14 IREC Farmers' Newsletter No. 199 — Autumn 2018 QUICK TAKE The planning of cotton rotations requires consideration of long-term effects of soil compaction and disease build-up. Michael Braunack of CSIRO and Emma Ayliffe of Summit Ag explain what to look for in a soil pit dug across beds in a cotton field. THINK LONG TERM TO CAPTURE THE UPSIDE OF COTTON RETURNS l  Think long term about protecting and improving the soil health of individual fields to capture the upside of good returns from cotton. l  Yield decline in back to back cotton can be as high as 1.5 bales/ha year on year, caused by compaction and disease build-up. l  Black root rot is occurring in Murrumbidgee fields after about five or six cotton crops — even when the cotton is grown in rotation with cereals. l  A comparison of three cotton rotations showed back to back rotation of cotton had the highest gross income but it also had the lowest gross margin over a ten-year period, due to yield reductions when compared with cotton–fallow and cotton–wheat–fallow rotations. Cotton has well and truly staked its claim in southern irrigated cropping systems. As crop area doubles, attention to rotations and sustainability is needed. Kieran O’Keeffe CottonInfo Regional Extension Officer Southern NSW EXPANSION in the area planted to cotton in southern NSW and northern Victoria has been quite incredible (Figure 1). From a little over 10,000 ha in 2014, the southern planting area has increased quickly, particularly since 2011 after the millennial drought. The 2017–18 area planted to cotton is 90,415 ha. Across the southern cotton growing region there are 216 growers this season, with 67 first-time growers. Table 1 shows the breakdown of area and growers for the valleys within the region. A number of factors have combined to see the large increase in area and growers. Prices and returns per megalitre have been good over a number of seasons, infrastructure and agronomic support have