Medium-textured Soils Research Articles

Field experiments with anhydrous ammonia

AbstractThe results are reported of 50 experiments carried out by the National Agricultural Advisory Service comparing injected anhydrous ammonia with solid ammonium nitrate for arable crops and grass. Autumn‐applied anhydrous ammonia was found to be inefficient for arable crops owing to winter loss by leaching. Spring injections for spring cereals and sugar‐beet were as effective as ammonium nitrate provided that soil conditions allowed efficient injection. Spring injections for winter wheat were as effective as ammonium nitrate on light and medium textured soils but less so on clay soils. The slow‐acting nature of anhydrous ammonia resulted in less lodging than did ammonium nitrate and less resultant yield depression under conditions leading to severe lodging in cereals.In grassland, the slow‐acting nature of anhydrous ammonia gave a delayed response compared with ammonium nitrate but did not result in an even spread of growth throughout the season. Early spring injections resulted in a better seasonal distribution of response in high rainfall areas than in areas of low rainfall.

Soil-physical aspects of zero-tillage experiments.

Structural determinations (visual rating, penetro-meter resistance, core sampling) in zero-tillage experiments on various soils (marine loam, river clay, sand etc) showed greater soil densities in unfilled plots than after plowing (20 cm), while mean pore-space and standard deviation of pore-space were generally lower in untilled plots. Moisture content at pF2 was often lower on untilled plots, and the latter possessed many more spots of low air content than ploughed plots did. Satisfactory yields of potato of good quality were produced, at least on medium-textured soils, after several years of zero-tillage. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Effects of Sources of Phosphorus Under Varying Soil Temperature and Moisture Regimes on the Emergence of Winter Wheat

AbstractThe effects of several sources of phosphorus on the emergence of winter wheat (Triticum aestivum L.) were compared when applied in a band with the seed under controlled temperature and moisture conditions. The detrimental effects of a given fertilizer treatment on emergence increased as temperature increased from 15 to 25C. Increasing soil moisture stress from 1 to 3 bars also reduced emergence. The harmful effects of increasing the temperature from 15 to 25C were greater than the harmful effects of increasing moisture tension from 1 to 3 bars. Emergence was reduced to a much greater extent on a sandy soil than on a medium textured soil for a given fertilizer treatment. The effects of temperature, moisture, and soil texture appeared to be cumulative.Ammonium polyphosphate, ordinary superphosphate, and concentrated superphosphate had approximately equal effects on emergence and were much less detrimental than monoammonium and diammonium phosphate which were about equal. Ammonium phosphate sulfate decreased emergence to a much greater extent than any other source.Banding of concentrated superphosphate with the seed reduced emergence as much as 40% in the field. This reduced emergence, however, had no effect on yield of grain.

MOISTURE BALANCE IN SOILS OF THE EDMONTON AREA

Estimated moisture deficits for the period from May to September were calculated for 22 soil types in the Edmonton area. These included the major soils and covered a wide range of textures. Total available water capacities to a depth of 122 cm ranged from 5 to 30 cm. Potential evapotranspiration values were calculated, using the Penman method, from available meteorological data. Actual evapotranspiration was estimated and the deficits determined. These were found to vary for any one particular soil type according to its location in the area. Coarse-textured soils had deficits in the 8- to 12-cm range, medium-textured soils in the 3.5- to 7-cm range, and fine-textured soils in the 2- to 5.5-cm range.

SNOW COVER EFFECT ON THE ERODIBLE SOIL FRACTION

The effect of snow cover on the overwinter breakdown of medium-textured soils in southwestern Saskatchewan was studied during the winter of 1967–1968. Where a continuous snow cover was provided artificially (with snow fencing), there was a decline in the percentage of soil particles < 1 mm in diameter from October to April, with a marked drop from February to March when the snowmelt was high. The percentage of fine soil aggregates in the unprotected field depended upon the amount of natural snow cover and the moistening effect of snowmelt which occurred from time to time. Where a snow cover was prevented artificially, surface drying occurred and the exposed soil layer became highly erosive, particularly during February and March when air temperatures fluctuated widely. The fact that this occurred on treatments where air circulation was permitted and not under polyethylene cover is interpreted as evidence of the importance of water loss by sublimation iii the process of deaggregation.

INFLUENCE OF LOW SEEDING RATES ON WHEAT YIELD IN SOUTHWESTERN SASKATCHEWAN

Spring wheat seeding rates of 22, 45, 67, and 101 kg/ha were compared in a field experiment on a medium-textured soil at Swift Current, Saskatchewan, over the period 1960–1968. Data collected during eight years indicated that when weeds, insects and diseases were chemically controlled, low seeding rates produced significantly more grain than higher seeding rates, with greatest increases occurring during years of severe moisture stress. Low seeding rates produced longer heads, heavier kernels, and in some cases taller plants. Plant population differences resulting from the variation in seeding rate were largely eliminated by plant survival and tillering. The number of mature kernels per unit area did not differ significantly for all treatments.Seeding rates had an effect on the rate at which moisture was used by the crop. Soil moisture supplies were quickly exhausted on plots seeded at rates of 67 and 101 kg/ha, whereas moisture was available to the crop seeded at lower rates over a longer period. The crop seeded at 22 kg/ha matured 3 to 5 days later than that seeded at 101 kg/ha.

Neutralizing Soil Acidity under Bermudagrass Sod

AbstractThe effectiveness of surface‐applied lime in preventing subsoil acidification from residually acid N sources used on Coastal bermudagrass (Cynodon dactylon L. Pers.) was influenced by (i) soil type, (ii) lime rate, (iii) N source, and (iv) N rate. Lime applied at a rate equivalent to acidity of the N source maintained both pH and exchangeable bases in a loamy sand but not in a clay loam soil. Lime applied at three times the N fertilizer equivalent acidity was more effective in correcting subsoil acidity than were lower rates, and the effect was more pronounced in the coarse‐ than in the fine‐textured soil.Calcium gluconate was highly effective in increasing subsoil pH and exchangeable base level under Coastal bermudagrass but caused an undesirable fungal bloom. Surface‐applied NaNO3 was effective in correcting subsoil acidity in both a coarse‐ and a fine‐textured soil without accumulation of Na, and the effect was relatively uniform throughout the depth of profile sampled (45 cm). Calcium nitrate was also effective in increasing subsoil pH and exchangeable Ca in medium textured soil to a depth of 45 cm, with less pronounced effects down to 75 cm. Residual basicity of Ca(NO3)2, as measured by increase in exchangeable Ca in the soil profile, ranged from 1.7 to 2.5 kg CaCO3 per kg N, depending upon rate of application.

RESIDUAL EFFECTS FROM FERTILIZER ON NATIVE RANGE IN SOUTHWESTERN SASKATCHEWAN

Residual effects of fertilizer on native grassland throughout southwestern Saskatchewan persisted for six years or more, and were more important than the initial response. These residual effects resulted in yield increases and in increased phosphorus content of the forage. The sodium bicarbonate-extractable (available) phosphorus in the soil was increased by the use of phosphatic fertilizer; this increase persisted for six years after fertilizer application. The correlation coefficients between yield response and measured soil properties were not high for any of the measurements. The yield response was more closely related to the amounts of available N in the soil, the pH, and the texture than to the other soil and plant measurements. Responses were greatest on medium-textured soils, low in fertility and with a pH above 7.

EFFECTS OF SURFICIAL GEOLOGY ON STREAMFLOW DISTRIBUTION IN SOUTHERN ONTARIO

The monthly streamflow distribution on four pairs of watersheds in southern Ontario was investigated. The dominant parent geological materials on the four pairs of watersheds were as follows: A, coarse-textured soils; B, moderately fine-textured soils formed on very fine sands and silts; C, medium-textured soils formed on till; D, fine-textured soils formed on till. The March–April runoff from the watersheds of fine-textured soils (D) was 56% of the annual runoff over a 9-year period, and from the watersheds of coarse-textured soils (A) it was only 34% of the annual runoff during the same time period. Larger amounts of groundwater recharge on watersheds of coarse-textured soils resulted in higher summer flows, more uniform seasonal flow, and reduced spring runoff extremes.The groundwater daily recession constant was likewise higher for the streams draining coarse-textured soils. The average estimated equivalent groundwater storage remaining when the monthly discharge was at a rate that was exceeded for 90% of the time, was as follows for the four geological classes: A, 0.267 in.; B, 0.090 in.; C, 0.035 in.; D, 0.007 in.

Effect of Rice Culture on the Reclamation of Sodic Soils1

AbstractGreenhouse and laboratory studies were undertaken to examine the effect of rice culture on the reclamation of sodic soils.Rice culture hastened the reclamation of coarse‐textured sodic soils, but did not improve the reclamation efficiency per unit of water leached through the soil. The beneficial effects on coarse‐textured soils were traced to a more rapid removal of entrapped air from the larger conducting pores of the soils during rice culture.After several weeks of rice growth on a mediumtextured soil, the reclamation efficiency per unit of water leached did begin to increase. However, the simultaneous increase in soil hydraulic conductivity suggested that the effect was caused by an increase in the percentage of the cross‐sectional area of the soil that was serviced by conducting pores, rater than by any enhanced solubility of CaCO3 in the presence of CO2 given off by the rice roots.

Soil moisture deficiencies in puddled pastures

Abstract The effects of a period of heavy animal treading in wet weather on the subsequent moisture status of two pasture topsoils were investigated in replicated trials on medium-textured alluvial soils. The surface soil was found to be significantly denser in the heavily-trodden plots than in the untrodden controls for as long as six months after the treading. The higher density was accompanied by a lessened ability to store water in the readily available moisture range, up to moisture contents in equilibrium with a suction of one atmosphere. Topsoil moisture contents, whether determined gravimetrically or by plaster of Paris resistance elements, were also found to be lower in the heavily trodden plots on several occasions in the six months following the treading. These observations indicate a mechanism whereby soil changes produced by incautious grazing in winter could reduce growth during the following summer.

TRENDS IN DAMAGE BY WIREWORMS (COLEOPTERA: ELATERIDAE) IN GRAIN CROPS IN SASKATCHEWAN, 1954–1961

Survey of grain crops in Saskatchewan showed that most of the serious damage by wireworms occurred in the western two-thirds of the province. The average damage for ail soil and cropping conditions was greatest in wheat, less in barley, and least in oats. Serious damage occurred occasionally in barley and oats. With wheat and barley, damage was generally greater on summer-fallow than on stubble, and greater in medium-textured soils than in heavy soils. With oats there were some deviations from this pattern. Damage in wheat on summerfallow declined gradually from 1954 to 1961, but the proportion of fields showing some wireworm damage remained fairly constant. Thus, in spite of the widespread use of chemical seed treatments, the potential wireworm hazard has not diminished.

Laboratory and field studies on the relation of arabis mosaic virus to its nematode vector Xiphinema diversicaudatum (Micoletzky)

SUMMARY Xiphinema diversicaudatum is widely distributed in southern Britain, mainly in heavy soils, but also in the peat soil of the Fens and in medium textured soils in the south‐west. Patches of plants infected with arabis mosaic virus (AMV) in a range of crops including some, like celery and marrow, not before known to be hosts, coincide with patches of soil infested with X. diversicaudatum. Roots of some plants infested with the nematode carried small galls; not all such plants were infected with, or even susceptible to, AMV. Adult X. diversicaudatum transmitted AMV more readily than larvae, but none of 103 nematodes, transferred when moulting, infected healthy plants. X. diversicaudatum were still infective after 24 days in moist peat, free from plants. X. diversicaudatum is common in several districts in soil from old hedgerows but not in the adjacent fields. Hedgerow trees seem to be hosts of the nematode and at least one, elder, is also a host of AMV. In other districts, plants with AMV occur in crops near to infested hedges or isolated trees, and on land taken into cultivation after being derelict. In the Tamar Valley, Devon, X. diversicaudatum is common in pastures; white clover in these often contains AMV. Planting such fields with strawberry leads to disease outbreaks.A few X. diversicaudatum occur down to 3 ft. in soil, but most are at 3–9 in. At a site where arable land has reverted to woodland, the nematodes apparently have spread from a hedge into the woodland at an average rate of 1 ft. per year over a period of 75 years. It is suggested that both X. diversicaudatum and AMV are common constituents of natural woodland in Britain and that their incidence has decreased since the advent of agriculture.

Use of Deep-Freezing in the Preservation and Preparation of Fresh Soil Samples

IN the course of determining the levels of mineral nitrogen in soils, and the extra amounts produced on incubation, a method of maintaining soil samples in their field condition was required. The use of chemical inhibitors to stop microbiological activity was rejected since these change the balance of the soil micro-organisms. A further difficulty was that when arable land is sampled in the winter or early spring the structure of medium and heavy textured soils is destroyed by the operations involved. It was hoped that maintaining soils about freezing point would arrest microbiological activity without altering the results of subsequent incubation and also that freezing would restore or even improve the structure.

Influence of Sample Pretreatment on Soil Moisture Retention

AbstractThe effect of sample pretreatment on soil‐moisture retention was measured on eight Wisconsin soils to find the moisture tension range in which undisrupted soil samples are necessary to represent the moisture relations of field soils. The moisture retention of samples with pretreatments either of 2‐mm. sieving or puddling was compared with the retention of undisrupted cores over the moisture tension range of 0.01 to 15 atm.In general, the moisture retention of sieved samples of the medium textured soils studied was increased over core samples at tensions less than 0.4 atm. There was no general relationship in the tension range of 0.4 to 1.0 atm. because of the irregular nature of the release curves of individual soils. Sieving decreased moisture retention about 1 part in 10 at tensions greater than 1.0 atm. Thus sieved samples of the medium textured soils studied can be used to approximate undisrupted soils in the high tension range with a relative error of 10%. Core samples should be used at tensions less than 1.0 atm. to avoid relative errors greater than 10% (up to 30%).Puddled samples retained considerably more water than cores in the tension range from 0.1 to 2.0 atm. although they differed little from core samples at tensions less than 0.05 to 0.1 atm. and greater than 5.0 atm. Puddled soils give a better approximation of undisrupted soils than sieved soils at tensions between 5 and 15 atm.

Permeability and Intake Rates of Medium Textured Soils in Relation to Silt Content and Degree of Compaction

AbstractFrom 1948 through 1953, percolation rates were determined for 215 medium textured layers of soil from farmland in Arizona, Colorado, New Mexico, and Utah. Knowledge of the differences in percolation rates are helpful in establishing soil treatment units. This knowledge helps to indicate those areas most apt to be damaged by overirrigation, feasibility of reclamation of saline and alkali affected soils and to design effective drainage systems. Water‐intake rates for these layers of soil at field moisture were determined for the first 2 hours. In many cases they were compared with either irrigation intake rates or infiltrometer values. Thus, it was possible to locate not only limiting layers but also to develop clues for soils with different intake rates. The results were helpful in grouping soil units which have similar requirements for irrigation layout and tillage practices.Medium textured soils, containing less than 2.5% organic matter, but more than 40% silt, behaved like silt loams and tended to have slow permeability and intake rates. In contrast, medium textured soils which contained less than 40% silt had moderate permeability and moderate intake rates unless they were compact and had few effective pores. Both permeability and intake rates varied with compaction of the soil. Three degrees of compaction or bulk density appeared to be significant. However, the limits for classes of bulk density were higher for sandy loams, sandy clay loams, and loams containing less than 40% silt than for the loams and silt loams containing 40% or more silt. Direction of natural breakage, especially in firm soils, and the number of effective pores per square foot were also important clues in evaluating permeability and intake rates. Each of these clues must be considered with reference to the others.

Effect of Tillage Practices Upon Intake Rates, Runoff and Soil Losses of Dry‐Farm Land Soils

AbstractDuring the growing season, serious losses of water and soil occur on extensive areas of dry‐farm land in New Mexico, Colorado, and Utah due to poor surface soil condition and to the presence of tillage pans, usually at depths of from 3 to 8 inches. Studies were made of runoff and soil losses from plots containing 30½ square feet. Simulated 10‐year storms were applied to these plots to evaluate tillage practices.The following conclusions were made during these studies. Chiseling through the tillage pan every 12 inches reduced both soil and water loss more than cultivation with either sweeps or one way disks on deep, medium textured soils. Excessive runoff and erosion occurred where the chisel spacing was 5 feet, or where chiseling, sweeps, and oneway did not penetrate through the tillage pan.Runoff from snow on frozen ground causes serious losses of soil and water in northern Utah. A frozen watershed that had been chiseled lost 0.61 inch less runoff than a similar watershed that had been cultivated with a oneway disk. Medium textured soils high in silt, when frozen at high moisture contents, had slow intake rates, irrespective of tillage practices.

The Agricultural Value of California Soils

N California in recent years work has been done toward the evaluating of soils in relation to their suitability for plant growth. Such work is naturally of geographic interest. The method adopted for rating the agricultural value of the soils is explained in some detail in two bulletins issued by the Agricultural Experiment Station at Berkeley.' The index used is defined as the numerical expression of the degree to which a particular soil presents conditions favorable for plant growth and crop production under good environmental conditions.2 Three general factors are considered: A, character of the soil profile; B, surface-soil texture; and C, modifying conditions, such as drainage and alkali. The ideal condition for each factor is 100 per cent. The rating is a multiple of the three figures allotted tothe three factors; hence a low figure for any one factor will influence the resultant rating. For example, Hanford fine sandy loam may be allotted 100 per cent for each of the three factors: the index rating would then be I00. On the other hand, presence of alkali may lead to the allotment of 25 per cent to factor C, and the index rating then becomes 25. All characteristics of soil profile are evaluated by factor A except surface texture. These characteristics are determined by kind of parent material, its mode of formation or accumulation, and the age or degree of modification of the soil material by the weathering agencies of climate, supplemented by vegetation and opposed by erosion and deposition. The agricultural soils of California are placed in six groups according to physical profile characteristics. (I) Unweathered or slightly weathered secondary soils, loose and friable, with a depth of six feet or more, have ratings of 95 to 100 per cent. (2) Deep, moderately weathered secondary soils, less permeable because of their compact subsoils, have ratings of 80 to 95 per cent. (3) Strongly weathered secondary soils with dense clay subsoils, developed on unconsolidated material, have ratings of 40 to 8o per cent. (4) Maturely weathered secondary soils with hardpan, usually with a dense overlying clay layer, have ratings of 5 to 60 per cent according to the depth to the cemented layer. (5) Strongly weathered soils with dense clay subsoils resting on a consolidated hardpan-like substratum have ratings of 20 to 40 per cent. (6) Primary soils underlain by bedrock and developed from it have ratings of 20 to 70 per cent according to the depth to the bedrock. These profile groups are associated with various conditions of surface relief: I, flat or gently sloping alluvial flood plains; 2 and 4, valley floors and benches or terraces which may be eroded to a varying degree, the surface of the fourth group perhaps characterized by hog wallows; 3, terraces or benches, perhaps somewhat eroded; 5, high eroded marine terraces on the coastal plain; 6, rolling, hilly, or mountainous topography. Factor B concerns surface-soil texture and thus covers consistency, porosity, permeability, and tilth or arability.3 The highest ratings, as we should expect, go to soils of medium texture, the lowest to soils of very heavy and very light texture and to those that are very gravelly or stony. Soils with much sand or gravel are relatively low in plant nutrients and do not retain moisture; on the other hand, many clays are difficult to handle, though they may contain maximum moisture and nutrients.