COVER CROPS CULTIVATED IN SUMMER FALLOW UNDER VARYING SPATIAL ARRANGEMENTS IMPROVED SOIL PROPERTIES OF DRYLAND LOESS PLATEAU OF CHINA

The present studies were aimed to investigate the impact of cultivating different cover crops on soil fertility for 2-yrs at different cropping densities and cropping patterns during the summer fallow period in the loess plateau of China. In the first experiment, under split plot design a summer fallow treatment was compared with four different cover crops including mung bean (Phaseolus radiatus L.), huai bean (Glycine ussuriensis Regel et Maack), hairy vetch (Vicia villosa Roth), and rapeseed (Brassica napus L.) under varying cover cropping patterns (crop rotation and crop relay intercropping). The second experiment was conducted with RCDB design to investigate four different cover crops (Huai bean, mung bean, hairy vetch and rapeseed) and four planting densities (75, 100, 125 and 150% of the recommended planting density). The results revealed that mung bean, huai bean and hairy vetch at 150% of planting density produced the highest biomass, while the rapeseed at 75% planting densities yielded higher biomass compared to the local recommended rate. Moreover, huai bean and rapeseed rotation resulted in higher contents of soil organic matter, total and mineral N, available P and K contents in comparison to the fallow treatment. Thus, Huai bean and rapeseed wheat rotations are effective strategies in order to improve crops productivity and soil quality in the Loess Plateau of China.