| Increasing in both food production and smallholder’s income is a main target for China agricultural development. A multiple-year field study and an on-farm survey were conducted to investigate yield advantage and economic return of the wheat-maize/watermelon intercropping system as compared with the wheat-maize double cropping system on the southern of Hebei Province, China. The intercropping yield advantage was further examined by exploring plant-plant interaction through a root barrier experiment in the field. Basing on the studies in term of intercropping advantage and productivity we found key factors currently impeding farmers to achieve higher productivity. We examined those factors separately in the field, and then improved growth condition of the cropping system to build a preliminary technology system for high yield and high resource use efficiency. We finally realized the synergetic development of high yield, high nutrient use efficiency and high economic return in wheat-maize/watermelon intercropping system. The main conclusions were concluded as following:(1) From the results of farm household survey, we found that farmer’s income increased14695yuan ha-1in the cropping system of wheat-maize/watermelon compared with wheat-maize double cropping system. Average yield of wheat and maize in the cropping system of wheat-maize/watermelon was11.41ha-1, lower than23%compared with wheat-maize double cropping, and32.71ha-1watermelon fruit was yielded in wheat-maize/watermelon.(2) The interactions from shoots were obviously observed in field experiments. In our experiments, the interactions between crops were mainly from crops’aboveground part, while the belowground interactions didn’t have a significant effect on aboveground biomass and yield in the current study. The border row effect of intercropped wheat resulted in advantages both in aboveground biomass and grain yield, and there was no significant difference between fruit yields of intercropping and sole watermelon, while aboveground biomass and grain yield of intercropped maize decreased significantly due to shade effect from intercropped watermelon’s canopy.(3) Based on the results from on-farm survey and field experiment, we found that continuous cropping obstacles in watermelon, low productivity in maize and excessive fertilization were the three key limit factors in current farmers’practice. Compared with famers’practice, grafted watermelon seedlings could increase fruit yield (from4.7t ha-1to40.0t ha-1) by improving root development; five-days of sowing date of maize advanced could exploit the intercropping advantage of maize and watermelon and enhance intercropped maize grain yield by1.0-1.9t ha-1, while no significant reduction in intercropped watermelon yield; reduction of fertilizer input could decrease nutrient surplus in wheat-mazie/watermelon, the nutrient surplus of N, P2O5and K2O were reduced by148,54and84kg ha1, respectively.(4) Results from on-farm experiments indicated that maize grain yield was significantly increased by63-69%while the yields of wheat and watermelon were maintained, also the nutrient input was reduced by23-58%and surplus was reduced by8-69%, and the economic return was increased by 8515-12783yuan ha-1by improved practice (including grafted watermelon seedlings, good variety of maize, ahead of sowing data of maize and reduction fertilization amount). Potassium requirement of watermelon during the period from wheat harvest to watermelon fruit development could be achived by the potassium from wheat residual and reduce dependent on chemical potassium fertilizer.(5) In summary, our results indicated that the high productivity, high resource use efficiency and high economic return could be achived in wheat-maize/watermelon, suggesting that it could be a practical approach for future agriculture development in China based on small house-holders, which could provide the multi-functions for food production, increasing farmer’s income and food diversification. |
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