Browsing by Subject "Deficit irrigation"
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Item Continuous canopy temperature as a tool for managing deficit irrigation(2012-12) Young, Andrew W.; Dotray, Peter A.; Mahan, James R.; Payton, Paxton R.Deficit irrigation is becoming a trend in agricultural lands with reduced water. With the declining water resources comes renewed interest in deficit irrigation strategies and enhanced management capabilities to provide water when and where it is needed. However, in the past, plant-monitoring capabilities to assess water status of the plant were very costly and labor intensive. The innovation in infrared thermometry systems has allowed for the technology to become smaller and more cost efficient. This investigation uses the established method of BIOTIC developed by research scientist at USDA/ARS. The BIOTIC method has been patented and licensed by a new technology startup company, Smartfield™, under the moniker Smartcrop™. The research conducted used the Smartcrop™ technology, which consists of wireless infrared sensors and base stations for recording data from sensors. This thesis focused on the 2009 and 2010 cotton growing seasons in the Lubbock area. Water and yield data were discussed and analyzed in detail along with other environmental data relevant to plant growth and yield. Analysis and discussion of large temperature data sets were conducted. Canopy temperature comparisons were made using the BIOTIC method along with air vs. canopy temperature comparisons and treatment temperature comparisons. Vapor pressure deficits were also discussed in detail for selected treatments over the growing seasons. Finally, daytime average canopy temperature comparisons provided accurate estimates of water through the plant as a predictor of yield.Item Cotton Lint Yield, Fiber Quality, and Water-Use Efficiency as Influenced by Cultivar and Irrigation Level(2013-05) Cave, Justin; Keeling, Wayne; Dotray, Peter A.; Ritchie, Glen L.; Johnson, JeffCotton is produced in the Texas High Plains under a wide range of water levels, ranging from dryland (rainfed) to full irrigation, with irrigation levels that depend on well capacities. With declining pumping capacities, it is important to maximize water-use efficiency (WUE) through crop management and cultivar selection. The objectives of this research were to 1) evaluate the lint yield and fiber quality of current commercial and experimental cotton cultivars, 2) determine the WUE of these cultivars in different irrigation settings 3) identify the returns above cost for each cultivar within irrigation treatments, and 4) determine which cultivar is best for producers with varying levels of irrigation water and risk preference on the Texas High Plains. Field studies were conducted in 2011 and 2012 to evaluate new cultivars under varying irrigation inputs at Lamesa and Lubbock, TX. The experimental design at both locations was a split plot design with irrigation as the main effect and cultivar as the split effect. Eight cultivars [DP 0912 B2RF, DP 1032 B2RF, DP 1044 B2RF, DP 1212 B2RF, DP 1219 B2RF, 11R110B2R2, 11R112B2R2 (DP 1321 B2RF), and 11R159B2R2 (DP 1359 B2RF)] and four irrigation levels, replicated three times were evaluated in 2011 at Lubbock and Lamesa. Target irrigation levels were 0, 30, 60, and 90% ET replacement. In 2012, twelve cultivars with four replications were evaluated including the eight from 2011. The four additional experimental cultivars included: 11R124B2R2 (DP 1311 B2RF), 11R136B2R2, 11R154B2R2, and 12R242B2R2. Due to the excessive temperatures and drought conditions experienced in 2011, a reduction in yield and fiber quality was seen at both locations. At both locations in both years, increased yields were produced at increased irrigation levels; however, no cultivar by irrigation level interaction was observed. In 2012 at Lamesa, WUE declined as irrigation increased while no differences in WUE between irrigation levels were observed in Lubbock. Over all four trials, no cultivar by irrigation interaction for WUE was observed. Staple length tended to increase as irrigation increased, while the relationship of other fiber quality parameters was less pronounced. Net returns varied among cultivars, and influenced which cultivars were preferred by producers with different risk preferences. In both years at Lubbock, DP 1321 B2RF was the most preferred cultivar for risk averse producers, while DP 1219 B2RF and DP 1359 B2RF were among the most preferred cultivars for risk averse producers in three out of the four trials. In both 2012 locations, 11R136B2R2 had fiber length greater than or equal to all other cultivars.Item Effects of irrigation termination date on cotton yield and fiber quality(2012-05) Reeves, Heath; Ritchie, Glen L.; Bednarz, Craig W.; Hequet, Eric F.; Johnson, JeffFiber immaturity decreases profits for many cotton producers on the Texas High Plains. Correct timing of the final irrigation may enhance crop maturity and conserve water. Irrigation termination shortly after physiological cutout may inhibit the production of young fruit and divert additional resources to existing fruit, promoting fiber maturity. The objective of this research was to determine if proper irrigation termination can increase crop maturity rate and improve fiber quality without affecting yield. Studies were conducted for three site-years on sub-surface drip irrigation at Halfway, New Deal, and Lubbock, Texas in 2010 and 2011. Multiple cultivars were grown under three irrigation termination methods: incremental termination at nodes above white flower (NAWF) = 5 + 2 weeks; incremental termination at NAWF = 5 + 4 weeks; and complete irrigation cut-off at NAWF = 5 + 6 weeks. Production and retention of the uppermost flowers and fruit were measured, as well as fiber quality from the harvested plots. In 2010, length was improved with earlier termination at the Halfway location. At the Quaker location, seed yield, lint, turnout, and length improved with later termination, but micronaire became less desirable. In 2011, turnout and micronaire were improved with earlier irrigation termination. When the cost of irrigation was low, the 4 week irrigation treatment was the most profitable in 2010, but as the cost of irrigation reached $10/ha-cm, the Halfway location became more profitable with the 2 week irrigation. In 2011, net income between irrigations was not statistically different.Item Production and soil effects of sorghum biofuel cropping systems in semiarid marginal regions(2012-05) Cotton, Jon; Moore-Kucera, Jennifer; Acosta-Martinez, Veronica; Burow, Gloria B.; Wester, David B.In order to meet the growing demands for food, fiber, and biofuels, land management decisions will require identification of lands most suitable for each crop. Biofuel production that occurs on lands otherwise constrained for other intensive agricultural production by soil or water limitations (i.e., marginal lands) may not only meet some of these demands but, if managed properly, may also help improve soil function. For large-scale application to be sustainable, identification of crop type most efficient for feedstock production as well as impacts on soil and water resources are necessary. In this study, forage sorghum (Sorghum bicolor L. Moench) cropping systems were initiated in the semiarid Southern High Plains (SHP) of the U.S. to evaluate potential biofuel production and potential benefits on soils that are depleted of organic matter (< 0.7%) due to previous cropping history. Systems consisted of two sorghum cultivars (Sorghum Partners 1990 = SP 1990 and PaceSetter bmr = PS bmr) differing in lignin content due to brown midrib trait (bmr-12) that were tested under two different water levels (non-irrigated or deficit irrigation of 2.88 mm day-1), and biomass removal rate treatments of 50% and 100%. Forage sorghum SP1990 (non bmr) produced significantly higher weight and volumes of biomass than PS bmr under both deficit irrigation and no irrigation in the two years of study. However, PS bmr biomass was converted into ethanol (EtOH) 54% more efficiently during both years. When below average precipitation occurred during the first year of the study, both cultivars produced similar amounts of EtOH at each irrigation level (1,600 to 3,380 L ha-1). When higher than average precipitation occurred during the second year, higher biomass production of SP 1990 resulted in more EtOH production than PS bmr (3,380 vs. 2,640 L ha-1). Irrigation resulted in 26-49% more biomass and 28-72% more EtOH production during both growing seasons, indicating that non-irrigated production resulted in deficit water conditions regardless of precipitation. Overall EtOH production ranged from 1,600 to 3,380 L ha-1 during both years of the study. Changes in soil microbial properties (0-10 cm), known to be sensitive econsensors, were measured during the two year transition from previous long-term cotton cropping systems to the sorghum biofuel cropping systems. Increases in microbial biomass C (MBC) and N (MBN) (16-17%) and differences in fatty acid methyl ester (FAME) profiles were observed after one growing season. Additionally, soil enzyme activities (EAs) targeting C, N, P, and S increased 15-75% after two growing seasons. Increases in EAs 16-19%) and differences in FAME profiles were seen due to the irrigation treatment, which may be due to the increase in belowground biomass production even under deficit irrigation. When biomass was not fully removed (50% removal treatment), increases in MBC and MBN (11-15%), b-glucosidase (C cycling) and alkaline phosphatase (P cycling) (12-22%) occurred, which is likely attributed to the protection of the soil surface from aeolian erosion provided by the surface residue. The cultivars tested, which produced biomass with different chemical composition, had little effect on the soil microbial properties measured during the time frame of this study. This study indicates that chemical modifications and biomass yield potential are critical factors when selecting sorghum characteristics for use as biofuel feedstocks under marginal water-deficit conditions. These cropping systems also have the potential to improve sandy, low organic matter soils in this semiarid region, as was shown by increases in microbial biomass and soil functionality indicated by EAs after only two growing seasons. Early results from this study suggest sorghum biofuel cropping systems can be a sustainable practice for marginal lands in the SHP; however, tracking of long-term changes are necessary to fully evaluate effects. It is hypothesized that soil properties will continue to improve, especially in the lower biomass removal level as more above-ground biomass will be incorporated and decomposed. It is unclear how the chemical composition of biomass from different sorghum cultivars will impact soil properties but differences in organic matter accumulation and enhanced biochemical cycling are possible. Finally, additional research on incorporating biofuel production into traditional cotton production, along with the evaluation of novel sorghum cultivars specifically bred for use as feedstock, are important focuses for the application of biofuel production in the semiarid SHP.Item Water use efficiency and irrigation response of cotton cultivars under sub-surface drip irrigation in West Texas(2012-05) Snowden, Michael; Ritchie, Glen L.; Thompson, Thomas L.; Mulligan, KevinThe High Plains Aquifer is the source of nearly all agriculture irrigation water in the Texas High Plains, and its resources are being depleted due to withdrawals that greatly exceed recharge. Decreasing water availability has led to research on water use requirements of most agronomic crops, including yield and quality impacts of deficit irrigation. Some drought-tolerant crops such as cotton (Gossypium hirsutum L.), can adapt well to deficit irrigation. The objectives of this study were to i) evaluate the water use efficiency and boll distribution patterns of cotton cultivars at varying levels of sub-surface drip irrigation from severe-deficit to fully irrigated, ii) compare growth and yield characteristics between cultivars at varying irrigation levels, and iii) determine yield stability under deficit irrigation in West Texas. Yield, water use efficiency and boll distribution were compared during 2010 and 2011 for cultivars DP 0912, DP 0924, DP 0935, DP 1028, DP 1032, DP 1044, and FM 9160. In 2010, FM 9160, DP 1044, and DP 0912 had the three highest average yields and water use efficiencies. DP1044 and FM9160 performed very well under deficit irrigation. In 2011 cultivar DP1044 again was a top performer along with DP0935 and DP0924. Average yield ranges of 1077 to 1256 kg ha-1for 2010 and 958 to 1074 kg ha-1 for 2011 were common to those produced in West Texas. Water use efficiency was also common for West Texas with ranges of 0.23 to 0.27 for 2010 and 0.17 to 0.19 kg m-3 for 2011. Boll distribution patterns varied significantly between cultivars and within irrigation treatments. Three cultivars (DP1044, FM 9160 and DP 0935) increased fruit production near the top of the plants in response to irrigation, and also had good yield and yield stability; their yield patterns may be favorable for limited water conditions in the Texas High Plains.Item Yield and quality responses of corn silage genotypes under reduced irrigation in the Texas High Plains(2012-05) Spinhirne, Bruce; Xu, Wenwei; Dotray, Peter A.; Doerfert, DavidTwo main options exist for producers to optimize the production of corn silage in limited-irrigation systems. First, they can utilize best management practices to make optimum use of inputs. Secondly, they can select hybrids that will maximize production from limited inputs. The intent of this study was to explore both options by characterizing the effects of moisture stress on silage corn and by comparing relative performance of a diverse group of silage corn hybrids. The overall objective of this study was to determine genotype effects of 20 silage corn hybrids and the effects of environmental stress on silage corn yield and quality. Environmental stress was considered to be primarily caused by the deficit of moisture inputs to crop demand. To adequately accomplish this objective, four sub-objectives were created.