Study on compound cropping systems of food and forage in North China Plain

The shortage of high quality roughage has become the limited factors in the large-scale mixed farm in North China Plain. The present study constructed the compound cropping systems which adapt to the demands of the livestock and improve the productivity of the mixed farm, and also can provide the scientific basic for cropping structure adjustment. According to the practice, seven compound cropping systems were built with food and forage crops. Combined field experiment and laboratory measurement, the production effect, the light energy use efficiency and the yields of neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), crude fiber (CF), general energy (GE), net energy (NE) of these seven systems were compared. Compared with the compound cropping system of winter wheat-summer maize (CK), the yields of dry matter production of the compound cropping system of spring maize-summer maize increased 5.95%, the light energy use efficiency, temperature efficiency and the radiation use efficiency of whole year in this system increased 52.00%, 49.55%, 56.25%, respectively. The nutrient and energy yields of the compound cropping system of sorghum sudangrass-ryegrass were the highest, and also had the higher light use efficiency. Compared with the systems of spring maize-ryegrass, spring maize intercropping alfalfa and spring maize-summer maize, the yield of CP of the compound cropping system of sorghum sudangrass-ryegrass increased 65.92%, 80.65% and 132.03%, respectively. The yield of NE of the compound cropping system of sorghum sudangrass-ryegrass increased 21.63% compared with CK, and increased 21.50% and 24.08%, compared with the systems of spring maize-summer maize and spring maize-ryegrass. The cropping systems of spring maize-summer maize, sorghum sudangrass-ryegrass, spring maize-ryegrass and spring maize intercropping alfalfa were the important supplement cropping systems of winter wheat-summer maize, and also adapted to the development of the mixed farm in North China Plain, with high-yielding and high light use efficiency cropping systems.