Corn performance under managed drought stress and in a kura clover living mulch intercropping system

Authors: ZIYUMO, CATHRINE - University Of Minnesota; ALBRECHT, KENNETH - University Of Wisconsin; Baker, John; BERNARDO, REX - University Of Minnesota

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2013
Publication Date: 2/28/2013
Publication URL: http://handle.nal.usda.gov/10113/57471
Citation: Ziyumo, C., Albrecht, K.E., Baker, J.M., Bernardo, R. 2013. Corn performance under managed drought stress and in a kura clover living mulch intercropping system. Agronomy Journal. 105(3):579-586.

Interpretive Summary: A corn (Zea mays L.) and kura clover (Trifolium ambiguum M. Bieb.) intercropping system can provide a number of important benefits relative to a conventional corn field: less nitrogen fertilizer is needed, and the clover protects the soil surface against erosion. However, adoption of this system has been limited due to the possibility that competition for water between the grain crop and the living mulch crop will lead to reduced corn yields. To address this, we conducted a study to determine if the use of drought-tolerant corn varieities could minimize these yield losses and also to see if strong suppression of the clover with herbicide might have different impacts on the yields of drought-tolerant and drought-susceptible corn varieties. Five drought-tolerant and five drought-susceptible varieites were selected in drought trials conducted in Minnesota in 2009 and 2010. The drought-tolerant varieties had mean grain yields under drought conditions of 9.66 Mg ha-1, roughly twice that of the drought-susceptible hybrids. All 10 of these selections were then evaluated in 2011 in fields in Minnesota and Wisconsin, in which they were planted on both living and killed kura clover. The drought-tolerant hybrids had mean yields of 12.9 MG ha-1 in the killed clover and 13.69 Mg ha-1 in the living mulch treatment, while the drought-sensitive lines had yields of 4.53 Mg ha-1 in the killled clover and 3.48 Mg ha-1 in the living mulch. We conclude that drought-tolerant hybrids can maintain their yields in living mulch systems, and that the use of these varieties may encourage adoption of this conservation practice.

Technical Abstract: A corn (Zea mays L.) and kura clover (Trifolium ambiguum M. Bieb.) intercropping system provides ecological services but competition for water between the grain crop and the living mulch crop leads to reduced corn yields. Our objectives in this study were to determine (i) if drought-tolerant corn can minimize the grain yield losses incurred when corn is intercropped with kura clover and (ii) if strong suppression of the kura clover living mulch minimizes the loss in grain yield of drought-tolerant and drought-susceptible corn. From drought trials at Minnesota in 2009 and 2010, we identified five drought-tolerant and five drought-susceptible hybrids from the intermated B73 × Mo17 population. Under drought conditions, mean grain yields were 9.66 Mg ha-1 for the drought tolerant hybrids and 4.82 Mg ha-1 for the drought susceptible hybrids. The 10 hybrids were then evaluated in Minnesota and Wisconsin in 2011 in a kura clover living mulch intercropping system. Drought tolerant hybrids had statistically equal mean grain yields of 12.90 Mg ha-1 in the killed mulch treatment and 13.69 Mg ha-1 in the living mulch treatment. In contrast, mean grain yields of drought-susceptible hybrids were significantly reduced from 4.53 Mg ha-1 in the killed mulch treatment to 3.48 Mg ha-1 in the living mulch treatment. For the drought tolerant hybrids, mulch recovery at corn harvest was significantly lower with killed kura clover (41%) than with living kura clover (50%). Overall, our results indicate that drought-tolerant corn can maintain high yields and allow sufficient regrowth of kura clover.