Effect Of Cutting Management On Forage Yield And Quality Of Lucerne Grassland On The Loess Plateau

The Loess Plateau is one of the most important dry farming areas of China, where crop production is low and unstable, and the environment deterioration becomes more and more serious. So, to establish and develop grassland agriculture is an excellent option for food safety, ecological civilization, and sustainable development of animal husbandry in this area. Lucerne is an important forage species for the grassland agriculture. Cutting is the main way to use lucerne. However, the traditional cutting management serious restricted the stability and improvement of lucerne yield and quality in this area. In this study, on the Loess Plateau, forage yield, the contents of crude protein and detergent fibers were measured under different cutting dates, cutting heights and cutting intervals. The objective is to find some better cutting management to gain good forage productivity.1) The total yield of lucerne was10.06,9.36,10.12and9.42t/ha when cutting was performed at the early flowering,50%flowering, full flowering and podding stages. There was no difference in total yield among different cutting dates. Leaf biomass was4.09,2.78,3.57and2.72t/ha at early flowering,50%flowering, full flowering and podding stages. The content of crude protein in stem and leaf decreased gradually as cutting was delayed, while the contents of neutral and acid detergent fibers didn’t change significantly. Average individual plant number decreased from early flowering to podding stage, but there was no difference between the first two stages and between the latter two stages. And the branch number was reduced and base area increased as cutting was delayed. It suggested that cutting at early flowering stage promises the maximal leaf biomass production and good total forage yield which is not lower than those cut at other stages on the Loess Plateau. The forage quality is better and the regrowing ability is stronger.2) The forage yield of lucerne in2009was10.73t/ha under cutting at ground level and10.21t/ha under cutting with5cm stubble left, while in2010, they were 11.23t/ha at ground level and10.61t/ha with5cm stubble left. However, there was no significant difference in forage yield between two stubble heights. Under different stubble heights, there was no difference in crude protein content of leaf and stem, but the content decreased as cutting was delayed. And there was no difference in the contents of neutral and acid detergent fibers between two heights and among different cutting time. It showed that a certain amount of stubble left (i.e.5cm) after cutting doesn’t lead to significant reduction in forage yield and quality on the Loess Plateau. Additionally, the stubble cannot only help improve the survival rate of lucerne during winter, but also increase the coverage of the surface soil.3) The forage yield of lucerne was4.62,7.93and8.18t/ha, respectively when cutting was performed every three, six and nine weeks. There was no significant difference between the latter two intervals. The content of crude protein in leaf and stem decreased as the cutting interval was extended, as well as the percentage of leaf biomass in total biomass. There was no difference in branch number among different cutting intervals. And canopy leaf area index was the lowest at3-week interval, while light transmittance was the highest. There was no difference in canopy leaf area index and light transmittance between six-and nine-week intervals. It suggested that six-week cutting interval was suitable for lucerne utilization on the Loess Plateau, promising optimal forage yield and quality.