Soil consistency as a factor determining the soil structure of clay soils.

The deterioration of the aggregation of several Dutch clay soils during the period after plowing seems to be caused by a plastic transformation of the soil aggregates under the influence of mechanical forces, even very weak ones such as the weight of the top soil. It depends on the consistency and moisture characteristics of the soil, the drainage of the top soil, etc. The location of the point pF 1.9 ("field capacity") on the moisture percentage scale with regard to the upper plastic limit, the sticky point and the lower plastic limit appears to be a better index for the structure of clay soils than figures obtained from a wet-sieving analysis, and some results of experiments on the effects of lime, gypsum and soil conditioners on soil structure illustrate this.-From authors' summary. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Vulnerability of soil aggregates in relation to soil properties

Plant Soil and Environment ◽

10.17221/4376-pse ◽

2011 ◽

Vol 48 (No. 8) ◽

pp. 329-334

Author(s):

L. Borůvka ◽

M. Valla ◽

H. Donátová ◽

K. Němeček

Keyword(s):

Soil Properties ◽

Soil Structure ◽

Soil Aggregates ◽

Aggregate Size ◽

Fine Sand ◽

Mechanical Forces ◽

Soil Characteristic ◽

Fine Silt ◽

Wetting And Drying ◽

Humus Quality

Stability of soil structure represents an indicator of soil quality. The aim of this paper was to assess the effect of soil properties on structure vulnerability in an Orthic Luvisol. The aggregates were most vulnerable to fast wetting (mean Kv1 = 9.99, i.e. this effect can decrease the aggregate size 9.99 times). Lower destruction was caused by slow wetting and drying (Kv2 = 3.70) and mechanical forces (Kv3 = 1.67). Fine silt (particles of 0.002–0.01 mm) was the most important soil characteristic decreasing aggregate vulnerability (r = –0.334, –0.248, and –0.393 for Kv1, Kv2, and Kv3, respectively). Silt (0.01–0.05 mm) increased vulnerability to fast wetting (r = 0.318). Very fine sand (0.05–0.1 mm) increased vulnerability to mechanical impacts (r = 0.307). Organic carbon decreased vulnerability only slightly. Humus quality was rather related to porosity. Higher moisture of samples in time of collection increased aggregate vulnerability. Multiple regression, used for description of the effect of basic soil properties, provided the best model for Kv1 (R2 = 27.45%), the poorest for Kv2 (R2 = 7.23%).

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Structural decline of soils, assessment and prevention

Soil Research ◽

10.1071/sr9910905 ◽

1991 ◽

Vol 29 (6) ◽

pp. 905 ◽

Cited By ~ 27

Author(s):

WW Emerson

Keyword(s):

Structural Damage ◽

Soil Aggregates ◽

Total Porosity ◽

Field Capacity ◽

The Other ◽

Clay Soils ◽

Particle Bonding ◽

Remoulded Soil ◽

Cracking Clays

Two extreme textural types of cultivated surface soils are mainly considered here, non-shrinking red-brown earths and highly shrinking cracking clays. Total porosity is used to assess the structural status of the former. Values are compared with the highest and lowest values found in the field. For the latter, the criterion used is the porosity of dry aggregates or clods. Values here are taken from the literature. To find out why inter-particle bonding in soil aggregates is insufficient to stop structural decline, a scheme has been developed which includes a modified version of Emerson's (1967) classification of soil aggregates. Slaking is carefully assessed. The bulk density of a cube made from soil at 'field capacity' is measured as well as testing another for dispersion. Class 3 is now divided into 3a and 3b, according to the degree of dispersion of remoulded soil in water. Also apart from soils which disperse spontaneously from dry, classes 1 and 2, the dispersion of all soils is assessed after remoulding at 'field capacity'. It has been found that the red-brown earth site which had the best visual structure also had the largest total porosity and aggregates in class 4. At the worst site, aggregates were in class 3a and the porosity had been reduced to that of the soil cube. For cracking clays, porosity is appreciably higher where the aggregates are in class 4 rather than class 3a. Water content/dispersion curves are presented for the clays showing the extent of the increase in OD apparently associated with the presence of carbonate. Dispersion of sheared, class 3a soil immersed in water is only an outward sign of the structural damage caused when the soil is sheared too wet. If the soil is dried instead, porosity is still lost. Mechanisms are suggested by which the structure of class 3a clay soils are improved by adding carbonate. The slumping of red-brown earths and the use of surface dressings of gypsum to prevent severe dispersion after cultivation wet are discussed. The structural stability of aggregates in the other five classes is briefly considered. Classes 1 and 2 require an ameliorant to be added, the rest pose few problems.

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Soil Water Studies in Oxisols and Ultisols of Puerto Rico: I. Water Movement

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v60i3.10530 ◽

1969 ◽

Vol 60 ◽

pp. 375-385

Author(s):

James M. Wolf ◽

Matthew Drosdoff

Keyword(s):

Soil Water ◽

Water Movement ◽

Soil Aggregates ◽

Flow Characteristics ◽

Field Capacity ◽

Water Infiltration ◽

Clay Soils ◽

Water Release ◽

Soil Water Tension ◽

Free Drainage

Soil water experiments were conducted to determine the water supplying characteristics of two clayey Ultisols, a clayey Oxisol, and a sandy Oxisol. Water infiltration into all soils was very rapid, reaching 9 cm/hr after 1 hr of continuous flooding. The strong structural stability of the clay soils permitted infiltration rates in excess of that for the sandy soil. Lateral water movement, downslope, was a significant factor in observed high rates of water infiltration and may partially account for downslope movement of nitrates. Values of soil water tension after 2 to 3 days of free drainage did not exceed 20 to 80 cm of water (roughly 1/50 to 1/12 bar). Field capacity was established to be 1/15 bar for the sandy Oxisol and 1/20 bar for the clayey Oxisol and Ultisols. Two avenues of soil water movement were postulated: Capillary pores (between soil particles) and non-capillary pores (between soil aggregates). Because of water movement in non-capillary pores, flow characteristics of the clay soils resembled that of the sand. In terms of soil water release characteristics, the clays and the sand were similar.

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Earthworm Burrowing Activity and Its Effects on Soil Hydraulic Properties under Different Soil Moisture Conditions from the Loess Plateau, China

Sustainability ◽

10.3390/su12219303 ◽

2020 ◽

Vol 12 (21) ◽

pp. 9303

Author(s):

Shuhai Wen ◽

Ming’an Shao ◽

Jiao Wang

Keyword(s):

Soil Moisture ◽

Loess Plateau ◽

Hydraulic Properties ◽

Soil Depth ◽

Soil Aggregates ◽

Field Capacity ◽

Soil Hydraulic Properties ◽

The Loess Plateau ◽

Burrowing Activity ◽

Soil Hydraulic

Earthworm activity has become more important in the Loess Plateau, where hydrological processes are crucial for ecosystem sustainability. In this study, we conducted a laboratory microcosm experiment to determine the various burrowing activities of Eisenia fetida and their impact on the soil hydraulic properties in response to different levels of soil moisture (50%, 70%, 90% of field capacity) in two common soil types (loessial and Lou soil) obtained from the Loess Plateau. Burrowing activity of E. fetida increased with higher soil moisture and was greater in loessial than in Lou soil. Most burrowing activities occurred within the top 5 cm and decreased with increasing soil depth. Macropores and burrow branching, which are highly related to the earthworm burrowing, were more prevalent in wetter soil. Earthworms significantly altered the formation of large soil aggregates (AGL, diameter >2 mm) under different soil moistures and depths. Distinct earthworm burrowing activities, controlled by soil moisture, altered soil hydraulic properties. However, soil saturated hydraulic conductivity (Ks) showed little differences between different treatments due to the horizontal and high–branched burrows of E. fetida, although higher burrowing activities were found in wetter soil. Soil field capacity was highest in drier soil due to the less macropores and burrowing activities.

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The effect of krilium soil conditioner on the yield of wheat

Australian Journal of Experimental Agriculture ◽

10.1071/ea9640363 ◽

1964 ◽

Vol 4 (15) ◽

pp. 363

Author(s):

TC Stoneman

Keyword(s):

Field Trial ◽

Soil Structure ◽

Soil Aggregates ◽

Wheat Yield ◽

Water Stability ◽

Soil Conditioner ◽

Barrel Medic

A field trial investigated the effect of improved soil structure on wheat yield. Krilium, a synthetic polyelectrolyte soil conditioner, was used to improve structure. The water stability of the soil aggregates was significantly increased on the plots treated with the conditioner. The conditioner treated plots also had significantly higher yields and 1000-grain weights than the untreated plots. The effect of the soil conditioner persisted into the year after cropping, when the plots were sown to Barrel Medic (Medicago tribuloides Desr.). The Barrel Medic establishment was significantly greater on the conditioner treated plots.

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Manufactured Soil Aggregates for Studying Microhabitats

10.5194/egusphere-egu2020-9512 ◽

2020 ◽

Author(s):

Harry Harvey ◽

Ricky Wildman ◽

Sacha Mooney ◽

Simon Avery

Keyword(s):

Soil Structure ◽

Soil Aggregates ◽

Environmental Stressors ◽

Yeast Cells ◽

Dependent Manner ◽

Microbial Composition ◽

X Ray ◽

Natural Counterpart ◽

Physical Variables

Environmental perturbation, anthropogenic or otherwise, can have a profound effect on soil microbiota and essential biogeochemical processes. The general resistance and adaptation of yeasts and other fungi to stressors has been well studied in vitro however, the influence of key physical variables, such as how soil structure regulates fungal response to perturbation, is poorly understood. In this study, we developed an approach to manufacture soil macroaggregates that are characteristically similar to their natural counterpart (determined by X-ray CT) and with defined microbial composition. This new tool allowed us to examine the influence of soil aggregation on fungal stress response by manufacturing aggregates with yeast cells either within, or on, the aggregate surface. Environmental stressors including heavy metals, anoxia, and heat stress were applied to these aggregates to capture an array of environmental stressors and assay differences in survival between exo-and-endo aggregate cells. Results generated with this new tool indicate that the location of yeast cells in soil macroaggregates can impact on their survival, in a stressor- and time-dependent manner.

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Evaluation of load support capacity of remoulded fine and coarse textured soils as affected by wetting and drying cycles

Soil Research ◽

10.1071/sr14209 ◽

2015 ◽

Vol 53 (5) ◽

pp. 512 ◽

Cited By ~ 4

Author(s):

Maryam Salehian Dastjerdi ◽

Abbas Hemmat

Keyword(s):

Soil Structure ◽

Cylindrical Sample ◽

Plastic Limit ◽

Confined Compression ◽

Flood Irrigation ◽

Wetting And Drying ◽

Wetting And Drying Cycles ◽

Significant Difference ◽

Compaction Stress ◽

Water Contents

Soils of south of Iran used for sugarcane production are frequently exposed to wetting and drying cycles under flood irrigation. The effects of this process on estimation of the load support capacity (pre-compaction stress; σpc) of two soils using plate sinkage test (PST) and confined compression test (CCT) were studied. Large reconstructed specimens of topsoils were subjected to 5 wetting and drying cycles. The specimens, with/without wetting and drying cycles, were then compressed under two pre-loads (100 and 200 kPa) at two water contents (0.9 PL and 1.1 PL, where PL is plastic limit). The centre section of the preloaded soil specimens was ﬁrstly submitted to a 50 mm PST; then immediately one cylindrical sample was cored for CCT. The results indicated that for both soils, without wetting and drying cycles, σpc estimated from PST did not show any significant difference with the values of preload. This method can, therefore, be used to determine the load support capacity for tilled soils. However, wetting and drying cycles caused a significant over-estimation of σpc by PST. Thus, the concept of pre-compaction stress does not account for the effects of changes in soil structure due to wetting and drying.

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Effects of some soil conditions on sugar-beet seedling emergence

The Journal of Agricultural Science ◽

10.1017/s0021859600025934 ◽

1972 ◽

Vol 79 (3) ◽

pp. 543-545 ◽

Cited By ~ 2

Author(s):

P. C. Longden

Keyword(s):

Soil Moisture ◽

Sugar Beet ◽

Clay Soil ◽

Sandy Loam ◽

Seedling Emergence ◽

Clay Soils ◽

Soil Types ◽

Soil Conditions ◽

Soil Conditioners ◽

Water Holding

SUMMARYSeven soil conditioners added to a sandy clay soil at Saxmundham did not benefit sugar-beet seedling emergence in four experiments in 3 years. In microplots at Broom's Barn free draining peat and sandy loam gave consistently more seedlings than limestone loam or flinty loam. In the laboratory, for each of three soil types, emergence was maximal only for a small soil moisture range and decreased rapidly when soils became drier or wetter. This suggests that conditioners which increase water-holding capacity should be tested on sandy loams rather than clay soils and that seed-bed preparation on heavier soils should seek to aerate the soil.

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Observations on the taxonomy and biology of Tylenchorhynchus macrurus (Goodey, 1932) Filipjev, 1936 and Tylenchorhynchus icarus sp.nov.

Parasitology ◽

10.1017/s0031182000074424 ◽

1964 ◽

Vol 54 (1) ◽

pp. 129-144 ◽

Cited By ~ 9

Author(s):

H. R. Wallace ◽

D. N. Greet

Keyword(s):

Oxygen Consumption ◽

Osmotic Pressure ◽

Field Capacity ◽

Parasitic Nematodes ◽

Plant Parasitic Nematodes ◽

Free Living ◽

Separate Species ◽

Large Form ◽

Female Tail ◽

Top Soil

The large and small forms of Tylenchorhynchus macrurus are distinguished as separate species. The large form becomes T. icarus and differs from the small form, T. macrurus in the greater number of annules on the female tail, longer stylet and slimmer body. The oxygen consumption of both species is similar when assessed in terms of body surface area. Soil samples from the field indicated that (a) greatest concentrations of T. icarus occurred at about 5 cm. depth, (b) few occurred below 24 cm., the depth of the top soil, and (c) numbers of T. icarus in the top 5 cm. of soil decreased during dry periods and increased after rain. T. icarus migrates to the wet end of a moisture gradient and has maximum mobility in soil at a moisture content corresponding to field capacity and at 20° C. T. icarus survived osmotic pressure equivalent to 1 m urea for 4 days. Their oxygen consumption increased with increasing osmotic pressure but in 1 m urea there was a decline which was even more pronounced in 2 m urea. Of a population of T. icarus 35% survived for 32 weeks in soil with plants. In damp sand at 10° C, oxygen consumption was steady for 32 weeks but after 48 weeks the nematodes were dead. It is suggested that the free-living stages of plant parasitic nematodes have similar migratory habits.

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Pengaruh kombinasi jamur Trichoderma harzianum dan bokashi terhadap pertumbuhan tiga kultivar kedelai

Kultivasi ◽

10.24198/kultivasi.v19i2.26469 ◽

2020 ◽

Vol 19 (2) ◽

Author(s):

Rosiman Rosiman ◽

Sumadi Sumadi ◽

Meddy Rachmadi

Keyword(s):

Plant Growth ◽

Soil Fertility ◽

Trichoderma Harzianum ◽

Soil Structure ◽

Soil Aggregates ◽

Block Design ◽

Growth And Yield ◽

Soybean Cultivars ◽

Randomized Block Design ◽

Two Factors

AbstrakPupuk Bokashi dapat meningkatkan kesuburan tanah melalui pembentukan agregat tanah sehingga dapat memperbaiki struktur tanah. Penambahan Trichoderna harzianum pada bokashi dapat mempercepat proses dekomposisi, menjaga kesuburan media, dan meningkatkan pertumbuhan tanaman. Penelitian ini bertujuan untuk menguji kombinasi Trichoderma harzianum dan pupuk bokashi untuk meningkatkan pertumbuhan dan hasil tiga kultivar kedelai. Penelitian dilakukan dengan menggunakan Rancangan Acak Kelompok (RAK) pada dua faktor terhadap tiga kultivar kedelai (Ringgit, Wilis, dan Anjasmoro) dengan kombinasi Trichoderma harzianum dan Bokashi 0 t/ha, 5 t/ha, 10 t/ha, dan 15 t/ha. Hasil penelitian ini menunjukkan bahwa efektivitas kombinasi Trichoderma harzianum dan bokashi pada pertumbuhan dan hasil tergantung pada masing-masing kultivar. dosis kombinasi 5 t/ha Trichoderma harzianum dan bokashi dapat meningkatkan pertumbuhan dan hasil kultivar Ringgit, Wilis dan Anjasmoro.Kata Kunci: Trichoderma harziaum, bokashi, pertumbuhan, kedelai AbstractBokashi fertilizer can increase soil fertility through the formation of soil aggregates so that it can improve soil structure. The addition of Trichoderna harzianum to bokashi can accelerate the decomposition process, maintain media fertility, and increase plant growth. This study aimed to evaluate the combination of Trichoderma harzianum and bokashi fertilizer to increase the growth and yield of three soybean cultivars. The study used Randomized Block Design (RBD) with two factors: three soybean cultivars (Ringgit, Wilis, and Anjasmoro) and combination of Trichoderma harzianum and Bokashi 0 t/ha, 5 t/ha, 10 t/ha, and 15 t/ha. The results of this study indicated that the effectiveness of the combination of Trichoderma harzianum and bokashi on growth and yield depends on each cultivar. The combined dose of 5 t/ha Trichoderma harzianum and bokashi could increase the growth and yield of cultivar Ringgit, Wilis and Anjasmoro.Keywords: Trichoderma harzianum, bokashi, growth, soybean

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