Perennial Filter Strips Reduce Nitrate Levels in Soil and Shallow Groundwater after Grassland-to-Cropland Conversion

Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland-to-cropland conversion on nitrate-nitrogen (NO3–N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3–N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed-scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20% PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no-till 2-yr corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3–N concentration from 2005 to 2008. The results indicated significant increases in NO3–N concentration in soil and groundwater following grassland-to-cropland conversion. Nitrate-nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long-term monitoring is needed to observe and understand the full response to land-use conversion

Yield response of seedless watermelon to different drip irrigation strategies under Mediterranean conditions

[EN] Water is an essential resource for food production, as agriculture consumes close to 70% of the total freshwater, and its shortage is becoming critical in arid and semiarid areas of the world. Therefore, it is important to use water more efficiently. The objectives of this project are to determine the productive response and the irrigation water use efficiency of seedless watermelon to three irrigation management strategies over two growing seasons. This was done by applying 100, 75 and 50% of the irrigation water requirements (IWR) the first year, in the second year added six additional treatments, of which three treatments were regulated deficit irrigation with 75% IWR during the vegetative growth, fruit development and fruit ripening stages, and the other three treatments were with 50% IWR during the same stages. The exposure of watermelon plants to severe deficit irrigation resulted in a reduction in dry biomass, total and marketable yield, average fruit weight, fruit number and harvest index, and without improvement of marketable fruit quality. The fruit ripening was the less sensitive stage to water deficits. Relative water content and cell membrane stability index decreased as the water deficit increased. Irrigation water use efficiency decreased to a lesser extend during the fruit ripening stage than when water restriction were applied during different growth stages. If water is readily available, irrigating with 100% of water requirements is recommended, but in the case of water scarcity, applying water shortage during fruit ripening stage would be advisable.Abdelkhalik, A.; Pascual-Seva, N.; Nájera, I.; Giner, A.; Baixauli Soria, C.; Pascual España, B. (2019). Yield response of seedless watermelon to different drip irrigation strategies under Mediterranean conditions. Agricultural Water Management. 212:99-110. https://doi.org/10.1016/j.agwat.2018.08.0449911021

Tombigbee River Basin, Alabama and Mississippi, Water and Related Land Resources

Excerpts from the report: The Tombigbee River Basin is part of a sub-region of the South Atlantic-Gulf Region. The basin is located in Western Alabama and Northeastern Mississippi. It comprises all or part of 16 counties in Alabama and 19 counties in Mississippi. The boundary encompasses 8.8 million acres of land and water, with 4.9 million acres in Alabama and 3.9 million acres in Mississippi. It is approximately 85 miles wide and 260 miles long. The basin consists of the drainage area of the Tombigbee River above the confluence with the Alabama River, except for the drainage area of the Black Warrior River that flows into the Tombigbee River near Demopolis, Alabama. The eastern boundary is the divide of the Alabama and Black Warrior Rivers. The Tennessee and Hatchie River Systems make up the northern boundary. The western boundary consists of the divides of the Tallahatchie, Yalobusha, Big Black, Pearl, Chickasawhay, and Escatawpa Rivers. The purpose of the study was to formulate alternative plans and suggest an alternative for use in facilitating the coordinated and orderly conservation, development, utilization, and management of the water and related land resources of the basin. Achievement of this purpose required an assessment of the water and related land resource problems, needs, and development potentials of the basin

Little Blue River Basin, Nebraska, Water and Related Land Resources

Excerpts from the report: The Little Blue River is a tributary of the Big Blue River. It originates in the loess plains of south central Nebraska and flows in a south easterly direction to its junction with the Big Blue River near Waterville, Kansas. The area of the Little Blue River Basin in Nebraska totals just under 2,691 square miles, or 1,722,200 acres. Principal tributaries include Big Sandy Creek, having a drainage area of 638 square miles; Rose Creek, 203 square miles; Spring Creek, 180 square miles; and Pawnee Creek, 126 square miles. The total length of the Little Blue River in Nebraska is approximately 200 miles. The Little Blue River drains nearly all of Thayer County and parts of 10 other counties in Nebraska. The report is based upon a study of upstream watershed needs and opportunities for flood prevention; agricultural, municipal, and industrial water supply; fish and wildlife habitat; recreation facilities; and water quality control. The main objectives of the USDA study are to: (1) inventory the natural resources of the basin; (2) analyze the basin's economy relative to present conditions, historic trends, and projections; (3) determine the cause, extent, and frequency of the basin's resource problems; (4) determine the present and future need for development based on resource problems and projected economic activity; (5) describe the pertinent existing water and related land resource projects and programs; (6) describe the physical potential or capability of the basin to supply water and related land resources for development to meet identifiable needs; and (7) describe the opportunities for development through USDA projects and programs and determine their impacts upon the basin