In Australia, cotton (Gossypium hirsutum L.) is grown in both rain-fed and irrigated systems, 
but the majority of production is irrigated. Despite this, little is known about the impact of 
these irrigated production systems on soil nutrient distribution in comparison to dryland 
systems. This study aims investigate and compare the distribution of soil nutrients and 
properties in adjacent irrigated and dryland crop production systems in different regions of 
NSW. Soil samples were collected from four different farms in southern, central and northern 
regions of NSW. Soil types at the sampled sites included Vertosols and a Chromosol. Soil 
properties were analysed to a depth of 90 cm, which is the typical rooting depth of cotton 
plants. 
The topsoil pH for irrigated samples was found to be significantly higher than adjacent 
dryland samples from Narrabri and Darlington Point, and some Narromine samples. 
Throughout the soil depth, pH increased for all samples. As pH increased, plant micronutrient 
availability (Fe, Cu, Mn, Zn), appeared to decrease. Topsoil stratification of phosphorus (P) 
and potassium (K) was also apparent in both irrigated and dryland systems. The irrigated 
samples from Narromine were found to have a significantly greater electrical conductivity 
(EC) and exchangeable sodium percentage (ESP) (%) than their adjacent dryland samples. It 
is speculated this significant difference may be due to the use poor quality irrigation water 
with a high concentration of dissolved salts. It is believed the higher salt content of these 
irrigated soils may have a negative flow on effect to crop production, reducing nutrient 
availability, uptake, and crop yield