Quantifying And Closing Yield Gaps For Winter Wheat And Summer Maize Rotation In Smallholder Farming System

As benefit from the green revolution technologies, developing countries which are characteristic by smallholder farming, have achieved substantial yield increase. However, with the population growth and increased consumption of animal protein, food security will still be a major topic worldwide. The study was conducted in Quzhou County which is a representative agricultural county in Hebei Province of the North China Plain. In this study, yield gaps of winter wheat/summer maize and yield limiting factors were analyzed based on years of farmer survey. After verifying the potential of high yield and high efficiency technologies under conventional farming practice, technical regulation of winter wheat/summer maize rotation was optimized and established. Finally, we explored the technology transfer ways in the case of smallholder farming system. The main results were concluded as follows:1. For winter wheat, based on 1026 results of 3-year continuous farmer survey, the yield of conventional farming practice was 7.1 Mg ha^-1. Yield gaps between average farmer yield and experimental and between high-yielding fields were 2.7 Mg ha^-1 and 1.6 Mg ha^-1, respectively. Average farmer practice achieved 72% and 82% of the experimental and high-yielding field yields. The study revealed that various factors contributed the big yield variation between farmers’ fields, including soil property, soil preparation method, winter wheat variety, sowing rate, sowing date, irrigation condition, plant protection condition and nutrient management condition.2. For summer maize, result shown that the yield of conventional farming practice was 8.0 Mg ha^-1. Yield gaps between average farmer yield and experimental and between high-yielding field were 3.1 Mg ha^-1 and 2.6 Mg ha^-1, respectively. Average farmer practice achieved 72% and 75% of the experimental and high-yielding field yields. The study revealed that various factors resulted in the big summer maize yield variation between farmers’fields, including soil property, maize hybrid, seed coating, sowing date, planting density, plant protection and nutrient management conditions.3. For winter wheat, based years of on-farm experiments, the technologies of deep tillage, optimized variety, optimized sowing date, optimized sowing rate and formulated fertilizer were convinced to be effective for improving both yield and N use efficiency. The rates of yield increase were 12.0%, 15.7%,23.9%,15.1% and 6.5%, respectively for the technologies mentioned above. The rates of PFPN increase were 12.0%,15.7%,23.9%,15.1% and 38.2%, respectively.4. For summer maize, results shown that the technologies of optimized maize hybrid, improving density, optimized sowing date, real-time harvest and formulated fertilizer were also convinced to be effective for improving both yield and N use efficiency. The rates of yield increase were 3.0%, 20.7%,15.0%,21.0% and 1.9%. The rates of PFPN increase were 3.0%,20.7%,15.0% and 21.0% for optimized maize hybrid, improving density, optimized sowing date and real-time harvest, respectively. But the formulated fertilizer technology decreased the PFPn by 50.6%。5. Based on the analysis above, we integrated a technology package including precision seeding, optimized maize hybrid, improving density, formulated fertilizer and topdressing. The study proved that farmer training and training and organizing could improve the technique adoption rate from 31-52% for conventional farming practice to 56-65% for training group and to 78-90% for training and organizing group. As a result, farmer training increased maize yield and PFPN by 10% and 22%, while farmer training and organizing increased maize yield and PFPN by 18% and 37%, respectively.6. Based on the analysis of yield limiting factor and the results achieved above, we integrated a technology package including optimized winter wheat verieties, optimized sowing rate, optimized sowing date and formulated fertilizer. The study proved that technique adoption rate could be improved from 33%-77% for conventional farming practice to 47%-82% for training group and to 52%-99% for taringing and organizing group. As a result, farmer training and organizing increased winter wheat yield and PFPn by 20.6% and 9.4%.Farmer training imcreased yield by 4.4%.