Phenology, Productivity, and Water Use of Pearl Millet in the Wisconsin Central Sands.

Wisconsin is a top producer of canning vegetables and potatoes, many of them grown in the Wisconsin Central Sands (CS), a region dominated by well-drained sandy soils that require extensive irrigation. However, this water use has become a controversial issue, a decline in stream headwater baseflow has been attributed to groundwater pumping for irrigation. Current research is examining the effects of irrigation on groundwater recharge and evapotranspiration in potatoes and corn; however, the role played by cover crops has received less attention. Cover crops are often utilized for erosion control in the CS, but can also help increase soil organic carbon, improve soil structure, add nutrients to the soil, and increase soil water holding capacity. Pearl millet is of particular interest because it can help repress a common root-lesion nematode (Pratylenchus penetrans) found in potato, whereas other more common cover crops, such as oats and rye, are good hosts for this pest. Therefore, utilizing pearl millet could reduce fumigation rates while still providing all of the benefits of a typical cover crop. This study looks at the phenological growth, productivity, and water use of pearl millet on a 28 ha commercial vegetable production field in the CS. To do so, we will utilize data collected on leaf area index (with a LI-COR 2200), leaf photosynthetic response to light, temperature, and vapor pressure deficit (using a LI-COR 6400), above and belowground net primary productivity (NPP) using biomass sampling and in-growth root cores, and water balance from in-field passive capillary lysimeters and soil moisture probes (from Decagon Devices). These data will be used to determine how pearl millet provides for environmental and ecological needs of the region.