Modeled El Niño-Southern Oscillation Effects on Grain Sorghum under Varying Irrigation Strategies and Cultural Practices

Equatorial sea surface temperatures vary systematically to cause the El Niño southern oscillation (ENSO) that produces predictable weather patterns in North America and may permit longrange climate predictions and eventual proactive summer crop irrigation management. The declining Ogallala Aquifer in the Southern High Plains and consequently limited well capacities challenge producers to adapt cropping practices for irrigation that doesn’t meet crop water demand. Our objective was to evaluate sorghum [Sorghum bicolor (L.) Moench] yield response to ENSO climate-informed management of cultural practices and irrigation strategies on a Pullman soil (fine, mixed, superactive, thermic Torrertic Paleustoll). We used the simulation model SORKAM and long-term (1961–2000) weather records from Bushland, TX, classified by ENSO phase to calculate sorghum grain yields for all combinations of irrigation levels (0.0, 2.5, 3.75, or 5.0 mm d–1), planting day of year (DOY = 135, 156, 176), and cultivar maturity (early, 95 d; medium, 105 d; late, 120 d). Using the September–November Oceanic Niño Index (ONI) to identify ENSO phase, La Niña years had 50 mm less precipitation and a corresponding 14.5% reduction in overall yield to 4550 kg ha–1 for sorghum planted at 16 plants m–2 population. Late maturing cultivars and late planting led to sorghum freeze injury and reduced yields regardless of ENSO phase. While yields consistently increased with irrigation, we conclude that concentrating water to irrigate an area partitioned 2:1 or 1:1 at 3.75- or 5.0-mm d–1 with complementary dryland produced \u3e30% more grain, overall, than uniformly irrigating an area at 2.5 mm d–1

Proceedings of the 21st annual Central Plains irrigation conference, Colby Kansas, February 24-25, 2009

Presented at the 21st annual Central Plains irrigation conference on February 24-25, 2009 in Colby, Kansas.Includes bibliographical references.Crop production was compared under subsurface drip irrigation (SDI), low energy precision applicators (LEPA), low elevation spray applicators (LESA), and mid elevation spray applicators (MESA) at the USDA-Agricultural Research Service Conservation and Production Research Laboratory, Bushland, Tex., USA. Each irrigation method was compared at irrigation rates meeting 25, 50, 75, and 100% of full crop evapotranspiration (ETc). Crops included three seasons of grain sorghum, one season of soybean (planted following a cotton crop that was destroyed by hail), and four seasons of upland cotton. For grain sorghum, SDI followed by LEPA, MESA, and LESA resulted in greater grain yield, water use efficiency, and irrigation water use efficiency at the 25- and 50% irrigation rates, whereas MESA followed by LESA outperformed LEPA and SDI at the 75- and 100% irrigation rates. For soybean, the same trend was observed at the 25- and 50% irrigation rates, whereas SDI followed by MESA, LEPA, and LESA resulted in the best crop response at the 75% irrigation rate, and MESA followed by SDI, LESA, and LEPA resulted in the best crop response at the 100% irrigation rate. Cotton response was consistently best for SDI, followed by LEPA, and either MESA or LESA at all irrigation rates. Within each irrigation rate, few significant differences were observed among irrigation methods in total seasonal water use for all crops

Ground water and surface water under stress

Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.Includes bibliographical references.Renewed interest in cotton production in the Ogallala aquifer region can be tied to development of early maturing varieties, and declining water levels in the Ogallala aquifer. However, the feasibility of growing cotton considering thermal characteristics of the region has not been determined. In this study, the heat unit based county-wide exceedance probability curves for potential cotton yield were developed using a long term temperature dataset (1971-2000) and identified counties that have the potential to grow cotton at 1- and 2-year return periods. Out of 131 counties in the study area, 105 counties have the potential to grow cotton with lint yield more than 500 kg/ha. Evaluation of county-wide potential cotton yield indicate that yield goals based on a 2-year return period may improve the chances of better profits to producers than yield goals with 1-year return period. However, management uncertainties on irrigation efficiencies, fertilizer and pest management, planting and harvesting schedule may require further consideration for estimating potential cotton yield. Nevertheless, these results show that cotton is a suitable alternative crop for most counties in southwest Kansas and all counties in Texas and Oklahoma Panhandles. Also, a significant reduction in annual water withdrawals (about 60.4 million ha-mm) from the Ogallala aquifer for irrigation is possible if producers were to switch 50 percent of their corn acreage to cotton in counties that have yield potential more than 500 kg/ha

Ground water and surface water under stress

Presented at Ground water and surface water under stress: competition, interaction, solutions: a USCID water management conference on October 25-28, 2006 in Boise, Idaho.Includes bibliographical references.Irrigated crop production in the Texas High Plains is dependent on the Ogallala Aquifer, which has declined by up to 50 percent in some areas since irrigation development began in the 1930-40s. About 6.5 million acre-feet (ac-ft) of water was pumped to irrigate 4.6 million acres in 2000, with most irrigation demand being for corn and cotton production. Cotton is produced primarily in the Southern Texas High Plains, with corn and winter wheat comprising most of the irrigated area in the Northern Texas High Plains. However, cotton production is expanding northward again and replacing corn in some areas because both crops currently have similar revenue potential but cotton has about half the irrigation water requirement, and may result in profitable yields under dryland and deficit irrigated conditions. In the Northern Texas High Plains, combined annual irrigation demand for corn and cotton could be reduced from 2.6 to 2.0 million ac-ft by replacing 50 percent of the irrigated corn area with cotton, and combined irrigation demand could be reduced to 1.6 million ac-ft if cotton irrigation applications were reduced to 50 percent of full crop evapotranspiration minus rainfall. In the Southern Texas High Plains, annual irrigation demand for cotton could be reduced from 1.4 to 1.0 million ac-ft if overall irrigations were reduced to 50 percent of full crop evapotranspiration minus rainfall. Deficit irrigation results in some yield penalty; however, if the crop is relatively drought tolerant, this may be offset somewhat by the reduced energy costs of pumping

Empowering Advisors to Facilitate Change

Advancing group dynamics is difficult. In order for students to learn, develop, and grow within an organization, they need to be empowered by their advisor to feel that their ideas and contributions are both important and valuable. This concept of empowerment means providing freedom for people to do successfully what they want to do, rather than getting them to do what you want them to do (Whetten & Cameron, 2011). As an advisor to a student-led organization, it is important to empower students to identify specific actions and strategies that facilitate change and achieve the outcomes of the organization

Groundwater Nitrogen Source Identification and Remediation in the Texas High Plains and Rolling Plains Regions

Nitrogen in groundwater, more specifically nitrate, is common in certain areas and is often associated with agricultural production or urban areas underlain by coarse soils. While the presence of nitrates in groundwater is not debated, the specific sources or cause of the elevated nitrate in these areas is often questioned. The Texas High Plains and Rolling Plains regions are two areas in the state where elevated nitrates are readily found in groundwater and such questions regarding its cause and source are raised. These areas include portions of the Ogallala and Seymour Aquifers which both exhibit elevated nitrates in certain areas. In an effort to address questions about sources and causes of elevated groundwater nitrate and to provide sound data on potential management strategies that can remediate groundwater nitrate levels, this project was developed. The primary objective was to identify sources of groundwater nitrate in the Texas High Plains and Rolling Plains and the secondary objective was to evaluate and demonstrate strategies and practices for reducing nitrate levels in these same areas. Collectively, this effort was able to provide insight into the potential sources of nitrate found in groundwater while also demonstrating how available nitrates can be captured as a beneficial resource and effectively removed from the underlying aquifer