Comparing inter-specific competition for continuous corn grown in a living mulch with stover removal.

摘要

Corn stover returns nutrients to the soil, decreases soil erosion, and helps maintain overall soil properties. Additionally, corn stover may provide producers an additional market for selling biomass, but long term stover removal has been determined to cause detrimental environmental effects (Wilhelm et al., 1986; Mann et al., 2002; Nelson, 2002). Living mulches, or perennial groundcovers, grow simultaneously with the main row crop and are maintained as living groundcover throughout the growing season. Groundcovers grown in the interrow of row crops can provide beneficial functions such as weed suppression, nutrient cycling, and increase water infiltration, but should not disrupt corn development and productivity. The objectives of this research were to quantify soil and plant water use in continuous corn with and without a living mulch with stover removal. Corn was planted into living mulch groundcovers of creeping red fescue (CF) (Festuca rubra L.), and Kentucky bluegrass (KB) (Poa pratensis L.) in 2008 and 2009 near Ames, IA. Management was no-tillage (NT) with a pre-planting paraquat burn-down followed by two post-planting glyphosate applications (PQ) during the season. Kentucky bluegrass (P = 0.3743) was less competitive than CF (P = 0.0482) compared to a no living mulch control for soil water content (SWC) at the 15 cm soil depth during the vegetative growth period in 2008. Additionally in 2008, both KB (0.3681 m3 m-3) and CF (0.3696 m3 m-3) were significant compared to a no living mulch control (0.3473 m3 m-3) for SWC at the 15 cm soil depth during the post-maturity period. There were no significant affects on SWC at the 15 cm level among treatments in 2009. Soil water content at the 45 cm soil depth and soil temperature (ST) at the 15 cm soil depth were non-significant among treatments both years. Living mulch did affect leaf area index (LAI) at V6, V12, and R1 in 2008, and only at V6 in 2009. Carbon dioxide exchange rate (CER) and corn transpiration rate (TR) were not affected by groundcover either year. Reproductive water use efficiency (RWUE) for KB (50 and 41 g grain cm water-1) was greater compared to the control (41 and 36 g grain cm water-1) by 22 and 14% in 2008 and 2009, respectively. Kentucky bluegrass was less competitive than CF both years, and used water more efficiently during reproductive growth compared to a no-living mulch control. Therefore, KB demonstrates the greatest potential to implementing living mulches in a corn bioenergy cropping systems.