Effects of Conservation Tillage Measures on Soil Aggregates Stability and Soil Organic Carbon in Two Sequence Rotation System with Spring Wheat and Field Pea

A study of different conservation tillage measures was conducted in Lijiabu town of Dingxi city,Gansu province on semi-arid area of the west Loess Plateau,by which effects of tillage measures on mechanical-stable aggregates,water-stable aggregates,stability coefficient and soil organic carbon in soil layer of 0～5 cm,5～10 cm,10～30 cm was determined.The results showed that,both in two rotation sequence,macro-aggregates was dominant in all of mechanism-stable aggregates measured by dry sieve method,but there was no significant difference in different treatment.Moreover,compared with conventional tillage,no-tillage with stubble retention,no-tillage with no straw cover as well as conventional tillage with straw incorporated could improve content of water-stable aggregates and aggregates stability more or less after 5 years rotation.For soil organic carbon content, no-tillage with stubble cover and conventional tillage with straw incorporated was higher than conventional tillage in 0～30 cm.But the treatment of no-tillage with no straw cover was higher than conventional tillage in spring wheat→field pea→spring wheat rotation sequence,lower than that of conventional tillage in field pea→spring wheat→field pea rotation sequence.