Zoning in on hostile subsoils

摘要

Hostile subsoils (high salinity, sodicity, highly alkaline or acidic pH, soil compaction, toxic levels of boron, and so on) are a problem for many farmers in southern Australia. Subsoil limitations to root growth prevent crops from using stored subsoil moisture and nutrients, and thus from achieving maximum yields and responses to fertiliser applications. Management of nitrogen application with regard to subsoil limitations can improve yield without increasing fertiliser inputs. Where subsoils havehigh limitations to root growth, applying nitrogen by broadcasting at sowing has proved the least useful application method. Methods such as mid-row banding, which delays nitrogen availability to roots, or top-dressing late in the season give better yields and better nitrogen-use efficiency on these soils. Where subsoil limitations to root growth are minor, the method of nitrogen application matters less in obtaining good yields.