Potential importance of the subsoil for the P and Mg nutrition of wheat
48
Citation
17
Reference
10
Related Paper
Citation Trend
Keywords:
Subsoil
Topsoil
Abstract Eight trenches were excavated to a depth of 4.6 m and filled with one of three different textures of spoil to evaluate topsoil and subsoil thickness requirements for crop production on nonsaline, nonsodic spoil material. Yields of wheat ( Triticum aestivum L.) in 1979 and 1982, barley ( Hordeum vulgare L.) in 1980, and corn ( Zea mays L.) in 1981 and 1983 were compared on plots with 0.23, 0.46, or 0.69 m of topsoil replaced over loamy sand spoil with and without subsoil, over clay loam spoil, or over silty clay loam spoil. Crop yields increased with increasing thickness of replaced topsoil, especially on trenches filled with loamy sand spoil. Crop yields were greater when subsoil was replaced than when no subsoil was replaced on loamy sand spoil at a given topsoil thickness. Average yields from the trenches were equal to or better than average yields from undisturbed plots in 1979 and 1983. On irrigated plots in 1983, response of silage and corn grain to subsoil/spoil treatments was similar to the nonirrigated plots. Wheat grown on irrigated plots in 1982 did not respond significantly to topsoil thickness or subsoil/spoil treatments. At least 0.69 m of topsoil plus subsoil was required to achieve highest yields on nonsodic, nonsaline, loamy sand spoil, but 0.46 to 0.69 m of topsoil was sufficient for highest yields on clay loam and silty clay loam nonsaline, nonsodic spoil. Crop yields were not increased by broadcast applications of N and P fertilizer.
Subsoil
Topsoil
Cite
Citations (15)
Topsoil application along roadsides results in added expense, delays seeding newly constructed areas, and creates potential erosion sites when moisture and seedbed conditions may be optimum for germination and plant growth. Two experiments were conducted to compare establishment of vegetation on graded highway cuts. One was concluded on Groseclose subsoil near Blacksburg, Virginia, comparing surface application on NPK fertilizer and lime (L) on smooth (glazed) subsoil, on tilled subsoil before NPKL application, on tilled subsoil after NPKL application, and with surface application of NPKL to 15 cm of topsoil. Experiment 2 was conducted on Lenoir subsoil near Gloucester to compare a 15-cm layer of tilled topsoil to tilled subsoil, and smooth top soil to glazed subsoil. Each area was fertilized with NPK at rates of 168-146-139, 112-98-93, and 84-73-70 (kg/ha). Incorporated NPKL and roughened subsoils gave 8 and 11% better vegetative cover (about 0.3 more crownvetch (Coronilla varia L.) plants/dm2) than did 15 cm of topsoil over subsoil. Tilled topsoil or subsoil had about a fourfold better vegetative cover than when either was left smooth. Erosion was 50 and 25% as great on tilled topsoil and subsoil, respectively, than on either left smooth. Bulk density of smooth and roughened topsoil or subsoil ranged from 1.38 to 1.42 g/cm3 as compared to 1.76 g/cm3 for the compacted smooth subsoil. Likewise, total porosity was increased from 22 to 42% above glazed subsoil by roughening and use of topsoil. The altered physical properties created by roughening increased plant growth by increasing soil moisture content of the topsoil by 23% and that of the topsoil by 45% and by decreasing soil temperature. Tilled subsoils with adequate soil amendments can result in satisfactory plant covers similar to those obtained by topsoiling at a much lower cost.
Subsoil
Topsoil
Seedbed
Cite
Citations (5)
Electromagnetic induction soil sensors are an increasingly important source of secondary information to predict soil texture. In a 10.5‐ha polder field, an EM38DD survey was performed with a resolution of 2 by 2 m and 78 soil samples were analyzed for sub‐ and topsoil texture. Due to the presence of former water channels in the subsoil, the coefficient of variation of the subsoil clay content (45%) was much larger compared with the topsoil (13%). The horizontal (EC a –H) and vertical (EC a –V) electrical conductivity measurements displayed a similar pattern, indicating a dominant influence of the subsoil features on both signals. To extract topsoil textural information from the depth‐weighted EM38DD signals we turned to artificial neural networks (ANNs). We evaluated the effect of different input layers on the ability to predict the topsoil clay content. To identify the response of the topsoil, both EM38DD orientations were used. To examine the influence of the local neighborhood, contextual EC a information by means of a window around each soil sample was added to the input. The best ANN model used both EC a –H and EC a –V data but no contextual information: a mean squared estimation error of 2.83% 2 was achieved, explaining 65.5% of the topsoil clay variability with a variance of 0.052% 2 So, with the help of ANNs, the prediction of the topsoil clay content was optimized through an integrated use of the two EM38DD signals.
Topsoil
Subsoil
Soil texture
Cite
Citations (34)