Root proliferation across a nitrogen fertilizer gradient as a measure of nitrogen use in maize (Zea mays L.)
Seehaver, Sarah Ann
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This study investigates corn plant root proliferation in a no till, irrigated maize (Zea mays L.) system by comparing root preference for in growth soil cores with either a control soil or soil homogenized with 2% ground Red Clover over an increasing nitrogen fertilizer gradient. The N Rate study on the Long Term Ecological Research (LTER) site in southwest Michigan is a means in which to examine whether maize root systems react among varied applications of nitrogen fertilizer similar to grain yields. Grain yields are a measure of effectiveness of nitrogen fertilizer but other systems such as N20 fluxes and root measurements can be used as an indicator to when there is hypothetical nitrogen saturation in the agroecosystem. As a measure of the effectiveness of nitrogen fertilizer on this particular corn system, we placed soil cores along 7 degrees of nitrogen fertilizer that were harvested to examine the root difference between control cores made of the soil of the same field and those which held a soil mixed with organic matter, providing a saturation of nitrogen for which the plant may forage. Each experimental unit contains both of these soil cores to gain insight into general root proliferation in each fertilizer treatment as well as a comparative root choice between an enriched N supply and a control soil as the applications increase. A significant amount of root proliferation is seen at the low end of the N fertilizer gradient, shown by an increase in root biomass, root tips, and root length. This is demonstrated in the entirety of the experimental unit control and amended soil cores - suggesting that corn plant roots increase foraging amidst nitrogen starvation. At the high end of nitrogen fertilizer, however, there is seen a plateau affect in which the corn plants not only decrease the proliferation comparatively, but also stop distinguishing between control and amended soil cores.
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