Location: Agroecosystems Management ResearchTitle: Maize water use in living mulch systems with stover removal Author
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2011
Publication Date: 10/31/2011
Citation: Wiggans, D.R., Singer, J.W., Moore, K.J., Lamkey, K.R. 2011. Maize water use in living mulch systems with stover removal. Crop Science. 52:327-338. Interpretive Summary: Redesigning agriculture to meet the needs of food and biofuels. Scientists at the ARS National Laboratory for Agriculture and the Environment in Ames, and Iowa State University have shown that no-till corn grown in a Kentucky bluegrass living mulch system can offset soil carbon depletion and reduce soil erosion even when stover is harvested for biomass. The Renewable Fuel Standard-2 allows up to 16-billion gallons of cellulosic biofuels to be blended annually with gasoline. Corn stover biomass has been identified as a possible feedstock to help meet this demand, but there can be negative environment consequences if too much crop residue is removed from fields after grain harvest. Corn grain yields in living mulch systems are no different than those grown under control no-tillage conditions. Even more important, the living mulch system also allows for greater potential cellulosic biomass harvest for biofuels, while maintaining grain production, and providing greater protection to the soil and water quality by reduced erosion and nutrient leaching. This research demonstrates that it is possible to reduce the perceived conflicts of increased biofuels production with existing crop production and improve environmental quality in the Upper Midwest region.
Technical Abstract: Constraints to maize stover biomass harvest may be mitigated by using a living mulch (LM) to offset C exports and control soil erosion. Living mulches can compete with the main crop for resources, particularly water. The objectives of this research were to quantify soil water dynamics and maize water use in continuous maize with stover removal. Continuous soil water content (SWC) and reproductive whole-plant water use were measured in no-till maize growing in LM’s of creeping red fescue (CF)(Festuca rubra L.), Kentucky bluegrass (KB) (Poa pratensis L.), and a no LM control between 2008 and 2010 near Ames, IA. In two years with excessive rainfall (2008 and 2010), LM’s increased SWC compared with the control at 15 cm. Excessive SWC in the no-till LM treatments lowered grain yield in 2008 and 2010, although a KB strip-till treatment had similar yields all three years. Reproductive water use efficiency for no-till KB in 2008 and 2009 (51 and 42 g grain cm water-1) was 21 and 14% greater than the control (42 and 37) but 24% lower in 2010 (41 vs. 51). Maize water use in the control during reproductive growth exhibited a bimodal response averaged across the three study years with peak water use occurring at the R1-2 growth interval (0.58 cm d-1) and declining to 0.26 cm d-1 during R5-6. In contrast, no-till KB exhibited a simple negative linear relationship with water use rates declining from a high of 0.47 cm d-1 during the R1-2 growth interval to 0.22 cm d-1 during R5-6. These results indicate LM’s may increase SWC and utilize water more effectively, particularly when combining strip-till and herbicide management.