By combining the results of the tests that were carried out at the Australian Cotton Research Institute in Narrabri, a fairly in-depth and extensive understanding of the Brown Vertosols or Dermosols can be obtained. In carrying out this analysis, it also became apparent how strongly the management regime of a site can effect a site, even if they are the same genotype.

This knowledge of the survey site allows for the assessment of present management strategies, with emphases on soil conservation, and suggestions on how improvements could be made.

The tilled area of the survey site consisted of a thin surface crust, overlying a tilled zone, which acts as a type of much, temporarily increasing the macroporosity of this zone. Results of the hydraulic conductivity, and Ksat, from the Double Ring and the permeameters, show that these properties are larger in the mulch-like tilled sites than in the pasture. Under this, where the soil is undisturbed, the characteristics of the tilled and the pasture site are much the same, as was evident by the similar Ksat values from the Amoozometer at this depth.

The moisture content was found to be significantly higher in the tilled zone than in the pasture. This can be attributed to a combination of the higher infiltration rate allowing more water into the profile in the tilled, as well as the water extraction by the plants in the pasture.

As irrigation is used extensively in the Namoi Valley, it is a factor that must be taken into consideration for soil management. Tilling has the effect of increasing the water infiltration, and therefore is beneficial in combination with irrigation.

Unlike other areas in Australia, such as where extensive salinisation of irrigated soils has occurred, from our survey at Narrabri no evidence of salinity was found with the EM devices. It is not expected that much leaching will occur from irrigation, due to the shrink-swelling properties of these clays, which slows infiltration.

After rainfall and/or irrigation, these soils become extremely sticky due to the high clay content. This makes them very succeptible to compaction, surface smearing and general structural decline if mismanaged. This mismanagement includes variabilities such as trafficablilty of heavy machinery or live stock before the soil is adequately dried out. Compaction by heavy machinery is reduced by having set area in the fields on which the machinery can pass over, therefore only compacting certain selected areas.

The threat of erosion is not all that significant in this area, due to the extremely flat landscape which illuminates colluvial erosion. Other forms of erosion are also be reduced by the good structure of these soils, although tillage does somewhat reduce the strength. Yet employing management techniques such as stubble retention and minimum tilling practices could further reduce erosion.

Another good management strategy is to allow the fields to be in fallow in a rotation cycle. This has numerous benefits, including structural rejuvenation, erosion prevention and by growing such plants as legume, the chemical composition of the soil is improved.

A major part of soil conservation is to be able to monitor or measure different soil properties, so as to ascertain whether these properties are improving, staying constant or degrading over time. As farmers have long work hours from morning till evening, and may not have much excess money, the equipment should not be too labor intensive, too complicated or too expensive, but it should still achieve fairly accurate results. Table 3 lists all the equipment used, as well as factors which may influence the extent to which this equipment is practical.
 
 

As the soil is naturally in a good state and there are many cheap and simple monitoring methods, there is no reason why the soil at Narrabri should become degraded due to cotton growing if proper management strategies are employed.