Improving crop productivity by overcoming soil constraints

13 March 2018
Grower News

Department researcher Stephen Davies will speak about soil research, funded by the Grains Research Development Corporation, at Talkin’ Soil Health conferences at Dalwallinu on 13 March and Katanning on 15 March hosted by Natural Resource Management groups.

He said soil constraints were common in Western Australia’s agricultural soils and could be inherent or induced. “Soil constraints are an issue for local grain growers because they limit crop productivity by reducing crop establishment, affect root development into the subsoil and limit the capacity of crops to uptake water and nutrients. “They can also make crops more susceptible to damage from diseases, pests, weeds, drought, frost and heat stress.

“The department trials a range of soil renovation practices intended to improve the condition of soils to determine the effects on both soils and crops.”

On sandplain soils, this could involve the use of one-off deep tillage to overcome physical constraints and improve soil structure and the application of soil amendments, such as lime, subsoil clay, organic materials and nutrients to overcome chemical and soil fertility constraints.

Soil amelioration, soil inversion and lime incorporation, and claying and incorporation are among the practices investigated.

Dr Davies said practices such as soil inversion, deep soil mixing and topsoil slotting could increase organic matter, nutrients and lime deeper in the soil profile and had been demonstrated to increase root density in the subsoil. “Long-term research has demonstrated that the removal of multiple soil constraints and improvements in soil condition can result in significant improvements in crop productivity, with better root access to water and nutrients.

“The removal of multiple soil constraints typically increases crop grain yields by 0.4 to 1.5 t/ha, or 30 to 100 percent, across a range of sandplain soil types, with sustained yield responses, and treatments often returning a profit in the first or second year.”

Soil renovation could also result in improved weed control and crop competition, efficient use of water and nutrients and reduced crop damage from frost, heat and water stress.

“Some soil amelioration practices come with risks, including short-term wind erosion, poor seeding depth due to soft soil, crop damage from herbicides and lifting potentially toxic subsoil to the surface,” Dr Davies said.

Recent department research is exploring the potential benefits of applying targeted organic and soil amendments with soil renovation, aimed at developing resilient and sustained crop production benefits in drier, warmer environments.

Other department researchers to present at the soil health events include Tim Overheu on practices that benefit soil health, Chris Gazey on long-term soil pH changes from catchment scale monitoring in collaboration with Precision SoilTech, and Ed Barrett-Lennard on improved grain growing and grazing on saline soils.

Source: Western Australia Department of Primary Industries and Regional Development