|LI, MAONA - China Agricultural University|
|LIU, YANG - China Agricultural University|
|YAN, HAIJUN - China Agricultural University|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2017
Publication Date: 5/23/2018
Citation: Li, M., Liu, Y., Yan, H., Sui, R. 2018. Effects of irrigation amounts on alfalfa yield and quality with center pivot system. Transactions of the ASABE. 60(5):1633-1644.
Interpretive Summary: As a high quality forage, alfalfa is sensitive to water stress. Careful water management is required for alfalfa production. The researcher at USDA-ARS Crop Production Systems Research Unit in Stoneville, MS with collaborators from China Agricultural University, Beijing, studied the effect of sprinkler irrigation depth and uniformity on alfalfa yield and quality in a semi-arid region in China. Based on the crop evapotranspiration (ET), three irrigation levels (100%ET, 80%ET, 60%ET) were used in alfalfa for two growing seasons. Results indicates that 60%ET level caused an obvious yield reduction. Alfalfa grades were unaffected by irrigation levels. Crop water productivity decreased by successive harvest and increased with decreasing irrigation level. The 80% ET irrigation level in the first and second cuttings and 60% ET irrigation level in the third cutting were recommended due to the serious water shortage situation in Western Inner Mongolia. Distributions of the annual yield and quality were highly related to the water distribution of the center pivot irrigation system. Over-irrigation caused by the end gun decreased the quality and water use efficiency. Results from this study could be useful for irrigation management in alfalfa production.
Technical Abstract: Irrigation amounts are one of the most important factors that need to be considered in the irrigation management of a center pivot irrigation system for alfalfa producers. In 2014 and 2015, a field study was conducted at Saiwusu, Inner Mongolia, China. Three irrigation levels (100%, 80%, 60% ET) were used to evaluate the effects of irrigation amounts on alfalfa yield and quality. For assessing the effects of water distribution variation of center pivot system on alfalfa yield and quality, water application depths, alfalfa yield and quality between the first span, second span, overhang, and end gun were also compared. The results showed there was no significant difference in annual yield between 100% and 80% ET irrigation levels. Compared to the irrigation at 100% and 80% ET level, the irrigation at 60% ET level caused a significant reduction of yield by 10% and 11%, respectively. As the irrigation amounts decreased, total crop water use significantly declined from 617 to 405 mm, and water use efficiency (WUE) increased from 2.1 to 3.0 kg/m3. Relationships between yield and irrigation amounts were parabolic in each harvest. The proportions of seasonal irrigation amounts for each cuttings were approximately 27%, 34% and 39%, with contributions to annual yield accounting for 54%, 30% and 16%, respectively, indicating that the third harvest of alfalfa had a great potential to improve WUE and save more water. Irrigation levels had noticeable effect on the relative feed values (RFV), but no effect on crude protein (CP) concentrations. The 60% ET irrigation level was conductive to increase CP concentration and RFV of alfalfa but was of no help to improve its grade. The distributions of annual yield and quality were highly related to the water distribution of the system. The coefficient of variations (CVs) in annual yield, RFV and CP of the whole system were 5% to 12%, 2% to 8% and 1% to 8% respectively, while the CVs in actual irrigation amounts ranged from 11% to 13%. Over-irrigation caused by end gun slightly increased alfalfa annual yield, but it lowered the quality and WUE. Therefore, an end gun in the center pivot irrigation system should be carefully selected for improving uniformity of the water application. Irrigation level of 80% ET in the first and second cuttings and 60% ET irrigation level in the third cutting were recommended for alfalfa production in semi-arid region such as western Inner Mongolia in China.