Effects Of Water And Fertilizer In Artificial Leymus Chinensis Grassland

Leymus chinensis(Trin.)Tzvel is an important rhizomatous, perennial grass, which has developed stem, leaf and root system to prevent water loss and soil erosion, land degradation,restoration and reconstruction. The artificial Leymus chinensis(Trin.) Tzvel grassland is of great significance on the development of animal husbandry and grassland ecological construction.Water and fertilizer was regulated to establish high-yield, high-quality and high-efficiency management technology system of artificial Leymus chinensis(Trin.) Tzvel grassland. The experiment was conducted with Leymus chinensis(Trin.) Tzvel ‘Zhongke No.2.The experiment included five nitrogen levels treatments and three water levels treatment with three randomized blocks. In this study, a field experiment was conducted to understand the effects of water and nitrogen fertilizer on yield, quality, nutrition absorption, nitrogen use efficiency and soil quality. Results show that:(1) The early flowering stage had high hay yield, high nutrition value, excellent quality,good palatability. This stage was suitable for production of hay or silage. Nitrogen fertilizer could increase hay yield, crude protein content and crude fat content, but decrease the crude fiber content. Nitrogen fertilizer could increase the chlorophyll and nutrient content of Leymus chinensis. N, P, K nutrient average content in whole growth period increased by66.9%、27.0%、19.9% at most. The vigorous growth period of nutrient uptake was shooting to booting stage of Leymus chinensis. Nitrogen fertilizer could increase nutrient uptake, soil organic matter content, total N content, available P content, available K content. The nitrogen fertilizer rate of 129.2~150.1 kg·hm-2 was the optimum to the yield and yield was 10108.4~10749.2 kg·hm-2 in the early flowering stage. Nitrogen use efficiency was 68.7% ~ 70.1%.Pure nitrogen of per kilogram increased the yield of 45.0 ~ 47.1 kg. The N, P, K nutrient uptake and quality also was higher under nitrogen fertilizer rate of 129.2 ~ 150.1 kg·hm-2.This N rate is beneficial to reduce excess nutrients accumulation in the soil and threat to theenvironment. Nitrogen fertilizer increased production of Leymus chinensis, thus the more water was used and soil moisture content after harvest decreased in 0 ~ 200 cm soil layer.(2)The optimal amount of N fertilizer for seed yield was 104.9 kg·hm-2 in 2013 and180.0 kg·hm-2 in 2014, 2015. Spike number has largest direct path coefficient to seed yield(0.717) among all the variables, while tiller number had the highest indirect effect on seed yield through spike number, indicating that spike number contributes most to seed yield. The spike number was the key factor in influencing yield, which was not affected by N fertilizer application of current year, but was influenced by the precipitation from August to October and the amount of N fertilizer after mature stage in the previous year. Furthermore, the application of N fertilizer significantly increased spike length, florets/spikelet, grain number/spike and seed setting rate, but did not affected 1000-seed weight and spikelet/spike.The negative direct coefficient for spike number to spike length, 1000-seed weight and florets/spikelet could be offset by adding N fertilizer.(3) Water and nitrogen could improve hay yield and chlorophyll content, but excessive irrigation not beneficial to advance yield and chlorophyll content. The optimal amount of irrigation could promote dry matter accumulation and the absorption of N, P, K nutrients. N application and irrigation had a complementary effect on the phosphorus. Hay yield increased with N application and irrigation, with the higher hay yield of 10400 kg·hm-2 at N rate of 120kg·hm-2 and irrigation of 90 mm. N application and irrigation has significant effects on seed yield, with the higher seed yield at N rate of 120 kg·hm-2 and irrigation of 90 mm. The spike number was not affected by irrigation of current year. N fertilizer and irrigation could increase florets/spikelet, spike length and 1000-seed weight in current year.