Abstract
Alfalfa (Medicago sativa) is one of the major crops grown in Northern China in recent years, however, the current serious water shortage conditions present a challenge to the growth of this crop, especially if efficient use of water is considered in forage production for sustainability. This study aimed to evaluate alfalfa productivity and water use efficiency (WUE) under different sprinkler irrigation levels. This experiment was conducted at Shiyanghe Experimental Station for Water-Saving in Agriculture and Ecology of China Agricultural University in Wuwei, Gansu, China, over a period of two years. There were three irrigation treatments: A1: 100% measured evapotranspiration (ETc) of alfalfa; A2: irrigation amount was 66% of A1; A3: irrigation amount was 33% of A1; and a control of A4: no irrigation during the growing season. A randomized block design with three replications were applied. The results showed that the ETc and forage yield of alfalfa decreased, while WUE and crude protein (CP) increased with the decreasing irrigation amounts. The seasonal average ETc and yield ranged from 412 mm to 809 mm and from 11,577 to 18,636 kg/ha, respectively, under different irrigation levels. The highest yields were obtained from the first growth period in all treatments in both years, due to the winter irrigation and the longest growth period. Alfalfa grown under lesser irrigation treatment conditions had higher variability in ETc and yield, mainly due to the variability in the amount of rainfall during the growth period. The seasonal average WUE of treatments ranged from 22.78 to 26.84 kg/(mm·ha), and the highest WUE was obtained at the first growth period, regardless of treatments. Seasonal average CP content ranged from 18.99% to 22.99%. A significant linear relationship was found between yield and ETc or irrigation amount, and the fitting results varied between growth periods and years. The present results also implied that winter irrigation provided the space for saving water and should be applied at the end of each growing season to fill the soil profile, and to maintain a greater yield in the next growing season. During the growing season, more irrigation should be concentrated in the early growth period, especially in the second growth period.
Highlights
Since the Chinese government released the Alfalfa Development Plan for Dairy Industry Revitalization in January 2012, the planting area of alfalfa in China reached 4.71 million hectares by the end of 2015
This study showed that the crude protein (CP) content decreased with the increasing irrigation amount, which agrees with Holman et al [56] and Cavero et al [57], who studied the alfalfa production under solid-set sprinkler irrigation in a semi-arid climate
In the case of winter irrigation applied at the end of a previous growing season, irrigation water should be concentrated in the second growth period to maintain the seasonal yield with less irrigation, as the first growth period produced a high yield without irrigation in 2014. This experiment studied the response of alfalfa growth to different sprinkler irrigation levels, and the results indicated that the irrigation amount significantly affected the ETc, yield, forage quality, and water use efficiency (WUE) of alfalfa
Summary
Since the Chinese government released the Alfalfa Development Plan for Dairy Industry Revitalization in January 2012, the planting area of alfalfa in China reached 4.71 million hectares by the end of 2015. The hay yield of high-quality alfalfa increased by 8.2 times over the measurements taken in 2010 [1]. Every year China still has to import a significant amount of alfalfa forage. Alfalfa cultivation in China is mainly distributed in arid and semi-arid regions of the north and the northwest parts of the country. According to 2015 statistics regarding the six provinces in North and Northwest China, high-quality alfalfa acreage accounted for 89.8% of the country [1]. The north and northwest regions of China are located in arid and semi-arid areas where precipitation is scarce, evaporation is strong, and water resources are the key to restricting alfalfa production. The serious challenge of developing alfalfa production and sustainable use of water resources must be faced
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