[Ecological evaluation of different multiple cropping systems in red soil drylands.]

In order to maximize the ecological function of red soil drylands and to determine the desirable multiple cropping systems, we evaluated the productivity, circulation of materials, energy and value flows in four multiple cropping systems on the basis of a consecutive three-year field experiment. Four multiple cropping systems were designed: treatment A (CK): wheat/soybean-sesame; treatment B: mixed green manure (rape × Chinese milk vetch × radish)-soybean ‖ maize-mung bean‖ sesame; treatment C: ryegrass-peanut‖ maize-millet‖ buckwheat; and treatment D: rape-mung bean‖ sweet potato; where interplanting was expressed as '/', intercropping as '‖', planting after harvest as '-', and mixed cropping as '×'. Thirteen variables were employed to compare economic, ecological, and social benefits among the four cropping systems using grey relational analysis. The results showed that 'mixed green manure (rape × Chinese milk vetch × radish)-soybean‖ maize-mung bean‖ sesame' exhibited the highest grey relational degrees in terms of economic, ecological, and social benefits, and a highest grey relational degree at 0.847 in the integrative benefit. This treatment was the best multiple cropping pattern suitable for red soil drylands. Thus, this cropping system could have a positive impact on the layout and optimization of the structure of agricultural production in red soil dryland regions in the future.