Analysis of the spatial variability of maize root density

The spatial arrangement of maize roots was studied in a clay loam field in order to test the regularity of root arrangement, which is implicitly assumed when distances between neighbouring roots are calculated. For that. we carried out a mapping of root contacts on six superposed horizontal planes which cut the rooting volume of several area samples. Three situations were studied: (i) one inter-row out of two was compacted down to the base of the ploughed layer (28 cm), but not in non-tilled layers (28 to 200 cm); (ii) a mechanical obstacle was placed at the base of the ploughed layer; (iii) one inter-row out of two was compacted down to half the depth of the ploughed layer. On all horizontal planes, the spatial arrangement or root contacts followed a non-regular, clustered pattern for a 10−2m scale of study, even in parts of soil which had not been disturbed by compactions. In the first two situations, where obstacles met the base of the ploughed layer, root density in non-tilled layers was several times lower below the obstacles than below the remaining parts of the ploughed layer. This caused a 10−1 m sized variability which was superimposed on to the 10−2 m one. Conversely in the third situation, obstacles had no appreciable effect on root density in non-tilled layers. Obstacles located at the base of the ploughed layer therefore prevented root access to non-tilled layer and caused a ‘shadow effect’ in the non-tilled layers. This effect is probably due to the main vertical direction of roots in these layers.

[1]  Marie-Odile Jordan,et al.  Rythme d'apparition des racines primaires du maïs (Zea mays L.). II. - Variations observées sur quelques génotypes , 1987 .

[2]  P. B. Tinker,et al.  Uptake of solutes by multiple root systems from soil , 1971, Plant and Soil.

[3]  François Tardieu,et al.  Caractérisation en tant que capteur d'eau de l'enracinement du maïs en parcelle cultivée. II. - Une méthode d'étude de la répartition verticale et horizontale des racines , 1986 .

[4]  W. R. Gardner.  DYNAMIC ASPECTS OF WATER AVAILABILITY TO PLANTS , 1960 .

[5]  M. N. Nimah,et al.  Model for Estimating Soil Water, Plant, and Atmospheric Interrelations: I. Description and Sensitivity , 1973 .

[6]  W. R. Gardner.  Relation of Root Distribution to Water Uptake and Availability1 , 1964 .

[7]  P. Stengel,et al.  Densité texturale de sols naturels II. - Eléments d'interprétation , 1981 .

[8]  K. Barley.  INFLUENCE OF SOIL STRENGTH OF GROWTH OF ROOTS , 1963 .

[9]  P. Tinker.  Transport of Water to Plant Roots in Soil , 1976 .

[10]  P. B. Tinker,et al.  Uptake of solutes by multiple root systems from soil , 1972, Plant and Soil.

[11]  E. Newman.  RESISTANCE TO WATER FLOW IN SOIL AND PLANT I. SOIL RESISTANCE IN RELATION TO AMOUNTS OF ROOT: THEORETICAL , 1969 .

[12]  D. J. Campbell,et al.  Hand-held gamma-ray transmission equipment for the measurement of bulk density of field soils , 1971 .

[13]  F. Tardieu,et al.  Etat structural, enracinement et alimentation hydrique du maïs. II. — Croissance et disposition spatiale du système racinaire , 1987 .

[14]  S. A. Barber,et al.  Development and Distribution of the Corn Root System Under Field Conditions1 , 1974 .

[15]  H. M. Taylor,et al.  MICROCOMPUTER SIMULATION MODEL OF SOIL WATER EXTRACTION BY SOYBEANS , 1983 .

[16]  Howard M. Taylor,et al.  PENETRATION OF COTTON SEEDLINGN TAPROOTS AS INFLUENCED BY BULK DENSITY, MOISTURE CONTENT, AND STRENGTH OF SOIL , 1963 .

[17]  Fred J. Molz,et al.  Models of water transport in the soil‐plant system: A review , 1981 .

[18]  P. Tinker,et al.  Uptake of solutes by multiple root systems from soil , 1973, Plant and Soil.

[19]  J. Passioura.  Roots and Water Economy of Wheat , 1985 .

[20]  F. Tardieu,et al.  Caractérisation en tant que capteur d'eau de l'enracinement du maïs en parcelle cultivée. I: Discussion des critères d'étude , 1986 .

[21]  L. Bernstein,et al.  Soil Salinity Effects on the Chemical Composition of the Oil and the Oil Content of Safflower Seed1 , 1964 .

[22]  F. Tardieu,et al.  Etat structural, enracinement et alimentation hydrique du maïs. I. - Modélisation d'états structuraux types de la couche labourée , 1987 .

[23]  L. T. Kardos,et al.  Root Growth Through Porous Media Under Controlled Conditions: I. Effect of Pore Size and Rigidity1 , 1965 .

[24]  W. W. Nelson,et al.  Soybean and Corn Rooting in Southwestern Minnesota: II. Root Distributions and Related Water Inflow , 1975 .

[25]  A. Dexter,et al.  The behaviour of roots encountering cracks in soil , 1984, Plant and Soil.