Agriculture Reference
In-Depth Information
example, of changes in clay content or soil depth shown on the map agrees with
that found on the ground. Indeed, more intensive soil augering can be used to
spot-check the values of other soil properties, such as pH, color, stone content,
and profile form, which are based on the relatively few observations made in pro-
file pits.
Describing a Soil Profile
The soil profile should be examined in a backhoe pit, dug to at least 1.5 m or to
the parent material if this is shallower. The pit is necessary to reveal properties of
the soil in an undisturbed state, especially structure, which cannot be observed by
augering. From a deep pit examination, information can be obtained below the
sensing depth of ground-penetrating radar, laser-imaging radar, and EM survey.
Horizons and layers in a soil profile were introduced in box 1.1, chapter 1, distin-
guishable by such obvious properties as color, texture, and structure. Descriptions
of vineyard soils may refer to horizons or to depth intervals, such as 0-30, 30-60,
60-90, and 90-120 cm. Whichever approach is used, the main focus is on iden-
tifying the limitations to successful vine growth, especially with respect to drain-
age and root penetration, with the latter being more important in dry-grown
vineyards.
A survey report is enhanced by the inclusion of color diagrams of the
main soil profiles annotated with a description of their important features,
as listed in table 2.2, which draws on recommendations made by practicing
soil surveyors (e.g., McKenzie, 2000 and Maschmedt et al., 2002). Soil sur-
vey field handbooks, such as that of the Soil Survey Division Staff (1993)
or the National Committee on Soil and Terrain (2009), give more details of
methods.
To make measurements in the field, a surveyor requires the following tool kit:
• Atapemeasure(preferablymetric)
• Astrongknife(and/orgeologicalhammer)
• ApHtestkit
• AMunsellcolorchart(orpaintchips)
• Distilledwater(orrainwaterifnotavailable)andplasticcup
• Ahandlens(10
×
magnification)
• Asmallbottleof5%hydrochloricacidwithdropper
In addition to soil profile descriptions, winegrowers are interested in the fer-
tility of their soils, which involves laboratory testing (see “Soil Testing,” chapter 3)
and also whether there are potential biological problems (see “Soil Organisms,”
this chapter).