Impact of soil aeration on runoff characteristics in dual-purpose no-till wheat systems

Abstract

Dual-purpose wheat (Triticum aestivum L.) systems are an important practice in the Southern Great Plains of the United States. As no-till receives increasing interest, there are concerns that grazing no-till wheat increases soil compaction and reduces rainfall infiltration. The objective of this study was to evaluate runoff characteristics as impacted by tilling dual-purpose, no-till wheat systems using conventional and varying aeration methods. Tillage treatments included (1) no-till; (2) conventional till; and aeration roller angles of (3) 0°, (4) 5°, and (5) 10°. These treatments were evaluated on two grazing systems: (1) graze out and (2) graze/grain. Rainfall simulators were used to provide four storm events: two after tillage implementation and prior to grazing and two after harvest and grazing season. When runoff events occurred within three weeks of aeration, 5° and 10° roller angles reduced runoff volume, increased infiltration, and reduced nutrient losses compared to no-till. However, six weeks after tillage, no-till runoff volumes were lower than all other treatments except the 10° aeration treatment. Soluble reactive phosphorus (P), total P, and ammonium-nitrogen (NH₄-N) loads were significantly reduced by 5° and 10° aeration treatments when runoff events occurred within three weeks of tillage and immediately after fertilizer application. After 10 months of tillage implementation, infiltration was 10% to 52% greater on no-till plots compared to tilled treatments. For summer runoff events, graze out systems increased runoff by as much as 1.5-fold and decreased infiltration by as much as 1.3-fold compared to the graze/grain system. Overall, aeration was most effective in reducing runoff volumes and nutrient losses within three weeks after implementation and provided more positive effects than disking. If aeration is implemented with nutrient applications, nutrient losses could be reduced by more than 4-fold compared to no-till. Aeration may also be beneficial in no-till wheat systems that undergo much more intensive grazing systems than observed in this study. Ultimately, economic considerations must be carefully weighed when considering tillage of no-till, dual-purpose wheat systems.