Theses and Dissertations

Permanent URI for this collection

https://hdl.handle.net/10217/100514

Browse

Now showing 1 - 4 of 4

Open Access
Agronomic responses of grass and alfalfa hayfields to no and partial season irrigation as part of a Western Slope water bank
(Colorado State University. Libraries, 2015) Jones, Lyndsay P., author; Brummer, Joe, advisor; Cabot, Perry, committee member; Davis, Jessica, committee member
Prolonged drought and increasing demand for water resources has caused growing concern over Colorado's ability to fulfill legal water obligations as identified in the Colorado River Compact. A Western Slope Water Bank, which would entail agricultural water users entering into short-term leases and temporarily withholding or reducing irrigation, could be a partial solution to free up water to fulfill these obligations. Grass and alfalfa (Medicago sativa L.) hayfields may be ideal for inclusion in a water bank as they are the primary users of agricultural water in this region and may have a greater ability to withstand water stress in comparison to other crops. This study was conducted to determine effects of withholding irrigation for a full season from high elevation grass hayfields and implementing partial season irrigation on lower elevation alfalfa hayfields on forage yield, nutritional quality, and associated recovery period to confirm if this approach is worth pursuing. In Year 1, five established grass hayfields on the Colorado Western Slope were split into side-by-side plots, one of which was irrigated according to the manager’s normal practices as the control while the other was subjected to total cessation of irrigation. Both plots were irrigated in Year 2. In Year 1, average dry matter yields in non-irrigated plots were reduced to 39% (2497 kg ha-1) of the control (6377 kg ha-1). Neutral detergent fiber (aNDF) concentration in non-irrigated plots was 5% lower while crude protein (CP) content was 30% greater than the control. In-vitro true digestibility (IVTD) was unaffected by irrigation treatment. Yields of non-irrigated plots did not fully recover when returned to irrigation in Year 2 producing 49% (3623 kg ha-1) of the control (7442 kg ha-1). When returned to irrigation, aNDF concentrations were still reduced by 8% and CP contents were similar to that of the control. In the single site sampled after returning to full irrigation for 2 years, yields had fully recovered. It is probable that participation by producers in a water bank would be largely influenced by compensation for reduced yields the season of withholding irrigation as well as the following year when irrigation is returned to grass hayfields. Three established alfalfa fields were subjected to irrigation treatments including irrigation according to the manager’s normal practices (control), irrigation stopped after the 1st cutting (SA1), and irrigation stopped after the 2nd cutting (SA2) for 2 consecutive years. Averaged over both years, SA2 plots maintained production similar to the control in the 1st and 2nd cutting while SA1 plots were reduced to 61% (2089 kg ha-1) of the control (3430 kg ha-1) by the 2nd cutting. By the 3rd cutting, SA2 and SA1 yields decreased to 53% (1804 kg ha-1) and 30% (1013 kg ha-1) of the control, respectively. On a total season basis, both plots receiving partial season irrigation were reduced with SA2 plots producing 72% (7880 kg ha-1) and SA1 plots producing 33% (3650 kg ha-1) of the control (11040 kg ha-1). aNDF concentrations were greatest in the control at 34.6% and lowest in SA1 plots at 28.2%. By the 2nd cutting, SA1 plots had the highest IVTD (80%), and by the 3rd cutting, SA2 and SA1 plots were equally greater (80%) than the control (75%). Effects on CP content were inconsistent. These results suggest that reduced irrigation may improve forage quality slightly, but will significantly reduce yields. When irrigation is returned the following year, forages may have increased quality due to reduced fiber content, but grass yields will likely not fully recover while alfalfa yields may recover depending on length and severity of reduced irrigation. Due to its ability to recover, using partial season irrigation similar to that of the SA2 treatment on alfalfa hayfields may be the most practical approach to make water available to a Western Slope water bank.
Open Access
Alfalfa water use under deficit irrigation for farm savings
(Colorado State University. Libraries, 2022) Sitterson, Jan, author; Andales, Allan A., advisor; Mooney, Daniel F., committee member; Brummer, Joe E., committee member
Colorado water law allows for water rights to be leased between agriculture and municipality users. Decreasing the consumptive use (CU) of agricultural land while maintaining profits and yields will allow farmers to lease their water rights for revenue. Deficit irrigation is a water-saving approach to avoid the complete dry up of irrigated farmland while providing profitable yields and monetary gains from water transfers. To maximize water savings, efficient irrigation systems such as subsurface drip irrigation (SDI) are used to prevent water losses from soil evaporation. This study evaluated the feasibility of using SDI with deficit irrigation practices to grow alfalfa (Medicago Sativa L.) at production scale in northeast Colorado (2018 – 2022). Alfalfa was found to have good potential for decreasing CU due to its drought tolerance, multiple harvests per season, and improved quality of hay with less irrigation water. The Water Irrigation Scheduler for Efficient Application (WISE) model was also found to be a useful tool for estimating CU of deficit irrigated alfalfa and the regrowth phases after multiple harvests in a growing season. Mid-season corrections of the soil water deficit in WISE improved the accuracy of modeled CU. Overall the water savings from deficit irrigation at low, medium, and high irrigation levels with an SDI system can be profitable when prices for leasing water exceed hay prices per unit area of production.
Open Access
Evaluating the ASCE standardized Penman-Monteith equation and developing crop coefficients of alfalfa using a weighing lysimeter in southeast Colorado
(Colorado State University. Libraries, 2011) Al Wahaibi, Hamdan Salem, author; Andales, Allan A., advisor; Hansen, Neil, committee member; Trout, Thomas, committee member; Chávez, José, committee member
To view the abstract, please see the full text of the document.
Open Access
Intercropping alfalfa with select grass species for increased yield and quality under deficit irrigation
(Colorado State University. Libraries, 2023) Doyle, Hunter, author; Brummer, Joe, advisor; Cabot, Perry, committee member; Ippolito, Jim, committee member
Drought and water scarcity have plagued the Western US for decades. As these issues become more prevalent, we must explore possibilities to utilize available water more efficiently. The objective of this study was to: Evaluate the ability of mixed and stripped intercropping alfalfa with grasses to increase yield and quality of the forage produced under deficit irrigation. Alfalfa (Medicago sativa) is the most common forage grown in the West and is known for its high-water use. Intercropping alfalfa with perennial grasses can potentially improve water use efficiency. Orchardgrass (Dactylis glomerata), meadow brome (Bromus biebersteinii), and tall fescue (Festuca arundinacea) were mixed on the same bed or strip intercropped on alternating beds with alfalfa under 100% and 60% ET irrigation regimes using subsurface drip irrigation. Three cuts occurred in 2021 and 2022, with deficit irrigation starting after cut one. Yield, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), neutral detergent fiber digestibility (NDFD), and relative feed value (RFV) were analyzed in this study. During year one, irrigation did not have a significant impact on yield due to high precipitation and the fact that alfalfa performs well under deficit irrigation. Quality was not affected by irrigation treatments throughout both years of this study. Planting treatments significantly impacted yield and all quality parameters throughout this study. In 2021, mixed intercropping treatments averaged 14,210 kg ha-1, stripped treatments averaged 12,285 kg ha-1, and alfalfa averaged 13,406 kg ha-1; significant differences were not present. All mixed treatments, tall fescue stripped, and meadow brome stripped yields were similar to alfalfa in 2021. In 2021, quality was generally only reduced in mixed intercropping treatments compared to alfalfa in the first cutting. The inclusion of grasses with alfalfa reduced crude protein content and increased neutral detergent fiber content during cutting one, overall reducing quality. In cuttings two and three, mixed intercropping did not generally reduce quality. Stripped treatments also reduced quality in cutting one but did not have a large effect on quality in subsequent cuttings. Relative feed value, a common parameter used among producers, was similar among all treatments for all cuttings in 2021. In 2022, deficit irrigation had a significant impact on yield in cuttings two and three. Yields due to deficit irrigation were reduced by 22% and 35% in cuttings two and three, respectively. Total yearly yields were reduced by 12.5% between irrigation treatments. Total yields in mixed intercropping treatments were significantly higher than the alfalfa monoculture, especially the tall fescue and orchardgrass. Meadow brome generally had a higher yield than alfalfa, though not always significant. Mixed treatments averaged 13,308 kg ha-1 and stripped treatments averaged 9,488 kg ha-1 compared to alfalfa at 10,758 kg ha-1. Similar to 2021, quality was only reduced in intercropping treatments during the first cutting. Crude protein and RFV decreased while NDF and ADF increased in intercropping treatments compared to alfalfa alone, resulting in reduced quality. In subsequent cuttings, quality was generally similar among intercropping treatments and alfalfa alone. Mixed intercropping demonstrated to be more productive throughout both years of this study compared to stripped intercropping. Advantages from intercropping were reduced in stripped treatments due to independent cultivation and limited species interactions. Grass species did not have as large of an effect on yield and quality compared to intercropping method. Tall fescue typically performed the best of the grasses, yet all grasses in mixed intercropping performed well compared to alfalfa. Mixed intercropping grass with alfalfa can lead to increased yields with minimal effects on forage quality compared to alfalfa alone. As severe drought continues in areas across the Western US, mixed intercropping could be an option for maintaining or improving yields while producing similar forage quality compared to alfalfa alone under deficit irrigation.

Browse

Browsing Theses and Dissertations by Subject "alfalfa"

Results Per Page

Sort Options