Effects of fertilization methods on border effect of cereal-vegetablestrip intercropping system

Inter-specific interactions in cereal-vegetable strip intercropping system mainly occur at border-row areas. It is meaningful to know more about the differences in the growths of belowground (root) and aboveground (shoot) of crop systems between border-row and middle-row crops for establishment of a sustainable strip intercropping system. Two fertilization methods — chemical fertilization (CF) and combined application of organic materials and chemical fertilizers (OMFC), were used in a cereal-vegetable strip intercropping system (spring maize intercropped first with dwarf bean then with autumn Chinese cabbage, expressed as spring maize||bush beanautumn Chinese cabbage) and then yield, biomass, root and soil available NPK of border row, sub-border row and middle row of crops tested in relation to border effects on crops. The results showed that compared with middle row, aboveground biomass and yield of maize in border row increased significantly by 58.7% and 40.8% under the CF and OMCF fertilization methods, respectively. In contrast, vegetable growth in the border row was suppressed. However, aboveground biomass and yield of border row and sub-border row of bush bean under different fertilization conditions were less than those of middle row. Specifically, border row and sub-border row bush bean yields decreased by 49.7% and 45.6% under CF treatment, respectively. At silking stage of spring maize, the depth of maize root in border row was deeper than that in middle row, and growth direction of all the roots was partial to vegetable strip. Compared with CF treatment, maize root length and weight in the 015 cm soil layer in border row under OMCF treatment increased by 104.3% and 77.5%, respectively, while bush bean root length in the border row significantly decreased. Conversely, the roots of border row bush bean were inhibited when compared with middle row bush bean, which was much more severe under OMCF treatment. OMCF treatment strengthened intra-specific competition between spring maize and vegetable crops. In addition, the competitive advantage in nutrient absorption of border rows of spring maize significantly decreased soil available NPK contents in border row areas.