Economics of ameliorating soil constraints – on farm research

Abstract

• On farm research trials are an important supplement to intensive experimental (small plot) research with conclusions from both types of research informing our understanding of how to close the yield gap in constrained soils
• Yield responses in on farm trials were generally lower than those observed in small plot studies with somewhat similar interventions
• Lower responses were likely related to inadequate underlying nutrition, as evidenced by the large responses to organic nutrient additions and deep P placements in more northern sites
• The benefits of ripping, nutrition or organic matter are likely to be shorter-lived compared with calcium additions • Identifying the appropriate rate and placement/depth to intervene remains an outstanding, yet critical, knowledge gap.