5DENISON R F,DENNIS C B ,THOMAS E K.Crop yields over the first nine years of LTRAS, a long-term comparison of field crop systems in a Mediterranean climate[J].Field Crops Research, 2004 (86) :267-277.
6RAGNAR E,AUDUN K,OLAV N.A comparison of environmental,soil fertility ,yield, and economical effects in six cropping systems based on an 8-year experiment in Norway[J].Agricuhure Ecosystems & Environm- ent ,2002 (90) : 155-168.
9Denisona RF,Bryant DC,Kearney TE. Crop yields over the first nine years of LTRAS, a long-term comparison of field crop systems in a Mediterranean climate [J]. Field Crops Research, 2004,86 : 267-277.
10Eltun R,Korsaeth A,Nordheim O. A comparison of environmental, soil fertility, yield, and economical effects in six cropping systems based on an 8-year experiment in Norway [J]. Agriculture ,Ecosystems and Environment,2002,90:155-168.