且随着秸秆还田年限和用量的增加,作物的增产幅度也随之提高。起主要作用的产量构成因素是小麦、水稻的有效穗数以及油菜单株角果数和每角粒数。     

机械化整地方式对低洼水田土壤理化性质及水稻产量影响

低洼地是黑龙江省分布在三江平原地区的地势较低的一类耕地土壤,由于地势低、易受渍涝影响,土壤生产力低,作物产量低而不稳,提高这类土壤生产力对农业生产尤为重要。该文以低洼地典型的一类土壤沼泽土为供试土壤,采用大田对比试验的方法,开展旋耕、深松、深翻、深松鼠洞4种不同机械化整地方式对低洼水田理化性质改良效果的研究。结果表明:与常规旋耕比,深松、深翻机械整地可以使0～30cm土层土壤含水率降低10.03%～27.23%,土壤透水性提高,土壤容重增加0.05～0.18 g/cm3、增幅为6.60%～16.98%,差异显著,深松、深翻使土壤硬度提高,总孔隙降低幅度3.16%～11.92%,滞水现象得到改善,深松鼠洞机械整地效果与旋耕比差异不明显;在排水晒田后,土壤温度明显上升,平均每天增加1～2℃,深松效果好于深翻,土壤氮素供应强度增加;深松整地水稻产量连年增加,第1年增产4.21%,第2年增产10.46%,达到显著水平,深翻对水稻产量无影响,第2年有增加趋势,差异不显著,深松鼠洞整地第1年和第2年水稻产量与旋耕比无差异显著,在深松鼠洞改土技术及机械研发上要进行新的改进与探讨。     

The quality of exogenous organic matter: short-term effects on soil physical properties and soil organic matter fractions

We examined the short-term effect of five organic amendments and compared them to plots fertilized with inorganic fertilizer and unfertilized plots on aggregate stability and hydraulic conductivity, and on the OC and ON distribution in physically separated SOM fractions. After less than 1 year, the addition of organic amendments significantly increased ( P  <   0.01) the aggregate stability and hydraulic conductivity. The stability index ranged between 0.97 and 1.76 and the hydraulic conductivity between 1.23 and 2.80 × 10⁻³ m/s for the plots receiving organic amendments, compared with 0.34–0.43, and 0.42–0.64 × 10⁻³ m/s, respectively, for the unamended plots. There were significant differences between the organic amendments (P <  0.01), although these results were not unequivocal for both soil physical parameters. The total OC and ON content were significantly increased ( P  <   0.05) by only two applications of organic fertilizers: between 1.10 and 1.51% OC for the amended plots versus 0.98–1.08% for the unamended and between 0.092 and 0.131% ON versus 0.092–0.098% respectively. The amount of OC and ON in the free particulate organic matter fraction was also significantly increased ( P  <   0.05), but there were no significant differences ( P  <   0.05) in the OC and ON content in the POM occluded in micro-aggregates and in the silt + clay-sized organic matter fraction. The results showed that even in less than 1 year pronounced effects on soil physical properties and on the distribution of OC and ON in the SOM fractions occurred.     

Mulching effects on soil physical quality of an alfisol in western Nigeria

Degradation of soil physical quality, following deforestation and cultivation, is a major soil‐related constraint to an intensive use of soil for crop production in subhumid regions of subSaharan Africa. Use of crop residue mulch is an important strategy to minimize the risks of soil degradation. Therefore, a three‐year experiment was conducted to study the effects of five rates of mulch application (0, 2, 4, 6 and 8 Mg ha⁻¹ season⁻¹) on soil physical properties and growth and yield of maize (Zea mays). Mulch rate of rice straw significantly increased maize grain and stover yields during the first season, and the stover yield during the second season. In comparison with the control, the grain yield increased by 20 per cent at 2 Mg ha⁻¹ of mulch rate and by 33 per cent at 8 Mg ha⁻¹ of mulch rate. The rate of increase was 0·16 Mg ha⁻¹ for grain yield and 0·38 Mg ha⁻¹ for stover yield for every Mg of mulch applied. The increase in stover yield during the second season was 67 per cent for 8 Mg ha⁻¹ mulch rate compared with the unmulched control. Effects of mulch rate on soil physical properties were confined mostly to the surface 0–5 cm depth. For this depth, mulching decreased bulk density from 1·17 Mg m⁻³ for control to 0·98 Mg m⁻³, and penetration resistance from 1·54 kg cm⁻² to 1·07 kg cm⁻² for 8 Mg ha⁻¹ of mulch rate. Application of mulch up to 16 Mg ha⁻¹ yr⁻¹ for three consecutive years had no effect on soil physical properties below 5 cm depth. Experiments were probably not conducted for a long enough period. For mulch farming to be adopted by farmers of West Africa, it must be an integral part of the improved farming system. Copyright © 2000 John Wiley & Sons, Ltd.     

轮耕对土壤物理性状及水稻产量影响的初步研究

针对南方稻田连续免耕存在的主要问题,进行了土壤轮耕效应的初步研究。试验选择双季稻区连续7年免耕稻田,设置免耕、旋耕和翻耕3种耕作处理（即免耕-免耕,免耕-旋耕和免耕-翻耕）,早稻和晚稻采取同-耕作措施。研究结果表明：连续免耕后进行土壤耕作（翻耕、旋耕）可以降低耕作层土壤容重,增加土壤水贮量,尤为翻耕显著,早、晚稻均表现为这-趋势;晚稻收获时,表层0～5cm的毛管孔隙度表现为免耕-翻耕、免耕-旋耕在5％水平上显著高于免耕-免耕,而下层差异不显著;早、晚稻晒田时,表层0～5cm原状土饱和导水率均表现为免耕～翻耕在5％水平上显著高于免耕-免耕和免耕-旋耕,而5～10cm无显著性差异;早、晚稻的实际产量均表现为免耕-旋耕〉免耕-翻耕〉免耕-免耕,起主要作用的构成因素是有效穗数。     

保护性耕作对土壤物理特性及玉米产量的影响

保护性耕作措施是干旱区农田提高作物产量的新型耕作技术。为了探讨其区域适应性,在2004～2007年期间,以毛乌素沙地南缘的靖边县北部风沙区农田为研究对象,选用了免耕、秸秆覆盖、覆膜和传统翻耕(CK)4种措施,采用完全随机试验设计进行了田间定位试验研究。结果表明,秸秆覆盖和免耕地的地温在春播初期略比传统翻耕低0.1℃,但随后迅速回升,覆膜在玉米生长期都高于其他措施。耕作措施对播种前土壤容重没有显著影响,而对收获后土壤容重影响显著,与传统翻耕相比,免耕降低了表层土壤容重1.65%,但次层20～40 cm容重增加了1.8%。3种保护性耕作措施均增加了土壤含水量,顺序依次为秸秆覆盖>覆膜>免耕>翻耕,且在作物需水关键期免耕和秸秆覆盖下的土壤含水量相对稳定,保证作物需水,提高水分利用率,分别为8%、22.0%和13.3%。使作物分别增产4.44%、13.14%和19.26%。因此,保护性耕作在风沙区有利于改善农田土壤物理条件,提高作物产量,适于在风沙区推广。