The Productivity And Resource Use In Autumn-sown Oat And Common Vetch Intercropping System On The Loess Plateau

The Loess Plateau is one of the most important areas to establish and develop animal husbandry in the farming areas in China. It is fundamental to find new source of forage for the sustainable development of animal husbandry in this area. On the Loess Plateau, there is large amount of rainfall and the arable land is in fallow in autumn. So, it is an efficient way to sow oat intercropped with common vetch in this season, which cannot only afford green forage for animal husbandry, but also make more effective use of the rainfall and land in autumn. However, the productivity and resource use under autumn-sown oat and common vetch intercropping system were still not clear. In this study, autumn-sown oat was intercropped with common vetch at the ratios (oat/vetch):1:0,4:1,2:1,1:1,1:2,1:4and0:1. Forage yield, the contents of crude protein, detergent fibers, ash and organic matter, leaf area index and light-intercepting rate, soil nitrogen content, etc were measured to reveal the productivity and resource use on the Loess Plateau.1) Forage yield under intercropping peaked at the ratio (oat/vetch) of2:1with3264kg/ha, followed by2828kg/ha at1:1when the crops were at full flowering stage, indicating30%and13%higher than the yield of monocultured oat. When it was at the harvesting stage, the higher yields were5942kg/ha at1:1and4980kg/ha at2:1,50%and30%more than that under monocultured oat. Applied with low level of nitrogen fertiliser, the yield of the intercropping system under the ratio of1:1peaked with4511kg/ha at full flowering stage and8141kg/ha at harvesting stage, showing that the intercropping produced47%and11%more than monocultured oat did.2) The greater relative total yields at full flowering stage were1.39at2:1and1.24at1:1, while at harvesting stage, they were1.69at1:1and1.45at2:1. These results indicated that the land use efficiency under this intercropping system was improved by24%-69%compared with that under monocultured oat. The relative total yields at full flowering and harvesting stages peaked with1.76and1.42, both under the ratio of1:1, showing42%-76%increment of land use efficiency. It showed that the performance of autumn-sown oat intercropped with common vetch leads to the increase in land use efficiency with the maximal increment of76%.3) The contents of crude protein, detergent fibers, ash and organic matter didn’t change obviously in the stem and leaf of vetch and oat crop under the intercropping system as the ratio of oat vs. common vetch changed. It suggested that the forage mixture is more nutritious as more common vetch is sown in the intercropping system.4) Canopy leaf area index and light-intercepting rate of the intercropping system were the highest at full flowering stage and the lowest at booting stage. There was no significant difference in canopy leaf area index and light-intercepting rate among different ratios of oat vs. common vetch. It showed that on the Loess Plateau, autumn-sown oat intercropped with common vetch doesn’t lead to significant competition for light and heat under any ratios. There was no significant difference in the contents of soil water, total nitrogen and nitrate among different ratios. And there was no significant difference in the contents of soil water and total nitrogen between full flowering and harvesting stages, but soil nitrate content was the lowest at the harvesting stage. It suggested that the performance of autumn-sown oat intercropped with common vetch on the Loess Plateau helps make good use of soil water and soil nitrate and crop growth is not restricted by water supply, and to reduce nitrogen leaching in autumn.