Study On Water And Fertilizer Effects On Productivity And Quality Of Alfalfa

Alfalfa, as the most important green feed, is the material basis of herbivorous animal husbandry development, and will play an important role in animal husbandry development. Studying the effect of water and fertilizer on alfalfa productivity and quality will provide scientific basis for alfalfa production on the south of Beijing, which is of great significance to development of dairy industry in this area. Randomized trial of two factors was introduced on alfalfa planted 3 years ago on the south of Beijing, which included 4 irrigation amount levels,0,25,50,75mm per time, irrigation 3 times a year, and three kinds of phosphoric fertilizer,0,155,310kg/hm2, 12 treatments in total. At the stage of initial flowering, the yield, stem-leaf ratio, plant height, crude protein content, and neutral detergent fiber content of each treatment were measured and the weight of each branch of the second and third cut was calculated. Besides, photosynthetic characteristics were measured at branch stage of the third stubble. The results showed as follows:1. The study is conducted within the water and fertilizer gradient range. If adequate water was supplied in winter of last year, irrigation affected the yield of the first stubble indistinctively, while the second stubble, third stubble and annual yield increased with the irrigation amount. However, yield and plant height of the fourth cut reduced. In addition, irrigation did not affect the self-stem ratio of the first and fourth cut significantly, while stem-leaf ratio and weight of each brand of the second and third stubble increased with irrigation and fertilizer has no significant effect on the yield, plant height, and stem-leaf ratio.2. Irrigation had a greatest impact on stomata conductance con at branch stage, with coefficient of variation 17.88%. Many indicators, such as photosynthetic rate, transpiration rate, intercellular carbon dioxide concentration, and stomatal conductance, increased with irrigation amount, while the water use efficiency decreased. Alfalfa which had no irrigation received highest water use efficiency.3. Irrigation can help neutral detergent fiber content increase, but result in crude protein content reduced. The former improved with irrigation amount, however the latter dropped.4. Phosphate fertilizer can reduce neutral detergent fiber content, raised crude protein content. The latter increased with phosphate levels, while the former lowered, which enabled improved quality of alfalfa.Therefore, irrigation should be performed after the first and second cut, while at the growing period of the fourth cut it should not be irrigated. It should not be irrigated at the stage of turning green under the condition that it was irrigated adequately in the winter of last year. The best annual irrigation amount is 150mm if rainfall of growing season is 391mm. In this study, phosphate fertilizer is not needed from the perspective of increasing alfalfa production; but it will reduce the lower rate of soil available phosphorus, and helped improve the quality, so phosphate fertilizer is still proposed application on the view of soil fertility as well as quality improvement of alfalfa.