常规耕作的水土流失造成紫色土坡耕地土层浅薄化、土壤养分贫瘠化、土壤干旱化及土壤结构劣化等土壤肥力退化问题。1984－1996年长期田间试验结果表明，聚土免耕通过垄沟网状结构可保持水土，其多年平均径流与土壤侵蚀模数分别为657.7m^3 hm^-2和530.0t km^-2，而常规耕作的相应值分别为1754.0m^3 hm^-2和3122.0t km^-2，通过聚土与改土结合，聚土免耕活土层厚度平均增加11.8cm，聚土免耕耕作技术还通过垄沟强化培肥降低土壤容重，增加土壤有机质及N、P、K含量，改善土壤理化性状，恢复土壤肥力。聚土免耕作物产量比平作高15％－30％。1996－1998年秸秆覆盖实验结果表明，秸秆覆盖增加土壤有机质和养分含量，改善并维持土壤结构。聚土免耕与秸秆覆盖结合有利于土壤养分活化、土壤结构形成与维护，是紫色土退化旱地肥力恢复与重建的关键技术。

Soil erosion, soil fertility degeneration and land productivity loss are severe problems in hilly land of purple soil under conventional. tillage. A long-term field experiment was conducted during 1984 to 1996 to determine soil productivity in a typical hilly area of degraded upland of purple soil in Yanting, Sichuan province. Results showed that a conservation tillage system with ridge-furrow and seasonal no-tillage (SNTRCS) increased topsoil depth by 11.8 cm over the conventional tillage. Annual run off and soil loss were 657.7 m~3 hm~(-2) respectively, under conventional tillage. Soil structure and soil physical, chemical and biological properties were also improved when conservation tillage was adopted. Mulching experiments from 1996～1998 showed that mulching increase contents of organic matter and nutrients in the soil, which in turn improved and maintained soil structure. In conclusion, SNTRCS with mulching is suitable for soil and nutrient conservation, and structure amelioration, consequently for restoration of productivity in degraded hilly land of purple soil.